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In these YouTube videos we discuss the steps needed to create a building energy model using OpenStudio (and FloorSpaceJS, located within OpenStudio). We will be creating an energy model of a simple, rural fire station. The lessons progress from importing library files, creating geometry, setting site parameters, and creating schedules.
Building energy use is then calculated using the U.S. Department of Energy, EnergyPlus simulation engine via OpenStudio.
All software used for these calculations (SketchUp, OpenStudio, FloorSpaceJS, and EnergyPlus) are open-source and free to download.
1. Introduction to OpenStudio and EnergyPlus
Short description about OpenStudio and EnergyPlus. This video will introduce you to a little of the history of energy modeling and describe some of the computational capabilities of the OpenStudio program.
So the question is: What is open studio?
Simply put, OpenStudio is a graphical user interface for EnergyPlus. But, before we can fully answer this question, we need to know what energy modelling is and a little bit of its history.
I won't go very far back, just to the most recent and widespread use.
In the 1970s and 80s, computer programs were created to simulate building energy use with the goal of reducing energy consumption. By the 90s, the US Department of Energy had developed a robust program, free to the public, for this purpose. It was called DOE-2. Unfortunately, it required a lot of coding knowledge. They further developed a graphical user interface called eQuest. Today, eQuest is the most widely used program for simulating building energy use. It is free, however updates are no longer supported. In the 90s, the Department of Energy began developing the next generation of energy simulation program called EnergyPlus. Today it is the latest, stable building energy simulation program. It allows engineers, scientists, and the construction industry to predict and simulate how a building uses energy through its lifetime. EnergyPlus uses a lot of complex mathematical models to calculate energy use for a building. In addition, just like DOE-2, it is a very obscure, programming language oriented, program. Not very user friendly. By the late 2000s, DOE realized that in order to get widespread adoption of the program they needed to develop a robust easy-to-use graphical user interface. They developed OpenStudio. OpenStudio is a graphical user interface for creating inputs to EnergyPlus. The workflow starts with creating geometry using Floor Space JS, located within the OpenStudio program. Alternatively, if you have complex geometry you can use SketchUp and the OpenStudio plug-in. Or you can import geometry from IDF files, GBXML files, SDD files, or IFC files. Then you can assign space types and thermal zones to your 3D model. You could think of this 3D model as a shell that will later hold all of your energy modeling information. From there, you can modify the model by changing different parameters such as: How many people are in the building. You can change lighting power densities. You can change ventilation rates. You can change schedules for occupancy. You can change other schedules, like when the building is open or closed. You can change water usage or how many people are in the building at one time during the day. You can change the HVAC systems set points. Basically, anything you can do in an energy modeling program. You can do it in OpenStudio. It is a graphical user interface so it is very intuitive. Once you are done assembling the model of the building it exports it out to EnergyPlus. EnergyPlus crunches the numbers for you and delivers information about your building. The final result shows you lots of information like: Total and monthly energy use. Building envelope performance. Peak space and HVAC loads. Peak water usage and ventilation.
2. Building Energy Modeling in OpenStudio - Importing Library Files
In this video, we discuss how to import library files into OpenStudio.
Today, we are going to create an energy model for a fire station.
First we will start with opening a blank OpenStudio project.
Then we will save this as a new project in your project folder.
We will call it example 4. Save this? Yes.
We have a blank project here. There are no space types. You can see when I click the space type tab, there are no space types. First, we want to take a look at the project floor plan. This will show us what types of spaces we have in this project. There is an apparatus bay, decontamination laundry room, turnout locker room, corridor, storage, shower, office, and a community room. Next, we will import a library file that has the necessary templates. Go to File → Load Library and browse for the library file. We will use a previous project for a fire station as the library file. Click Open. Now the library should be loaded. To see the imported information, you can go to the Library tab in the upper right. We are on the Space Types tab, so we need to look in the Space Types library. Scroll down to find the fire station space types. Drag and drop the necessary space types into the project. OpenStudio uses space types to encode information about how particular spaces are used. This information includes loads such as people, lighting, infiltration, and plug loads, as well as their associated schedules. I will now add all of the space types we will need for this project. You may skip ahead to 3:14. Now we have all of our space types. The next task will be to add in a Construction Set for our fire station. Select the Construction Sets tab on the left-hand side. Again, go to the library files at the right, select Construction Sets, and browse for our imported fire station construction template. You may skip ahead to 4:30. Fire station, metal, right here. This is going to be a metal building, so we will drop this Construction Set into our construction sets for this project. Allow it some time to load. Okay. Now we have a fire station metal building. The exterior walls are metal, the slab is concrete, and the exterior roof is metal. You will want to double-check that these constructions match those of your current project. Next, we will go to the Schedules tab. You will notice that many of the schedules have already been imported when we brought in the space types. Occupancies, activities, lighting, etc. Okay. That is how you load information from a library file. The next episode will use FloorSpaceJS to create the building geometry.
3. Building Energy Modeling in OpenStudio - Create Geometry
In this video, we discuss how to create building geometry using FloorSpace JS within the OpenStudio application.
The next task is to create the geometry for the building.
First we will save the file as a new file. It is always good to save revisions of files in OpenStudio.
That way you can always go back to previous versions if you encounter trouble.
Next, we will check our Preferences under Units to ensure that we are working in the English Imperial system. Next, we will go to the Geometry tab on the left. Then, go to the Editor tab at the top. We will be using FloorSpaceJS to create the geometry. Click New. There are several options available to create geometry and use references. For now, we will create a new floor plan. Next, select the Import Image button to import the floor plan. You will want to move the floor plan to align with your origin. We will use zero-zero as our origin, so try to locate it as close as possible. Next, scale the image. You will notice that a scaling dimension has been placed on the image. This provides a reference for the size of the space. Scale the image by dragging the corner until it reaches 120 feet. Then, click outside of the image to lock it in place. We will now change our grid units to one-half of a foot. To create a new space, click the rectangle button. Click and drag to create the space. When you want to add a new space, click the plus button. You will notice that the cursor turns red when it locks onto the edge of a previous space. You may skip ahead to 4:30. The community room has an odd shape. We will create it by using multiple rectangles without clicking the add space plus button. You can see that the rectangles are additive. At this point, all spaces have been created. Next, rename the spaces to match the floor plan. Click the expand button. Rename Space 1-1 to 101, as shown on the floor plan. Continue and rename all of the spaces. You may skip ahead to 6:00. Next, assign space types to each space. Click the drop-down arrow and select the space type that applies to each room. For Space 101, select the Apparatus Bay. Repeat this process for all spaces. You may skip ahead to 7:00. Next, assign construction sets to each space. Since all spaces are within the same building, only one construction set is required. For this example, we will not use a pitched roof or a below-floor plenum. Check the floor-to-ceiling height and verify the plenum heights. The Apparatus Bay does not have a plenum. Offices, lockers, storage, and similar spaces do have a plenum. The community room does not have a plenum. We will not apply any floor offsets. Now we are finished. Click Merge with Current OSM. Finally, select the 3D View tab in the upper left. The model has been created and space types have been assigned. In the next video, we will continue by creating subsurface geometry and making additional assignments.
4. Building Energy Modeling in OpenStudio - Add Thermal Zones and Subsurfaces
In this video, we discuss how to add thermal zones and subsurface constructions to the building geometry using FloorSpace JS within the OpenStudio application.
We have completed the floor plan and geometry. The next task is to assign thermal zones to each space or a collection of spaces. Select the Assignments tab, expand the Thermal Zones tab, and add a thermal zone. We will call this thermal zone 101. To determine how many thermal zones are required, refer to the mechanical drawings, which show that nearly every space has its own thermal zone. Starting with the apparatus bay, we assign thermal zone 101 and then use the duplicate button to create additional zones such as 102 and so on. You may skip ahead to 2:22. Once all thermal zones are created, the Thermal Zones tab can be collapsed using the button in the upper-right corner. Thermal zones are then assigned by selecting thermal zone 101 and assigning it to space 101, thermal zone 102 to space 102, and continuing this process for all spaces. After assigning the thermal zones, we move on to adding subsurface components. Go to the Components tab at the top and select it. The first component added is a door, which is approximately 7 feet by 3 feet. From the drop-down menu, select Door and click the plus button. Expand the menu to confirm the door size, then hover over the top of the space and click to place the door. Next, add the windows, which are approximately 3 feet by 6 feet with a sill height of about 9 feet. Select Window from the drop-down menu, click the plus button, hover over the desired location, and click to place each window. Repeat this process for all windows and doors. For the glass doors, duplicate an existing door and change the type to a glass door. Use the same approach for similar doors, and finally add the overhead doors by selecting the overhead door type. This completes the addition of all windows and doors. Click the collapse button to close the tab and confirm that all subsurface components have been placed. That concludes the lesson. Click the Merge button to merge the geometry with the OpenStudio model, and then select the 3D View tab to see the final product.
5. Building Energy Modeling in OpenStudio - Site Tab
In this video, we discuss how to add a weather and design day file to your project. We also briefly mention some of the other information located on the site tab including measure tags, utility bill year vs. TMY year info, Daylight Saving, and Life Cycle Cost parameters, and utility bills.
Our next task is to fill out the information on the Site tab. We will save the file as a new version. On the Site tab, you will see various information related to weather, and the first task is to set the weather file. Since we do not have any weather files for this project, we will need to download them. Go to the EnergyPlus website and browse for the location. We will assume this project is located in Medford and use the TMY3 file, which is the most up-to-date weather file data. Click Download All. Once downloaded, place the files into the OpenStudio folder by browsing to your local disk, going to OpenStudio, and placing them into the EnergyPlus folder. Since there is no weather folder, we will create one. Next, go to Set Weather File and browse to the location where the weather file was saved. Select the EPW file, which is the EnergyPlus weather file. Then import the design day file (.DDY), which is one of the downloaded files. Browse to the OpenStudio EnergyPlus weather folder and select the DDY file. The design day file is used for sizing equipment that is specified as “auto size” in the project. You can review the design day parameters and modify them if needed. Also on the Site tab, you will notice the Measures tabs, which are used for advanced energy modeling. Climate zones can be selected here, but these will be discussed later. Another task on the Site tab is selecting the year. If you are modeling a building based on specific utility data, you would select that option. However, we will model the building using typical meteorological year data, so we will select that option instead. Since the project location in Medford observes daylight saving time, we will enable it and double-check that the start and end dates are correct. The Lifecycle Cost tab is used for cost analysis, which we will not cover at this time. Next, open the Utility Bills tab and note that a specific weather year must be selected to input utility data. We will select Calendar Year and choose the year 2000 as an example, then return to Utility Bills to see where data can be entered. We will cover this in a future lesson, so for now we will select First Day of Year to continue modeling based on typical meteorological year data. That concludes our lesson for today about the Site tab. Please hit like and subscribe! Next, go to Set Weather File and browse to the location where the weather file was saved. Select the EPW file, which is the EnergyPlus weather file. Then import the design day file (.DDY), which is one of the downloaded files. Browse to the OpenStudio EnergyPlus weather folder and select the DDY file. The design day file is used for sizing equipment that is specified as “auto size” in the project. You can review the design day parameters and modify them if needed. Also on the Site tab, you will notice the Measures tabs, which are used for advanced energy modeling. Climate zones can be selected here, but these will be discussed later. Another task on the Site tab is selecting the year. If you are modeling a building based on specific utility data, you would select that option. However, we will model the building using typical meteorological year data, so we will select that option instead. Since the project location in Medford observes daylight saving time, we will enable it and double-check that the start and end dates are correct. The Lifecycle Cost tab is used for cost analysis, which we will not cover at this time. Next, open the Utility Bills tab and note that a specific weather year must be selected to input utility data. We will select Calendar Year and choose the year 2000 as an example, then return to Utility Bills to see where data can be entered. We will cover this in a future lesson, so for now we will select First Day of Year to continue modeling based on typical meteorological year data. That concludes our lesson for today about the Site tab. Please hit like and subscribe!
6. Building Energy Modeling in OpenStudio - Schedules Tab
In this video, we discuss the difference between schedule sets and schedules, how to alter and add schedules, and some of the different schedule types.
Next, we will look at the Schedules tab on the left, starting with the Schedule Sets tab at the top. This tab shows schedule sets, which you can think of as a collection of different schedules. A schedule set is applied to a space type and includes schedules for people and loads within that space. For the fire station schedule set, we have people occupancy levels throughout the day, people activity levels in watts of heat output per person, lighting watt density levels that vary throughout the day, as well as electric equipment, gas equipment, water, steam, and infiltration schedules. You can drop a schedule into a schedule set by going to either the My Model tab or the Library tab and dragging and dropping it. We will do an example using the storage room schedule set. If there were a gas equipment load in the storage space, we would simply grab a gas schedule and drop it into the storage schedule set. This is just an example, and since we do not need it for this project, we will delete it. Creating a new schedule set is as easy as clicking the plus button, renaming it, and then dragging and dropping the desired schedules into the set. Next, we will go to the Schedules tab, which contains the individual schedules. One common example is the Always On schedule. This schedule is often used in energy modeling to override equipment so that it remains on throughout the entire year. The default value for this schedule is 1. We can create a new schedule by copying it using the x2 button and naming it Always Off. To change the value to 0, hover over the line, type 0, and press Enter. This creates an always-off schedule. There are different priority levels within each schedule. For example, you may want to override equipment sizing using design day values by creating a custom schedule for summer and winter design days. Another example is the clothing schedule. The default value of 1 indicates that occupants are wearing heavier clothing throughout the day. There is also a priority schedule that applies from May through the end of September, representing summer months when occupants wear lighter clothing. If we want to create a custom schedule for spring, we can click the plus button, copy Schedule Rule 1, and add it to the project as Schedule Rule 2. During spring mornings, occupants may wear coats and heavy sweaters, so we set the morning value to 1. Later in the day, as the building warms up, occupants remove layers, and the value is adjusted accordingly. To split the schedule, simply double-click on the line and enter the new values. Next, we will create a thermostat setpoint schedule. We can do this by going to the library we previously imported and selecting a thermostat schedule. For the Apparatus Bay, the temperature is held at a freeze-protection setpoint throughout the year. Drag this schedule into the project. The default value maintains the space at 38 degrees, just above freezing. You will notice weekend priorities where the temperature is raised to 60 degrees on Sundays and 70 degrees on Saturdays, likely for indoor gatherings. Now, let us create an HVAC heating setpoint schedule. Click the plus button, select Temperature as the schedule type, and click Apply. Name this schedule Heating HVAC. Since the building operates 24/7, we will set the temperature to 70 degrees for the entire day. This tells the HVAC system to maintain room temperature continuously. Next, copy this schedule using the x2 button and rename it Cooling HVAC. Change the value to 75 degrees and create a nighttime setback to save energy. Double-click on the line to create breaks and set the nighttime temperature to 80 degrees. This means the building is cooled during the day and allowed to warm slightly at night. You can zoom in to view the schedule in 15-minute or 1-minute increments and adjust the timing by dragging the vertical lines. We can also create a custom priority override schedule for a summer shutdown. Click the plus button, create a new profile, and select a priority. For example, we can define a shutdown during the first week of June and override the cooling setpoint to 80 degrees for that entire week. The purple highlight shows where this override applies throughout the year. Other types of schedules include laundry activity schedules, which define how much heat people produce in the laundry room, lighting schedules that control when lights turn on and off, gas schedules, and infiltration schedules that act as multipliers on space infiltration. Locker room lighting schedules often cycle on and off frequently because firefighters are responding to calls throughout the day and night. That is schedules in a nutshell. Please remember to click like and subscribe if you enjoyed this video.
7. Building Energy Modeling in OpenStudio - Construction Materials
In this video, we discuss the difference between material sets, assemblies, and materials, how to alter and add them, and how to access the Building Component Library.
Our next task is to review and edit the construction materials. We will go to the Constructions tab on the left. At the top, you will see several sub-tabs: Construction Sets, Constructions, and Materials. These are treated as a parent-child relationship. Construction Sets are a group of construction assemblies that are applied to the building. In the fire station metal construction set, you can see exterior surface constructions such as metal building exterior walls, concrete slab, and metal building roof. Interior surface constructions include interior walls, interior floors, and interior ceilings. Ground contact surfaces are all concrete. Exterior subsurface constructions include windows, doors, and skylights, while interior subsurface constructions apply to interior partitions with windows or doors. At the bottom are other constructions that may be applied. A construction set defines a collection of constructions that make up the building and can be applied to the entire building or portions of it. Next, we will look at the Constructions tab, which shows the individual construction assemblies. For example, the metal building roof is composed of metal roofing and roof insulation. These materials are applied in layers, starting from the outside and moving inward, and are used to calculate thermal conductivity and heat transfer properties. You will also notice measure tags associated with these constructions. These measure tags are used for advanced energy modeling and can later be referenced by energy efficiency measures to evaluate how changes affect building performance. To understand the roof insulation, we go to the Materials tab and select roof insulation 22. This material includes measure tags and thermal properties such as roughness, thickness, thermal conductivity, density, specific heat, and absorptance values. The thickness and thermal conductivity combine to create an R-27 thermal resistance. For this project, the roof consists of metal roofing, a thermal break spacer, and steel purlins with insulation. Since this insulation will not be used elsewhere, we rename it to Purlins and Insulation R-29 and update its properties to reflect a 10-inch thickness and an R-value of 29.88. Next, we create a thermal break by duplicating a material and renaming it Thermal Break R-3. This thermal break has an R-value of 3, a thickness of one-half inch, and a thermal conductivity of 0.1167. After creating these materials, we return to the metal building roof construction assembly. We remove the existing insulation layer and insert the thermal break between the metal roofing and the purlins and insulation. The updated roof assembly now consists of metal roofing, a thermal break, and purlins with insulation, giving an overall R-29 value. We rename this construction Roof Metal Building, and it automatically updates in the construction set. If you do not want to create custom materials and assemblies, you can use construction sets from the library by dragging and dropping them into place. This same process can be applied to roofs, windows, doors, walls, and floors. If a needed material is not available locally, you can access the Building Component Library by registering online and entering the authorization code. Once connected, you can search for components such as windows, download them, and then find them in the library tab. These components are marked with a BCL label and can be assigned to the appropriate construction category. That concludes the overview of constructions, construction sets, and materials. Thank you, and please like and subscribe!
8. Building Energy Modeling in OpenStudio - Buildings Loads
In this video, we discuss the various thermal, electrical, gas, and water loads specified for the buidling. We will do an example of how to create a new load and how to import a load from a library file.
Next, we will look at the loads inside our building. Select the Loads tab on the left. These are all of the heat, electrical, gas, and steam loads located within the building. There is also an internal mass definition for calculating thermal mass based on the density of materials located within the building. First, let us look at people definitions. These define occupant densities located within various spaces. These loads calculate the number of people within a space and how much heat output each person provides to the space, including carbon dioxide generation and the fraction of heat that is radiant. Occupancy can be specified by number of people, people per floor area, or floor area per person. Next, let us look at light definitions. Light definitions can be specified based on power, power per floor area, or power per person. You can also specify what fraction of the lighting is radiant, visible, and how much affects the return air to the HVAC system. Now let us do an example of adding an electrical equipment load. Assume we have a microwave located within the closed office. Currently, the closed office already has an electrical equipment definition, which likely represents printers, computers, and task lighting. We will use this as a template. Click the x2 button to duplicate it and rename it to Office Microwave. The microwave is designated in watts and is a 1200-watt microwave. When changed to watts, the watts per floor area value is automatically removed. This is how a new space load is created. However, the load must have a schedule assigned. To create the schedule, go to the Schedules tab. Click the plus sign to add a new object and select Schedule, then Fractional Schedule. Fractional schedules indicate how much the microwave is used throughout the day. Click Apply and rename it to Office Microwave Schedule. The microwave is used only for a few minutes at a time, typically during the morning, lunch, and evening hours. You may skip forward to 6:00. For simplification, use the default schedule. This completes the microwave schedule creation. Later, this schedule and load will be applied to a space type. Return to the Loads tab. There are additional loads that will be applied later in the project. That is how you create a space load. You may also drag and drop loads from your loaded library files. Go to the Library tab and select a light definition as an example. Scroll to light definitions and choose a lighting load, such as mid-rise apartment corridor lights. Drag and drop the definition into the project. Once added, a schedule must be created before assigning the load to a space. For now, it will not be used. You can remove unused objects by selecting the Purge All Unused Objects button, or by selecting the load and clicking the X button. Using the Purge All Unused Objects option helps reduce clutter in the project. It is good practice to periodically check for unused items, but be careful not to purge objects that have not yet been assigned to spaces. That is the Loads tab. Thank you. Please like and subscribe!
9. Building Energy Modeling in OpenStudio - Space Types
In a previous video, we imported space types for our project. In this video, we will revisit the space types tab and discuss how building constructions, loads, schedules, and infiltration are assigned to a space type.
Next, we will revisit the space types tab. Select the space types tab on the left. This is where we originally assigned space types to this project. If you would like to recall how to install space types, please review the previous video. Looking at these space types, you will notice that there is a default construction set, but it is empty. We need to assign a construction set to all of these spaces. Go to the My Model tab and drop down Construction Sets. Drag and drop our single construction set. To apply that construction set to all of the other space types, click the check boxes. Select the construction set you want to copy and click Apply To Selected. It automatically populates the construction set to all of the selected space types. This construction set defines what type of constructions these spaces will have. You can customize this by creating additional construction sets. To create additional construction sets, please see the previous video. Next, you will notice that each space type has a schedule set and an outdoor air specification. This ventilation specification tells the energy model how much ventilation is required for that space. In the next column, you will see space infiltration design flow rates. These infiltration rates can be defined based on floor area, total space, exterior surface area of roofs and walls, exterior walls, or air changes per hour. To create a different infiltration rate, simply rename it and change the values as needed. These can also be copied and applied using the same checkbox method. We will apply an infiltration rate to the space plenums. The final column shows Space Infiltration Effective Leakage Area. We will not be using this, but this is how you find information about it. Search for “Space Infiltration Effective Leakage Area” in your browser and look for Big Ladder Software or EnergyPlus input/output documentation. Big Ladder Software provides EnergyPlus input/output documentation online in HTML format. Select Effective Leakage Area or click the link to read about it. This method calculates infiltration differently and is typically used for smaller residential buildings. We will not use this for our project and will only use Space Infiltration Design Flow Rates. Next, go to the Loads tab at the top to see which loads have been applied to each individual space. For the Apparatus Bay, there is a lighting load definition and an associated schedule. There are also electrical equipment loads with their definitions and schedules, as well as infiltration loads with a load name and schedule. In a previous exercise, we created a microwave load to be applied to the closed office. You will notice that the microwave load is not currently applied to the office, so we need to add it. Go to the My Model tab and browse to Electrical Equipment Definitions. Locate the microwave load. It appears the microwave load definition may have been deleted or purged in the previous exercise. To add it back, go to the Loads tab, electrical equipment definitions, copy an existing load, and rename it. Next, return to the Space Types tab. Select Loads, scroll to the Closed Office space type, and from My Model, drag and drop the microwave load into the Closed Office. You will notice that the microwave has been automatically assigned the fire station equipment schedule. This needs to be changed. Go to My Model and browse to Rule Set Schedules. Locate the microwave schedule that was created earlier. Drag and drop it next to the microwave load. Now the microwave load and its schedule have been applied to the space type. You will see a multiplier value. This is used to fine-tune the model without changing loads or schedules. For example, if the microwave is used half as much as expected, you can change this value to apply a 0.5 multiplier. We will not adjust it here. Default values are shown in green, while overridden values appear in black. This is how you add loads and load schedules to a space type. There is also a filter button, which is useful for large projects. You can filter by people to see occupancy loads or by lights to see lighting loads. At the top, the Measures Tag tab is useful for advanced energy modeling. These tags act as keywords that energy efficiency measure programs use to evaluate how changes affect energy use. The Custom tab is used for custom programming. Next, we will briefly cover how to create a new space type. Click the plus button and rename the space type. We will call it Workshop. Apply a construction set, a schedule set, and an outdoor air specification. You can copy an existing one or select a different option. Go to the Library tab, select Specification Outdoor Air, and choose mechanical room ventilation. Next, select an infiltration design flow rate. Look for a mechanical room or utility option. Go to the Loads tab and locate the new Workshop space type. Drag and drop loads into the space. Since this is a machinery room, there will be no people definition. Add a lights definition and electrical equipment for utility or storage. Finally, assign an electrical equipment schedule. Go to My Model, Rule Set Schedules, and select an “always on” schedule. That completes the creation of a space type. To delete a space type, click the checkbox next to it and then click the X button at the bottom. Thank you. Please like and subscribe!
10. Building Energy Modeling in OpenStudio - Geometry Tab
In a previous video, we created our building geometry. In this video, we will revisit the geometry tab and discuss additional features for viewing and editing the 3D model with FloorspaceJS.
Next, we will go to the Geometry tab. The first tab is the 3D View in Geometry. This allows you to inspect the building model. Using the right mouse button, you can pan the model across the screen. Using the middle mouse button, you can zoom in and out. Using the left mouse button, you can rotate the model. On the right side, there are additional controls. Changing the orthographic control changes the perspective of the model. This can be useful for selecting specific items based on a view. Let us select the X view. Without orthographic turned on, the model shows a more perspective view. Next, there are rendering and filtering options. By default, the model is rendered by surface type. The roof appears beige, walls are brown, glazing and glass doors are transparent, overhead doors are dark brown, and the ground floor is gray. If we change the render mode to “Normal,” surfaces are rendered based on orientation. All surfaces are currently oriented correctly. If we hide the walls, all exterior surfaces appear gray and all interior surfaces appear red. If a surface were accidentally flipped, it would show red on the outside, indicating that it needs correction in the geometry editor. Next, select Boundary rendering. This shows how the energy model treats each surface. Most blue surfaces are exterior surfaces. If we hide walls, interior surfaces appear green. If we hide the roof, interior walls are green and the ground floor is brown. Exterior wind-exposed and sun-exposed surfaces appear blue. Next, render by Construction. This shows construction types. Purple indicates windows, teal indicates opaque doors, white indicates glazed doors, gray-brown indicates exterior walls, pink indicates the roof, and olive indicates the ground floor. This helps identify constructions assigned to specific spaces. Next, render by Thermal Zone. This shows all thermal zones in the building. These thermal zones were assigned in the first lesson. Some spaces may be combined into a single thermal zone. Next, render by Space Type. The Apparatus Bay appears green, plenums appear dark red, and other spaces such as storage, office, locker rooms, restrooms, and community spaces are shown in different colors. Rendering by Building Story shows only one color in this model because there is only one story. You can apply filters to hide certain surfaces or subsurfaces. For example, unchecking the roof allows you to see inside the building. You can also hide doors, windows, shading objects, or partitions if present. This model does not include shading objects or partitions. There is also a wireframe view option, though it is not commonly used. Next, go to the Editor tab. This is where we use FloorspaceJS. We will edit a space that was originally created as one large storage space but should be two separate spaces. First, delete Space 105/106 and Plenum 105/106. Then click the plus button and select the polygon tool. Click to draw the polygon and click the first point again to close it. If a mistake is made, use the undo button. If the program becomes slow or frozen, close OpenStudio and reopen the project. If changes were not saved, go to the project folder and locate the floorplan JSON file. Open the JSON file in a text editor and change the import/export setting to TRUE. Save the file. Next, open a web browser and go to unmethours.com. This website contains discussions related to OpenStudio and EnergyPlus. Search for “FloorspaceJS freezing” and review the results. FloorspaceJS also has an online version that runs in a web browser. Open the online FloorspaceJS tool and load the floorplan JSON file. You can now edit the floor plan in the browser. Delete the plenum and use the eraser tool to remove spaces. Use the duplicate tool to copy spaces. This is useful because it retains all previously assigned properties. Use the polygon tool to create a second storage space. The room is now split into two spaces. Next, go to Assignments and create a new thermal zone for the new space. FloorspaceJS also allows you to duplicate stories. The duplicate tool creates a new story above the existing one. You can edit story attributes using the expand button. The Fill tool allows you to copy spaces from one story to the story above. For example, clicking the fill tool on the Apparatus Bay creates a space above it. You will still need to assign space type, construction set, and thermal zone. This project does not require a second story, so delete it. When finished editing, click Save Floorplan and then Download. Move the downloaded JSON file into the OpenStudio project folder and replace the existing file. Return to OpenStudio and reload the project. Go to the Geometry tab and then the Editor. Preview the model and merge it with the current OSM file. Return to the 3D View to confirm the spaces were updated. Finally, go to the Spaces tab and rename the new spaces: Space 105, Space 106, 105 Plenum, and 106 Plenum. Go to the Thermal Zones tab and purge unused objects to remove extra zones created by FloorspaceJS. Save the OpenStudio file and review the updated geometry. Thank you. Please like and subscribe!
11. Building Energy Modeling in OpenStudio - Facility Tab
In this video, we will discuss how to orient our building relative to North. We will set defaults for space, constructions, and schedules. We will add exterior lighting. We will also briefly discuss adding stories to the building and adding shading elements.
The next tab is the Facilities tab. Go to the left and select the Facilities tab. On this tab, you can change the building name. We will name the building “Rural Fire Station.” Next, you will see Measure Tags, which we discussed earlier. Energy Efficiency Measures (EEMs) use these tags as keywords to modify parameters within the model. This feature is used for advanced energy modeling. You will also see the North Axis value, which is currently set to 0 degrees. If you go back to the Geometry tab, you can see the north direction represented by the green axis line. If you want to rotate the building so that north aligns with the red axis line, you would need to rotate the building by 90 degrees. To do this, return to the Facilities tab and change the North Axis value to 90 degrees. Next, you will see three default assignments that can be applied from your libraries: Space Types, Construction Sets, and Schedule Sets. This demonstrates the top-down, parent-child structure of OpenStudio. To illustrate this, some information has been removed from the model. If you go to the Spaces tab, you will notice that the Apparatus Bay no longer has a space type, default construction set, or default schedule set assigned. Return to the Facilities tab and assign default values at the facility level. Go to the My Model tab and select: - Space Types: Apparatus Bay - Construction Sets: Metal Fire Station - Schedule Sets: Fire Station Schedule Set Now go back to the Spaces tab. You will notice that the Apparatus Bay space type is populated, while the construction set and schedule set remain empty. This is because the spaces inherit these values from the facility-level defaults. Next, go to the Stories tab. This is where you can add additional building stories if they were not already created using FloorspaceJS or another geometry editor. Next, go to the Shading tab. The Shading tab is used to add geometry that is not part of the building itself, such as adjacent buildings or trees. Shading does not create loads but can reduce cooling loads by blocking sunlight. Shading will not be used in this model and will be covered in a future lesson. Next, go to the Exterior Equipment tab. This is where you can add exterior lighting to the building. For example, assume the building has exterior security lights. Click the + button to create new exterior lights. A load definition will be created automatically. Set the total wattage to 400 watts. Next, select the schedule. The default schedule is Always On. If needed, this schedule can be edited later in the Schedules tab. Next, review the Control Option. By default, the lights operate based on the schedule only. Alternatively, you can select Astronomical Clock. This option combines the schedule with a photocell that turns lights off during daylight hours. Next, you can apply a multiplier to adjust total wattage if needed. Finally, there is an End-Use Subcategory field. This is used for sub-metering. For example, you can rename it to “General Exterior Lights” to track exterior lighting energy use separately. That concludes the Facilities tab. Thank you. Please like and subscribe!
12. Building Energy Modeling in OpenStudio - Spaces Tab
In this video, we will discuss the parent-child-inheritance relationship of OpenStudio entities. We will also show how to edit spaces, loads, surfaces, and sub-surfaces at the lowest (space) level of the energy model.
Next, we will discuss the Spaces tab. At the top, we will start with the Properties tab. This tab lists all of the spaces in the project. As discussed in the previous video, any empty fields here will be populated from information defined at higher levels (such as Space Types or Facility defaults). The Spaces tab represents the lowest level in the hierarchy. If a specific space needs a unique load, construction, or setting that differs from other spaces, it should be edited here. If you select the Air Flow tab, you can view infiltration and outdoor air object names. These were defined earlier when we worked in the Space Types tab. All of this information is inherited from higher-level definitions unless overridden. Next, go to the Loads tab. This shows all loads collected from higher-level sources. For example, storage rooms 105 and 106 share the same space type. If only one storage room had a microwave, you could drag and drop the microwave load from My Model → Equipment Definitions into space 105. You would also assign a schedule to that microwave. This allows you to differentiate one space from another even if they share the same space type. We will delete this example afterward. Next, go to the Surfaces tab. The energy model is composed of surfaces and sub-surfaces. Surfaces include walls, roofs, floors, and ceilings. For example, if the Apparatus Bay had a different roof than the rest of the building, you could apply a different roof construction here by dragging it from the Library tab. When a value turns black, it means the default has been overridden. To revert to the default, select the item and click the X button. You can also do this for Sub Surfaces, which include windows, doors, skylights, and interior windows and doors. Sub-surfaces are children of surfaces. Here, we can review the constructions assigned to each sub-surface. Notice that the overhead doors have no construction assigned. This means a construction assembly has not been defined for overhead doors. Go to the Constructions tab and verify that overhead doors are missing. You can either define overhead doors at the construction set level for the entire project or apply them only to this space at the Spaces tab level. To apply overhead door constructions only to the Apparatus Bay, browse for a suitable door construction in the Library tab and drag and drop it here. To copy the same construction to other overhead doors, select the checkboxes and click Apply to Selected. Next, check the glass doors. If glass doors are not defined, go to the Constructions tab and select a suitable window construction from My Model. Applying this construction at the construction set level will assign it to all glass doors in the project. Returning to the Spaces tab, you will see that these values are now populated. Other tabs at the top include Interior Partitions and Shading. Interior partitions are used for partial-height walls such as office cubicles. This model does not include interior partitions. The Shading tab would be used to edit individual shading objects if they existed. That concludes the overview of the Spaces tab. Thank you. Please like and subscribe!
13. Building Energy Modeling in OpenStudio - Thermal Zones Tab
In this video, we will discuss how to rename thermal zones and add thermostat schedules. We will also discuss equipment sizing parameters and the use of ideal air loads.
Adding HVAC systems to the energy model will increase its complexity. We have turned on ideal air loads. So we will just run the energy model and resolve simple errors before we start adding more complexity to our model. Let us go to simulation settings and time steps. This sets the number of iterations that the program runs the energy model per hour. The number of iterations per hour is set for six time steps per hour. So, it simulates the building every 10 minutes. Let us reduce this down to one time step per hour. This will speed up our calculations. We can always come back and adjust this later. Next, let's go to measures. We want to add Diagnostics to the measures tab. Go to the right and select drop down, reporting, drop down, QA/QC. Select Add Output Diagnostics. If you do not have it, go to the bottom and click the Find Measures On BCL button. Browse to reporting, QA/QC. Search for "add". You can find Add Output Diagnostics here. If it is not checked, select it and click the download button. When the download is complete, drag and drop Add Output Diagnostics into the EnergyPlus measures. This adds additional diagnostics when running the energy model to help troubleshoot problem areas. Next, go to Run Simulation. Click Save and then click the Run button. The simulation fails and generates several errors. Browse to the model folder, open the run folder, and open the EPLUSOUT.ERR file using a text editor. There are two types of errors: warnings and severe errors. Severe errors stop the simulation before it finishes. Scroll down to locate the severe error. The error indicates a convergence problem with the Roof Metal Building material. Go to the Materials tab and locate the Thermal Break and Purlins and Insulation materials. Review the insulation values. The thermal break value is 0.1667 with a thickness of 1/2 inch, and the purlins and insulation value should be 0.335. Correcting this resolves the severe error. Save the project and rerun the simulation. The simulation completes successfully, but warnings remain. One warning indicates that the number of time steps per hour is lower than recommended. This can be ignored. Additional warnings relate to schedules that do not align with the selected time step, such as the locker room and microwave schedules. These schedules change within the hour, while the model runs hourly. These warnings can also be ignored. Other warnings reference default schedules such as always on and always off, which are integral to OpenStudio and cannot be edited. Ground surface temperature schedules are also missing, so the model uses the default constant temperature of 18 degrees Celsius. Warnings about coincident or collinear vertices indicate duplicated geometry points, which EnergyPlus automatically simplifies. These can be ignored. Unused construction warnings appear for components not used in the model, such as interior windows, doors, and partitions. These can be removed from the Construction Set tab. Use the Purge Unused Objects option in both the Constructions and Materials tabs to clean up the model. Comfort-related warnings appear for spaces without an assigned thermal comfort model. Go to the Space Types tab, select Loads, and add a Thermal Comfort Model Type for the affected spaces such as the laundry room and locker room. Warnings regarding infiltration occur in interior zones without exterior walls. These can be ignored or addressed by changing the infiltration calculation method. Cooling-related warnings indicate that some thermal zones do not have thermostat schedules assigned. Ideal air loads attempt to calculate cooling, but without thermostats the cooling load remains zero. Warnings about unused schedules can be investigated by enabling Display Unused Schedules in Add Output Diagnostics. Remove unnecessary schedules from storage rooms and the apparatus bay, then purge unused schedules. A warning related to the clothing schedule occurs because it was not applied to specific days. Assign the schedule to all days of the week and save the model. Rerun the simulation. Remaining warnings related to doors not fully surrounding sub-surfaces can be ignored. These warnings summarize non-critical issues. The key issues to resolve are severe errors, as they prevent the simulation from completing. Warnings help refine the model but do not necessarily stop it from running. Close the error file and proceed to the results summary. This will be reviewed in the next lesson. Thank you. Please like and subscribe!
14. Building Energy Modeling in OpenStudio - Troubleshooting
In this video, we will discuss how to run the energy model simulation. We will also show how to troubleshoot simulation warnings and errors.
Adding HVAC systems to the energy model will increase its complexity. We have turned on ideal air loads, so we will run the energy model and resolve simple errors before adding more complexity. Let us go to Simulation Settings and Time Steps. This controls how many times per hour the energy model runs. It is currently set to six time steps per hour, meaning the building is simulated every 10 minutes. Let us reduce this to one time step per hour to speed up calculations. We can adjust this later if needed. Next, go to Measures. We want to add Diagnostics to the Measures tab. On the right, select Reporting → QA/QC → Add Output Diagnostics. If you do not have it, click Find Measures on BCL, browse to Reporting → QA/QC, and search for “add.” You will find Add Output Diagnostics. If it is not checked, select it and download. Once downloaded, drag and drop Add Output Diagnostics into the EnergyPlus Measures. This adds additional diagnostics to help troubleshoot issues during simulation. Next, go to Run Simulation. Click Save and then Run. The simulation fails, producing several errors. Browse to the project folder, open the “run” folder, and open the EPLUSOUT.ERR file in a text editor. There are two types of errors: warnings and severe errors. Severe errors stop the simulation from completing. Scroll down to locate the severe error. The error indicates a convergence problem with a building material called Roof Metal Building. Go to the Materials tab, expand Materials, and locate Thermal Break and Purlins and Insulation. Review their insulation values. The Thermal Break value is 0.1667 with a thickness of 1/2 inch. The Purlins and Insulation value should be 0.335. Correcting this resolves the severe error. Close the error file, save the project, and rerun the simulation. The simulation completes successfully, but warnings remain. The first warning states that the number of time steps per hour is lower than the recommended minimum of four. This can be ignored. The next warnings relate to cooling HVAC schedules and occupant schedules that operate in smaller increments than the simulation time step. Since the simulation runs hourly, it cannot capture these short on-off cycles. These warnings can be ignored. Additional warnings reference Always On and Always Off schedules, which are integral to OpenStudio and cannot be edited. Another warning indicates that no ground surface temperature schedule exists, so the model uses a default constant temperature of 18°C. This is not a concern. Warnings about coincident or collinear vertices indicate duplicate geometry points. EnergyPlus automatically simplifies these, so they can be ignored. Warnings about unused constructions indicate that some construction assemblies are not used in the model, such as interior windows, doors, and partitions. These can be removed from the Construction Set tab. Go to the Constructions tab and use Purge Unused Objects. Repeat this process in the Materials tab. This reduces clutter and improves simulation performance. Next, warnings indicate that no thermal comfort model is assigned to some spaces, such as the laundry and locker room. Go to Space Types → Loads, select the load definition, click the plus button, and add a Thermal Comfort Model Type. Warnings related to infiltration occur in interior zones without exterior walls. These can be ignored or corrected by changing the infiltration calculation method. Warnings stating that cooling mode is zero indicate missing thermostat schedules. Ideal air loads attempt to calculate cooling, but without thermostats the cooling load remains zero. Warnings related to unused schedules can be investigated by enabling Display Unused Schedules in Add Output Diagnostics. Remove unnecessary schedules from storage rooms and the apparatus bay, then purge unused schedules. A warning about the clothing schedule occurs because it was not assigned to specific days. Assign it to all days of the week and save. Rerun the simulation. Remaining warnings related to doors not fully surrounding sub-surfaces can be ignored. Severe errors are the most critical, as they prevent the simulation from completing. Warnings help refine the model but do not necessarily affect results. Close the error file and review the Results Summary. This will be covered in the next lesson. Thank you. Please like and subscribe!
15. Building Energy Modeling in OpenStudio - Add Hot Water System
In this video, we will discuss how to add water use connections and create a domestic hot water system for our building.
Next, we will go back to the HVAC systems tab on the left and add the domestic hot water system. You can see that a water system is already in place, where water comes from the main, enters the building, and then goes to the sewer. To continue, we need to drag in a water use connection from the library. Go to the library tab, browse for water use connections from the fire station library file, and drag and drop it into place. After adding the water use connection, click on it to view the water use equipment located within the building. Go back to the library tab and search for water use equipment from the same fire station library file. Drag and drop it into place and review its attributes. The rural fire station whole-building water use equipment is defined for five occupants. When this water use equipment definition is added, it also includes water usage loads and associated schedules such as the hot water temperature setpoint schedule, sensible fractions schedule, and domestic hot water fraction schedule. Returning to the HVAC systems tab, select the water use equipment. This equipment will be located inside the building, and no specific space name will be assigned. At this point, there is no loop connected, so a hot water loop must be created. Go back to the water mains editor, click the plus button, and create a new empty plant loop. Add a constant-speed circulator pump from the library, followed by a 100-gallon, 12-kilowatt water heater from the fire station project library file. Then add a scheduled setpoint manager to maintain the loop temperature. Finally, assign the water use connection to the newly created plant loop by dragging it from the My Model tab into the loop. You can now edit the properties of the circulator pump, water heater, and temperature controller, including flow rates, efficiencies, and setpoint schedules. The temperature controller uses the SHW temperature schedule from the schedules tab. Once the loop is assigned, clicking the loop allows you to view additional domestic hot water loop properties. Thank you. Please like and subscribe!
16. Building Energy Modeling in OpenStudio - Add HVAC-1
In this video, we will discuss how to add a zone level exhaust system. We will also show how to create and assign a force air gas furnace to one of our thermal zones.
Next, we will model the HVAC systems, starting with the Apparatus Bay. This space includes a unit heater, a small exhaust fan for ventilation air requirements, and a large exhaust fan controlled by air pollution levels. First, go to the Thermal Zones tab and add the contaminant exhaust fan. From the Library tab, search for a zone exhaust fan and drag it into the Apparatus Bay equipment. Rename the fan to EF-03. For the availability schedule, assign the locker room occupancy schedule, assuming the fan operates whenever the fire crew responds to a call. Next, review the exhaust fan attributes. Set the pressure rise to 0.375 inches of static pressure and the maximum flow rate to 1632 CFM. If required, an energy meter can be added and named EF-03 Meter to track energy consumption. Since the fan operation is controlled by its own availability schedule, set the system availability manager coupling mode to decoupled. Leave the balanced exhaust fraction schedule blank so that the makeup air is drawn from the HVAC system serving the zone. Based on the building plans, the Apparatus Bay includes a gas-fired unit heater, a makeup air damper, and a small ventilation exhaust fan. These can be simplified into a single forced-air furnace system with outdoor air and exhaust air dampers. Go to the HVAC Systems tab, click the plus icon, and add a gas-fired warm air furnace. Rename the system to UH-01. Enable the outdoor air system and set the minimum outdoor airflow rate to autosize to meet ventilation requirements throughout the year. Set the furnace burner efficiency to 90% and leave the heating capacity as autosized. Finally, configure the remaining system components. Set the constant-volume fan pressure rise to 0.5 inches and autosize the airflow rate. Configure the setpoint manager with a minimum supply air temperature of 40°F and a maximum of 100°F, controlled by Thermal Zone 101. Leave the diffuser autosized, then drag Thermal Zone 101 from My Model into the HVAC air loop. This completes the HVAC modeling for the Apparatus Bay. Save and run the simulation to verify there are no errors. After assigning the HVAC system, confirm that the “Ideal Air Loads” option is unchecked for Thermal Zone 101. Thank you. Please like and subscribe!
17. Building Energy Modeling in OpenStudio - Add HVAC-2
In this video, we will discuss how to add zone level baseboard and electric forced air heaters. We will also add zone level packaged terminal heat pumps (split system DX heat pumps).
We are back at the thermal zones tab and the next task is to add zone level equipment to the remaining spaces. There are various electric heaters located throughout the building. In room 106, there is a 0.75 kilowatt electric wall heater baseboard. Go to the library tab, scroll down, and select the baseboard convective electric heater. Drag and drop it into the room, rename it, and hard size it to 750 watts. The same process is used for the rest of the electric heaters, including the baseboard in 105 and the unit heaters and forced-air electric heaters in rooms 102, 108, 109, and 110. For the unit heaters, browse to the library tab, select unit heater constant volume electric, drag and drop it in place, rename it, and leave the flow rates auto sized. You will also notice that there is a small exhaust fan in the laundry room. This fan is intermittent and intended for occupant use, so it will not be modeled, as it is fairly inconsequential for the overall energy model. Next, there are two split system heat pumps, one serving the office and one serving the large community room. We will start with the office in thermal zone 107. Go to the library tab, search for packaged terminal heat pump, and drag and drop it into place. This system does not have its own outdoor air, so it is hard sized to 0 CFM. The fan is constant volume, the DX heating coil and DX cooling coil are left auto sized, and the electric backup heating coil is also left auto sized. One important parameter to review is the minimum outdoor temperature for operation of the heating coil, which is set to 10 degrees. A similar system is used in the community room in thermal zone 110, and this system can be copied directly to that space. As equipment is added to each zone, the ideal air loads option is automatically turned off. Thermal zone 104, which is a small hallway, does not have any equipment, so ideal air loads can be turned off manually. If any equipment is accidentally misplaced, such as a fan coil unit located in the plenum, it can be deleted by selecting it and clicking the X button in the top right. At this point, all zones should have the appropriate equipment assigned, and the next task will be to install the ventilation air system. Thank you. Please like and subscribe.
18. Building Energy Modeling in OpenStudio - Add DOAS System
In this video, we will discuss how to add a dedicated outdoor air system. We will also discuss sequencing of zone level equipment and loads.
Next, we will add the dedicated outdoor air system (DOAS), but first we need to clean up the thermal zones tab. Several zones have heating or cooling schedules assigned even though they do not contain the appropriate equipment. Zone 102 does not have cooling equipment, so its cooling schedule can be removed. Zones 103 and 104 do not have cooling, and zone 104 also does not have heating. Zone 105 does not have cooling and appears to include an extra heater that should be deleted. Zones 106 and 108 also do not have cooling, while zone 107 does have cooling, so its cooling schedule should be added back. This cleanup ensures that schedules correctly match the equipment that is actually present in each zone. After cleaning up the zones, go to the HVAC systems tab to add the DOAS. Click the plus button, scroll down, and add an empty air loop to the model. Rename the system and allow it to auto size. Because this is a DOAS, the system will be sized based on ventilation requirements, and the design outdoor air flow rate will be auto sized. The system will operate as 100 percent outdoor air, so the heating maximum system air flow ratio must be set to 1. There is no cooling tempering in this system, only heating, and the supply air temperature design is set to 67°F. Make sure that 100 percent outdoor air is selected for both heating and cooling, and set the system outdoor air method to Zone Sum since the system uses constant volume diffusers. Next, go to the library tab and add the air loop HVAC outdoor air system to a supply-side node, leaving it auto sized with no economizer and no lockout. Add a constant volume fan to serve as the exhaust fan, then add another constant volume fan as the supply fan, leaving both fans auto sized. Add an electric ducted heating coil to the supply-side node and leave it auto sized. To control the electric heater, add a setpoint manager using the node temperature control strategy. Set the reference node to the node just upstream of the electric heater, use dry bulb control, and set both the minimum and maximum supply air temperature to 67°F. Finally, add the zones and diffusers to the DOAS. From the library tab, add an air terminal constant volume no-heat diffuser and use the branch splitter to assign the applicable thermal zones. For each zone, set “Account for Dedicated Outdoor Air System” to YES so that the DOAS load effects are applied before zone-level equipment sizing. Leave the control strategy as neutral supply air and hard size the low and high setpoints to 66 and 67. Confirm that the DOAS operates 24/7 using the always-on discrete schedule. In the thermal zones tab, ensure that the DOAS equipment appears first in the equipment list for each zone so that its heating is applied before other systems. For zones with multiple systems, such as zone 110, hard size the wall heater to 7 kW so the DOAS supplies heating first, followed by the wall heater and then the PTHP.
19. Building Energy Modeling in OpenStudio - Data Viewer
In this video, we will troubleshoot some unmet hours. We will discuss how to create trend information on output variables and how to display them using Data Viewer (DView). An overview of Data Viewer functionality is also provided.
We begin by running the model from the Run Simulation tab and clicking Run. The simulation completes successfully, so we move to the Results Summary tab to review the outputs. In the Zone Conditions section, we see charts that show annual temperature ranges for each thermal zone along with unmet heating and cooling hours. Thermal Zone 101, the Apparatus Bay, shows a wide range of low temperatures but only about 40 unmet heating hours for the year. This is expected because the space is configured for freeze protection only and is not fully conditioned. The Apparatus Bay also experiences frequent door openings and operation of a large exhaust fan when fire crews leave, which explains the temperature variability. There is no cooling in this zone, and although some hours show warmer conditions, overall performance is acceptable. Other occupied zones appear to perform well, while plenum zones show wider temperature ranges that are not a concern since they are not occupied spaces. One zone that stands out is Thermal Zone 102, the decontamination and laundry room. This zone does not have cooling equipment, so there are no unmet cooling hours, but the temperature range is very large, with many hours exceeding 88°F. To diagnose this issue more precisely, the model is rerun with additional output variables. In the Thermal Zones tab, the wall heater and its associated fan and heating coil are clearly renamed to make them easier to identify in the results. The exhaust fan is already labeled. Next, in the Output Variables tab, we enable heating coil heat rate, site outdoor air dry bulb temperature, and zone air temperature, leaving the timestep set to hourly to match the simulation settings. The model is saved and rerun, completing in approximately 11 seconds. After the rerun, we return to the Results Summary tab and open the detailed data viewer (DView), choosing to display results in imperial units. In the Hourly tab, we examine outdoor dry bulb temperature and site electricity usage and observe that electricity usage increases as outdoor temperature decreases, which is expected since most of the building is electrically heated. During summer months, electricity usage decreases, although some small cooling systems still contribute to electrical demand. Viewing the Daily tab shows similar trends but at a less detailed resolution, while the Monthly tab highlights higher watt-hour consumption in winter and lower usage in summer. The Heat Map for Thermal Zone 107 (the office) shows temperature variations by hour and month, with warmer conditions in summer and tighter temperature control in winter. At night, when the office is unoccupied, temperatures drop, and some summer days show limited nighttime cooling. Additional views such as Profile plots reveal design day trends, and selecting both dry bulb temperature and electricity usage confirms that lower outdoor temperatures correspond to higher energy use. Further analysis using the Statistics tab shows average, minimum, and maximum values for the trended data, with average electricity usage around 11,700 watt-hours. The PDF/CDF tab illustrates the probability distribution of electricity usage, showing low probability of high energy use in summer and higher usage during cold winter days. The Duration Curve tab shows hours at or above specific watt-hour levels, which can be useful for utility rate analysis. The Scatter Plot compares outdoor dry bulb temperature and electricity usage, clearly showing that energy consumption increases as temperatures drop. All of these datasets can be exported as CSV files, Excel files, images, or PDFs for further analysis. Returning to troubleshooting Thermal Zone 102, the hourly zone air temperature plot reveals extreme fluctuations, with temperatures sometimes reaching 150°F or higher. Plotting the electric wall heater output shows that it runs mainly during winter and shuts off as temperatures rise, indicating it is not the cause of overheating. Examining other equipment in the space reveals a gas-powered dryer. When gas consumption is plotted, it closely matches the periods of high zone temperature. Reviewing the Loads tab confirms that the gas dryer’s heat fraction lost to the space was set to zero, which is unrealistic. Most of the dryer’s heat should be exhausted, so this value is changed to 80 percent. The model is rerun, initially failing once but succeeding on the second attempt. The updated results show significantly reduced peak temperatures and a reduction in unmet cooling hours from over 4,000 to approximately 300. Some remaining issues are likely due to unbalanced exhaust airflow and infiltration, which will be addressed in a future lesson.
20. Building Energy Modeling in OpenStudio - Exhaust MUA
In this video, we will show how to model makeup air for an exhaust fan. We will discuss how EnergyPlus handles infiltration air balancing. We will model a makeup air louver using Infiltration:DesignFlowRate and scheduling.
For the decontamination laundry room, we have an exhaust fan and a make-up air louver located in the wall. While the exhaust fan is operating, the energy model currently has no way of knowing where the makeup air is coming from. In reality, the exhaust fan is simply exhausting infiltration air from the room. To address this, we return to the OpenStudio model and navigate to the Thermal Zones tab. In Thermal Zone 102, we confirm that the exhaust fan has been hard sized to 152 CFM. Out of curiosity, we then review the existing infiltration rate for this space by going to the EnergyPlus results, opening the Table of Contents, and selecting the Outdoor Air System section. Here, we see that the infiltration rate for this room is approximately 10 CFM, which means the exhaust fan is only exhausting that amount by default. EnergyPlus does not automatically balance airflows, so this must be done manually. To balance the airflow, we go back to the Space Types tab and select the Laundry Room / Decontamination Room space type. We edit the infiltration settings by changing the design flow rate calculation method to Flow per Space and set this value equal to the exhaust fan flow rate of 152 CFM. We delete the existing flow-per-surface-area value. There are additional coefficients available that account for infiltration effects related to temperature differences and wind velocity, but these are not applicable in this case. Our goal is simply to match the infiltration rate to the exhaust fan flow. By default, the EnergyPlus coefficients are set so that infiltration is based solely on a schedule, with temperature and wind effects effectively canceled out. If the building were sensitive to wind speed or temperature-driven infiltration, these coefficients would need to be adjusted. A reference PDF is available that explains these coefficients in greater detail. With the infiltration rate adjusted, it is also important to consider buildings that contain multiple laundry rooms. In such cases, each laundry room may require its own customized space type so that the infiltration flow rate correctly matches the zone exhaust fan serving that space. Next, we go to the Loads tab and review the Laundry Room / Decontamination Room infiltration settings. The infiltration is controlled by a laundry infiltration schedule, which can be reviewed in the Schedules tab. This schedule shows higher infiltration rates during daytime hours, likely tied to the occupancy schedule from 8 a.m. to 5 p.m., and lower rates during nighttime hours. The default design value is set to 100 percent, which ensures proper sizing of zone and HVAC equipment during both summer and winter conditions. During occupied hours, the schedule reaches 100 percent, which results in approximately 150 CFM of infiltration when the exhaust fan is operating. In the evening, when the exhaust fan shuts off, the infiltration rate should return to the default level of approximately 10 CFM. This corresponds to about 7 percent of the design flow rate. Therefore, the nighttime schedule values are adjusted to reflect typical infiltration levels when the exhaust fan is not running. After making these changes, the model is saved and the simulation is rerun. Finally, we review the results by going to the Results Summary tab and examining the Zone Conditions. The unmet hours at high temperatures have dropped significantly, and the zone temperatures have stabilized in the low 70s. Opening DView and reviewing the Daily tab confirms this improvement. During the winter months, the space temperature remains steady at approximately 70°F, eliminating the previous overheating issue. In the summer, temperatures do rise, which is expected in a laundry room without active cooling. Overall, the results appear reasonable and confirm that balancing the makeup air with the zone exhaust fan has resolved the issue. That concludes this lesson on balancing makeup air flows with zone exhaust fans.
21. Building Energy Modeling in OpenStudio - Transfer Air
In this video, we will show how to model transfer air between zones. We will also check some of the modeling assumptions and discuss how to get EnergyPlus results output in Imperial (IP) system units.
There are a few cleanup items that need to be addressed, starting with a review of the air loop details. When looking at the dedicated outdoor air system (DOAS), we can see that it is currently sized for 847 CFM, while our design criteria indicate that we only need approximately 475 CFM. This means we are overflowing air into certain areas and need to troubleshoot the issue. By going to the Outdoor Air tab, we can calculate airflow rates for individual zones. For example, Thermal Zone 103 has a volume of 1,170 cubic feet and an air change rate of 2.09 ACH, which results in roughly 40 CFM when divided by 60 minutes per hour. Zone 103 itself is scheduled for about 34 CFM, and when we include Thermal Zone 104 with an additional 6 CFM, the total comes out to about 40 CFM, which matches our calculation. While we could do this calculation for each zone, there is a more efficient way to review these airflow values. To do this, we go to the EnergyPlus results and open the Table of Contents, then select the HVAC Sizing Summary. This table shows the minimum outdoor air flow rates for each thermal zone, but by default the values are reported in cubic meters per second because EnergyPlus performs all calculations in SI units. Since we are working in IP units, we need to convert these values. We go to the Measures tab, remove the Output Diagnostics measure for now, and under Reporting → QA/QC select the EnergyPlus measure “Set Output Table to IP Units.” This measure is applied before the OpenStudio results measure because OpenStudio applies measures sequentially from top to bottom. However, OpenStudio results expect SI units, and converting to IP units first will cause an error. To avoid this, we delete the OpenStudio Results Summary measure, then rerun the model. If the run fails, simply rerunning it usually resolves the issue. Once complete, we return to the Results Summary tab, navigate to the HVAC Sizing Summary, and confirm that the airflow values are now reported in CFM. Thermal Zone 103 shows about 40 CFM as expected, Thermal Zone 107 shows approximately 16 CFM compared to its scheduled 14 CFM, and Thermal Zones 108/109 show around 14–15 CFM, even though these zones should only receive transfer air rather than outdoor air. Thermal Zone 110, the community room, is scheduled for 775 CFM, even though we only need about 360 CFM. To investigate this, we go to the Loads tab and review the People Definition for the community room. The occupancy density is set to 0.05 people per square foot, which corresponds to 50 people per 1,000 square feet and is code-compliant. However, the model assumes an occupancy of 97 people, while we are only expecting an average of about 49 people. We are taking credit for statistical occupancy, meaning the space will typically be occupied at about half of the code design value. To reflect this, we reduce the people per square foot value to 0.025, which is roughly half of the original value. After saving and rerunning the model, the airflow for Thermal Zone 110 drops to approximately 462 CFM. This is still slightly high but much closer to the target value, so we leave it as is. We then remove the IP units measure, reinstall the OpenStudio Results Summary measure, rerun the model, and save it as versions 21 and 22 for reference. Next, we address how transfer air is modeled. Based on the drawings, the locker and shower rooms have exhaust registers but no supply registers, relying instead on transfer air from Community Room 110. There are two exhaust registers totaling 360 CFM, with air transferring through the locker and shower rooms before being exhausted. OpenStudio does not handle transfer air well by default, though it can be modeled using an EnergyPlus measure from the Building Component Library. To implement this, we first remove Thermal Zone 108/109 from the DOAS system since it does not receive direct outdoor air. We then add the EnergyPlus “Add Zone Mixing Object” measure and configure it so that Thermal Zone 108/109 receives 90 CFM of transfer air from Thermal Zone 110 on a 24/7 schedule. We create this schedule in the Schedules tab using an On/Off schedule set to always on. Because the EnergyPlus zone mixing object transfers heat but does not balance airflows, we manually balance the air by adding a virtual exhaust fan of 90 CFM to Thermal Zone 110 and another exhaust fan of 90 CFM to Thermal Zone 108/109. The exhaust fan serving Thermal Zone 110 is set with zero pressure rise so it does not consume energy, while the exhaust fan for Thermal Zone 108/109 is matched to the DOAS fan efficiency and pressure rise. This balances the airflow so the model correctly accounts for transfer air. After rerunning the model, we compare the results of the transfer air model to the original 100% DOAS model. The total site energy use intensity remains approximately 65 in both cases, indicating that the transfer air has minimal impact on overall energy use because the amount of transferred air is relatively small. There is a slight increase in heating and cooling capacity required for Thermal Zone 110, but the difference is minimal. In models where a significant amount of air is transferred between zones and not conditioned by the DOAS, this approach can have a larger impact on zone equipment sizing. This is an important consideration depending on the complexity and size of the building model. That concludes this section. Thank you. Please like and subscribe.
22. Building Energy Modeling in OpenStudio - SketchUp-1
In this video, we will show how to modify the model geometry using SketchUp. With SketchUp, we are able to stretch geometry without deleting or creating new spaces using the move tool. We will also show how to input a simple shading device. Finally, we will compare energy consumption between the "square" model and the modified model.
We will now edit the building geometry using SketchUp. In this case, SketchUp Make 2017 is being used, which was free software at the time. Although it is no longer officially supported, it is still available for download. In the future, it may no longer be accessible or free. Before starting, we remove any unnecessary objects from the workspace. To use SketchUp with OpenStudio, the OpenStudio SketchUp extension must be installed. This can be verified by going to Window → Extension Manager, where the OpenStudio extension should appear as installed. Additional information on installing and using this extension can be found elsewhere. Next, we open the OpenStudio model file in SketchUp. At this stage, the building geometry appears as a simple block object, which is how FloorspaceJS initially creates models. For more advanced geometry editing, SketchUp is the preferred tool. The first step is to establish a scale by drawing a reference line of 50 feet. We then import the east elevation drawing and overlay it on the east side of the building. This elevation is scaled to match the 50-foot reference line. A vertical line is drawn from the midpoint of the roof up to the approximate roof peak and extended down toward both sides. Once the outline of the roof is established, the temporary construction lines are deleted. The roof outline is selected, and using the Move tool with the CTRL key, it is copied and pasted onto the opposite side of the building. After creating the roof outlines on both sides, we use guidelines to assist with drawing and delete unnecessary surfaces. Double-clicking into the space allows us to work directly with the geometry. We split the roof surface into two sections, select the ridge edge, and use the Move tool to raise it. If the edge does not move upward correctly, pressing the ALT key changes the axis reference, allowing vertical movement. This creates the roof ridge for one side of the building. Some unintended surfaces may appear during this process, which we temporarily hide. Using the Move tool again, we align these surfaces with the correct roof edges. This process is repeated for all other roof surfaces throughout the building. As edges are moved, additional surfaces may be created, but once the surfaces become planar, the unnecessary lines can be deleted to clean up the geometry. Once the roof geometry is complete, we verify that all surface boundary conditions are still correct. We switch the view to Render by Boundary Condition to confirm that the surfaces have retained their proper references. The Section Plane tool is used to inspect interior surfaces. Some surfaces may lose their boundary condition matching, which appears as blue coloring. These issues can be corrected manually, as demonstrated in other OpenStudio SketchUp tutorials focused on boundary conditions. After fixing these, we hide temporary geometry and remove construction guides. At this point, we realize that shading has not yet been added and must be addressed. To add shading, we redraw a 50-foot guideline along the blue axis and extend a line from the roof edge outward. Using the Move tool with CTRL, this line is copied to create the shading projection. We then create a new shading surface group using the Shading Surface Group tool and place it along the roof edge. By double-clicking into the shading group, we trace the shading geometry and exit the edit mode. Switching to Render by Surface Type allows us to verify shading orientation. The sun-exposed side should appear dark purple, while the shaded side appears light purple. If the shading is reversed, we edit the entity and use Reverse Faces to correct it. Once complete, the model now includes a pitched roof and shading surfaces. The OpenStudio model is saved and reopened in the OpenStudio application using File → Revert to Saved. Inspecting the geometry tab confirms that the model has been modified, though some roof surfaces may be subdivided due to connected geometry. OpenStudio may report warnings such as duplicate drawing interfaces or potential duplicate surfaces (for example, Surface 11, 15, and 16, or Face 3, 2, and 96). These issues are noted, and the model is saved under a new version number. Instead of fixing these directly in SketchUp—which can be unreliable due to known bugs—we open the OSM file directly and delete the problematic surfaces manually. After saving, the model is reloaded into SketchUp. Upon reloading, SketchUp may report that some surfaces lost matching boundary conditions and were converted to exterior surfaces. These changes are accepted. We then double-click into affected spaces and delete stray surfaces and line segments that are not attached to active geometry. Using the Unhide command helps reveal hidden geometry that may need correction. Some roof surfaces may appear split, and unnecessary lines are removed. Due to tolerance differences between SketchUp and OpenStudio, geometry editing can sometimes introduce glitches. If problems persist, the safest approach is to delete the affected roof geometry and recreate it carefully, ensuring that inferences align with the correct axes and active geometry edges. After rebuilding the roof, we verify boundary conditions again and rematch any surfaces as needed. A section cut is used to confirm that all surfaces are properly matched. Once verified, the model is saved and reopened in OpenStudio. The Geometry tab confirms that the geometry is now correct. The model is then run to ensure it simulates successfully. After the simulation completes, we review the results and compare energy performance between the original flat-roof model and the updated pitched-roof model with shading. Reviewing the reports, Version 22 (the square building) shows an annual energy consumption of 375,155 kBtu with an EUI of 64.57. The updated model with the sloped roof and shading shows an energy consumption of 378,217 kBtu and an EUI of 65.10. This indicates that the pitched roof with shading slightly increased overall energy use. This concludes the demonstration of editing geometry and adding shading surfaces using SketchUp. Thank you. Please like and subscribe.
23. Building Energy Modeling in OpenStudio - SketchUp-2
In this video, we will review some of basic functions used to create, visualize, and modify the model geometry using SketchUp. These will include: Create New OpenStudio Model from Wizard, Import/Export EnergyPlus IDF, New Space, New Shading Surface Group, New Interior Partition Surface Group, Surface Matching, Set Attributes for Selected Spaces, Create Spaces from Diagram, Project Loose Geometry, Inspector, Search Surfaces, Info Tool, Show Errors and Warnings, Launch OpenStudio, Online OpenStudio Help, Render By Surface Type, Render By Boundary Condition, Render By Construction, Render By Space Type, Render By Thermal Zone, Render By Building Story, Hide Rest of Model, View Hidden Geometry, View Model in X-Ray Mode, and Show Shadow Settings Dialog.
We will now go through some of the basics of using the SketchUp OpenStudio extension. First, we open SketchUp. There are two main options available. The older version, SketchUp Make 2017, is a free version that can still be used to create geometry and edit it with OpenStudio, as long as the SketchUp 2017 extension is compatible with the OpenStudio version being used (for example, OpenStudio 2.9.1). Another option is to create geometry using SketchUp 2017 Make and then import it into the most recent version of OpenStudio. However, once this is done, you will not be able to go back and edit the model using SketchUp 2017 Make. In this demonstration, we will be using the most recent versions of both OpenStudio and SketchUp. We open SketchUp 2020 and create a new, simple model. At this stage, we briefly review some of the basic icons and functions, noting that a more in-depth review of advanced tools will be covered later. To start a model, we click the “New OpenStudio Model From Wizard” icon. We choose not to save the current model. This wizard creates an OpenStudio model using built-in templates. OpenStudio includes templates that define construction types, materials, and space types. We select an office building with a 2010 building code reference, which is the most recent available in the template. All template options are left as true, and we click OK. Initially, a message may indicate that the model is empty, even though space types and construction sets are present. To verify what was created, we open the Inspector Tool. We see that 13 space types were created, along with a construction set, although some constructions such as floors, walls, and roofs may appear empty due to a temporary issue with the wizard. To resolve this, we purge schedules and construction sets and rerun the template generator using Extensions → User Scripts → On Demand Template Generators → Space Type and Construction Set Wizard. After running the wizard again, the model correctly shows 13 space types and one construction set, with default floor, wall, and roof constructions applied. With the template properly loaded, we proceed to draw the floor plan. Using the rectangle tool, we click the origin and draw a 20 ft by 20 ft (6.1 m by 6.1 m) space by entering exact dimensions. We copy and paste this to create multiple rooms and add another room behind them to complete the basic floor plan. After selecting the entire floor plan, we click the “Create Spaces From Diagram” button. This extrudes the spaces upward using a default floor-to-floor height of 10 ft (3 m). We specify a single floor and click OK, which creates three separate spaces. To add an additional space, such as a storage shed, we click the “New Space” button and place it on the corner of the building. By double-clicking, we enter edit mode and use SketchUp drawing tools to create a small rectangular space. Using the push-pull tool, we extrude it to a height of approximately 8 ft (2.4 m). After exiting edit mode, we adjust the height so it aligns with the roof by using push-pull again and referencing the adjacent surface. This completes the storage room. This demonstrates how spaces can be created either from a floor plan diagram or individually using the New Space button. Next, we review additional basic OpenStudio toolbar buttons. The Open OpenStudio Model button allows you to open an existing OpenStudio model created in the OpenStudio application. The Save OpenStudio Model button is critical; when working in SketchUp, you must use this button to save the OpenStudio model, as the regular SketchUp save function only saves the SketchUp file. The Save As button works as expected. There are also options to import EnergyPlus IDF files into SketchUp or export the OpenStudio model as an IDF for use in EnergyPlus. We then review the New Shading Surface Group button. This tool is used to create shading objects. By clicking the button and double-clicking to edit, we draw a shading surface extending outward from the building. If the shading surface is facing the wrong direction, we can right-click and use Reverse Faces to correct it. The correct orientation shows the sun-exposed side as dark purple. After reviewing this, we delete the shading surface for now. Next, we explore the New Interior Partition Surface Group tool. This is used to create interior partitions such as cubicles or furniture elements. We hide the ceiling, create a new partition group, and draw partition walls using lines and the push-pull tool. These partitions can be used for lighting calculations, as they affect daylight penetration, glare, and shading within a space. They can also be assigned construction types and used as thermal mass, absorbing and re-emitting heat throughout the day. Multiple partitions can be created, moved, rotated, and duplicated as needed. Alternatively, OpenStudio also supports simplified internal thermal mass without explicitly modeling partitions. We then restore the ceiling and move on to creating doors and windows. Using a section plane for visibility, we draw a door starting from the bottom edge with dimensions of 7 ft by 3 ft (2100 mm by 900 mm). Initially, the door may be created as a window, which can be corrected using the Inspector Tool by changing the subsurface type to a door. Doors appear brown, while windows appear transparent. Windows can be drawn directly while editing a space, or they can be created as loose geometry and projected onto spaces using the Project Loose Geometry tool. This allows windows to be added without entering individual space edit mode. We then review rendering modes. Render By Surface Type colors elements based on their type: walls, floors, roofs, and ceilings each have distinct colors. Render By Boundary Condition initially shows all surfaces as blue, indicating that EnergyPlus considers them exterior surfaces. To correctly model heat transfer between adjacent spaces, Surface Matching must be performed. Before matching, we use Intersect Entire Model to ensure geometry such as doors exists on both sides of shared walls. After intersecting, we use Match In Entire Model to correctly identify interior surfaces, which then appear green. In some cases, surfaces or subsurfaces may not match automatically due to geometry issues. These must be corrected manually using the Inspector Tool by matching subsurfaces (such as doors) to their corresponding surfaces. Occasionally, SketchUp fails to split surfaces correctly, requiring deletion and redrawing of walls or doors. Once all interior walls and subsurfaces are matched, EnergyPlus correctly understands heat transfer between spaces. We then review Render By Construction, which provides a different color scheme to help visualize construction assignments, and Render By Space Type, which colors spaces based on their assigned space types. Using the Set Attributes For Selected Spaces tool, we assign different space types such as open office, closed office, conference room, and storage room, and observe the color changes. Render By Thermal Zone shows how spaces are grouped into thermal zones. Initially, all spaces may belong to a single thermal zone, meaning they share one HVAC system and thermostat. Using the Set Attributes tool, we create new thermal zones to separate spaces that should be heated and cooled independently. Spaces assigned to the same thermal zone appear with the same color. Render By Building Story allows visualization by floor level. Spaces can be assigned to different building stories using the Set Attributes tool. Assigning stories is useful for visualization and for applying measures later, such as assigning HVAC equipment by floor. Additional tools include Hide Rest Of Model, which hides all other spaces while editing a selected space; View Hidden Geometry, which reveals hidden objects; and View Model in X-ray Mode, which makes walls transparent. The Show Shadow Settings Dialog allows visualization of solar shadows throughout the day and year, helping assess shading and daylighting impacts. Seasonal and time-of-day changes can be explored to observe shadow behavior. The OpenStudio Inspector Tool provides detailed information about selected elements, including surface type, construction assignment, and space association. The Set Attributes tool also allows assignment of construction sets, thermostats, and ideal air load settings. The Search Surfaces tool helps locate specific surfaces by name, while the Info Tool allows quick identification of surfaces and subsurfaces. The Show Errors and Warnings button displays model issues, many of which are automatically corrected upon reloading the model. The Online OpenStudio Help button provides access to official tutorials explaining each toolbar function. Finally, the Launch OpenStudio button opens the SketchUp-created model in the OpenStudio application, where the full energy modeling workflow can be completed. This concludes the overview of the basic functions of the OpenStudio SketchUp Plug-In. In the next video, more advanced topics such as lighting, daylighting controls, and shading controls will be discussed. Thank you. Please like and subscribe.
24. Add Heat Pump Hot Water System
In this video, we will discuss how to add a heat pump hot water system to a building domestic hot water loop.
In this episode, we replace an existing 100-gallon, 12 kW electric domestic hot water heater serving a fire station with a heat pump water heater (HPWH). The new system uses a heat pump for heating during mild conditions and includes electric resistance elements for backup during extreme conditions. The HPWH must be placed within a thermal zone in OpenStudio, so it is located in the Apparatus Bay (Thermal Zone 101). From the library, a “water heater: heat pump, wrapped condenser” is added to the zone equipment and renamed. Its associated stratified tank is then added to the domestic hot water loop from “My Model.” Initially, both the original electric heater and the HPWH remain in the loop so performance can be compared. The loop load distribution scheme is changed from Optimal to Sequential Load, and the heater order is swapped so the heat pump water heater is prioritized over the standard electric heater. After running the model, EnergyPlus reports show reduced annual energy use with the heat pump water heater compared to the baseline electric heater. Electricity use for water systems drops noticeably, confirming that the HPWH is providing energy savings. To ensure the system is properly configured, the HPWH tank parameters are reviewed and updated to match manufacturer data: tank volume is changed to 119 gallons, height to approximately 5.9 feet, and heater capacities are set to two 6 kW elements for a total of 12 kW. Heater control is set to Simultaneous so both elements can operate together if needed. Setpoint temperatures are maintained at 120°F with appropriate deadbands, and parasitic electric loads are left at default values to represent onboard electronics. The thermal zone–based configuration allows the tank’s ambient conditions to be tied to the Apparatus Bay. Skin loss is assumed to be fully transferred to the zone, and flow rates on both use and source sides are autosized. The compressor is then configured using manufacturer performance data, including rated heating capacity, coefficient of performance, evaporator and condenser conditions, and operating temperature limits (20°F to 110°F). The evaporator draws air from the zone only, meaning the HPWH slightly cools the Apparatus Bay as it extracts heat. Supplemental heater control logic is set to mutually exclusive to prioritize compressor operation in efficiency mode, with resistance elements engaging only when needed. Finally, output variables are added to visualize HPWH performance, including compressor electricity use, total water heating rate, and evaporator cooling rate. Simulation trends confirm that compressor operation aligns with hot water demand, increasing during periods of use and decreasing overnight. Zone temperature impacts are minimal due to the large space and relatively small heat pump. Comparison with the baseline confirms overall energy savings, validating the HPWH integration into the domestic hot water system. This completes the installation and verification of the heat pump water heater model.
25. Building Energy Modeling in OpenStudio - Results Summary
In this video, we will discuss how to include (Reporting Measures), access, and navigate some of the varios reports created by OpenStudio and EnergyPlus. We will also briefly discuss some of the information contained in the reports.
Now, we will briefly discuss reports. First, let's look at the Measures tab. One thing I forgot to mention last time is the OpenStudio Results measures, if you do not already have them installed. There are two different reports that you can output in addition to custom reports, and these are good default reports to use initially. The EnergyPlus output report is automatically generated, so we do not have to add a measure there, and you already see that we did output an additional diagnostic report. There is also an OpenStudio Results report, which can be found on the Building Component Library online. If you go to the Reporting drop-down under QA/QC, you can drag and drop OpenStudio Results into place. If you do not already have this, you can find it on the Building Component Library by clicking the “Find Measures on BCL” button, as we discussed in previous examples. Next, let us go to the Results Summary tab on the left. There are two different results reports that have been created for this model: the OpenStudio Results and the EnergyPlus Results, which you can select from the drop-down at the top. Both of these reports are created as HTML files. Browse to the OpenStudio project folder, open it, and go to the Reports folder. You will see both the EnergyPlus report and the OpenStudio Results report. Let us open the OpenStudio Results report, which opens in a standard web browser. The OpenStudio Results report is a summary of a lot of information about the energy model. It is not as comprehensive as the EnergyPlus report, but it is a little easier to read. It starts with summary information about the building, followed by a weather summary and sizing period design days, which relate to the design day file that was input at the beginning of the model and the assumptions used for auto-sizing the equipment. Next, there is an unmet hours summary, which is a good section to review. If you have unmet hours in your building, it may indicate issues with equipment sizing, space loads, or overlapping schedules. The unmet hours tolerance shows the tolerance used for reporting unmet hours. For more detail, you can go to Zone Conditions from the table of contents, where unmet heating hours are shown on the left and unmet cooling hours on the right. This table shows the range of temperatures that spaces experience throughout the year. If a space, such as Thermal Zone 103, falls below the heating setpoint for a certain number of hours, that is considered an unmet hour, especially if it occurs during occupied hours. Past unmet hours, the report provides an annual overview with tables showing end uses for equipment, utilities, electricity, and gas, as well as monthly overview tables for electricity and natural gas. District equipment is also shown here because ideal air loads were assigned to the thermal zones, which assume unlimited heating and cooling capacity. Continuing through the report, you can see peak demands for electricity and natural gas on a monthly basis, along with district heating and cooling. Since no utility bills were input, cost information is not shown. The report then moves into an envelope summary and space type breakdowns, showing how different space types are distributed in the building. For example, the Apparatus Bay takes up about 39% of the building area. Scrolling down, space summary details show information such as people, lighting, infiltration, and ventilation, along with interior lighting statistics, plug loads, and exterior lighting, including the astronomical clock that was added earlier. HVAC load profiles show monthly heating and cooling loads compared to outdoor air temperature, and Zone Conditions display temperature and humidity ranges. Additional tables include the zone overview, outdoor air statistics, site and source energy summaries, and schedules. Finally, the EnergyPlus Results report provides all of this information plus much more detail, accessible through the table of contents link, for users who want to explore the model in greater depth. Thank you. Please like and subscribe!