Page | 1 Building Energy Modeling with OpenStudio – Attendee Handout SimBuild 2012 Madison, Wisconsin July 30th, 2012 8am – 5pm What’s OpenStudio? A building energy modeling application suite Software for rapidly creating new analysis and design tools Exercise Instructions Section 1 – Model the Building Envelope Choose the “Large Hotel” building type template using the “New OpenStudio Model from Template” button. Draw a rectangle to represent the building envelope (see figure on next page) o Select the rectangle tool and click somewhere on your screen to set starting point. o Move the mouse up and to the right, then type 100’, 50’ and then press enter. o This text will show in the measurements box at the bottom right of your screen and will precisely size your rectangle. Tip: The main SketchUp tools you need are the rectangle, pencil, select tool, orbit, pan, and zoom Tip: Templates do not contain any geometry. They are data sets for specific building types. They contain data for constructions, loads and schedules for four different vintages across the US climate zones.
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Building Energy Modeling with OpenStudio – Attendee Handout
SimBuild 2012 Madison, Wisconsin
July 30th, 2012 8am – 5pm
What’s OpenStudio?
A building energy modeling application suite
Software for rapidly creating new analysis and design tools
Exercise Instructions
Section 1 – Model the Building Envelope
Choose the “Large Hotel” building type template using the “New OpenStudio Model from
Template” button.
Draw a rectangle to represent the building envelope (see figure on next page)
o Select the rectangle tool and click somewhere on your screen to set starting point.
o Move the mouse up and to the right, then type 100’, 50’ and then press enter.
o This text will show in the measurements box at the bottom right of your screen and will
precisely size your rectangle.
Tip: The main SketchUp tools you need are the rectangle, pencil, select
tool, orbit, pan, and zoom
Tip: Templates do not contain any geometry. They are data sets for specific building
types. They contain data for constructions, loads and schedules for four different
vintages across the US climate zones.
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Use the pencil tool to split up footprint to represent spaces shown above.
o SketchUp has an inference engine to help find midpoints.
Extrude the footprint into a two story building.
o Select all of the surfaces in your footprint by drawing a window with the
“Select” tool.
o Click the “Create Spaces from Diagram” button.
o Keep the default floor to floor height of 10’ and set number of floors to “2” and click
“OK”.
Set surface boundary conditions.
o Change to “Render by Boundary Condition” render mode.
o Click the “Surface Matching” tool and choose “Match in Entire Model”.
o Use the x‐ray mode or section cut to confirm green interior surfaces inside the model.
o Blue represents outdoor, tan is ground, and green is surface.
Apply a window to wall ratio to the building.
o Switch the render mode back to “Render by Surface Type”.
o Select all spaces by drawing a window with “Select” tool.
o Run the “Set Window to Wall Ratio” user script with the default values.
This is under the “Plugins/OpenStudio User Scripts/ Add or Alter Model
Elements” menu.
Tip: You can draw discrete windows and project them onto the model instead
of using the window to wall ratio.
Tip: The window to wall ratio script will remove existing windows but it leaves
doors alone. If it can’t meet the requested ratio then it won’t add a window.
Tip: Matched surfaces should be the same size and in the same position. The “Intersect
Entire Model” button will split surfaces that span over multiple base surfaces in adjacent
space.
Tip: You can double click to enter into a space, at which point you can alter
existing geometry or create new geometry. New geometry will be classified.
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Search for south facing windows.
o Click “Surface Search” tool.
o Choose “OS:SubSurface” for class, and 180 to 180 for orientation, then click “Search
Entire Model”.
o These surfaces that pass the test are visible and selected, everything else is hidden.
o Clicking “View Hidden Geometry” will shows the rest of the model in hatched mode.
Use overhang script on results of search to add overhangs based on projection factor.
o Run the “Add Overhangs by Projection Factor” user script with the default values.
This is under the “Plugins/OpenStudio User Scripts/ Add or Alter Model
Elements” menu.
o Click “Unhide All” in the Surface Search dialog to cancel the filter and show the rest of
the model.
Save the OpenStudio model as “Exercise_01.osm”.
Tip: Interior partition surfaces can be added to represent surfaces that exist in a space but are not
a space boundary. An air wall construction can be used for space boundaries that don’t represent
physical walls. Both of these objects are in support of Radiance simulations; however they can
provide benefit for EnergyPlus simulations as well. You can set the interior partition surfaces to act
as an internal mass objects.
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Section 2 – Assign Building Activity and Thermal Zones
Change to “Render by Space Type” render mode.
Use the context aware “Info Tool” to inspect the default space type for this template. It should
say “ASHRAE_189.1‐2009_ClimateZone 4‐8_LargeHotel_GuestRoom”.
Using the image below as a guide and the “Space Attributes” tool, assign space types to your
model.
o The four guest rooms don’t need any changes since they are going to use the building
default space type.
o Select the two spaces that are going to be a corridor. Drawing a window with the
“Select” tool may be tough; an alternative approach is to shift/click while using the
select tool to select multiple objects.
o Click the “Space Attributes” tool, choose the appropriate value from the “Space Type”
pull‐down menu, and click “OK”. We will use some of the other fields later on.
o Repeat the last two steps for the lobby and banquet spaces.
Change to “Render by Thermal Zone” render mode. Since we don’t have any thermal zones the
model should appear white.
Tip: Space Types contain data related to building activity, internal loads, and
schedules. Optionally they can also contain construction specific data.
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Using the image below as a guide use the “Space Attributes” tool to create and assign thermal
zones to your model.
o Select the two first floor guest rooms.
o Click the “Space Attributes” tool, choose “<new thermal zone>” from “Thermal Zone”
the pull‐down menu, and click “OK”.
o Repeat the two steps above for the four additional thermal zones. To keep your model
consistent with the one used for this exercise, add your zones numerically from low to
high. The zone names should then match what is shown below.
o Colors will not be the same, but that is ok. If you want to change thermal zone colors
you can use the paint bucket tool with an alt/click to edit the paint color.
Tip: You can rezone your building without having to alter any geometry. Just re‐
assign spaces to different thermal zones.
Tip: One or more spaces can be contained in a thermal zone. These spaces can have
different space types.
Tip: You can create a new zone and assign spaces to it, or you can choose from
existing thermal zones already in the model. For this exercise we will always make a
new thermal zone.
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Assign thermostats and setup Ideal Air Loads System.
o Select all of the spaces in your model and click the “Space Attributes” tool.
o Moving towards the bottom of the dialog set “Ideal Air Loads Status” to “Yes” and set
“Thermostat” to “LargeHotel_Thermostat”.
Add a daylighting control point to your model.
o Double click on the banquet room to open up this space for editing.
o Click the “Hide rest of Model” button to hide all other spaces.
o Click the “X‐ray” button to make the space transparent.
o Orbit around and zoom as needed so you can view the space from a high vantage point.
o Click the “New Daylighting Control” button.
o To add the control point in the center of the room hover the mouse over one of the
edge midpoints of the floor, and then hover over the midpoint of an adjacent floor
edge, then as you move toward the center of the room and see inference lines, click to
place the sensor. (see image below)
o Vertically the senor should default to 30” above the floor. If instead it is positioned
below the floor by 30” inches, or if you want to locate the sensor at a height other than
30” you can move it with the move tool.
Tip: While we just used a single thermostat for this exercise, you can have a unique
one for each thermal zone.
Tip: The “Space Type Report” user script can summarize some of your input data. It
can also be customized to show different input data.
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With the sensor still selected select the “Move” tool and click somewhere on
your screen to set a relative origin. Move the mouse vertically in 3d space
making sure you are on the “blue” axis. Then type 5’ to move the sensor to the
proper location.
Save the OpenStudio model as “Exercise_02.osm”, using the “Save OpenStudio
Model As” button.
Section 3 – Basic Simulation Run in OpenStudio Application
Click the “OpenStudio” button to launch your model in the OpenStudio Application.
Save the model as “Exercise_03.osm” using “SaveAs” under the file menu in the OpenStudio
Application.
The “Site” tab should be open by. Pick Chicago for both the EPW file and the DDY files.
o You can find these files in the EnergyPlus install folder under “WeatherData”
(e.g. C:\EnergyPlusV7‐1‐0\WeatherData)
Select the “Run Simulation” tab and click the green arrow to start a simulation.
o You can scroll down to view the progress of the simulation
o The tree sub‐tab shows you the behind the scenes workflow for running the simulation.
This workflow includes translating your OSM model to an IDF file which is passed off to
EnergyPlus. Results are then passed back to OpenStudio.
Select the “Results” tab to view the simulation results.
o Only lighting and equipment will show on the graphic charts. Heating and cooling for
Ideal Air Loads shows up under district heating and district cooling. You can scroll down
to see those tables.
o Once we add a full mechanical system then heating and cooling will show up under the
electricity and gas charts and tables, along with fans and pumps.
Section 4 – Adjust Internal Load Values
Save the model as “Exercise_04.osm”.
Investigate the model using the “Facility” tab.
o Select the “Facility” tab and sort by thermal zone.
o Expand out the tree by clicking on the arrows.
o Investigate Space Type.
Expand “OS:ThermalZone 1” and select one of the spaces
Look through the objects in the space type. The top contains spaces attributes,
internal loads are at the bottom.
Tip: Generally you don’t need to save a SketchUp file. The OSM file contains all of the
OpenStudio model data. If you want to save scene, styles, or non OpenStudio
geometry then saving the SketchUp SKP file may be beneficial.
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This space should have a guestroom space type in green text without an “X”.
This means that it is inherited. If you scroll to the bottom, you will see people,
lights, and equipment instances.
Go to the “My Model” tab and browse space types for any laundry or kitchen
space type, then drag the object over onto the “Space Type” drop zone for the
selected space.
The text on the “Space Type” drop zone should now be black and there will be
an “X” that lets you know it isn’t inherited.
If you scroll down you will notice that all of the loads have changed and a gas
load has been added.
Now go back to the “Space Type” drop zone, click the “X” and you will be back
to the large hotel guest room space type, the loads will return to their original
values.
o Investigate Thermal Zone assignment.
Select the same space in “OS:ThermalZone 1” that you were just using, and
scroll up to the top.
Now click on the “X” in the “Thermal Zone” drop zone.
You should see the selected space disappear in the tree from “OS:ThermalZone
1” and the text for “Unassigned Thermal Zone” should have turned red.
You can expand “Unassigned Thermal Zone” in the tree to find your space.
Select the space, go to “My Model”, look for the “Thermal Zones”, and drag
“OS:ThermalZone 1” to the “Thermal Zone” drop zone.
The space should now move in the tree back to “OS:ThermalZone 1”.
Adjust the lighting loads for the Banquet space type from 2009 to 2004.
o Select the “Space Type“ tab and click the icon to purge unused space objects.
o Select the Banquet space type and scroll down to the internal loads.
o In “My Model”, look for “Light Definitions” and search for “ASHRAE_90.1‐
2004_LargeHotel_Banquet_LightsDef”. Drag this object to the drop zone for the lighting
load. It will replace the original light.
Change the exterior wall construction.
Tip: You can grab the handle in at the end of the left pane to widen it. You can also
add an additional lighting object instead of replacing the existing one.
Tip: If a space isn’t part of a thermal zone, the internal and external loads from that
space won’t be part of the EnergyPlus simulation.
Tip: If you go back to the tree and look at “Large Hotel” you can see where the
default space type for the building is set, as well as the default construction set.
Tip: The “Add New Load” drop zone at the bottom of a space allows you to add loads
to a space beyond what it inherits from its space type.
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o Select the “Constructions“ tab and click the icon to purge unused space objects. There
should just be one construction set left.
o In “My Model”, look for under “Constructions” for an object named “ASHRAE_189.1‐
2009_ExtWall_SteelFrame_ClimateZone 4‐8”. Drag this object the drop zone for the