Using ArchiCAD for LEED Calculations
By giving the new material name a prefix of "SS," we can organize all the Sustainable Site materials together within the materials list. You may also want to set the Surface Color to green in the Exposure to Light tab and select an image for the material in the Texture tab.
Step 2: Set up a Custom Schedule using the Scheme Settings
The next step is to create a custom Interactive Schedule to track this material. To do this, we need to create a schedule to calculate the total green roof material as well as a second schedule to calculate the total roof surface. We can then use these two schedules to determine if we meet the LEED requirement that the green roof system covers at least 50 percent of the total roof area.
Let's start by opening the Scheme Settings dialog from the menu Document > Schedules & Lists > Schedules > Scheme Settings. Within the Scheme Settings, click the Create New button to add a new scheme. Within the Add Schedule Scheme dialog, select the items to list as "Construction Elements." Next, set the ID as "SS 7.2" and the name as "Reduce Heat Islands, Green Roof." Click the OK button when finished. A new Interactive Schedule is now available within the Scheme Settings.
Step 3: Configure the Criteria within the Scheme Settings
Now let's define what elements within our project we want to display within our schedule. To do this, set the Criteria as "Element Type" and "Is," and the Value to "Roof."
Click the Add button to add a new criteria so that we can define the Element Type in further detail. Select the "Top Material" option as a Criteria to represent the Roof material surface for the building. Then set the Value of the material to "SS | GreenGrid Vegetated Roof" that you created earlier.
If you want to track additional roof materials, repeat the above step for the Value and after each material added, set the and/or option to "or."
Step 4: Configure the Fields within the Scheme Settings
Next, we need to establish what type of data to display based on the criteria we specified above. In this step, we will set the Fields that will be displayed within the Interactive Schedule. With the Scheme Settings dialog still open, click the Fields tab to view the Available Parameters we can use as fields.
We will add three parameters to the Schedule Fields as follows: Quantity, Top Material and Top Surface. To do this, click the General parameters option in the Available Parameters, click the Quantity parameter, and click the Add button at the bottom of the dialog to add it to the Schedule Fields.
Next, click the Roof parameters option in the Available Parameters, click the Top Material parameter and click the Add button at the bottom of the dialog to add it to the Schedule Fields. Repeat this step for the Top Surface material directly below the Top Material.
Finally, click the Top Surface field in the Schedule Fields column and click the Sum button to total the calculated roof surfaces. The schedule to calculate the roof surfaces for green roof materials is now complete. Click the OK button to finish the schedule.
Step 5: View the Interactive Schedule
You can now assign the green roof material to roofs within your project and then view the Green Roofs schedule from the following menu: Document > Schedules & Lists > Schedules > SS 7.2 Reduce Heat Islands, Green Roofs.
The Interactive Schedule will open and display the three fields you created, along with the details for each green roof element within your project, based on the material you specified in the criteria.
Step 6: Compare to Total Roof Surface Area
To determine whether your project meets the LEED requirement of "green roof system covers at least 50 percent of the total roof area," you will need to create a second schedule that calculates the total roof surface area. To do this, follow the same steps above to create the Green Roofs schedule with the following changes.
Open the Scheme Settings, select the "SS 7.2 Reduce Heat Islands, Green Roofs" you created above, and click the Duplicate button. Change the name to "Reduce Heat Islands, Total Roofs" and click the OK button when finished.
In the Criteria tab, select the Top Material criteria and click the Remove button. Now click the OK button to complete the second schedule.
To view the total roof schedule, select the name from the following menu: Document > Schedules & Lists > Schedules > SS 7.2 Reduce Heat Islands, Total Roofs.
Now you can compare the calculated results of the two schedules to determine if the green roof surface area calculated in the first schedule is 50 percent or more of the total roof surface area calculated in the second schedule. Thus, in the example presented here, 6,030 square feet divided by 11,665 square feet shows that the green roof is 51.6 percent of the total roof area.
If we use the data from a BIM model, we can decrease the time that is necessary to create the required LEED calculations and realize greater accuracy. However, using ArchiCAD for "Sustainable Site" calculation is only one way to exploit the power of BIM for LEED certification. In actuality, there are several ways ArchiCAD can be used within the LEED calculation and management process.
For example, the following are methods taught recently during an online training series focused specifically on LEED credit management, calculations, and energy evaluation:
- Organizing the LEED Documentation
- Managing an Interactive LEED Credits Checklist Schedule
- Creating Calculations for LEED Credits:
- Materials & Resources Calculations
- Water Efficiency Calculations
- Building Reuse Calculations
- Daylight & View Study Calculations
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Thomas M. Simmons is the founder of ARCHVISTA, Inc. and LearnVirtual, and was formerly the director of technology at EHDD Architecture in San Francisco. He has authored several books on building information modeling, ArchiCAD, and architectural technology, and has spoken at major industry events. He has an M.Arch from UC Berkeley and a bachelor of environmental design from Texas A&M University.
This article is excerpted from Issue #52 of AECbytes Tips and Tricks (July 20, 2010), with permission of the publisher, AECbytes.