Simplifying LEED through the use of BIM software.

The use of BIM (Building Information Modeling) software in the design and construction industry has significantly increased over the last 15 years. This tool has been a great aid, helping conceptualize buildings in a three-dimensional way. It allows various team members to see where design features might conflict and cause problems. The use of BIM on LEED (Leadership in Energy and Environmental Design) projects can be invaluable to speed up the process of gathering data for LEEDonline submissions. BIM software provides a platform that keeps data consistent across the project between the various players regarding sustainability measures. This article explores how the use of BIM software is huge benefit for LEED projects.

BIM is a digital representation of physical and functional characteristics of a facility. BIM also is a shared knowledge resource for information about a facility, forming a reliable basis for decisions during its life- cycle; defined as existing from earliest conception to demolition¹. LEED is a certification system that looks at sustainability measures in building design and construction in several categories. A point system or scorecard is used to track the degree of implementation of the various measures. The scorecard provides a final number rating the structure for overall sustainability in seven categories; Location and Transportation, Sustainable Sites, Water Efficiency, Energy & Atmosphere, Material & Resources, Indoor Environmental Quality, and Innovation.

In order to use BIM software for LEED projects the relevant data has to be entered into a BIM software program (ArchiCAD, Revit). Schedules must be created to define the various building elements related to sustainability. Using the LEED scorecard in the software can help all members of the project team track sustainability measures (prerequisites and credits) being utilized². Information such as furniture elements, building envelope structural elements, plumbing fixture information, and rooftop structures can be included, all of which have an impact on LEED credits. This data can then be exported to computer simulation models and spreadsheets. These are used to calculate information for LEED credits. In many cases, however additional software may have to be employed to export the data into modeling software. There are three areas where the use of BIM software is particularly helpful for LEED.

The first of these areas is related to the Water Efficiency prerequisite and credit for Indoor Water Use Reduction. This prerequisite and credit require plumbing fixture information. A schedule can be created in the BIM software for the required data of the prerequisite and credit. For example, user types need to be created as part of this prerequisite and credit. Also, a list of all the plumbing fixtures and their flow rates needs to be included. Once these schedules are created, data can be exported into a spreadsheet and used to create a water reduction plan. Suppliers such as Toto and Kohler provide BIM objects which contain LEED-related data to help make this process easier³.

Energy modeling can also be simplified with the use of BIM software. The LEED prerequisite Minimum Energy Performance and credit Optimize Energy Performance are very important in the LEED certification process for projects if they use the energy model option. A total of 18 points can be gainedwith the credit. In many cases this is 20 percent of a project’s overall point score. In traditional energymodeling software, structural geometry and air-conditioning zones need to be input directly. By creating this information in BIM schedules, a significant amount of time can be saved in the energy modeling process. With most energy modeling software packages, the architectural geometry needs to be manually created. Being able to export data from BIM software eliminates this process. Most software allows you to do you error checks to see if spaces are duplicated and if building dimensions don’t match up.

It is also possible to export some data from programs like Revit into other software as a cross-check. Errors can be quickly detected and corrected in this way. Also air-conditioning zoning is a big part of the calculations for this process. Air-conditioning zones can be color-coded*4. This makes it easier to match up similar zone types. and see how the building is zoned hierarchically. Additionally, schedules can be created for process equipment, air-conditioning elements, and lighting which can be easily exported into the energy modeling software.

Lastly, we will explore how BIM software can have an impact on the IEQ (Indoor Environmental Quality) category. The prerequisite Minimum Indoor Air Quality Performance and credit Enhanced Indoor Air Quality Strategies require a lot of information about the ventilation, building population density, air flow rates, and building spaces. This information, the room area sizes, fan coil unit information, flow rate requirement per space can be added into a BIM software schedule. This data then can all be exported into a spreadsheet that will in turn plug into the LEED Calculator used for this prerequisite and credit. Some script writing and coding may be needed to translate this data into the spreadsheet formulas. The calculator will check if each space is in flow-rate compliance with the ASHRAE 62.1 Standard it is based on. If this is done during the design stage, decisions can be made to change equipment if some areas do not meet compliance.

In conclusion, if you want to make your LEED life easier, BIM software can be invaluable for saving the time required to gather data for LEED online and the its related modeling software. The process is not always smooth. Using BIM software will always require that data needs to be exported. It will be important to cross-check the information and its integration into the modeling software. The time saved, despite these challenges makes the use of BIM for LEED worth it. The process of gathering information for LEED submission can be challenging, so any improvement in gathering more information quickly is very useful.

1. Frequently Asked Questions About the National BIM Standard-United States – National BIM Standard – United States”, www.Nationalbimstandard.org, 17 October 2014.

2. LEED calculations with BIM, New York City Revit Users Group, April 2012, Amy Patel, https://www.meetup.com/NYC-RUG/events/39508552/

3. LEED calculations with BIM, New York City Revit Users Group, April 2012, Amy Patel, https://www.meetup.com/NYC-RUG/events/39508552/

4. A Study on the LEED Energy Simulation Process Using BIM, MDPI, Han-Soo Ryu – ERM Korea Co., Ltd., and Kyung-Soon Park – Dong-Eui University, 2 February 2016

Additional References:
1. BIM and sustainability concepts in construction projects: A Case Study, Istanbul Technical University, Bahriye Ilhan, Hakan Yaman,