- Jan 16, 2009
It’s Top Ten season again. That means sustainable design metrics have been tracked across the country and will be submitted soon for this year’s green project awards. One metric, the Environmental Protection Agency’s energy performance rating, is the key measure of commercial projects’ energy use and greenhouse gas emissions. Portfolio Manager is the tool of choice for operating projects, and also serves as the energy metric for the Leadership in Energy and Environmental Design Existing Buildings designation. It allows users to track multiple energy and water meters for a facility. The system benchmarks monthly utility data against past performance and compares it with weather-normalized information from around the country.This latter feature is unique in giving designers and owners a relative sense of how well their building is operating. The concept is fairly simple but quite powerful in the analysis. Every four years, the U.S. Department of Energy conducts a survey called Commercial Buildings Energy Consumption Survey (CBECS). The data set represents more than 5,000 buildings with a wide range of functions, locations, sizes, ages, operating schedules, et cetera–a statistically significant sample of the U.S. building stock. To review this data, the EPA established key energy drivers that are incorporated into Portfolio Manager and customized for each space type. Analysis of this data yields a 1-to-100 rating system that assigns a percentile to a project’s energy performance, as compared with CBECS data. Thus, a building that achieves a rating of 85 is among the top 15 percent of similar facilities’ performance. This rating is calculated from source energy, which accounts for transmission and distribution losses in a building’s fuel mix. Buildings that exceed a rating of 75 over 12 consecutive months are eligible to earn the ENERGY STAR label.The space types that can receive an EPA rating in Portfolio Manager are:• Banks/Financial Institutions• Courthouses• Hospitals (acute care and children’s)• Hotels and Motels• K-12 Schools• Medical Offices• Offices• Residence Halls/Dormitories• Retail Stores• Supermarkets• Warehouses (refrigerated and non-refrigerated)• Wastewater Treatment PlantsPortfolio Manager users can share building data with other users, one at a time, and the ENERGY STAR web site showcases labeled buildings and publishes aggregate annual savings. In 2007, EPA reported 1,400 buildings that earned the ENERGY STAR label, up 25 percent from 2006.Jared Silliker is a member of the American Institute of Architects Committee on the Environment, an associate at environmental consulting firm The Cadmus Group and a sustainable business MBA graduate at the Bainbridge Graduate Institute in Seattle.