Results from a recent Alliance for Environmental Sustainability (AES) research project suggest that Leadership in Energy and Environmental Design (LEED)-certified homes are substantially more energy efficient than their traditional counterparts.
In a newly-released report, AES analyzed data from LEED-certified homes in the Midwest found that the homes averaged 40 percent less energy use and utility costs per year when compared to conventional homes. From January through June 2010, AES collected building energy performance data for research on the energy efficiency of homes certified to the LEED rating system.
The research compiled information from pre-occupancy energy modeling of 144 LEED-certified projects that were located in the Midwest from climate zones ranging as far south as Cincinnati to as far north as Minneapolis. The data indicated numerous advantages in energy reduction and costs in these homes compared to baseline average homes measured by the same energy modeling system, according to AES.
"All data is based on comparing pre-occupancy computer modeling data of LEED homes against non-LEED homes with a Home Energy Rating System (HERS) score of 100 and does not in any way represent post-occupancy performance or actual savings realized through any home utility bills," AES stated. "KWh [Kilowatt-hours] and CCF [100 cubic feet] savings results may be skewed by unique systems installed on various homes such as renewable energy, geothermal heating/cooling, propane, electric heating (water heating), and average regional energy prices."
The report does not cover the full benefits of a LEED-certified house because it only focuses on energy relating to electricity in kilowatt-hours and heating in CCFs. Benefits not addressed include a home's water reduction, biodiversity, reduced risk of sick home syndrome, improved quality of life and comfort, reduced waste sent to the landfill, reduced urban sprawl, and many other benefits associated with a LEED certified home.
Energy modeling was performed individually by the energy rater for each home, and in its nature is only a predictor of the building design case compared to the typical behavioral use patterns in the typical home in the typical climate zone, so true performance rates will vary.
After aggregating the data across all 144 LEED-certified homes, trends started to emerge. Homes that received the LEED for Homes third-party green building certification saved 38 percent in energy use and 42 percent in costs, with the following specific breakdown:
- 28 percent less kWhs with 32 percent electricity savings.
- 48 percent less CCFs with 51 percent heating savings.
- 7 pounds of carbon-dioxide emissions reduced.
- 38 pounds of sulfur-dioxide emissions reduced.
- 28 pounds of nitrous-oxide emissions reduced.
AES then isolated groups to compare performance across different LEED certification levels:
- LEED Platinum homes saw, on average, a 41 percent savings in total energy consumed and a 46 percent savings in total costs incurred.
- LEED Gold-certified homes save 46 percent in energy use and 42 percent in costs.
- LEED Silver-certified save 29 percent in energy use and 24 percent in costs.
- Standard LEED-certified homes save 30 percent in energy use and 30 percent in costs.
"We see ... that a LEED-certified home will be in a better position when it comes to the consumption of energy, whether it be electricity or gas," AES said. "By extension, these certified green homes also will be in a better financial position, as the home will render less operational costs to its owner."