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Faded Green? A Post Occupancy Study of Green Homes

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Principal Investigator/Project Leader: 
Department of Project: 
Department of Environmental Conservation
Project Description: 

Sustainable design and construction techniques for the United States housing sector are the most economically-effective strategies for preserving natural resources, reducing greenhouse gas emissions, and creating future energy security. More than 90-percent of the housing built in the Northeast is constructed from wood harvested from forests in New England. In the United States, 55-percent of timber production goes into the production of buildings. This embodied energy as well as the operational energy from lighting, heating, and cooling homes accounts for almost half of all environmental impacts in the United States (EPA 2002). These impacts are projected to become more significant as building construction increases. Efforts are being made by builders, engineers, and architects to reduce the environmental impact of buildings to meet the challenges of climate change and energy security. Issues related to building energy conservation, indoor air quality, and renewable energy sources are becoming priorities in  residential home-building.

A growing number of owners and developers now use third-party national certification programs like that of the United States Green Building Council's 'LEED' Rating System to design, construct, and market high performance homes. However, there is little certainty that a green home design will be a green home in operation (Wedding et al. 2007). This is because 'LEED for Homes' does not require post-occupancy evaluations and commissioning at least one year after after occupancy. As a result, certification is based on the predictions of the delivery team rather than actual operations and maintenance data. It has been widely argued that a home that has been designed according to LEED green building standards may not necessarily be sustainable unless the systems operations and maintenance are tuned up and owners are trained to manage their energy use over time (Gifford 2009). The most accurate way to determine the environmental impact of a home is by conducting a post-occupancy audit, one to two years after it has been constructed and occupied.

In this research, we will conduct environmental audits of fourteen LEED-certified homes in New England at least twelve months after they were built and occupied. We will evaluate our findings by comparing baseline (predicted) performance data (LEED documentation) with actual operational data (our field data) in order to identify the issues that effect green to gray fading. For future research, we will expand our study to include green certified homes in other climate zones, as well as develop an auditing protocol and evaluation strategy for LEED-certified commercial buildings, schools, and multifamily housing projects. Finally, we will create a searchable online database of our findings to educate the public about green building design and construction strategies, offer feedback about technologies and systems that are effective, and make recommendations about how to improve green rating systems such as LEED.

Energy topics: 
Renewable Heating and Cooling