LEED 2009 Recertification of Existing Buildings: Bonus Effect

This study aimed to assess the impact of a four-point bonus system on recertification in Leadership in Energy and Environmental Design for Existing Buildings (LEED-EB) 2009 office space projects in four metropolitan cities: Washington, DC, Chicago, New York, and San Francisco. We analyzed 123 paired LEED-EB 2009 projects where each pair (i.e., certification–recertification) was used on the same building. The percentage of average score was used to evaluate differences in certification–recertification strategies: (1) gold-gold with and without the bonus, (2) silver-gold with and without the bonus, and (3) platinum-platinum with the bonus. The replication method was used to evaluate the overall tendency for four metropolitan cities. We found that while LEED-EB 2009 projects used a four-point recertification bonus, achievements in the materials and resources (MR) and indoor environmental quality (EQ) categories declined in each of the four metropolitan cities. We identified this overall tendency at three levels of certification–recertification: gold-gold, silver-gold, and platinum-platinum. We hypothesized that if the use of a four-point recertification bonus in LEED-EB 2009 projects resulted in lower achievements in the MR/EQ categories, then the use of the 10-point recertification bonus in LEED-EB 4.1 projects could lead to a deterioration in the sustainability of existing office buildings.