LEED-NCV3 silver and gold certified projects in the US: An observational study

The Leadership in Energy and Environmental Design (LEED) rating system has been widely used in the US. However, until now, there has been no clear understanding of the strategies that should be used to make the transition from Silver to Gold certified projects. The aim of this study was to determine the trends in certified projects for both Silver and Gold LEED for New Construction and Major Renovations (LEED-NCv3) in 2016. Three performances, including (i) certification, (ii) category/subcat-egory/sub-subcategory certification, and (iii) cross-certification, were evaluated for both Silver and Gold LEED-NCv3 certified projects. For an ordinal measurement scale, a two-tailed Mann-Whitney U test was used. For a ratio measurement scale, an unpaired two-tailed t-test was used. If eight or more Silver and Gold certified projects occurred in the same state, then the state was selected for statistical analysis. As a result, ten states were selected. The following was revealed: (i) low certification performances for both Silver and Gold; (ii) high category performance for Sustainable Sites and Innovation in Design and low category performance for Energy and Atmosphere for both Silver and Gold projects; and (iii) three different strategies of certified projects in transition from Silver to Gold that include (a) energy-emphasized (e.g., CA), (b) non-energy-emphasized (e.g., NY), and (c) integrated (e.g., GA) strategies. We speculate that the possible reasons for such deviations in the decision strategies were due to differences between the adopted ASHRAE 90.1 standards (ASHRAE Standard 90.1 2007 or ASHRAE Standard 90.1 2010) in each of the states.