Five Years Later: Second Round Institutional Energy Retrofit Analysis Procedure

This paper provides a continuation of the results and efforts to continuously maintain and use a fleet of 120 detailed Building Energy Models (BEM) of the Sandia National Laboratories New Mexico and California sites. The fleet has continued to be used in new applications beyond its 1st round of site-wide energy retrofit and climate assessments in 2014-2017. These include resilient energy systems assessments in 2018-2019 and institutional peak electric load characterization in 2020. The most recent work is a 2nd round site-wide energy retrofit assessment that is being planned. This paper shows the 10 step procedure planned for this 2^nd assessment and contrasts it to the 1st round of institutional energy retrofit analyses. The procedure involves calculating difference metrics between the various steps in the procedure that highlight the accuracy of the energy retrofit decisions being made. Here, energy retrofit decisions involve deciding what specific building and energy retrofit is the next best choice based on metrics such as total energy saved, carbon offset, or energy cost savings minus the energy retrofit implementation cost. The first difference metric ∆₁₁ assesses the robustness of energy retrofit decisions with respect to historical, climate change, and extreme event weather futures, the second ∆₁₅ assesses the robustness of energy retrofit decisions by comparing results before and after BEM calibration. This provides information that helps to show if the retrofit is very sensitive to other BEM input parameters that are also uncertain. The third metric ∆₁₉ involves empirical validation of energy savings or other metrics used based on actual metered results. A demonstration of calculating ∆₁₁ shows how important climate and future weather is to energy retrofit decisions for a 96 BEM study with 2 energy retrofits involving roof insulation and external wall insulation. Weather files for 2017-2020, Typical Meteorologic Year 3 (TMY3), and 3 extreme event scenarios were included for different weather futures. The results show that variations in energy savings are significant and the optimal decision set with baseline year 2020 is only stable to 30 decisions of the 192 potential energy retrofit decisions. This shows that using a single weather future is likely to lead to sub-optimal choices.