METHODOLOGY FOR ANALYZING THE TECHNICAL POTENTIAL FOR ENERGY PERFORMANCE IN THE U.S. COMMERCIAL BUILDINGS SECTOR WITH DETAILED ENERGY MODELING

This paper summarizes a methodology for developing quantitative answers to the question, “How low can energy use go within the commercial buildings sector?” The basic process is to take each building in the 1999 CBECS public use data files and create a baseline building energy model for it as if it were being built new in 2005 with code-minimum energy performance. The 1999 CBECS data form a statistical model of the commercial buildings sector by using a set of 5,430 buildings with weighting factors to indicate how many more such buildings are represented by each member. For each building, we used 1999 CBECS data on floor area, number of floors, census division, basic climatic design criteria, principal building activity, and number of employees. The expanded building descriptions needed for detailed energy modeling with EnergyPlus were generated by applying ASHRAE Standard 90.1-2004 and augmenting with data from Huang and Franconi (1999), probabilistic assignments, and other assumptions. The technical potential of energy design measures, for the sector as a whole, were then evaluated by altering and rerunning the energy models, comparing perturbed results to each baseline, and then aggregating performance metrics. The primary benefit of the method is that the CBECS weighting factors provide a robust way of aggregating national results from simulations of individual buildings. However, it is also challenging because it requires considerable computing resources. The methodology is recommended for future analyses when the results must properly reflect the national implications and when only a limited number of scenarios need to be investigated.