Estimating thermal performance and energy saving potential of residential buildings using utility bills

The objective of this study is to provide a practical method for estimating the energy saving potential of residential buildings using utility bills that are relatively easy to obtain from occupied buildings. The building characteristics and utility bills for three years, 2009-2011, were sampled from 128 apartment complexes, including 52,731 individual housing units. The utility billing data contain the monthly energy use of electricity, natural gas, and district heat for each complex. The energy uses of each complex were characterized using change-point linear regression models which described energy use as a function of monthly outdoor temperature and statistical parameters. The change-point models are statistically well fitted with actual monthly energy use, and the parameters of the models are capable of characterizing the energy use of residential buildings with hydronic radiant floor heating equipment. From the results, significant opportunities for space heating energy saving are identified in the sample complexes. The most sensitive and informative parameter for space heating energy saving is heating slope. The heating slope can represent the heat loss from the envelope and the efficiency of space heating. The method developed in this study can help to quantify the thermal performance of residential buildings, and also to identify the best type of energy efficiency opportunity. (C) 2015 Elsevier B.V. All rights reserved.