Analysis of Energy Efficiency Measures in Rehabilitation of Multifamily Housing Units

Abstract

An apartment building in Austin, Texas, and one in Boston, Massachusetts, were analyzed to determine the cost-effectiveness of energy efficiency measures. To determine expected energy and cost savings resulting from a set of proposed retrofit measures, hour-by-hour simulations were conducted using the DOE-2.1C building energy analysis computer program. Based on detailed audit data, supplemented by field-measurements in the case of the Austin apartment building, the simulations were run for base case (preretrofit) conditions for each building. Metered electricity and gas consumption was used to calibrate the input data. A series of proposed retrofit measures was run for each building using the calibrated preretrofit model as the reference. Annual energy and cost savings were calculated separately for each measure and for the combined set of measures. For the Austin building the combined set of 11 measures yielded expected savings of $3,710/year, a 42% savings in site energy. The combination of the 7 measures considered for the Boston building yielded expected savings of $1.292/year, and annual energy savings of nearly 75%. Measured in situ air conditioner performance for two of the Austin apartments showed EERs of 5.70 and 5.55, indicating an efficiency degradation of 22% and 24%, respectively, after 16 years of operation.