Determining a Community Retrofit Strategy for the Aging Housing Stock Using Utility and Assessor Data

Residential buildings account for about 21.5% of the nation’s primary energy consumption and carbon emissions, and about 38% of electricity use. The housing stock in the United States consists of over 128 million residences with over 60% being constructed prior to 1979 when building codes and regulations began standardizing building practices. Seeking an opportunity to understand and reduce consumption, the scientific community developed a number of model-driven auditing software. While these computer models have been successful in predicting usage patterns in newer residential structures, they have been inaccurate in predicting and analyzing energy use in aging housing stock, predominantly homes built prior to 1979. The problem then remains how these homes should be retrofitted and what is the best approach in analyzing and understanding consumption patterns, especially those that consume an inappropriate amount of energy. Using a rural community in Iowa, 480 older homes were used to expand on the scientific research of residential energy consumption and usage patterns. Analysis was accomplished using a three step process. First, historical utility data was paired with assessor data to identify BTU per Square Footage rankings using a multiple regression analysis together with the stepwise regression. Second, a qualitative survey was administered to identify homeowner perception and current usage patterns. Lastly, the building envelope on existing homes was tested to determine air exchanges per hour to the actual energy used. The statistical analysis inferred the necessity of using actual historical utility data when determining the current home energy usage instead of computer simulation models. Older homes show no significant commonalities in regards to style, year built, condition, and/or appraised cost that would allow a precise computer modeled approach to energy savings calculations. The perception survey results supported previous research concluding awareness of energy efficiency techniques may actually lower base utility consumption. The on-site analysis indicated the building envelope provided the best opportunity for permanent improvement in comparison to other energy offender solutions; however, it was determined that more research is needed on the use of blower door and effective building envelope improvements. Even so, strategies were developed to address the challenges of residential energy offenders. It was concluded that actual historical data has a higher potential to be more accurate when trying to understand energy consumption and patterns. Adviser: Charles W. Berryma