Plan for evaluation of Austin Energy Green Building’s Multifamily Rating Program

Sammanfattning: Austin Energy Green Building (AEGB) started their multifamily rating program in 1999. It is a green building program where participants can receive different ratings, 1-5 stars, depending on how many requirements the building fulfills. AEGB wants to evaluate the projected energy and demand savings from the multifamily program to be able to report to Austin Energy at the end of the fiscal year. Buildings going through the multifamily rating program can either use a prescriptive approach or a performance approach. For the prescriptive approach the savings are evaluated with the help of a deemed savings value. For the performance approach the participant needs to turn in an energy model of the proposed buildings with modeled projected energy and demand savings. The purpose of this degree project was to develop a plan for evaluation of the projected savings from the multifamily rating program.  AEGB will need to be able to compare the projected energy and demand savings with the actual energy and demand savings from the buildings that have gone through the program. Focus has been on finding a suitable evaluation approach, based on the available data. Criteria for inclusion were determined. Evaluation of all buildings is not be possible and therefore a sample size needed to be determined for the population. The projected energy savings data was analyzed. A way to account for apartments without full year use data was studied as well as common criteria for uncertainty analysis. It was suggested that one year of full energy use data was enough as criterion for buildings to be a part of the population to be evaluated, which gave a population size of 29 buildings.  of the buildings received a 1-3 star rating and they account for about  or  of the projected energy savings. If a simple random sample is used with a confidence level of  and  relative precision the sample will be 21 buildings. If the relative precision is changed to  the sample will contain 11 buildings. Another option is to use stratified random sample, and sample sizes were calculated by star rating and size of the buildings. A number of different ways of accounting for vacant units were found however the latest vacancy rate for multifamily buildings in Austin was . This corresponds to about  in lost projected energy savings for the buildings that have gone through AEGB’s multifamily program. Lastly, post occupancy evaluation (POE) will be recommended for this evaluation effort of AEGB’s multifamily program.