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An Evaluation of Energy-Saving Retrofits from the Texas LoanSTAR Program
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This report discusses the LoanSTAR retrofit savings through December 1993 with an emphasis on the Constant Volume to Variable Air Volume air-handler retrofits. The report also summarizes several key findings about the LoanSTAR program which has 70 sites monitored as of December 1993.
DescriptionBy December 1993, on average, the retrofits in the LoanSTAR program were performing within the expectations of the energy audits as indicated which speaks well of the value of the effort to monitor the savings and feedback the results to the participating agencies. For certain of the sites the retrofits out-performed the estimates by substantial margins (as much as 3 times the estimates), whereas in some cases almost no savings occurred. On average the estimated paybacks of 3.8 years are in the same range as the measured paybacks of 5.06 years. The average investment for the agencies with completed retrofits as of December 1993 was $2.43 per square foot with the largest majority of sites in the $2 to $3 per square foot range. Thirteen sites which contained Constant Volume to Variable Air Volume air-handler retrofits were further evaluated to determine why some sites were good performers and why some were not. A detailed analysis of the hourly before/after air-handler electricity consumption indicates that fan over-sizing plays a major role in the cost effectiveness of these retrofits. In the performing sites the fan over-sizing was 3 to 6 times what is needed by the VAV system in the post-retrofit period. In the non-performing sites the fan oversizing was about 2 times what the VAV system uses in the post-retrofit period.
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Haberl, J. S.; Claridge, D. E.; Heneghan, T.; Sieggreen, R.; Sims, J. (1996). An Evaluation of Energy-Saving Retrofits from the Texas LoanSTAR Program. Energy Systems Laboratory (http://esl.tamu.edu), Texas A&M University; Department of Mechanical Engineering, Texas A&M University. Available electronically from