BA-92-03-2 -- Energy Performance of Heat Pumps in New Commercial Buildings in the Pacific Northwest PDF

Reviews the performance of efficient heat pumps in new commercial buildings in the Pacific Northwest. The objective of the analysis is to explore differences between modelled and monitored heat pump performance and to examine the performance of high-COP heat pumps. A detailed case study compares hourly monitored heat pump data to results from a DOE-2.1C computer simulation model. Design predictions and heat pump characteristics are presented for five small buildings. The simulation overestimated fan energy use since, unlike in the actual building, the fan is modelled as "on" for full-hour increments. In general, the measured coefficient of performance (COP) values show that the heat pumps are operating well, averaging slightly higher than the modelled average. The measured COP is within 10% of the average measured COP for the majority of the hours. It was found that the need to control and minimise the use of supplemental electric resistance heat can be as important as the use of efficient heat pumps. In the case study building, ramp-up thermostats could have reduced electricity used for morning warmup and lowered the peak electric demand. The average COP investigations suggest that as an alternative to detailed modelling, analysts interested in evaluating the actual energy impacts of efficiency improvements in occupied buildings should consider basing results on short-term monitoring. Reviews a simplified evaluation of the energy savings from high-COP heat pumps based on annual compressor energy use and average COP values. At a minimum, simple instrumentation to disaggregate compressor and resistance heat energy use can provide useful data to evaluate actual heat pump energy performance.

KEYWORDS: energy consumption, electricity consumption, heat pumps, performance, commercial, buildings, USA, coefficient of performance, calculating, monitoring, comparing, case studies, computer programs, designing, properties, fans, measuring, energy conservation, compressors