Design Approach and Performance Analysis of a Small Integrated Heat Pump (IHP) for Net Zero Energy Homes (NEH)

This paper describes the design and performance analysis of a variable-capacity heat pump system developed for a small [1800ft (167 m)] prototype net ZEH with an average design cooling load of 1.25 tons (4.4 kW) in five selected US climates. The heat pump integrates space heating and cooling, water heating, ventilation, and humidity control (humidification and dehumidification) functions into a single integrated heat pump (IHP) unit. The design approach uses one small variable-capacity compressor to meet all the above functions in an energy efficient manner. Modal performance comparisons to an earlier IHP product are shown relative to the proposed new design for net ZEH application. The annual performance analysis approach using TRNSYS in conjunction with the ORNL Heat Pump Design Model is discussed. Annual performance projections for a range of locations are compared to those of a base system consisting of separate pieces of equipment to perform the same functions. The ZEH IHP is projected to reduce energy use for space heating & cooling, water heating, dehumidification, and ventilation for a net ZEH by about 50% compared to that of the base system.