$olarEnergy Vol. 28, No. 3, pp. 217-226, 1982 O03g-O92X1821030217-10503.0010 Printed in Great Britain. Pergamon Press Ltd, A COMPARATIVE STUDY OF SOLAR ASSISTED HEAT PUMP SYSTEMS FOR CANADIAN LOCATIONS M. CHANDRASHEKAR, N. T. LE, H. F. SULLIVAN and K. G. T. HOLLANDS University of Waterloo,Waterloo, Ontario, Canada, N2L 3G1 (Received 27 October 1980; revision accepted 24 July 1981) Abstract--The feasibilityof solar assisted heat pump systems for space heating and domestic hot water preheating in Canada is examined by simulating the performance of these systems on a computer using the program WATSUN. Simulationsare carried out using meteorologicaldata for seven representative Canadian cities, two different buildingtypes, and six types of system configurations. For the solar assisted heat pump system, twenty year life cycle cost comparisons are made with two reference systems, namely a conventionalresistance heating system and an air-to-air heat pump system, based on current economic parameters and projected escalation scenarios for electricity rates. Results of the study show that the solar assisted heat pump systems conserve significantamounts of energy over resistance heating and heat pump systems. On the life cycle unit cost basis, solar assisted heat pump system costs are relatively insensitive to location, but the dependence on building types is substantial with multiplex dwellings showing the least cost. Liquid based dual source solar assisted heat pump systems are found to be cost effective over resistance heating (but not over an air-to-air heat pump system) at some of the locations for multiplexunits. They are not cost effectivefor single family dwellingsat the present time. 1. INTRODUCTION There has been considerable interest shown in solar assisted heat pump (SAHP) systems in recent years [1-5]. The objective of the present study is to carry out detailed simulation of a number of SAHP system configurations at a number of climatically representative Canadian cities for two different building types. The study addresses both the energy and economic aspects of solar assisted heat pump systems in comparison with two reference systems, namely, the conventional electric resistance heating system (baseboard electric) and the air-to-air heat pump system. The sensitivity of the sys- tems to variations in such parameter values as collector covers, heat pump capacity, storage volume and economic parameters is also investigated. The original WATSUN computer program [8] was modified to include heat pumps. The original strategy, namely an hour by hour simulation of the dynamic behaviour of the system driven by hourly meteorological data, space heating demand, internal gain, direct solar gain and hot water demand schedules, is retained. Based on the system configuration and the operating strategy, the hour by hour energy quantities are accumulated and displayed on a daily, monthly or yearly basis. Such data permit the energy comparisons for various solar assisted heat pump systems with the selected reference systems. Models are used to calculate both capital costs and yearly operating costs and to express these costs in terms of present values normalized per unit of energy. The comparisons are made for an assumed system life of 20yr. The additional assumptions which this entails (namely, required yearly maintenance, inflation rate, cost of borrowing money, cost of electricity, etc.) place an uncertainty on the economic data calculated. Recogniz- ing these limitations, the authors have attempted to use the best available information and to fully document the assumptions used [6]. The two building types investigated are the single family and the 10-unit multiplex dwellings. The selected cities for the study are Vancouver, Edmonton, Winnipeg, Toronto, Ottawa, Montreal and Fredericton. The six SAHP system configurations are shown in Fig. 1 and include liquid-based SAHP systems using parallel, series, dual source and dual storage configurations (Sys- tems 1, 2, 5, 6) and air-based parallel and dual source configurations (Systems 3 and 4). Since a previous study[7, 8] had identified Winnipeg and Vancouver as representing the extremes in terms of the effect of meteorological data on solar systems, the first series of simulations involved all six SAHP systems but only these two cities. After narrowing the number of system types to air and liquid-based dual source systems, the effect of other parameters such as geographic loca- tion, collector performance, building type, etc. are in- vestigated. The study is constrained to look at the energy demands for space heating and domestic hot water loads, and energy requirements for cooling are outside the bounds of this study primarily because msot locations in Canada do not require residential cooling. 2. METHOD OFANALYSIS AND DATA The WATSUN program consists of a number of modular subroutines which simulate particular solar heating system configurations and operating strategy; they make use of other subroutines which contain solar component models, (e.g. flat plate collectors, liquid and rock bed storage, heat pump, etc.) and codes for in- put/output, meteorological data processing, and economic analysis. 217