Council backs heat pumps

Press, 4 October 1977, Page 10

Council backs heat pumps

Heat pumps, which extract heat from a stream or the soil outside to warm the inside of the house, and use far less electricity than conventional heaters, appear to be an attractive proposition in the colder parts of New Zealand, according to the annual report of the Clear Air Council.

The report expresses concern at the delays in establishing a clear-air zone in Christchurch and suggests that the lack of a comprehensive and equitable energy policy has stultified efforts to control Christchurch’s air-pollution problem. Electricity is the preferred alternative to coalburning open fires because it is clean, convenient, and almost universally available.

“The more economically electricity is used in households the more secure is its future use for domestic space and water heating. The device which offers the most promise in contributing to this end is the electrically - driven heat pump.” A heat pump is like a refrigerator run in reverse. It transfers heat by evaporating and condensing a working fluid. Used for domestic heating and, according to operating conditions, it can pump two or three units of heat into the house for every unit of electricity used to drive it, the additional heat

being extracted from the atmosphere, the soil, surface water, or the water table. Solar energy can be used in combination with the heat pump. Early heat pumps often broke down but more reliable models have been marketed and pumps designed for domestic heating are expected soon, the report says.

The report quotes from a study entitled “The Feasibility of Heat Pumps for Residential Space Heating in New Zealand,” by R. A. Shaw and J. Stephenson, of the University of Auckland.

This study, commissioned by the Energy Research and Development Committee, concluded that the seasonal coefficient of performance — the ratio of heat energy output to electrical energy input — of a suitable domestic-heating heat pump is of the order of 2.5 under New Zealand conditions.

For the heat pump to show economic advantage over its relatively low-cost electrical resistance heater competitor, its high operational efficiency must more than compensate for its relatively high capital cost. Comparison is complicated by the need to supplement the output of an economically-sized heat pump to provide full comfort conditions when the outside temperature falls below that at which the heat pump can satisfy the house heating load.