Solar heating is still lukewarm

Press, 19 August 1981, Page 23

Solar heating is still lukewarm

By

PRUDENCE GREGORY

7 , information section,

Ministry of Works and Development

Home-owners and businessmen alike have mostly hesitated to commit themselves to solar heating in New Zealand, despite rising electricity prices and warnings of shortages if the country has a couple of low rainfall years before various new energy schemes come into full production.

The reluctance is understandable. New Zealand’s is a highly mobile population, and when the more innovative age groups within it do decide to stay put and buy a home, they tend not to be interested in improvements like solar heating, with what is known as a long “payback” period; they want a fast return on their money, as does the businessman. Manufacturers are aware of this and say that solar heating panels, properly installed, need not involve a long pay-back period and do give a good return on capital investment.

Still, people hesitate, with the exception of an agency which has provided solar heating that works effectively in a whole range of buildings all over the country. They include Penrose High School in Auckland, the McLean Building in Napier, the Northland Technical Institute, the Courtenay Place Telephone Exchange in Wellington, Gisborne’s government workshops? The agency concerned is the Ministry of Works and Development whose policy is to install solar water heating in all government buildings when funds are available. M.W.D.’s mechanical engineers have been working to

develop solar energy for not much’more than 10 years, which means they regard the necessary engineering techniques as being still in their infancy. All the same, they are “into” solar energy to get experience, so that if and when it becomes cheaper and therefore more popular — or if other power sources become scarcer — they will be able to help out the community in general. One of the department’s most interesting solar heating projects, still at the

sketch plan stage, is in Christchurch where engineers are planning a “trombe” wall (the name comes from the French professor who developed it). Destined • to become part of the D.S.I.R.’s herbarium at Lincoln College, it is a north wall that consists of concrete with a black surface which is encased in glass. It will provide heat for the building and also cool it in summer. The staff involved work in the Bates Building, where solar water heating has been going well

for five years. Further north, the telephone exchange operators in Courtenay Place use solar heated water for hand washing; the replaced electric hot water cylinders are now only a stand-by. Penrose High School relies exclusively on solar heat for both hand basins and showers. In fact, the Department of Education has been interested in solar heating for hand washing for some time — in 1979 it had D.S.I.R. solar units tested by M.W.D.

tor possible future use in schools. As far as the all-important homes are concerned, the Ministry’s people began helping the Housing Corporation to develop home units a decade ago. As a result, hot water in many Housing Corporation homes now comes from solar heating units, including some built for the hydro dam work-force at Cromwell in Central Otago. The D.S.I.R. is co-operat-ing with the M.W.D. on one of the most interesting new

projects — Wellington’s William Clayton Building. Apart from its unique seismic design and office planning features, it will also use solar heat, not only for hot water but also as an energy source for space heating. One could go on and on: a museum, prison officers' quarters, workmen’s huts — all have been or are being built with solar heating. Of course, nothing new is without its challenges, and Ministry engineers are apt to stress them when enthusiastic lay people ask why the new form of energy is not being used more. Like wind power, solar power seems simple, but, because of its unpredictability, it can be very complicated to harness effectively.

There is, for instance, a building in Dunedin on which a solar unit was tried out. Ostensibly frost-proof, the joints sprang leaks after the first light frost and the solar installation has not worked since. As someone remarked: “There is a shortage of solar hours in Dunedin . . .” Part of the answer to many of the challenges presented by sun power may lie in a small solar energy unit built for the Agriculture Department at Palmerston North. This unit is what engineers call “fully instru-

mented for monitoring

another way of saying that what happens in the unit can be measured, analysed properly, and taken into account in future design work. Historically, M.W.D. is not and was never intended to be a testing agency, like the D.S.I.R. but it is moving towards making and interpreting more such measurements whenever money and staff permit.

In Auckland, for instance, a 15 panel solar unit on H.M.N.Z.S. Tamaki’s gymnasium extension will be fully instrumented for monitoring in about six months time. And at the other end of the island, there is the 14-storey Vogel Building which houses M.W.D.’s own head office. Its solar heating units have already shown that solar energy can be collected and used to save fuel costs, but now the whole system is undergoing further detailed tests and evaluation It seems that New Zealanders can look forward to advances on the use of Old Sol in the over-all' energy scheme, whether as a worthwhile partner for traditional fuels or even as soloist, should some of the pessimists’' darker prophecies about costs and finite resources turn out to be accurate.