Solar air conditioning - cool green tech (part 4)

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Previous articles here and here have looked at green tips and green building technologies for staying cool this summer, and with the announcement on August 18, 2010 that Vestas, the world's leading wind turbine manufacturer, will construct a super eco-friendly LEED platinum building in Portland for its North American headquarters, it appears energy saving technologies for homes and buildings are continuing to gain momentum.

Reports so far say the Vestas building will include an eco-terrace roof, under-floor ventilation, and a very high-tech feature called “operable windows,” which do in fact produce significant energy savings, so it is a shame that more commercial buildings do not use them. Those features are commendable, as well as the fact that the building is expected to have the largest array of solar panels in the area. Not mentioned, however, was if any solar heating or cooling options were considered.

Despite the common perception that solar technologies would not work well in a rainy city like Portland, both solar thermal and photovoltaic systems can and do work well here throughout the year, but they could work exceptionally well for cooling purposes during the hot dry summer season.

Solar absorption cooling is the most direct way to use heat energy from the sun to provide cooling. Absorption chillers are very efficient devices that have long been used for commercial refrigeration, but systems tend to be large, complex, and a bit expensive for residential use. Recent products, such as this, can in theory be used for some residential applications, but minimum sizes start at about 10 tons of air conditioning, while most residential central air systems are only about 3-5 tons.

For a commercial building, however, a solar thermal system could be an excellent way to produce both heating and cooling. Advanced vacuum tube heat collectors, such as these, are highly efficient alternatives to traditional flat panel systems, and are especially good for cooler and cloudier climates like Portland. Such systems can provide hot water and heating, as well as cooling.

LEED platinum certification requires leadership in using the latest technologies, so if one wishes to create a truly green building of this level, a solar thermal heating and cooling might be the kind of thing that sets such a building apart.

Next, the final article (for now) in this series on green technology for summer cooling will examine the use of advanced heat pumps for both cooling and heating.