Passive Solar Energy Reaches Peak Performance

24th February 2012

That should have been yesterday - if the measure was the maximum energy output per day for the year to date. The temperature in the solar chimney got up to over 60 degrees C and air was coming into the house at around 45 degrees C. The house heated up to 25 degrees C and the thermostatically controlled fan ran for eight hours – two hours after sunset as the wall in the chimney heated up well above the temperature in the house. However, the outside temperature was high for the time of year – 17 degrees C – so not that much of a challenge. It is not often that in February thoughts turn to storing heat. But last weekend the system performed far more impressive feats...

Just over a week ago the system faced a much tougher test and I like to think an outside temperature of minus 4 degrees C and air coming into the house at 40 degrees C was the actual peak performance. The pipes in the workshop next to my office froze and stayed frozen for three days. However those days were clear and there was up to eight hours of sunshine. This bought back memories of the sub-zero conditions in which I built the system and conservatory. However this time around I was sat in the conservatory in shirtsleeves even though cool air from the house was fed though for warming before being returned to the house via the loft. Not bad considering the conventional central heating was reduced to tick over mode.

Perhaps what is needed is a scientific definition of peak performance of this system based on inside and outside air temperatures. The number of lacerations received while attempting to put the cat out might be the answer.

Have a good weekend and stay cosy.

Peter Kruger

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