With the pool water evaporating each dry, hot summer, and an ineffective northern wall, one homeowner converted both to be water and energy saving assets. Ken Self shares his story with ReNew.
Returning to Australia after six years in the UK, we were faced with an energy and water saving challenge, namely our 1950s house in the north-eastern suburbs of Melbourne. It was 2007 in the midst of a drought with tight water restrictions in place. The in-ground swimming pool was losing so much water through evaporation that we couldn’t keep the filter pump operating.
Water loss was temporarily fixed by connecting a downpipe diverter to send rainwater to the pool. A 5000 litre water tank was installed so we could keep the garden alive despite water restrictions.
Other small retrofits, such as fixing the dilapidated ceiling insulation and adding reflective foil in the ceiling to deflect the summer sun, helped a little with thermal comfort and efficiency, as did dismantling one of the two hot water systems (the old electric one in favour of the newer gas model).
The tanks filled slowly as there was little rainfall. The pool stayed unused and the summers were still hot and the winters cold. Removing the old electric hot water system halved our electricity usage, but most of that was taken up by gas usage.
Our efforts had been ad-hoc; to really make a difference we needed to invest more wisely.
Thoroughly tested
Before launching into renovations we tested the house from high to low to find its thermal weak points.
We estimated the R-value of all the external surfaces of the house such as ceiling, walls, windows, floor, and the area of each, to work out how much energy, in kilowatt-hours, was flowing out of the house per degree of temperature per hour, day or year. We also estimated how much energy was captured from the sun through windows. We studied passive heating and cooling and were particularly interested in the Passivhaus standard from Europe and the concept of thermal comfort.
Our measurements, using the concept of ‘heating degree days’ and ‘cooling degree days’, showed that more energy was going into keeping the house warm in winter. A heating degree day measures how much heating (in kWh) is needed to maintain a desired temperature, in Melbourne say 20°C.
Read the full article in ReNew 118This entry was posted on Monday, December 12th, 2011 at 10:28 am