Over the weekend Melbourne went through our biggest heatwave so far this summer, and the first real test of my external blinds, which were fitted to the house early this year.
Looking at the two nearest weather stations to me, yesterday the temperature at Melbourne (Olympic Park) peaked at 40.7 at 4:27pm. At Moorabbin Airport it peaked at 41.2 at 3:30pm. Happily by about 6:30pm the temperature had dropped about 10 degrees, but the lowest measurements overnight were in the high-20s.
I was away (in air-conditioned comfort for most of the day), but inside the house on Saturday it got to about 30 degrees. This compares to an inside peak of 33 degrees when I last measured it properly in 2014.
So on the face of it, the external blinds make about 3 degrees difference, which does take the edge off the heat, and combined with plenty of fans can make for a reasonable level of comfort. Fans all night have made sleep perfectly possible, and looking at our power consumption in daytime, keeping the house to 30 degrees while using fans, computers, TVs etc and still only burning 670
kW watts of power doesn’t seem too bad.
Good roof insulation was installed some years ago, but seems to help more in winter than summer. Other options to explore would include wall insulation and double glazing. (One ceiling fan, suspected to be 15+ years old, also needs repair, as it’s stopped working.)
While they slow down the warming of the house, what the blinds and other passive measures don’t do is completely stop it getting hot, or cool things down. For that I would need actual air-conditioning or a split system, which I’ve tried to avoid, but is an idea I am slowly warming to. (Sorry x 2.) Perhaps to be installed with solar, to assuage guilt about increased energy consumption/emissions. Bear in mind of course the other measures have reduced what any cooling system would need to do.