Last year, I mentioned double glazing as a way to keep the summer heat out and the winter heat in. A much more cost-effective option, however, is the use of curtains.
Curtains and blinds help prevent heat loss and gain by trapping a blanket of air next to the window. The best results come from ‘fabrics that insulate well, for example heavy fabrics or curtains with thermal lining or layers’ (via Your Energy Savings).
The curtains we inherited from the previous owner were rubbish. They were sun-damaged, mismatched, and threadbare:
Thanks to the power of Google, we were able to source some quality secondhand curtains. There’s a store called Johnny’s Furniture in Eumemmerring (Dandenong) which stock ex-hotel furniture. They sell piles of Sheridan/Mantra/Hilton cast-offs, so we were able to get matching curtains made from heavy, tightly woven fabric. Unlike a lot of the ready mades available from Ikea and fabric stores, these ex-hotel curtains were also lined.
They were a bit longer than what was needed, so Mum spent a few mornings furiously hemming away. Dad was also nice enough to replace the mismatched curtain rails with uniform tracks.
While we don’t have quantitative temperature comparisons*, we’re observing a difference in comfort levels. When the curtains are not closed in the afternoon, you can really feel the sun’s intensity in front of the west-facing window. Pull the curtain across and the heat/glare reduces noticeably.
For our north-facing windows, we’ve also had adjustable awnings** installed.
‘When a window is hit by direct sunlight, heat comes in and the window is a source of heat gain. When a window is in shade, heat from inside will leave, and the window becomes a source of heat loss’ (via ABC’s Carbon Cops). Therefore using awnings in summer reduces direct solar gain and encourages heat loss via transfer/convection. And according to Sustainability Victoria, our choice of thick, opaque fabric means better shade. Squee!
Next step is figuring out how to retrofit invisible pelmets (or something similar) to reduce heat loss/gain from thermal convection.
* I bought a couple of Oregon weather station monitors and Cheap Geek installed them around the house but so far we’ve only got flat batteries as a result. :(
**We chose adjustable awnings because we wanted to be able to harvest as much sunlight in winter, maximising direct solar gain.