While we’re on the topic of energy efficiency and retrofitting … another really worthwhile thing we’ve done is insulate our wall cavities.
Our house is one of the early brick veneer houses constructed in Adelaide. It has a brick on the outside and an early form of plasterboard (incorporating horse hair) on the inside. There’s a pretty hefty gap between the brick and the plasterboard, and we’ve filled that gap with Rockwool insulation.
Rockwool is made from volcanic rock melted at high temperatures and spun into either batts, mats or loose clumps. I dread to think of the embodied energy of this product, but we preferred it to the fibreglass or cellulose alternatives, all things considered.
In our case, loose Rockwool clumps were blown down into the wall cavities with a special hose, like a fire hose. The installers just lifted roof tiles above our walls and blew the Rockwool in. It only took a few hours. (We needed to do some preparatory work first though, like sealing up the old external wall vents, and removing internal fly screens from our old sash windows, so we could properly insulate under the windows.)
And boy, what a difference the insulation has made. Our place used to have freezing internal walls in winter, which sucked out any heat and kept the rooms really chilly. Now, the walls are much warmer, and we often notice that we need to turn heaters off because it gets too warm. It’s a really noticeable difference, and it makes a difference in summer too, and it helps suppress outside noise. It’s arguably one of the best retrofits we’ve done at our place.
Installing wall insulation is probably not the sort of thing which one would do if planning to move houses after only a few years. I guess that’s why so many houses are so poorly insulated – people don’t think it’s worth the money, so they put up with badly insulated homes which get really cold in winter and hot in summer. In our case, we’re planning to stay put, and we value the extra comfort as much as the reduction in heating and cooling costs.