With winter approaching again, I have undertaken some improvements to the Casa del Cottage.
So can efficiency be retrofitted? Yes, but it’s difficult to get the best results – especially if you already have solar power. As a qualified contractor, I often complain that my fellow licensees are sometimes hopeless. Many simply don’t realize how important it is to get the details right, and perhaps even more of them don’t care?
Add to this the tendency to be conservative or even suspicious of changes in building practices and to underpin the entire system with cheapness, and the long-term results are inconvenient and expensive.
Get what you pay for
To a certain extent, people get what they deserve. Keeping up with the Joneses means eye-catching finishes and pretty porticos eat up the budget, even though we should be splurging on insulated panels and extra-thick wall frames.
Unfortunately, we all pay too much for fashion. Despite some improvements in standards, the woeful design and execution of Australia’s glorified tents is generally overcome by brute force and energy consumption.
Investors buy them, developers dump them and energy companies collect revenue, but it’s residents who pay for the bad decisions season after season. Tenants are most at risk because they are unable to improve the situation.
Isolation is more important in the beginning
My little house probably dates back to the 1940s. It features weatherboard cladding, fibrous plaster cladding and little else on the walls. Although the ceiling has mineral fiber/rock wool insulation, the floor is not insulated and there are gaps and drafts everywhere else.
We recently had the bathroom renovated, which was housed under the original porch outside of the house proper.
The whole project was a bit of a disaster (I wish there was a “bathroom” option for SolarQuotes, but that’s a story for another time).
In green we see that the electrician simply threw away the ceiling insulation, while the carpenter forgot about the niche and let a piece of wall insulation fall out.
Retrofitting is difficult
While the bathroom walls were being exposed, the contractor put mats throughout the wall framing and I made sure they fit properly. Except where they fought because the carpenter wasn’t competent and didn’t give a damn.
The current interior wall of the house is insulated, but only reaches the lower ceiling height of the bathroom. The upper part of the wall, like the other external walls, remained uninsulated.
I took a thermal image in the summer that clearly shows the problem.
Have a blast
I’m cursing myself for not realizing it at the time, but insulating the wall would have been a lot easier if the bathroom ceiling wasn’t there.
However, there was a spare bag of insulation left and I thought I would try to fit some of it – the only problem was the very poor access. Any normal person would pull off some roofing iron to get into the limited space, but my options were limited by the zealot who had already put up PV solar panels everywhere.
This is a good example of why we recommend getting any roof improvements or repairs done before installing a solar system.
I opened an access panel under the porch so that the bathroom exhaust fan could be routed out of the attic space. So I threw a long closet door in there that I could crawl on and pushed a few mats of rock wool in front of me.
The insulation is wrapped around the corner and held in place with a string. By law none of these lines need to be cut off, none of them are “accessible” unless you are a crazy person.
What a bloody mission
Using a bread knife, I cut the insulation to size, inserted a few screws with an impact driver, and then used construction twine to secure the batts in place. I continued working, inserting the pink lint into the cavities as far as I could.
It was hot, dirty, and especially uncomfortable because I didn’t want to crash through the new bathroom ceiling, but there wasn’t enough room to crawl either. The distance from my knee to my butt was greater than the available headroom.
A slightly unsatisfactory result
No matter how bold the attempt, the problem was always how well the mats could be installed, and in this case it was difficult.
Insulation works when it rests on a surface. It must trap air and prevent drafts from dissipating heat, but must not be compressed.
Perhaps the best way to demonstrate this is to instinctively pull the sheets up to your neck when you go to bed, right? When you press an electric pad against your skin, it may be hot, but the air around you under the blanket takes a while to warm up.
When you lift your knees, reality becomes clear to you. The skin stays warm where the blanket makes contact, but cool air from the room flows in to fill the gap.
The same applies to poorly fitted insulation. If your “ceiling” has gaps totaling 5% coverage, you will lose half of the rated power.
An enclosed veranda forms the bathroom, so the ceiling is lower on the outside. The hallway was not insulated but is now “inside” the house. The attic space is blazing hot.
The wall above the ceiling line is now better insulated, but nothing special.
Do it right the first time
In many cases it is impossible to repair bad buildings. You can’t turn the place to face the sun or go under the concrete slab for insulation, but that doesn’t mean we shouldn’t make improvements.
Double glazed windows could be an option, I built them myself inexpensively. Walls can be improved by gutting the house or cutting a few dozen holes to pour beads into the cavity, but it is difficult to increase wall thickness.
However, draft excluders and ceiling insulation are a simple and very effective improvement. It is a worthwhile effect for the effort expended.
Whatever efficiency you can claim, it will help you pay your bills and, more importantly, it will make your home inherently more comfortable, even before you turn on the air conditioning. This lower energy consumption means that when installing solar panels, a smaller and cheaper system may suffice.
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