Sept 7, 2018: Lighter Roofs and Cheaper PHEVs

Why Dark Roofs Are ‘Crazy’

I’ve been saying it for years and it’s nice to see that the message seems to be getting through. This week I received the the following email from one Newsletter readers…

Hi Andy,
I decided to replace the roof on the house I live some 7 years ago. It’s situated in the Macedon Ranges area of Victoria, which is best described as sub-alpine, and as is commonplace in Australia, also gets some ferociously hot weather come summertime. Daytime temperatures inside the old brick veneer house would get up to 30 deg, and down to 6 on frosty mornings. This was mostly due to the appalling spec house design and build, inadequate or absent insulation, old single-glazing and draughts, coupled with poor heating systems. Occupants must have just wrapped up in winter and drunk many cold beverages in summer. Pretty typical nationwide really.

The original roofing was Wunderlich terracotta tiles, and then, after a tree fell on the roof they were completely replaced (presumaby on insurance) with Monier concrete tiles. By the time I got there about 30 years later there were old thin yellow batts covered in dust and leaf litter, small branches and detritus from the tree fall, and the old tiles were well past their limited prime. No longer sealed by glaze they let in moisture and the house was damp in winter. In summer the roof space temperature was close to 65. The batts would have only been R2 at their best, and this area demands at least R3.5. Bushfire is also a consideration here, and I wondered about all the leaf litter accumulating at the roof edges. Although expensive it was time to replace the lot.

I chose to reroof with Colorbond in Paperbark (much lighter shade than the brown tiles) and put down foil faced roof blanket over the new top-hat battens. I installed R3.5 earthwool bulk insulation- after getting some poor buggers to clean out the roof space of all the accumulated crud and the dusty,thin insulation. To finish I installed a clear whirlybird vent so I could see what was going on in the roofspace if I ever got up there, because the sheets and blanket exclude nearly all daylight, and because various ventilation fans simply vented into the roofspace only.
I wanted it to be dry and lose heat in summer. Having read your highly informative article on FLIR photos of house structures, I would be interested to know what heat gets lost in winter through that vent.

The difference is startling, especially inside the roofspace. The house interior can drop to 8 if unoccupied and unheated, and it still can climb to 28 in heatwave conditions, but it is drier, and easier and cheaper to heat. I don’t have any airconditioning, and I think careful management of gardens and shade onto windows would be sufficient to let ventilation take care of hot weather. There is much still to be done, but the reroofing, which probably came to about $20,000, was a vast improvement, not least of all in looks. Much of the housing stock in this country is dreadfully inconsistent with the climate, and I reckon that can be put down to simple greed on the part of developers trying to get sales with appealing features rather than good design. Right now, and I cannot believe this is happening still, swathes of suburbia are covered in slate grey tiled roofs. Crazy.


A sea of dark tile roofs is a common site in Australian subdivisions. (Source: The Fifth Estate)

A sea of dark tile roofs is a common sight in Australian subdivisions. (Source: The Fifth Estate)

Thanks Lucinda, I couldn’t have said it better myself. You’re right that the poor-performing house you describe in the first paragraph is absolutely typical here in Australia. I’m happy that you chose to re-roof using light-coloured steel with anit-con blanket and good ceiling insulation. Venting the roof space is also essential in my opinion.

Not only does it remove excess heat and keep the house cooler in summer, it also removes excess humidity and keeps the house drier in winter. Winter is when condensation is more likely and can lead to moisture and mould problems, especially in poorly-vented attics. So yes, you might lose a bit of heat through the vent but it’s more important to get rid of any excess moisture, especially if you have bathroom or kitchen fans vented into the attic instead of to the outdoors as they should be.

In my opinion, you need good roof-space ventilation PLUS good insulation and air-sealing at ceiling level to keep the heat inside you house in winter (and outside in summer).

Mitsubishi Drops Price of Outlander PHEV.

Regular readers will know how much we love our Plug-in Hybrid Outlander. We’ve had ours for nearly two years now and it’s proven perfect for us. We’ve used it to haul building materials and tow trailers. We’ve taken it on long trips, camped in the back and, most importantly, used a lot of our excess solar power to charge it for most of our local driving. Lately it’s been absolutely perfect for our time on Russell Island. In fact we haven’t put any petrol in it for the entire three months we’ve been here.

Our Plug-in Hybrid Electric Vehicle loaded up and ready for adventure.

Our Plug-in Hybrid Electric Vehicle loaded up and ready for adventure.

It’s such a wonderful vehicle I’m constantly surprised that Mitsubishi doesn’t make more of an effort to advertise or sell them. So I was surprised and delighted to read in this article from the Sydney Morning Herald, that Mitsubishi has dropped the price of the base model PHEV. It’s still pretty expensive at $46,000 but at least they’re doing something to entice people to buy them.

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