I have been busy preparing my house for winter. Last winter (the first in this house) we did little apart from install curtains, and the interior of the house regularly dropped to 13 C on cold winter mornings. To be honest, this is quite bearable, especially with the electric blanket we use on the couch when reading or using the computer. But, it would be nice if the house was a bit warmer in winter.
Heat retention
Before working on heating, it is
vital to minimise heat loss, otherwise any heat just rushes out of the house again. This has two main parts:
- drafts -- do this first. Drafts are a killer
- insulation -- stop heat conducting out
Our house is very drafty. Here's what I'm doing (work in progress):
- go around the entire house with a caulking gun and seal up all the skirting-board to floorboard interface with gap filler
- go around the ceilings, and fill all the gaps where the light supply cable penetrates the ceiling
- put door skirts on all external doors
- put rubber seats around all external doors so that they seal
- Install a DraftStoppa on the bathroom exhaust fan
- replace the kitchen exhaust fan with a proper (closing) duct that goes outside the roof
If I get time, I will also
- remove all light switches and power points in cavity walls and seal the cable penetration
- work on the windows to improve their seal
though, I suspect this might take until next year.
In parallel to this, I have also put a heap of insulation (rockwool) in the ceiling. There was insulation already, but it is old, dirty, compressed and thin and I just laid the new on top of the old, hoping that was adequate. I really didn't want to disturb 40 years of rat urine in the existing insulation! This job is only 1/2 done -- it's very easy to procrastinate going into the roof...
I have also started planning to retrofit double-glazing to some of the windows. For some windows, this will be easy. For some, hard. I'll leave the details of this to another article in the future.
Heating
Once the house is better at retaining heat, it will benefit from having more heat injected into it. To do this, I have started building a solar space heater from some salvaged material I had. Here's what I've used:
- some corrogated iron, from the carport I pulled down
- some light meranti timber from the pergola I repaired
- Some other salvaged timber of unknown heritage
I snapped a few photos as things progressed:
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| Materials I am using, mostly reused except for the roll of plastic sheeting top-left |
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| Beginning of the framing. I decided to make the frame to fit the plastic sheeting rather than the iron. This means that the frame is wider than the iron, which was a bit awkward to fill without cutting a long thin bit of iron (which I didn't want to do for waste). I had a couple of pieces of flashing lying around, which I was able to rivit to the iron and seal. |
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| The unit on the roof. I decided to use an existing TV antenna to support it. As we don't have a TV, it's good to see the antenna is finally good for something! |
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| Another shot of it installed on the roof. A rear brace is visible. It's important that it is anchored well, as it's a bit like a giant sail on the roof. Note the aluminium rails on the roof. I used some solar PV brackets that slide under the tiles and anchor to the roof purlens. I hope it's strong enough! |
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| A closer shot of the side. I also used tin to help anchor the struts to the frame (stop the nails pulling out). I've angled it quite steeply (over 70 degrees), so that summer sun won't make it too hot (this is because the sun is higher in the sky in summer) |
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| A view behind. Here you can clearly see the flashing, as well as the two struts and the anchoring to the TV antenna. I plan to put in a third strut. Behind it, you can see a 30 L solar hot water system that will supply only the kitchen. More about this in a future post. |
Next step
I will buy some ducting, and a through-tile to let me get the ducting into the roof. I'll need to work out an air blower and switching. I need to insulate the back of the collector (to reduce heat loss). Note too that the unit needs to be quite well sealed, otherwise cold air will reduce its efficacy.
EDIT: I forgot to mention that I also need to paint the inside of the box matt black, and cover the front with the roll of plastic shown in the photo. I'll also put some small vents along the bottom of the box for fresh air to enter (although another option is for the box to accept air from the house, heat it and return it through a second duct -- I'd rather have fresh air I think).
Expectation
The collecting area is 3.1 m by 1 m. Assuming I can get it working fairly efficiently, I think it should be equivalent to at least a 1 kW bar heater in the lounge room when it's sunny. It might even be as good as a 2 kW heater. Time will tell...
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This post was written by Angus Wallace and first appeared at guesstimatedapproximations.blogspot.com.au
