Wednesday, December 30, 2009

About the heat...

Hi everyone,
Our last post about heat, or lack of, got a lot of comments. I started to write a reply comment, but decided to just make it a post. All of the suggestions we received were pretty good, but...

We weigh 7600lbs on a 7000 trailer, so things that add weight are pretty much out. Also, while we love our location, it isn't necessarily permanent, so a trombe wall is out.

Our tiny house is pretty well sealed up. This is good. It means we don't have drafts. And that means we stay warmer. But it also means that using a wood stove would be a problem. Wood stoves suck air for combustion from there surrounding area. In a house with a bit of a draft and a lot of volume this is ok. In a well sealed tiny house, believe it or not, the stove would draw the oxygen out of your breathable air faster than new air would come in. So, you'd have to keep a window open when using it. And that might not be bad, but it might offset some of the gains of using it. A wood stove is also heavy and requires a lot of space around it. I'm not knocking wood stoves. I love them. But in this kind of small mobile space keep the trade offs in mind before installing one.

Refrigerators are another example of a small space fighting to hold its temperature against a larger space. Eventually, if the refrig is unplugged, the inside temperature will match the outside temperature. So you have to run the compressor to maintain the temperature. And we have to run our little heater to maintain our warmth. And actually, with our little stove we can get it up to 65 to 70 degrees, so it is ok. We just have to run it more than we thought.

I think one of the things Arlene wants to communicate is that if you are thinking of building a tiny house, be aware that it might not hold onto the heat as well as you might think. You do have to run the heater. Yeah, you could add more insulation, just be aware of what that might mean in terms of cost and weight and such. If you are in a very cold area, it is probably worth it to add a bit more insulation than we have. But up here we only have a few months of cold a year, and it isn't as cold as, say, Minnesota or Calgary.

In terms of heating, since September we have gone through one 5 gallon bottle of propane and are on the second. I figure that isn't too bad.

Saturday, December 26, 2009

Heating a tiny house

Well, we followed the suggestions as to what insulation to use to build our tiny cottage (2" thick rigid foam planks sealed around the edges with expanding soy foam). But because of the ratio of exterior walls to interior volume, and that we have no air pockets like a heated hallway or closets, we are chillier than I had expected us to be.

I think because it's a very tiny home that takes less energy to heat, I expected it to be toasty inside all of the time. Oh, not so...

On average, we run a 20 to 25 degree difference compared the outside temperature without running the heat, or summertime fan, during normal working hours. (If we never turned on the heat at all this would not be the case.) It turns out that we're cooler in the heat of summer yes. But also cooler in the cold of winter.

There had been an unusually cold day (29F degrees) last month but then it quickly warmed up again. We were comfortable that night so I thought that if the cold weather lasted longer that we'd stay comfortable enough. This past week/current week the high was/is supposed to hover at 32F and the low will be about 22F. This has meant a steady cold and it's been much trickier to stay warm.

Last night we'd had the Newport 900 boat heater on for about 4 hours. At 9pm, the outside temperature was 33F, the inside was 67F with the interior humidity at 48%. This morning at 5am outside was 24F, inside was 52F, and (since we don't keep the dehumidifier on at night) the humidity was 59% . Not as toasty as I'd like to be inside. We were used to turning the heat on very infrequently before moving into the cottage, and we'd simply wear a sweater and slippers at home. In this place, we use more fuel to heat the place and we wear an extra sweater. (We've become quicker at getting dressed first thing in the morning too!) If producing less of a carbon footprint is the reason you want to live in a tiny house, you'll have to figure out how to use less fuel for heating even if this is less expansive than heating a larger space. Insulation is the key; I have no definitive answer as to what to use yet though.

We have winterized, and will continue to do more as we think of what else can be done. We know the following information for sure because (tech geek that he is) Jeff bought two scientific temperature rods that he hooks directly up to his laptop for digital readings:

In early November we started by buying honeycomb shades to better insulate our windows and they keep the inside warmer by 6 degrees. Yes, we bought Low E double pane windows and installed them properly. We have 10 windows plus one skylight.

The industrial felt floor cover feels warmer to the touch than the wood floor, but we've tested it against the wood floor and it doesn't help the inside temperature at all.

I have stuffed dense foam into the 'attic fan' vent louvers and the bathroom exhaust fan outside as well as stuffed the skylight area.

We bought a dehumidifier because we started to get condensation on the window interiors and we don't want mold to form. Before we had the gauge to measure the humidity, the first 36 hours the machine was on we filled the 12 pint reservoir. Since then we leave it on from 5am until about 8pm and it takes two weeks to fill. We now hover between 49% and 60% humidity (gotta breathe but we don't cook at home and we shower at the gym or indoor pool each morning after we workout). We like how the dehumidifier evens out the temperature in the cottage by blowing cooler air up so that the heated air is forced downward. We sit downstairs and want it warmer until we go upstairs to sleep. The sleeping loft area gets heated fairly quickly by the two of us breathing since it's about the size of a two person tent.

We bought a heated water hose from and it works exactly as advertised.

We've thought about insulating drapes but have decided to wait on those. I need to do more research.

If we were to build another tiny home, or to make some suggestions, it would be:

  • Buy more heating power than you think it will take if you live in a place that gets cold. (Will a radiant heated floor work in a tiny mobile cottage? I don't know.)
  • Either buy a different type of insulation or beef up the 2" thick panels because it doesn't retain heat well since these structures are all exterior walls.
  • I don't know if having a full loft, rather than a partial loft, would keep it warmer downstairs in the winter. It might, but it might also be much hotter upstairs in the summer. We like the air circulation and light. The high ceiling in the living area makes it feel larger so I'm not sure we'd change this design.
  • Jeff suggests fewer windows.

We hope that you're staying warm this time of year.

Until Spring we'll be posting to this blog only once a month. Currently we're fine tuning the cottage to make it more comfortable so there's not much to post. As it warms up here though, we'd like to settle in a bit more by building a small deck and planting a vegetable garden.

Happy Holidays and have a very Happy New Year!