How to Calculate Monolithic Dome Heating
By mati. Filed in Monolithic Dome Planning Tips |Tags: BTU, BTU calculations, BTU calculator, Construction of a Monolithic Dome, energy efficient homes, heating systems, How to Make a Monolithic Dome, layout tips, Monolithic Dome
According to Monolithic Dome Institute’s calculations, a monolithic dome only needs about 1/4 of the normal heating requirements for a regular stick framed house. To calculate how many BTUs a normal stick framed house needs, you multiply each of the rooms and add them up like this:
length x width x height x 4,
and this gives you the amounts of BTUs needed.
In a monolithic dome, you only need one quarter of that, so basically
length x width x height of all the rooms.
Although we didn’t think it sounded like enough heat, Monolithic Dome Institute had done so much research done about it, that we ended up trusting the numbers, crossing our fingers and putting the amount of heating in that they recommended. The winters here in Colorado can be harsh and long, so we were actually pretty worried about wether the tiny hot water radiators we put in was going to be enough to heat the dome.
When the winter came and we turned the heating on, the boiler ran almost constantly for the first two weeks. And although the dome was perfectly warm and comfortable inside, our second worry was what the heating bill was going to be. It didn’t seem very energy efficient to us, and we were biting our nails!
However, we had no reason to worry. We discovered that there were two reasons why the boiler ran so much the first two weeks. One reason was the fact that the concrete had to be charged with heat. This is the case any time you need to heat a large amount of heatmass the first time. The other reason was the fact that the concrete still contained quite a bit of moisture, which had to be dried out. For the first year, the concrete kept releasing moisture, so we ended up having to buy two de-humidifiers to help dry it out.
After the first two weeks, the boiler stopped running so much. In addition, we had a thermostatic timer that turned off the boiler at 10pm and back on at 7am, and it only lost 3 degrees overnight, even in the coldest part of winter! The reason why it held the temperature so well overnight, has to do with having heatmass on the inside of the dome. We have tried living in an ICF house (isolated concrete form), which is supposed to have the same performance R-value of 60, but it didn’t hold the heat as well overnight as the dome did. That is why I say “nothing compares to a dome!”
After the first month, the amount of propane we used to heat the dome was so low that the gas delivery guy asked if we only used the house as a holiday home, since we were using so little gas. (We only used about 50 gallons per month in the winter, and kept the dome at 72 degrees! Not bad for heating 1871 sq ft!)
After the heatmass on the inside of the dome had been charged, it took less than half the amount of propane that a normal stick frame house requires to keep it warm through the winter. As an example, we can compare the propane use with the house we are renting now. The rental, which has radiant floor heat, takes 100 gallons of propane per month just to heat the first floor to 64 degrees in the winter, and the second floor is heated with a wood stove (and this is supposed to be a well insulated house!) Well, like I said before, radiant floor heat is useless, or perhaps I should be diplomatic enough to call it “highly inefficient,” and basically, nothing beats the energy efficiency and comfort levels in a monolithic dome!
In the new dome that we are going to make this summer, we also want to add a sunroom on the south side for passive solar heat and a fireplace in the living room. That way, we’ll probably use hardly any propane to heat the dome through the winter.
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