Terra-Dome Earth Shelter Build

[sajurcaju]

We've been using a lot more propane this winter than expected. We have about 1900 square feet of heated house, 4" insulation on the outside of the concrete. Roof has 3" around the edges, 4" in the middle. Floor is 2" insulation under the pex heat tubing. In December-January we used 6.8 gallons of propane per day.

We added plastic over all the windows. For the skylight, we put an inside cover made from twinwall (like in a greenhouse). Two pieces of twinwall, one lying on the other. The skylight has a little ledge just under the dome which is where the twinwall rests. These changes reduced our propane use by 10% in January-February despite colder average outside temps.

We're still working on finding problem areas, but the real improvement will come next year when I am planning on building a bunch of solar hot water panels.

One more note: the shop is unheated, but has 2" insulation. It has not gotten below 35F this winter. It will get some heat next year, but thought people would be interested.

Steve
Maine

 

[SamWalton]

We had some nice weather this weekend and worked on removing all the foam HVAC register extensions. They all worked great. The fit couldn't be better. We had to grind the high spots from the cement edges to level and provide a flush fit. We cut the custom boot boxes flush to the surface and cleaned up two of the drains. I am also working on getting the electric service by writing some property easements. I already have the required NEMA 3R breaker box required by our local electric cooperative.

 

[SamWalton]

We've been using a lot more propane this winter than expected. We have about 1900 square feet of heated house, 4" insulation on the outside of the concrete. Roof has 3" around the edges, 4" in the middle. Floor is 2" insulation under the pex heat tubing. In December-January we used 6.8 gallons of propane per day.

We added plastic over all the windows. For the skylight, we put an inside cover made from twinwall (like in a greenhouse). Two pieces of twinwall, one lying on the other. The skylight has a little ledge just under the dome which is where the twinwall rests. These changes reduced our propane use by 10% in January-February despite colder average outside temps.

We're still working on finding problem areas, but the real improvement will come next year when I am planning on building a bunch of solar hot water panels.

One more note: the shop is unheated, but has 2" insulation. It has not gotten below 35F this winter. It will get some heat next year, but thought people would be interested.

Steve
Maine

I would consider using a hydroponic pump to produce all your hot water. These devices produce up to 70% more energy out than used to drive the small motor.
YouTube - FUELLESS HEATER NO FUEL NO GAS NO WOOD NO GREEN HOUSE GASES
Home - Hydro Dynamics, Inc. - Cavitation Reactors
I believe the company was forced to stay away from home heating devices but I am sure someone is making small units.

 

[carpolisher]

We've been using a lot more propane this winter than expected. We have about 1900 square feet of heated house, 4" insulation on the outside of the concrete. Roof has 3" around the edges, 4" in the middle. Floor is 2" insulation under the pex heat tubing. In December-January we used 6.8 gallons of propane per day.

We added plastic over all the windows. For the skylight, we put an inside cover made from twinwall (like in a greenhouse). Two pieces of twinwall, one lying on the other. The skylight has a little ledge just under the dome which is where the twinwall rests. These changes reduced our propane use by 10% in January-February despite colder average outside temps.

We're still working on finding problem areas, but the real improvement will come next year when I am planning on building a bunch of solar hot water panels.

One more note: the shop is unheated, but has 2" insulation. It has not gotten below 35F this winter. It will get some heat next year, but thought people would be interested.

Steve
Maine

Steve,

I was wondering what type thermostat you are using? Because of the slow response of the high mass a simple on off air stat is not suitable. Thermostats that use pulse width modulation for temperature control is much more effective and efficient. There are air sensing and floor sensing models or both.

Bob

 

[sajurcaju]

Steve,

I was wondering what type thermostat you are using? Because of the slow response of the high mass a simple on off air stat is not suitable. Thermostats that use pulse width modulation for temperature control is much more effective and efficient. There are air sensing and floor sensing models or both.

Bob

Hi Bob,
We have Watts Radiant thermostats, with both air and floor sensors, regulating on air. From what I've read, they are set up ok, although I don't know about the numeric values matching the house. The folks who advised on the heat supposedly took the construction into account.

We've found one error in the heat advice. All of the house, except my daughter's room, is in tile. Her room has some Pergo flooring over the concrete. She also has that zone's thermostat (air regulating, floor limiting). The sensor in the floor shuts off her heat before the air comes up to temp (under floor gets too hot). We could move the thermostat, but not the floor sensor . If I crank up the max floor temp, places like under the bed (i.e. covered places) get pretty hot, so she's just living with lower air temps.

Steve
Maine

 

[KubotainNH]

I was wondering what you folks were using for thermostats also. In my radiant heat stick built house most of mine are the normal mercury type ones but I have a programmable one for the 1st floor. I've been thinking of trying one of these: A3030101 - Uponor (Wirsbo) A3030101 - Wirsbo Radiant Thermostat (WT 1), Heat Only, Two-wire to see how well they work. I like how they can be set to make short cycles when nearing the desired temp. Drives me nuts when my pumps are full on when the temp outside is not too far from the inside but I'm not one to walk around and turn all the t-stats down because I'll forget to turn them back up

 

[sajurcaju]

I was wondering what you folks were using for thermostats also. In my radiant heat stick built house most of mine are the normal mercury type ones but I have a programmable one for the 1st floor. I've been thinking of trying one of these: A3030101 - Uponor (Wirsbo) A3030101 - Wirsbo Radiant Thermostat (WT 1), Heat Only, Two-wire to see how well they work. I like how they can be set to make short cycles when nearing the desired temp. Drives me nuts when my pumps are full on when the temp outside is not too far from the inside but I'm not one to walk around and turn all the t-stats down because I'll forget to turn them back up

You also need some idea of how to set the parameters on the thermostats, otherwise you're shooting in the dark. It isn't as simple as buying a different thermostat. You almost certainly need something better than old fashioned bang-bang thermostats, however.

Tekmar is the only place I've found with anything useful. Check out E001 and E006:
tekmar Essays
They at least give you insight into the issues.

Steve
Maine

 

[carpolisher]

You also need some idea of how to set the parameters on the thermostats, otherwise you're shooting in the dark. It isn't as simple as buying a different thermostat. You almost certainly need something better than old fashioned bang-bang thermostats, however.

Tekmar is the only place I've found with anything useful. Check out E001 and E006:
tekmar Essays
They at least give you insight into the issues.

Steve
Maine

The thermostat is only one part of the equation. As you can see the concept of radiant heat is simple but the controls can be complicated. Many earth sheltered homes have some degree of passive solar gain which further complicate the ability to effectively and effeciently control floor/air temperatures. The whole system needs to be designed according to the situation. A well designed system will incorporate a properly sized heating unit capable of responding to the requirements of each individual zone. This may include intelligent controls communicating with the boiler capable of monitoring, analyzing , prioritizing and staging etc. ie. it makes no sense to supply 20,000 btus to a bedroom requiring only 5,000 btus.

Just my 2 cents...

Bob

 

[SamWalton]

I decided to take a few days off to focus on the house. I wrote our easement for the electric company and got them to approve it. I discovered I already had the second easement ready to record for a portion of the electric on an adjoining property. We went to Home Depot to purchase a shower, two more doors and locks. We got the exterior steel door installed between the garage and the great room and insulated part of the wall. We will drywall the great room side tomorrow and work to seal a few leaks on the roof.

 

[SamWalton]

We are finally ready of the electric service to be installed. We also decided to go with the local water over drilling a well. Today we cleaned and applied more of that water proofing on the leaking cold joints and our second coat on the wall straps. We also installed one sheet of drywall. We will wait to see if we still have a leak before installing the second sheet of drywall. We began drilling the pressure treated 2x6 for the wall between the kitchen and the bath laundry room.