Earth home heating

Im  planning an earth home.  Im getting older and want to make sure Im not creating too much work for myself.  Of those of you that currently live in a bermed  or earth sheltered home, how do you heat it?  I  had a neighbor that built one in 1976 when he retired from farming in Iowa.  Its a pretty good size house.  Ive  been there twice, both times it was brutally cold with high winds.  Inside was super cozy.  They had a small fire going in the fireplace (Heatalator?) that would distribute heat to other rooms.  There  was an electric furnace installed, because they had to, which in 20ish years had never been on.  They said they didnt even know if it worked.

Windows did most of the heating.  He had a little Datsun pickup with a load of wood on it.  I asked how much he use..."Oh maybe a load or two."

I will put in redundant systems.  The plan will be like a ranch style with bedrooms (2) down a hall.(about 1400 sq ft)  Ill have a wood burner of some sort in the living room/kitchen.  Should it be a large stove?  Masonry heater too much?  There will be lots of window area facing south doing most of the work.  I also want radiant heat in the floor in case Im not able to collect firewood.

What has your experience been.  I live in central Iowa so super hot summers and super colds winters can be considered normal.  Anyone in my area?

I have no experience though a rocket mass heater sounds perfect to me.

I think that Wheaton Labs use those, too.

I have a Liberator Stove in my house now.  I like the idea of burning very little wood, but I wonder since one doesnt have to raise the temp much from earth temp to comfort level, what kind would I use?   I really like the big masonry heaters but would that over heat the house?

I think it depends more on how often and how much you would burn. If it is efficient enough, you might want to have a separate stove for cooking (rocket stove?) that won’t store so much heat.

My understanding is that unlike a conventional wood stove, rocket mass and masonry heaters heat a space slowly because first a mass is heated, then the mass radiates heat out through the day and night, even without a fire going inside.

When you speak of an Earth home which style are you thinking off?
- Adobe brick
- Rammed earth
- Earthship
- underground in a hillside with solar windows

John, I wont have much hillside to dig into so it will be concrete block with  dirt piled up the sides and some on the roof.  Much window space facing south.  Wife wants a shed roof with clerestory windows but very little angle.  Small windows and maybe a 2-12 roof angle towards the back.

Jim, depending on the size you want there are many plans available for this type of construction.
A concrete for to manage moisture is common, and the walls can be made from;
- concrete blocks
- poured insitu walls
- tilt slabs
Waterproofing is not difficult if good steps are followed.
Roof structure can be;
- cast concrete
- steel beams
- timber
Using internal walls as roof supports long spans are avoided

Jim Pecenka wrote:...maybe a 2-12 roof angle towards the back.

In rainy and snowy Iowa I would not recommend anything less than 6-12.

How much wall insulation are you planning?
Will you build masonry interior walls?

I live in a tiny (~500 sq ft) bermed house that is still under construction. I heat it with sun and a small diesel heater at night. The plan is to put in a rocket stove in the back with the bench heating the back wall and mass.

Do EVERYTHING to waterproof the foundation.

R.Scott, can you give us more details it sounds interesting?

Mine is loosely based on an Earthship, but the walls are built with overpour blocks—2x2x6 foot retaining wall blocks made with surplus concrete from the batch plant.  They were set in two hours with a mini ex, not two years of pounding tires.

R.Scott any photos possible please?

John C Daley wrote:R.Scott any photos possible please?

Not enough internet here, I’ll have to remember next time I go to town.

Earth berm passive solar with active thermal air add on here.  Solar thermal collector added mid way thru the winter 7 years ago.  I have managed 4 of the last 6 years without heating.(although this last winter shouldn't really count as it was so warm.)  Now most people are going to require more heat.  My criteria has been lighting the heater when I dropped below 50 degrees F.  Had one year in that that I had 2 days below that but was too busy to light the heater.  North central Wyoming at just over 4000 feet in elevation.  Good area for solar so minor advantage there.

thermal collector panel

added interior air circulation

interior circulation added.

The home was built in 1983-1984 and was over insulated for its era.  To meet minimum modern insulation code for this area today, it would need 1 more inch of insulation in the walls and 2 more inches in the ceiling.  Extremely well sealed.  If running the clothes drier something needs to be open or it can back draft either the heater or the water heater.  Full basement and earth berm on 3 sides for the upstairs.  It is less than perfect but given budget constraints and what we knew then I am still incredibly happy with the house as is.

Heating is one really old room propane heater when heated.  The house with 4 people living in it used just over 500 gallons a year.  That ran the heater, clothes drier, water heater, cook stove.  AC wise we never had more than a single 18,000 BTU window air conditioner mounted on the wrong side of the house in the middle of a south facing brown wall.  Worst year in that time it struggled to keep the house comfortable for about 6 weeks.

First off let me say while earth berm or earth sheltered makes some things easier it is not necessary.  A well built modern house can do everything the earth sheltered home can do for the most part.  Tornado and extreme weather event resistance being the exception.  What makes this house work is high thermal mass, well insulated and well sealed and those can be accomplished in almost any home.

Now if I could go back in time and change some things realizing the house was built on a shoestring budget wise.  Listed here are the heating, cooling and fresh air

My #1 answer is that under the build up soil in the middle of the footing under the basement floor there would have been hydronic tubing.   This would have put it roughly 2 feet of earth and concrete over the tubing.  What I am finding now is the set point for the house in winter is basically the basement floor temperature with the systems I have in place now.  If I could start heating under the floor in July or Aug as part of air conditioning the house there should be a 2 to 3 month time delay before it gets to the floor.  The house can use some air conditioning typically into late October.  A 30 watt pump and transfer heat to under the basement from upstairs.  Given our budget even that little one would have been a stretch but if it was in the rest of retrofit is way more doable.

Stretching #1 would be around the basement burying the rest of the dirt side hydronic tubing for cooling primarily but some heating too.  All the dirt was moved anyway so the tubing and some labor would have been the only needed.  The online information suggests that 12,000 BTU's of cooling needs 400 to 600 feet of 3/4" black poly.  Now knowing now I probably need 18,000 BTUs that would have meant worst case was 900 feet of poly.   Now for the sake of argument say the basement hole was 4 feet each direction larger than the basement.  16 x 60 and we only wrapped 3 sides of the basement and lets say we did one half the loop 2 feet out and the other half 4 feet out in each layer.   Simplify and skip curves in the math 64 +18(2) = 100 for the inner half, 68 +20(2) = 108 for the outer half.  Call that 200 ft per layer and 4 layers would have gotten 800 feet cooling there and say another 150 feet under the basement floor.  Start at footing level for coil 1, coil 2 up 2 feet for basement floor level, coil 3 2 more feet up for 2 feet above basement floor level and final 4th coil at 4 feet above basement floor level.  Normal basement that would only leave say 2 feet of cover over the top coil but earth berm there is easily another 6 to 8 feet of cover over it and all that earth was moved anyway for construction so no real added cost that way.  

#2 change: would have been designing the wall for folded path solar thermal air collectors.  Blocking, headers etc.  There again the collector wouldn't have needed to go in to begin with, if the prep work was done originally.

#3 change: buried air inlet tube to moderate incoming air year round.  According to the Ceres greenhouse information 83 feet of 4 inch drain pipe 8 feet down will pull air all winter long and never drop below freezing.  Guessing 2 tubes for enough volume also buried in the berm.  Then if I could run that thru an HRV core heat loss bringing fresh air in would be minimal.  Burying the tube and getting it thru the concrete wall would take some planning.

#4 change here is my write up on the thinking clerestory window design thinking.  Material cost change is small.

#5 change here is my write on roof overhang change?  Most questionable one in the thinking but I believe it would both make the house stronger and increase energy in.  

#6 change.  Do a hydronic ceiling(not floor) in the upstairs.  Summer air conditions,  Winter both heats sometimes and air conditions sometimes.  Carry the heat to the earth based hydronic choosing where the water goes first.   This is without a heat pump but if you found a heat pump needed nearly everything is already there to implement.

Then modern addition would be what if all the windows went to the R20?  R20 windows

combine that with better insulation, better air sealing and most of the heating and cooling needs be covered.  

I've been designing an earth-sheltered home in my head, I don't have land yet to actually build anything. I'm in Texas so there's a greater need for cooling, but still some need of heating; I am leaning towards piping in the floor and/or ceiling for radiant heating and cooling, with large insulated hot and cold water storage/buffer tanks. This would allow multiple sources of heating/cooling (separate dehumidification would be required, and to prevent sweating the cooling water in the radiant system would need to be kept above the dewpoint temperature). I'm also considering the use of phase-change materials in the storage tanks to increase the amount of BTUs that can be stored.

My hope is the earth sheltering and PAHS (passive annual heat storage - see book by John Hait) would cover the majority of the heating/cooling needs, but secondary/supplementary options I'm considering using for creating hot & cold water for the radiant system include the following:
--Rocket wood fired water heater
--Heat Pumps:
   --Water-to-water: pull heat from the cold storage tank into the hot storage tank
   --Air-to-water: heat or cool one tank when the other is already at temperature
   --Water-to-water: heat or cool individual tank same as above, but pulling/dumping heat to/from a pond and/or underground piping (i.e. ground-source/geothermal heat pump)
--Propane on demand water heater
--Solar hot water panels
--Radiant cooling water panels
--Heat pipes between the outside air and the storage tanks

Let’s see if this works….