Efficacy of laying insulation flat on ground around house?

In summary, this plan would give no noticeable improvement in the home's temperature variations. The time scale is too long.
  • #1
shane2
89
3
OK, sounds nutty in a limited short title, but...

For a planned dome home in an area where average annual air temperature is 72 degrees, and thus steady state ground temperature at 20' deep or so stays within a pretty narrow range near that 72 degrees year round average above, and where house will purposely not have it's concrete pad or footings insulated so as to have earth, by design, be in contact as a heat sink in summer and heat provider in winter, how much would the following contribute to help that ideal work?

From exterior edges of dome home extending outward 12' in all directions, there would be a 12' continuous deck surrounding the dome, laid flat upon the ground, that was made only of 4" polyurethane freezer panels. (These have galvanized metal on both sides with the 4" of polyurethane sandwiched in the middle. Assume no air or moisture infiltration between the bottom of them and the ground.)

How much would that insulation set up help to dampen the hot/cold summer/winter temperature swings of the Earth immediately below the concrete pad all along the outer edges of the dome?

FYI, cost is not an issue or question here, these are used/surplus 50 cents a sq ft panels, and also the seamless installation and waterproofing and UV protection of exposed ends is not an issue either. Also, consider the color reflectance of the top surface as 'neutral', equally absorbing sun in winter and reflecting sun in summer, to take solar gain or lack of out of the equation, so as to be just looking at the air temperature seasonal swings affect on the Earth below them.

What I'm trying to get a fix on is, with this 4" of insulation extending out 12' in all directions away from the concrete floor atop the earth, how much might that insulation be helping keep that concrete floor nearer to 72 degrees compared to not having installed any such insulated decking?

Appreciate any thoughts and/or suggestions to improve on above.
 
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  • #2
This plan would give no noticeable improvement in the home's temperature variations. The time scale is too long. Temperature variations might be delayed a week at the most.
 
  • #3
What are the average summer and winter temperatures? And is he house heated and air conditioned?
 
  • #4
Frost Protected Shallow Foundations (FPSF) employing below surface horizontal insulation
wings outward from bldg is well accepted and basically same concept I'm exploring here.

images?q=tbn:ANd9GcRjae7BT2BhzmO35tHFxN6iKfJKJl1xXRcMZTgWiJRHBCYwmDlx.jpg


Specifically, how effective 4" of insulation (approx 24 r-value) extending 12' out on the surface
would be in narrowing that ground temperature swing range under the dome pad that normally
only narrows tightly at deeper depths as it approaches the average annual air temperature.
191-2.jpg

Another way to ask is; How many feet of dry Earth does it require to achieve an r-value of 24?
And, yes, I understand that the large heat capacity mass differences of Earth and insulation
complicate any straight comparisons of heat flow projections based solely on r-values.
 
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  • #5
russ_watters said:
What are the average summer and winter temperatures? And is he house heated and air conditioned?

I don't have summer/winter averages handy, but the cooling degree days are about twice the heating degree days.

Average annual air temperature is 72 F, which I understand is best indicator of what the stable ground temperature will be at 5 or 6 meters down.

It's what I'd like to maximize being closer tied into, with proposal of insulating ground surrounding structure, to then minimize heating and cooling loads, both of which will be available, if necessary.
 
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  • #6
Can you tell us the location?
 
  • #7
Spinnor said:
Can you tell us the location?
West Texas
 
  • #9
Last edited by a moderator:
  • #10
shane2 said:
OK, sounds nutty in a limited short title, but...

For a planned dome home in an area where average annual air temperature is 72 degrees, and thus steady state ground temperature at 20' deep or so stays within a pretty narrow range near that 72 degrees year round average above, and where house will purposely not have it's concrete pad or footings insulated so as to have earth, by design, be in contact as a heat sink in summer and heat provider in winter, how much would the following contribute to help that ideal work?

From exterior edges of dome home extending outward 12' in all directions, there would be a 12' continuous deck surrounding the dome, laid flat upon the ground, that was made only of 4" polyurethane freezer panels. (These have galvanized metal on both sides with the 4" of polyurethane sandwiched in the middle. Assume no air or moisture infiltration between the bottom of them and the ground.)

How much would that insulation set up help to dampen the hot/cold summer/winter temperature swings of the Earth immediately below the concrete pad all along the outer edges of the dome?

FYI, cost is not an issue or question here, these are used/surplus 50 cents a sq ft panels, and also the seamless installation and waterproofing and UV protection of exposed ends is not an issue either. Also, consider the color reflectance of the top surface as 'neutral', equally absorbing sun in winter and reflecting sun in summer, to take solar gain or lack of out of the equation, so as to be just looking at the air temperature seasonal swings affect on the Earth below them.

What I'm trying to get a fix on is, with this 4" of insulation extending out 12' in all directions away from the concrete floor atop the earth, how much might that insulation be helping keep that concrete floor nearer to 72 degrees compared to not having installed any such insulated decking?

Appreciate any thoughts and/or suggestions to improve on above.
As a suggestion, imo dampness would tend to accumulate in the volume downside and to climb from underground around into the dome _interor_ through trhe floor, counterfeiting the intended goal.
 
  • #11
Mantuano said:
As a suggestion, imo dampness would tend to accumulate in the volume downside and to climb from underground around into the dome _interor_ through trhe floor, counterfeiting the intended goal.
A vapor barrier on the ground, beneath the floor, should lower risk of any moisture intrusion from below, if that's what you were thinking.
Also, local environment is extremely dry year round, very low humidity, 10 inches rain annually and most of that runs off, not soaking in.
 

1. What is the purpose of laying insulation flat on the ground around a house?

The purpose of laying insulation flat on the ground around a house is to prevent heat loss from the house's foundation. By creating a barrier between the ground and the house, the insulation helps to maintain the temperature inside the house and reduce energy costs.

2. Does laying insulation flat on the ground around a house really make a difference?

Yes, laying insulation flat on the ground around a house can make a significant difference in energy efficiency. It helps to prevent heat from escaping through the foundation, which can account for up to 20% of a home's total heat loss.

3. What type of insulation is best for laying flat on the ground around a house?

Fiberglass insulation is typically the best choice for laying flat on the ground around a house. It is moisture resistant and can withstand the weight of the house without compressing, which can reduce its effectiveness.

4. Can laying insulation flat on the ground around a house help with noise reduction?

Yes, insulation can help to reduce noise from outside. It acts as a sound barrier and can absorb some of the noise before it enters the house through the foundation.

5. Are there any drawbacks to laying insulation flat on the ground around a house?

One potential drawback is the risk of moisture buildup if the insulation is not properly installed or if there are any gaps or tears. This can lead to mold growth and damage to the foundation. It's important to ensure proper installation and maintenance to avoid these issues.

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