Hi Jim, read the article, very interesting and goes along with what I am investigating. The system approach I am talking about will have 98%-100% solar fractions after just one annual cycle. It works well specifically with ICF since you can insert pex tubes into the concrete cavity before the pour. The pex pipes have several purposes, one of which is providing a thermal barrier - against heat or cold. This system can also be used on SIPS, but since SIPS are not hollow to begin with, it would take on the process of retro fitting.

A hybrid approach that I have been considering for construction in the North East, is a FPSF slab, with a partial crawl space for mechanicals. The dimension of the slab will be 33' x 33' and a 3' deep sump / crawl area will be 8' x 33' running across the middle of the slab. The sump area will be easily covered with SIP panels providing insulation, and an access hatch will provide access to all the plumbing and electrical for the building. Other than running a few wires through the walls, EVERYTHING (kitchen, 1 1/2 bath, washer, dryer, etc..) will be in the central core above the sump area, so everything will be somewhat accessible for repairs.

tlynch, sounds like you have a plan! You will have roughly 400sqf on eather side of your crawl area. That is 800sqf all together of wonderful, beautiful thermal mass - under neath the house. Why not tap in to it? If I told you that with this space available you could have enough energy to actually have a "zero energy" house, would you be interested?

dmaceld, with your last print you have come up with some good suggestions, objections and opinions. Here is how I would store the energy: I would go 3' lower than my slab on grade (whether that is a basement, stemwall or actually a slab on grade does not matter). I would line the perimeter walls with 3" of EPS panel. As I back fill I would lay down PEX tubing in a serpentinous way. The tubing could actually be in layers on top of each other. Before pouring the slab and during the back filling water needs to be pumped into these tubes to avoid collapse. After pouring your floor slab (basement floor or slab on grade) you have valid ground loops available for your "heat" circuit. That is all you would use this for, heating your house. To cool your house, you would go down 6-8 feet "outside" the perimeter walls and lay your PEX tubing in a meandering way, back fill, and that is your cooling circuit. Would you buy into that?

Manfred, are you looking to heat and cool with the earth as source and sink at a temperature high/low enough to not have to use a heat pump? I have serious doubts you can do it feasibly. The temperature of earth down to about 6' to 10' deep follows the seasonal temp of the atmosphere. Below that it is pretty much a constant 50 to 55F. That's a good temperature from which to extract heat to heat the house to 70F + by using a heat pump. It's also a good temp to absorb heat during the cooling cycle of the year, again using a heat pump (usually referred to as an air conditioner during the summertime). I don't see it as being a good temp to do either on its own.

That's why I would advocate injecting excess summer heat into the same region from which you extract winter heat. I've read some discussions about one drawback with geosource, that is gradual cooling of a large volume of earth around ground loops where the annual load is mostly heating. The reverse also occurs where the load is mostly cooling on an annual basis, i.e., the ground heats up. That's one reason wells are a good choice for geosource systems. Continuous supply of heat in the winter brought in by moving ground water, and a continuous sink for a/c heat in the summer by carrying it away. Keep in mind you're trying to extract/inject heat into a thimble size volume inside a swimming pool size earth volume.

From what I've read heat moves rather slowly through earth, so I see a problem with your idea of insulating the perimeter wall and dumping the summer heat external to it. The heat you suck up from below the slab won't get replenished fast enough to avoid cooling the earth inside the perimeter, and the heat you're injecting into the ground doesn't get recaptured.

dmaceld, good points, but I am here to tell you that the earth can be heated up to a specific core temperature within the insulated styrofoam perimeter. It will take about a year to stabilize this thermal transfer into and out of the earth. But, yes, the storage of energy in the earth is no fiction, and yes the energy can be harnessed and transferred into the earth.

Manfred,

Are you suggesting that during warmer periods you can store enough energy as heat in the earth below a house to help warm a house for the colder months?

Let say I placed a 3' deep, perfectly insulated tank under my house, it would hole 3000 cubic feet of water. 22,441 gallons.

(I am going to assumer we are storing the energy in water for my calcs)

Lets assume that you could heat the water to 110 degrees over the summer using solar panels.

Lets say that you want to heat your house to 68 degrees. The delta is 42 degrees.

42 X 8.34 BTU x 22,441 = 7 860 633 BTUs of energy stored in the water. (not sure what it would be if I stored it in the earth and not water)

A super insulated 1,000 sf house might require 20,000 btu / hour to heat.

So that would only be 16 days of heat if everything were perfect.

In this system you could obviously keep adding energy to the system using solar throughout the Winter.

Do you propose that the earth would hold more energy than water?

tlynch, no I am not proposing that the earth would hold more energy than water. I don't think that a water tank underneath the bottom slab is a "permanent" solution. With permanent I am talking about 10, 20, 50, 100 years. So why not stay with mother earth? BTU (british thermal units) is an old measurement not usually used or understood anymore. Who knows really what a BTU means? Unless you look it up, I beg to bet no one does, execpt for the experts in thermodynamics. Your conclusions to require 20000BTU/hour to heat a 1000sqf are not correct.

The system I am talking about gets replenished with energy year round. Solar energy of course. And yes, I am saying that with this system you can heat your house in the winter and cool the house in the summer.

Manfred,

I find your threads very interesting. I would like to know more. Do you have hands on experience with your system? How much does it cost over other
systems? Do you install it, or is it for the DIY ?

I would like to know more, as I would like to build in a year or so. I,m sold on ICF. The rest i'm still researching.

Thanks,
Vic

Manfred,

 a BTU if I remember the amout of heat to change 1 L of water 1 deg. in temp .

If you would burn 1 stick match fully that is 1 BTU.

Do I got it right? I have been out of school a long time

I saw an article a few years ago about using an earth berm type system.. because of water levels the house "basement " was built on the flat ground then dirt fill was brought in and sloped at about a 30 degree angle then covered with plastic to keep the rain from soaking in.  the top soil was added above and lawn planted. The theory was that wet soil; would transfer heat away.  and the earth mass would stabaiize at about 55 to 60 degrees. I never saw  a followup on how it worked .  If the dry earth was better,

woulf, to be honest I always have to refer to my formulas. I grew up with the metric system where a pound is 500 gram and not 454 grams. So all of the calculations get confusion. The best explanation I found is that 1 BTU is the amount of energy it takes to heat up 1 pound of water (now is that the metric 500 grams or the British 454 grams?) at its heaviest state (59 degree F) by 1 degree Fahrenheit. I have been out of school a long time as well.

vmg, not so fast. One has to understand the system first before the final analysis is done. This is not a DIY system simply because it is based on specific calculations that take into account the location, thermodynamics of soil, thermoregulation in the house, shell of house and so on. There are 3 more components to this system that we have not discussed yet. Is it financially feasable, could you afford it - should you afford it? Hell, yes.

Manfred,

Pex tubing in the wall cavity.

How do you install the pex tubing on a two story?
Are you pouring both stories at once, so you don't splice the tubing?
Is it ok to spice the tubing, or does it have to be continous?

Thanks,
vic

timothale, an earthberm in itself is a wonderful idea. All natural insulation and a constant state of temperature to deal with. This system though goes beyond the natural energy radiation of the earth. Heat ( energy) is injected and extracted. Heat injection is controlled to specific locations with isolated loops. It is hottest in the middle of the slabs and it cools off towards the perimeter. To give you an idea, there are 3 temperature zones from the middle to the outside (perimeter) The middle (core) temperature is equal to 95F, the next zone is 77F and the outer zone close to the perimeter is 64F. So, any temperature directly underneath the slab is warmer than the temp gradient of a basement temp (50F - 55F).

vmg, you insert the tubing into the rebar chairs as you go along with your build of the ICF walls - you splice where you have to. You still pour the walls in a fashoin as every ICF expert/installer, DIY is comfortable in doing. Nothing has changed in the ICF install, except you have added another material into the cavity

Manfred,

Does the floor radiate heat during the summer into the house?
Is the floor warm in the winter?
how hard is it to regulate the temp.

Vic

The temperature is regulated by sensors and a computer motherboard. The same kind of computerized regulation that is installed now-a-days to tell the furnace to come on or the air-conditioner to spring into action. So, the temperature is regualted by sensors and is as easy as you turning the dial. The floor does not radiate heat into house during the summer, nor does it radiate coolness into the house during the winter. THis is accomplished by thermal barriers placed in the floor and the walls. The dynamics of flow and temperature shift is, again, regulated by the sensors.

If your going to use the roof for solar energy, is the unit unattractive like most solar systems.
i would like to have my home to be attractive from the road. Any pictures?

The pex tubing is placed again in a serpentinous way directly on top of the roof platform in between slats. The solar thermal collection is not visible at all.