Looking for natural cooling ideas

[stumpfield]

Here is an idea I read about years ago and thought would be fairly easy and relatively inexpensive. The idea was to dig a large trench about 6’ down where the ground temps stayed constant year round in the upper sixties. Then they installed metal culvert pipe, don’t recall the size, in a “U” shape beginning and terminating at the foundation wall. After backfilling and building the home a blower was installed on one side of the pipe to force house air through the pipe. The theory was to take the hot/cold house air and condition it in the pipe to closer that of the ground temps by moving it through the culvert pipe. I would think that the longer the culverts loop the more it would condition the air being moved through it.

We had good results at a weekend home by building a cupola in the center over the area our woodstove sets. The cupola is about 6’ by 8’ and has six awning windows that are operated by electric motors from a wall switch. In the winter it lets us vent off excess heat from the woodstove and in the summer acts like a chimney to draw heat out of the house when the windows are open on the lower floors.

MarkV

A friend's dad in the area built his home with the culvert pipe idea. He ran about 200' of 18" culvert pipe underground away from the house but it never really worked. To be effective, he would need somewhere around 2000+'. There's not enough time to cool the air in such a short run.

The cupola in the center is what I plan to incorporate into my plan. Except I call it an observation tower instead. It will be a 12'x12' room with a spiral staircase in the center and windows on all side. During the summer time, heat will rise to this area and vent out naturally. It will also take advantage of the summer breeze. I can accelerate air flow by open/close different windows to cause a siphon effect to suck hot and stale air out of the house without the use of fans. What I need is a source of cooler air for the intake side. I'm thinking of running a copper pipe down to the well and loop back up to act as a condenser. Since it's submerge under water a few hundred feet underground, it should cool the air through the pipe pretty quickly.
I guess I'm trying to make the house itself as a slow pace air conditioner.

 

[Paddy]

High Beam,

You can have a slab above grade. Look at a parking gargage. Most of the world builds with concrete footers to roof. I plan on building a 3 story home soon and it will be concrete except porch roofs. They sell foam panels for forming the floor/roof slabs

Other comments outside the scope of your post
IFCs can be very missleading with regards to Therma mass. Two main points I do not like about them. 1) The advertize R-Equivalence using the U factor (Thermo Mass rating). Thermal mass mainly helps when outside temp swings above and below inside desired temps DAILY. For example, in the MN twin Cities, ave winter temp fluction never get above inside desired temps. Same can be true for FL, hot all 24Hr. In AZ, you get nice temp swings and you can stored the heat of the day for use in the chilly night. Second point, 2) IFC have insulation on both sides! This nearly isolates/insulates your Thermal mass from receiving/releasing energy!

 

[Highbeam]

Thanks Paddy, I was also wondering about the insulation on both sides of the ICF as a barrier to good utilization of the thermal mass. The other company makes a pre-made wall with 2" of exterior concrete, 2" foam, and then 4" of interior concrete. These seem to offer better thermal mass exposure and even better exterior water resistance but what about the inside? You need to run your wires somewhere and putting a simple studwall with sheetrock up seems to defeat the purpose. How do you plan to build the 3 story concrete home? Traditional formed and poured walls with foam applied to the outside?

Tilt up walls like they use in commercial warehouses?

I am a big concrete fan ever since school where a good professor let us experiment with admixtures and proportions to make concrete cylinders and then crush them to figure out what worked.

 

[Paddy]

HighBeam,

I see your an engineer also. Concrete construction is old hat in Europe, seems like we have to re-invent the wheel!

Still working on the details for my home. But it will be concrete! Many reasons, fire, sound proof, wood decay. I will be going for a Spanish vila style, red tiles for porch roofs and stuco walls.

I have seen a neat material AAC, Airated Autoclave Concrete. This concrete that has 70% by volume/weight/(thermal mass) and air. There is chem process that expands it and them it is cured with heat. They sell blocks and panels. Cuts with a saw. It is expensive!

I have playing with the idea of contracting a standard wall pour using standard forming. Main diff would be 6" of blue foam down the center. In the foam I would have 2" conduit for ele. I will have to tie the inside and outside panels attached ever few feet via removal of a small section of foam. The 6" foam panel will centered in a 12 to 14" wide concrete form. This concrete on both in/outside will give both thermal mass and great fire protection from the foam. At floor levels there will be reduced foam to cary the floor loads but still isolate the interior slab from the outside wall. The floors can be of two commom methods, 1) steel framing with a 4" poured slab or 2) cast in place joist/slab style the foam floor panel gives you. I have seen these foam floor panels, they are really nifty. They have the profile of a typical floor system. Depending on your span, the "joists" grow taller as required. So for example, a joist might be 6" wide by 14" tall spaced every 3-4 ' on center. The joist will have rebar and the slab will have wire. The foam panel has 4" dia runs for utilities between every joist. Before the pour, the panels require suport every 6' from below. You can skip the foam floor panels and form it out out plywood, labor vs material. Again, foam inside the home make me nervous, due to off gassing/fire.

Patrick

 

[dfkrug]

It is true that some ICF sellers quote "equivalent" R values of as
high as 48. That means you would have to build a framed wall
with r-48 insulation for the same energy performance. The actual
R-values of most finished ICF systems are about R-22. The key
energy performance advantages of ICFs are first, less air leaks, 2nd
good insulation, and 3rd high thermal mass. The last is most
effective when a large portion of the house is underground, as with
a basement or a hillside structure.

It is true that the IDEAL construction of a high thermal mass wall
may not look like a typical ICF, with 2-4" ins, then 6-8" concrete,
then 2-4" of insulation. But an ICF is designed for ease of construction.
Large cast walls with sheets of insulation embedded inside are
very expensive and difficult to build. Cutting and placing 4-ft long
ICF blocks weighing 6 lb each is easy.

I built 4 of my own projects this way, and I was involved as a consultant,
trainer, distributor on about 2 dozen. I am no longer in that biz.

ICF construction is becoming popular in most of the US, and has been
popular in Canada for many years. Many other countries do not even allow
wood frame house construction, so many concrete and masonry techniques
are used. You would see more in the US if owners learned about it and
demanded it of their builders. Or built their own houses. Builders will
generally not choose it, usually because most of its benefits acrue to the
owner, not the builder.

BTW, I love the concrete foor systems like PanelDeck, but it is quite
expensive and you need an engineer's stamp for the shoring as well as the
structure itself.

 

[dfkrug]

The toxicity of the common pentane-expanded polystyrene foam
used in many ICFs is lower that than of unfinished red oak. Oak
is the benchmark for smoke toxicity. Furthermore, the proper
installation of EPS ICFs require a 15 minute fire barrier on inside
wall surfaces. Ususally that is 1/2" drywall.

 

[Highbeam]

Don't forget good old cocrete block walls. The inside plastered over and the outside with insulation and an exterior siding applied. The block cavities can be used for rebar and concrete alternating with voidspace for running wires. Some thermal mass sites even recommend building dry stacked block walls.

When my neighbor built a home with ICFs on the bottom story, the ICFs required a lot of bracing during the concrete pour not unlike the bracing to hold the forms of a poured concrete wall. He drywalled the inside and sided the exposed parts of the outside of this daylight basement level. In the end, I don't think it was much easier to build. Easier to stack for sure.

I don't want foam on the inside. I'm thinking poured or block walls now.

Does the HVAC of a concrete floor and walled house all come from above? All of the vents for my current HVAC are mounted to the floor and the intake to the ceiling.

 

[dfkrug]

Don't forget good old cocrete block walls....

Does the HVAC of a concrete floor and walled house all come from above? All of the vents for my current HVAC are mounted to the floor and the intake to the ceiling.

Concrete blocks are no stronger than 2x6 framing, even with grout
and rebar. Hard to install. Furring strips reqd on inside. Foam panels
need to be glued to exterior. Don't forget, WA state has some seismic
issues.

Re heating ducts, mine are under a slab. You want heating ducts low
for upward convection, esp in a hi-ceiling house. In very hot climes, your
house should be designed for cooling and the heating/cooling ducts should
be high. My under-slab ducts use standard rectangular galv steel sections,
insulated with 1" eps, and I covered them with Wonderboard so the
concrete workers would not crush them by walking on them during the
pour.

 

[stumpfield]

Don't forget good old cocrete block walls. The inside plastered over and the outside with insulation and an exterior siding applied. The block cavities can be used for rebar and concrete alternating with voidspace for running wires. Some thermal mass sites even recommend building dry stacked block walls.

Good old concrete block walls is what I planned for the interior partion walls. To add even more mass, I will also add pre-cast stone or river rock facing to the interior block wall at certain locations. The rest just plaster to cut cost. The exterior envelope is conventional 2x6 with insulation.

 

[jimg]

Dont think anyone has yet mentioned a basement. My former home was cut into a hill which left 3.5 sides well underground. During the heat of the summer we'd eat and sleep down there as it was many degrees cooler than the upper floors. It was also a great place to store food. We'd dehumidify it which made it feel a bit cooler.