High Efficiency House Ideas

DavidC

I still agree that the ICF's are a very good option. But what I learned on the building science website is that the thermal mass is of no use in heat calculations in northern climates. When the daytime highs are lower than the heated space requirements the heat transfer from the heated mass is greater towards the outdoors than the living space. This negates the thermal mass.

In the southwest it will heat the building because the inside/outside temp deferential is much closer than in the great white north. Here the daytime highs often exceed the controled inside temp so there is a gain.

Should the OP visit www.buildingscience.com he can get unbiased comparisons of most building systems in use. Very informative site.

Good Luck
Dave

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sawyerEd

Dear Vrooman,
Congratulations on getting into energy efficient construction, remember that to be truly green you to need to consider the total carbon footprint of all the materials and building techniques of the project. The above members have warned you about major problems with tight houses, moisture control and indoor air quality. Air to air heat exchanger and ventilation systems will increase the cost of your project substantially. They need to be designed and installed carefully to match the extreme climatic conditions you have in Manitoba. You need to take some measures to reduce sources of indoor pollution when choosing materials for a very tight house. Materials, finishes and furnishings made with solvent based glues or polymers (vinyl and polystyrene) may need to be eliminated; they will continue to gas off VOC's for a long time after installation. Sources of carbon dioxide (other than the occupants) or carbon monoxide may have to be eliminated from the home. ICF constuction is widely accepted but is not the best way to build a basement. Take a look at the precast panels produced by companies such as superiorwalls.com and visit one of their projects. Someday 80% of all residential basements will be built this way. We are a little confused about how you propose to install the vapor barrier in your double wall design, perhaps a drawing would help. It sounds like you are installing the vapor barrier on the inside of the balloon frame and building another 2x4 wall inside of that!!
Thanks, Ed.

monticellohomes

I am working on my first highly energy efficient home and a few items I've found that seem to be great for this type of home are:

Dow's SIS panels, we were able to sheath the home in this in one step rather than wrapping with OSB and then foam on the outside of that...it also eliminates the need for house wrap.

Zo-e-shield windows by WeatherSheild. (Other manftrs can get the zo-e glass as well), but it outperforms low-e again helping with efficiency.

ERV like everyone above has discussed.

And a product I just learned about and am very interested is the Green Switch...with the throw of one switch you can turn off all non necessary lights, etc when you leave the home.

woodworkbykirk

in canada the program we have is called R-2000,

-higher standards for air loss, higher standards for window and door heat loss and gain, all fixtures must be low flow, higher efficiency heating system, higher insulation values ( gained by installing 2" foam on the exterior of home), reduced electrical use. to name some things

its comparable to the passive house


as for icf's, a 6" icf wall has a r-value of rougly 50 -60 as oppposed to a 6" frame wall which is r-19 before adding 2" foam. i know a few people who have icf homes and their heating costs are insanely low compared to a house of same size thats wood framed

Vrooman

Here is a crude drawing, Kind of hard to see, but hopefully you can understand.

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Vrooman

The joist pocket will be insulated on the warm side of the poly, i believe National Building Code says 2/3 has to be on the cold side.

sawyerEd

Thanks for drawing Vrooman. The 2/3 on the cold side formula prevents the vapor barrier from becoming a condensation surface. It may be hard to install the rim joist in the pocket and the attach the floor joist without damage to the vapor barrier. The drawing does not show the headers or plates in the 2x4 walls. Your double wall looks like a sound transmission class wall and if you use that description the framers and inspector will know what you are talking about. You should check out the SIS Dow panels mentioned above if they allow the wall to breathe that would be a better solution than foam that will trap any stray moisture in the wall. We haven't talked about how you intend to seal electrical and plumbing entries through the wall and ceiling. I don't like the looks of the staggered wall in the basement sorry. I think the stem wall should be precast R28 concrete panels or second choice ICF, third choice 6" reinforced concrete with insulating board. then the wall can be finished flat. It appears that you are bringing the insulating panels up to the top cord of the truss. Make sure you don't close in the attic so much that it can't be thoroughly ventilated.
I think you should have an engineer involved in this project as long as you are not getting them to do the drawings he should be able to give you some good advice for not a lot of cash.

Vrooman

Thanks for the advice sawyerEd. The staggered wall in the basement might be framed up, depending on the home owner's preferance. I have a ledge in the basement of my own home, and it is kind of nice for pictures or whatever.
The bearing walls will be the 2x6 Outside wall, and the 2x4 wall holding the floor up.

The 2x4 4 foot wall will be built first with poly between the top plates (with acoustical sealant to seal nails) So, being careful, we should be able to save the poly from any damage.

I have a method a carpentry instructor at college showed me for sealing stack vents, I will have to draw that up sometime soon. He is a registered R2000 builder, so he is very invoved in this type on construction. I will be looking into the R2000 program and use this house as the qualifying house.

All electrical in exterior walls and ceiling will have plastic boxes (not sure if they have a certain name). I am looking in to it, but I think you need to put blocking to compress the seal around electrical boxes.

The insulation is shown to run up the cords of the truss, which should really matter, I still have a 3.5`` air space from the top cords, But insulation stops will cut that down to 1 inch or so.

I will definatly have a good HRV in this house, it is required by code.

My other idea for an energy efficient house is one inch of P2000 and empty stud cavities

sawyerEd

Keep us posted on some of the design choices you make. I've got a berm design on for next spring and I will post the detail drawings here when I get them approved by my engineer. It will have radiant in floor heating powered by an outside boiler that will burn my sawmill waste. There are a number of issues involved with the slab and foundation. We are trying to achieve R28 in the walls and R40 in ceiling with capillary and thermal breaks. I bought this plan from homeplans.com, enter in search box plan #, H-938-1A. Looking forward to exchanging ideas. sawyerEd

gregj

vrooman,

Take a hard look at cellulose vs fiberglass. Fiberglass allows a lot more convective air movement (not good).

GreginAlaska

I had a house designed that was a hybrid between a monolithic dome roof (steel re-enforced concrete) and 8 inch ICF walls. The house, including the garage and three tower levels, was to be about 3900 square feet. The designer claimed the roof would have an effective R value of R-60 - 70, can't remember what the walls were supposed to be. An engineer rated the heat requirement at 40,000 btu + or - 6000 btu at minus 25 F. IS that good for that size of house? Not sure what the volume of the house was supposed to be, the walls were about 9 feet and the MD roof rose another 7.5 feet at the apex. The top of the tower walls is 26'9". Once it came out of engineering, it would need 40,000 pounds of steel and 300 yards of concrete. That's a LOT more than I was led to believe it would require, the designer is not an engineer, I think he was rather surprised too. Not sure I'm going to build it now, but I might. I will definitely be using ICF walls.

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sawyerEd

GreginAlaska, I lived in a concrete dome once and I was horrified how heavy it was. Inadequate foundations eventually caused the structure to be abandoned. Make sure you have some good engineering done before taking on a structure like the one in the picture. Make sure you check out the cost of finishing out thick EPS walls on the ICF. Concrete walls are better when they are warm and dry encasing them in a thick coat of EPS may not be the best plan. sawyerEd

GreginAlaska

I've checked it all out...my engineer is one who is involved in writing federal codes for thin shelled concrete buildings.

Chris Zweifel P.E., S.E.
ZZConsulting

About the only thing that would be better at being strong, energy efficient, and cost effective here , would be a straight monolithic dome. But I don't like the looks of them.

GreginAlaska

Hey ED, I figured out what the shell of that house would weigh, it would only be 1,174,000. pounds. yikes

ContractorPete

R-Value of concrete is .3 per inch. Most 6" ICFs are about R-24. Add the concrete and you net a R-25.8 . As far as the 'thermal' mass of the concrete inside the ICF, it is there but definitly not as effective if you were to leave the concrete exposed on the inside of the house. Remember the concrete has 2.5-2.75" of polystyrene on each side. The thermal gains that the concrete picks up will be limited by the amount of insulation that is covering it. It is definitly there though. Fiberglass is a thing of the past.

GreginAlaska

If I was an ICF manufacturer, I would be trying to figure a way to remove the inside foam, after the concrete is set, and have a way of attaching it to the outside. That would be especially cool if it left the webs so you would still have attachment points for sheetrock etc.

joasis

Greg, the reason ICF's work so well is that the interior foam can be cut and wiring and boxes cut in, no big deal. It adds to sound deadening.

I can see issues in extremely cold climates with the mass of the wall cooling significantly, and given that scenario, I would probably add foam board and a reflective barrier to the exterior before final finish.

In Oklahoma, we believe the ICF walls "act" like an R40....simply because they are air tight and the mass of the wall is stable at probably 65 degrees.

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GreginAlaska

Oh ya, I forgot about using it as an area for chases and sound control. I see Quad-Lock is making a form that you can use to add foam insulation to the exterior. They also make a 4" thick panel, you could put a 4" on the outside and a 2.5" on the inside...but I think I will be using Amvic, they have a plant in Anchorage.

ContractorPete

Logix is coming out with a new version of their knock down form (XRV) that allows you to put together different EPS panel widths up to 8" thick on each side. This would net you up to an R-66.

I haven't got pricing on it yet, but im already putting together marketing for it.

GreginAlaska

Wow Pete! I wonder if it will lower the amount of bracing needed?

I got an email that said Fox blocks is coming out with a pre-formed radius curve block. That's kinda cool too.