Vrooman

This coming spring we will be building a small house that the customer wants extremly energy effiecient.
This will not be a hard build, the house will be a 28x36 rectangle.

Here are the plans as of now:

-4 foot basement wall
-4 foot 2x4 ponywall supporting only the floor system
-14' 2x4 wall from the concrete wall to the trusses
-another 8'2x4 wall built inside on the upper floor 4" away (to allow for 2 R20 batts in the wall)
-high heel trusses with r60 in the attic
-2" SM foam board from footing to top plate
-top quality triple pane low-e windows and high quality doors

The purpose of the balloon type framing is so we can wrap the poly around the floor system and have a perfect seal. We will be insulating the joist pockets on the warm side of the poly to bring it up to the same as the rest of the wall

Any other ideas you guys have used to create tight efficient homes?

billy d

genecarp

There is so much info out there, one basic item i would include would be a nicely designed WHOLE HOUSE FAN. if this is a climate that requires A/C, a good fan will minimize the need to run the A/C.

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neolitic

Air to air heat exchanger.
The tighter you build it,
the more important it is
to supply fresh air.

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mics_54

I been thinking lately...an igloo has the entrance low so that heat cannot escape. How about an arctic entry at ground level. If you are on a four foot crawl that would place your entry door four feet lower than your living space. Also sprayed foam insulation eliminates the need for a vapor barrier and increases structural integrity. Window placement best utilizing natural light. One consideration...how will you control the heat and humidity/moisture in the crawl space? Floor sheathing usually meets code requirements for vapor retarding when installed correctly. if you have plumbing in the crawl space it still has to keep warm. The vapor barrier need to go on the ground. Neolitic is right...a tight house is desired to CONTROL the air changes....not eliminate them.

Vrooman

It is code to have an air exchanger here in any new house so that will be a must.
If you re-read my first post, it has a full 8' basement, there is a 4' ponywall on top of the concrete wall. Then approximatly a 14' wall from the concrete to the trusses, so it will have a double wall in the basement as well.

This house will have a grade entrance as well as a upper floor level entrance.

I am trying to do this fairly cost efficient too, since fibreglass insulation is cheaper than spray foam I will be using as much as possible.

Keep in mind this is in Canada, the temperature flucuates between +40 celcius to -50 celcius So heating and cooling are both factors.

I will be placing windows in stratigic spots so to get as much solar gain as possible in the winter when the sun is lower in the sky. and roof over hangs that will shade those windows in the summer when the sun is higher in the sky.

For a furnace, I want to put a electric one in, I have heard mixed opinions on geo-thermal, but havent done much research on it.

nap

where the dickens in Canada are you getting those temp swings

(for those US folks he said -58º to +104º F) Mighty extreme.


What is the ground water temp in your area? and how far down do you have to go down to hit a stable temp?

Vrooman

Im not sure on the ground temperature, I will have to look into that.

Those temps are with wind chill and humidex, but still it gets damn cold and damn hot here. Those arent normal temps though, but it usually gets there at least once a year.

dlcj

What about ICFs from footing all the way to roof. Bolt floor systems to inside so exterior walls are unbroken. Not sure about the r-value on them but i think they can be custom ordered. Joasis knows more about those than i do. I agree on the geothermal for heating & cooling. Probably the cheapest in the long run.

Vrooman

ICF's is a good idea, but i think I can get a much better R-value out of wood walls for quite a bit cheaper.

joasis

I think you need better research...ICF's beat wood walls and fiberglass is a waste.

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genecarp

GEO IS GREAT, up front costs are significant, electric heat is generally expensive to run, although with the current economy and oil prices that may be changing. if wood is available, consider a wood furnace.

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dlcj

The only thing i dont like about icfs is that i cant afford them.

How bout a wood furnace that heats water for radient floor heat along with air duct system.

On my future house that will be a rustic post&beam style, im toying with a junk yard inspired idea for a external wood furnace the heats water for the floor and also through used car radiators with 12v fans attached for every room. Fans and pumps powerd by solar charged 12v batteries. Lots of bugs to be worked out i know but it will make heat on the cheap.

genecarp

Look into an indoor wood furnace, higher efficiency, cleaner burning. google GREENWOOD FURNACES. best out there.

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orson

Since you're not considering ICF's you are going to need to insulate either the exterior of the basemtn walls, the interior of the basement walls, or the basement ceiling.

Here's some good reading to start with:

http://apps1.eere.energy.gov/consume.../mytopic=11470

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joasis

ICF's can be done as low as $10 a sq/ft on wall, plus finish. Pretty reasonable for what you get.

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DavidC

I agree on the ICF's, but if you stick with wood frame exterior you will get more R/inch with cellulose. Also it is easier to get a nice tight job than with fiberglass, which is too easy to miss a detail or pack too tight.

Just my thought.

Good Luck
Dave

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Vrooman

I was going to do the 4' concrete basement wall an ICF, but my 2x4 plate will not have enough end bearing if it is flush with the styrofoam. so, the plan is to run the 1" of extruded polystyrene right down to the footing on the outside and have a 2x4 frost wall with r20 inside against the concrete.
Prove me wrong, but expanded polystyrene (bead board), is R3.7/inch? giving you approx R13 for the wall without including thermal mass factors.
How can that be better than an R45 exterior wall? (2 layers R20 and 1" extruded)

I will be able to make a perfect seal with the baloon-type framing from concrete to trusses, eliminating the need to individually seal each joist pocket. Spray foaming the pockets would be the easy way, but that would only be sealed as well as the VDR rating of OSB subfloor. So, in turn would not be "perfectly" sealed.

Seems to be a lot of thinking for a little 28x36 box, but it will be fun to see what it will turn out like.

DavidC

I've heard that if you ask 3 contractors the same question you will get 4 opinions. :>)

I was discussing the R value of ICF's with a supplier recently and he claimed that the R vlue of concrete was supposedly 4.5/inch. Didn't look it up to verify personally, but I'm sure it must have some R value to add to the mix.

11" of cellulose would yeild an R-41.5 + another 5 from your foam board = R46.5, less infiltration, better sound control. FG will deteriorate over time and lose R value.

Check out @ www.buildingscience.com.

Good Luck
Dave

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SLSTech

Don't forget with ICF's you get thermal mass, more strength, they are completed quicker, 1 contractor doing the work, it is generally cheaper than what you are describing & doesn't rot

With the wood walls, you have multiple contractor's working on it which takes longer & if 1 makes a mistake / doesn't understand the principles involved, you have wasted a lot of money

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