[Greenbuilding] Slab heat loss calculation

Norbert Senf mheat at mha-net.org
Sat Aug 24 06:42:48 CDT 2013


Or, you could invest that $1350 in a US 30 yr 
bond @3.8% instead of styrofoam and get $51.00 per year instead of $4.00.

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A 5 lb piece of wood burned at 70% efficiency 
gives about 32,000 BTU. That would cover the slab 
heat loss for 7 days. For a 5 month heating 
season, it would need 100 lbs of wood. Doubling 
the foam thickness to R20 would save about 50 lbs 
of wood per year. At $240 per cord, that's a saving of about $4.00 per year.

At $1.50/sq ft for the extra foam (not counting 
labour), 900 sq ft would cost $1350, for a simple 
payback of 337 years..........N


At 05:44 AM 8/24/2013 -0400, you wrote:
>RT <archilogic at yahoo.ca> writes:
>
>>... In putting our pants back on frontwards, 
>>someone noticed that we had all received tattoos onto our backsides:
>>
>>? ? ? ? ? "? q? =? A [ dT ( K/s + hc ) +? ( ? * T^4 ) ]? "
>(snip)

-------------------------------------------
Norbert Senf---------- mheat(at)heatkit.com
Masonry Stove Builders
25 Brouse Rd.
RR 5, Shawville------- www.heatkit.com
Québec J0X 2Y0-------- fax:-----819.647.6082
---------------------- voice:---819.647.5092









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