Posted By NRT.Rob on 21 Jun 2011 09:22 AM
16.4 Degrees with joist trak and a wood floor would be about a 110 supply, and you're then in the promised land...

Is that 16.4 degrees the outdoor ambient temperature or a typo?

The 110*F supply sounds possible as many rooms are below that.

Thanks

John

Sorry I meant 16.4 BTUs/sq ft, in reference to his numbers.

The designer has used a flooring R value between 1.0 and 1.5.

Good news for you. Based on Joist Trak 8" OC spacing, that puts your supply temperature more down in the 90F range. You might want to go over that part again with the designer.

Sorry I meant 16.4 BTUs/sq ft, in reference to his numbers.

His numbers say "8.4 BTU/sq. ft. ", unless something has been edited.

"The one room requiring 120*F supply works out to 16.5 BTU/sq. ft. (room loss / room area)."

that's the room we're concerned with, not the building average.

Posted By NRT.Rob on 21 Jun 2011 09:22 AM
16.4 Degrees with joist trak and a wood floor would be about a 110 supply, and you're then in the promised land... 

Rob

How do you calculate 110*F supply?

(16.4 BTU/sq. ft., not Degrees)

Thanks

John

John7,

May I ask what exposure and charistics is the room with the 16.5 BTU/sf? I'm wondering if there's a lot of heat loss because of windows, and whether those windows are facing in a way that you might benefit from passive solar.

I think from a permitting perspective you'll need to work out the numbers to the satisfaction of the building department, but from a practical perspective, how often and how long does Vancouver get down to 18F that you may need to worry about insufficient heating in that one room?

We've been running an Altherma here in Toronto, and last winter we ran it at 113F to a fan coil, and ran it down to 13F or so before we flipped over to backup natural gas, and that was a handful of days. The fan coil was supplying a 6350+sqft of conditioned area, 4350 above grade on an ICF/SIP combo build. My (inexperienced) gut feeling is that you'll probably do just fine funning it at 113F or maybe even a bit higher. The couple of days where you need to run on backup if you choose to run the loop at 120F(whether electric integrated or in a bivalent operation) is still probably worth the savings in a season.

Victor Kam
http://www.ecobuilthome.ca
A 4350sqft Cold Climate Net-Zero Energy Initiative

Victor

I heard about your project and am quite interested in it. Although your in a more severe climate and your home is twice the size of my project.

Room exposure:
That room is a main floor corner. There is a heated basement below and well insulated attic above. The room is a basic square with exterior exposed walls on two sides and a short portion of one of the return walls (alongside a elevated deck). There are five 32x44 windows of the standard double pane argon gas low-e vinyl type. I believe 3 are fixed and two are casement opening. There is also a large opening to the dining room but I don't think that makes any difference.

Our winters are very wet and cloudy (its possible to go 60 days without blue sky). Conversely our summers are very sunny and dry. There is no potential for winter solar. That said the windows are on the south and west sides.

For what its worth although the design temperature is 18*F we did have -2*F for one day last winter (or was it the previous winter?) so the design temperature is not the absolute lowest you can expect but rather some kind of "lowest average". Probably lowest 5% percentile.

Could you email me? I'd really like to see some photos of your installation and ask some technical questions.

John

John7, are you inland or in Vancouver proper?

Posted By ICFHybrid on 06 Jul 2011 08:26 AM
John7, are you inland or in Vancouver proper?

Port Coquitlam. Thanks.