Quad "Pane" Windows

[semipro]

I thought this might interest some here.
Quad in the title is quoted because one of the options includes 2 outer glass panes and 2 inner layers of suspended film.
It still offers only a 25% improvement over dual pane systems which is not a lot considering the low R starting point.
(broken link removed to https://www.gsa.gov/cdnstatic/Applied_Research/048-GPG%20Findings%20Quad%20Pane%20Windows.pdf)

(broken image removed)

 

[peakbagger]

One of the big issues discussed in my passive house course was the difficulty and price of buying truly high performance windows. Almost all of them come from Europe and are custom built to order. Deliveries are long and they require more time and care to install. The folks with practical experience claim plan on spending an entire day to install the first one. The net result is they are incredible efficient, but a cost benefit ratio needs to be done. They are not optional on a Passive House but hard to justify with typical house built to current energy standards.

 

[begreen]

My sister's attached greenhouse has super insulated windows. IIRC they are R=10 rated and were made by either Goodyear or Goodrich. They turn the greenhouse into a nice heat producer during the day and help it retain heat overnight.

 

[DBoon]

My renovated house has a heat loss of about 20,000 BTU/hour at 0 degrees F outside temperature. About half of that comes from windows - 2/3 of which are original (not drafty) wood windows with wooden storms (about R-2 insulation value) and the other 1/3 are new Marvin Windows (about R-4). If I replaced all of the wooden windows with better R-4 windows, I would save about 17% of the heat cost of my home. If I installed all R-8 windows, I would save about 40% of the heat cost of my home.

OK - here is where it gets ridiculous - I have a geothermal heat pump that uses about 4 MWh/year. If I bought that electricity at about 12 cents/kWh (the going cost in Central, NY) it would cost me $500/year for heating. R-8 windows would save me $200/year. Not worth it. That's why I saved as many of the original windows as I could.

Even if my heat cost me three times as much it would still not be worth it.