Full view glass garage doors heatloss
Has anyone compared whether it’s “worth” trying to get an insulated glass garage door when a fullview glass garage door is desired.
I wonder what’s an educated guess for heat loss would be for the average 2 car garage (20×30) with a 16×10′ glass garage door – insulated glass vs non insulated glass. When kept at 60F with a minisplit in zone 5 (80301). Assume standard r19 stick framed walls, r10 insulated slab, r60 and living space above.
I do not ever plan to cool this space though. It never gets that hot even when it’s 100f outside.
I feel that r value of the glass is pointless when air leaks and the aluminum frame pretty much dictates the heat loss.
Id like to see if it’s better to put the money towards more PV instead of the up cost of insulated glass (+$10k minimum from what I’m seeing)
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OK, zip code 80301 is Boulder, CO, your heating design temperature is 0F.
The heat loss through the rest of the building is irrelevant.
Heat loss through a surface is temperature difference (60F) times area (160 square feet) divided by R-value. Let's say the regular glass is R0.9 and the insulated glass is R2.0.
So the regular glass gives a heat loss of 60*160/0.9= 10,667 BTU/hr. The insulated glass gives 60*160/2= 4800 BTU/hr.
The insulated glass loses 80 BTU per degree-hour, or 1920 BTU per degree-day. The regular glass is 4266 BTU per degree day. Boulder has about 5500 degree-days per year, so the difference is about 13 million BTU per year.
That's equivalent to about 3800 kWh of electricity. At a COP of 2.5 that would be 1500 kWh of consumption. Where I am that's about $400 per year.
If what you really want is a glass garage door, I'd insulate between the garage and the house better and keep the garage cooler in the winter. I'd even consider having it unheated.
These numbers are extremely helpful to me. Thank you!
and turns out my cost comparisons were off by a lot. I was comparing higher end insulated glass doors against uninsulated from a much cheaper brand. I believe a more fair comparison the cost difference comes to more like $2000-3000. I'm now more convinced that I should get insulated glass with insulated frame. They claim r3.9 insulated aluminum frame with low E 1/2" IGU.
I have to ask 'why?'
The glass door will weigh a ton compared to foam/aluminum and require larger more expensive supports and big springs
IT will need to be laminated or at least tempered
A 1/2 inch IGU, 16 feet wide? Hmmm.....
What direction does the door face?
Any direction other than due North will increase solar heat load, so don't count on not needing AC
IF you have something expensive in the garage, maybe you don't want to show it off 24/7?
If you don't have something expensive in the garage, maybe you don't want to show it off 24/7?
That said, you will lose more heat due to air leaks
A garage door is the only door on the building without a proper frame.
I would be more interested in the particular door's sealing scheme than anything else.
I still get miffed over the lack of progres in residential garage doors and air sealing.
Bi-fold garage doors need to become a thing for residential.
It is first what I mentioned: no door frame.
Second quality of wheels and hardware.
I rebuild my doors, and I think I posted here about it, and they are pretty darn tight several years later.
TO be better they would need wheels with zero play and every one would need adjustments.
WE complain about shoddy installs, but with what the installer is given , what is one to expect