tom wrote:

I have an old rental property in Statesville NC.

I plan to put in central heat/AC. Trying to decide between propane
gas pack and heat pump. The contractor recommended adding insulation
and replacement windows.

I plan to get blow in insulation in enclosed walls. Have a bid for
cellulose.

And battings and blow in for accessible attic areas.

The real question is windows. I could put in replacement windows at
about $214 per window installed. But I don't see them paying off.
The U factor is .37.

But the U. factor for a storm window over and old window is .6
according to this site:

http://www.servicemagic.com/article....dows.8839.html

I might get by replacing all or part of the storm windows. I am not
sure how much a storm window will cost, its been hard to find pricing
on the web.

I did some calculations and I just cannot see a replacement window
saving more than $10 to $15 per year based on those U-factors.
Probably less since I assumed a 50 degree F differential
for 180 days per year which seems a bit high and I used $20 per
million BTU of heating/cooling cost and 12 square foot window.

214 per window, vs unknown storm window cost and installation time.

The rental is about 3 hours drive so I do have to go to some trouble
to travel down and install storm windows.

It will cost around $4000 if I go with replacment windows.


There are many things other than just U factor that can make replacement
windows improve energy efficiency and comfort. That, of course, depends
upon your old windows.

New windows probably don't leak nearly as much as your old ones.
Air leaks (in the winter) often cause a layer of cold air along
the floor, which makes people feel cold even if the thermostat is
set to something reasonable.
New windows are usually "low-e". That is, they have a metal film
in between the double panes that reflects infra-red and UV. That keeps
the temperature down in the summer, reduces the sunlight fading of
furnishings, and reduces the perceived (i.e. not indicated by a thermometer)
cold of sitting near a window in the winter.

Compared to prices where I am $214 per window sounds like quite a bargain.