I live in the mid-Atlantic in a 100 year old house, and I'm looking for a way to reduce my heating bill. Last winter, I left the thermostat at 68F, and our gas bills were incredibly high, despite still feeling cold inside the entire time. I received an energy audit, but, except for confirming the fact that we have no insulation in the walls, it was pretty worthless. All of their recommendations came out to cost about $25k (after government rebates) and they calculated that it wouldn't pay for itself for 47 years. Needless to say, I decided to not use their services.

This winter, I hope to make at least one serious improvement to the house to help out with heating efficiency. Some of my ideas are listed below. I am wondering which will get me the most bang for my buck, or if there are other potential projects which I haven't thought of.

Add Wall Insulation

The house doesn't have any insulation in the walls. The plan would be to tear down the walls in select rooms and add fiberglass batt insulation, then put drywall back up. I am hesitant to use foam insulation mainly because I plan on redoing some of the electrical wiring, and I feel like using foam insulation would wake that very difficult. Plus, when I take the walls down, I can run electrical lines at the same time as adding the insulation. Taking down the walls and installing the insulation would probably be a DIY job, but I might hire someone to do the drywall.

I have already replaced the old modly, compacted insulation in the attic with 6" fiberglass between the ceiling joists, but I could probably add more too.

Replace Boiler

We have a gas boiler that heats water (not steam) for cast iron radiators in each room, but it looks pretty old. The "Energy Guide" sticker on the furnace says the efficiency is 83.5%. I know that some more modern hot water boilers have efficiency ratings as high as 95%, so another idea would be to replace the boiler with a new efficient boiler. I would have to high someone to install the boiler - at least the gas lines.

Replace the Windows

All of the windows in the house are original, so there is a lot of heat escaping through the windows. Since replacing windows in the entire house is a pretty large undertaking, I would probably just figure out which are the worst offenders and replace them. This would also be a pro job.

Which of these would give me the most bang for my buck for reducing my heating bill? Is there anything else I missed?

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    Your biggest bang for the buck is DIY. All the jobs you're talking about are mostly labor. Commented Nov 3, 2019 at 17:42
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    Cold walls will make you feel cold, even when the room air temperature reads high enough. Think of it as "cold radiators." Tapestries work because they block the cold radiator effect. Also, they have no contact with the cold wall, and thus can warm up to the room air temperature. On a large wall you could have cloth covered panels of rigid foam hanging close to the wall surface. The cloth is for decoration, similar to sound panels.
    – John Canon
    Commented Nov 3, 2019 at 18:05
  • Do you have ceiling insulation?
    – Mark
    Commented Nov 4, 2019 at 1:53
  • Tapestries are the way to go. In the rock castles of Northern Italy, which are still habited, you see thick tapestries strung on every way during winter. These keep the cold walls from "sucking" the heat out of the room. For a modern spin, check out this framed canvas with mylar backing: jasonmorrison.net/content/2008/…
    – bishop
    Commented Nov 4, 2019 at 6:48
  • Modern condensing hot water boilers in the UK have efficiencies greater than 100%. (This is because 100% efficiency was calculated assuming that all the water of combustion would leave as steam. If it is turned into liquid water, that is a whole chunk of extra heat available.) I don't know if efficiency is calculated the same way in the US. Commented Nov 4, 2019 at 8:39

2 Answers 2


Replacing the windows with modern double-paned isn't worth the cost; they're not that much better. However, I would recommend looking around for gaps around the windows where the putty stuff has dried out and repairing them. That's a mostly-labor job, and isn't that hard.

In general, your first goal should be to seal any gaps. This is not only much cheaper than buying insulation, but can be done DIY. Look around windows, doors, and vents, as well as any other place where there are intentional holes in the house. These tend not to be done that well, and you may find unintentional gaps.

Is your house on a slab? You didn't talk about the floor insulation.

A new boiler could directly save you roughly 10% on your gas bill, but would be expensive. (You can run the numbers yourself.)

  • The foundation is concrete slab with stone walls. The basement extends about 1-2 ft above ground with the rest of it below ground. Is there anything that can be done on the basement side of things to keep the house warm? The basement is generally warmer than the rest of the house because the boiler and the radiator pipes are down there. Commented Nov 3, 2019 at 19:30
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    Is the basement intentionally warm, though? The basement can either be inside or outside of the insulation layer, depending on what is easiest. You can either insulate the walls and floor in the basement (fix any water issues first), or insulate the pipes down there until the basement is colder than the rest of the house, then insulate the basement ceiling. Commented Nov 3, 2019 at 19:56
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    My only criticism is that you don't emphasize "SEAL ANY GAPS" enough. I've lived in a 1905 house, and they leak air like a sieve. Commented Nov 4, 2019 at 8:41
  • That's the real problem with old windows, not their R-value. There's also 'temporary' (yeah, right) caulk or that stupid shrink wrap plastic sheet stuff. gah....
    – Mazura
    Commented Nov 6, 2019 at 3:39

How many sq ft is the home? $25K will buy more DIY insulation than you can probably use unless the house is enormous.

If you are tearing the drywall out to insulate anyway, I would do any electrical work 1st and then use spray foam insulation. But, it is costly. In my experience the biggest bang for the buck would be :

1) insulate walls (spray foam or batt) and seal windows/doors. Silicone caulk is relatively cheap. Batt insulation is too. Can you put 6" batt in your walls? I doubt it on a house that old, but if you can--do it. the cost delta for 6" vs 3.5" should be minimal. This is another way in which SF will outperform batt. More R-value per inch.
2) add 12-18" of fiberglass or rock-wool batt and/or blown-in insulation in the attic. Definitely a DIY project. 3) insulate the joist band in your basement-- SF would work best, but anything is better than nothing. If SF is out of your price range, you can buy R-10 foam board and cut pieces to fit around the joist band and seal the edges with Great-stuff. I imagine your basement will be noticeably warmer after doing this.

As others have stated, this is all DIY and material costs should pale in comparison to paying someone to do the labor (spray foam being the exception). But SF not only insulates well, it also superbly eliminates air leaks. After 1-3 are done, see if your gas bill is still too high. I bet suggestions 1-3 will cut it by 30-50%. If you need more savings, then I would start replacing doors and windows. I cannot imagine heating bills in the mid-Atlantic area for a home with zero wall insulation and only 6" in the ceiling. BRRRR!

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