Energy costs in old home vs new (how much, new home)

[Citykid3785]

Can anyone provide any information on how much more their energy costs increased/decreased moving from an old home to a new (or vice-versa).

Let's assume we are comparing similar sized homes, one built in the last 10 years, verses one built pre-1950.

Are energy costs for older homes 10% more? 30%?

Thanks for any insight into the matter!

[BryaninMSP]

There are "good" old homes and "bad" old homes when it comes to energy efficiency. I had a "bad" old home once where my gas bill for one particularly cold month was $425. This was for a 1,700 square foot house in southern Minnesota. Compare that to my 20-year-old house in the Cities now, which is 3,600 square feet and my heating bills are never more than about $150, even in the coldest months.

With "good" old homes, the attic insulation will have been upgraded, the windows will have been updated and the difference between older homes and newer homes in terms of efficiency will be smaller (though newer homes will almost always be more efficient). It really varies house-to-house and there are definitely trade-offs in character, original build quality, etc.

[aus1ander]

An original 1940s or 1950s home will be fairly expensive to heat during winter as insulation standards and window efficiency has greatly improved.

Newer homes are definitely more energy efficient, but they are building them so "tight" that you may have the opposite problem--a new home that doesn't "breath" requiring expensive ERV systems.

If you buy an older home that has been renovated, make sure the insulation and windows have been replaced. You should aim for R50 in the attic (assuming its not a 1.5 story home where there is no "attic") either with blown cellulose insulation or spray foam. Older homes are prone to attic bypasses that can greatly increase the risk for heat loss in winter and ice dams. Any insulation updates should include searching and sealing all possible bypasses.

I personally prefer older homes for their charm.

[uptown_urbanist]

I assume it depends so much on other factors besides age to make it impossible to accurately compare (assuming you are looking for rules of thumb for setting your house budget?). Our 100+ year old house has had a lot of energy efficiency upgrades, including my favorite - radiant floor heating (at least on the first floor)!

[Citykid3785]

Originally Posted by aus1ander

An original 1940s or 1950s home will be fairly expensive to heat during winter as insulation standards and window efficiency has greatly improved.

Newer homes are definitely more energy efficient, but they are building them so "tight" that you may have the opposite problem--a new home that doesn't "breath" requiring expensive ERV systems.

If you buy an older home that has been renovated, make sure the insulation and windows have been replaced. You should aim for R50 in the attic (assuming its not a 1.5 story home where there is no "attic") either with blown cellulose insulation or spray foam. Older homes are prone to attic bypasses that can greatly increase the risk for heat loss in winter and ice dams. Any insulation updates should include searching and sealing all possible bypasses.

I personally prefer older homes for their charm.

I appreciate your wisdom. We were looking at a late 40's house that has the original single pane windows, and I don't recall seeing insulation when I peeked in the attic. Our current home was completely flipped in 2011 (new windows, roof, etc.) so we could be going from predictable to unpredictable. Being that the home and taxes themselves cost more (plus its and exta 400 sqft), I'm trying to cover all my expense bases