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Comment by losvedir | Hacker News Reader

This makes me so overwhelmed. I own a house built in the 1950s and I want to make it more energy efficient, but where do I begin, and how do I change parts of it without causing other problems.

Can I improve insulation without causing moisture and mold at the boundary? Can I upgrade my furnace to a heatpump without first improving insulation and air tightness? Which of the several ways I've read about is the best to condition my crawl space? And now I'm reading that I shouldn't seal up the drafts in my home without one of these air exchangers? Etc etc

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See if you can get an energy audit from your electric or gas company.

You can definitely upgrade your furnace without first improving insulation and air tightness. There are other conceptually simple changes that will improve efficiency with low risk of causing other problems (e.g. attic insulation, blown in wall insulation, replacement windows). The energy audit will include an analysis.

Home efficiency is pretty complex. Read up a lot before paying for any changes. Even today, many new homes aren't built to be airtight. There are air gaps everywhere. An HRV/ERV may help reduce energy costs because air has to enter the house from somewhere, but in older homes I'm not sure the slight benefits one will gains will be worth the cost and extra complexity (an HRV/ERV needs to be cleaned twice a year).

The audit should have some information about what is going to be the most beneficial cost wise. Additional insulation is often a pretty safe win (especially if it doesn't change the moisture barrier).

Of course there can be other goals. I don't expect that upgrading my 80% AFUE furnace would save me any money. High efficiency furnaces cost more, break faster and it would require more work to install one vs just replacing with an 83% unit. But it would change how air moves in the house, instead of drawing combustion air from the conditioned space, a high efficiency furnace would pull it from outside, so it would be easier to humidify the house to a more comfortable level (a medium size wick humidifier doesn't keep the house above 20% on colder days).

Blown-in wall insulation is terrible in cold climates. With no vapor barrier, any moisture from the living space will condense once it hits the "cold zone", which is likely inside the wall, and thus lead to rot (and mold) over time.

A lot of the improvements would be built around any renovations / remodels you want to undertake. One of our previous homes was built in the 1900's. One of the things we did that were immediately noticed were upgrading windows to double pane. Again not feasible if you don't need the upgrade, but for us it was a worthwhile investment. We also found that leaving doors closed in various rooms was important to retaining heat. The hallways would be cooler but it made it much easier to spot warm parts of the home with a heater if absolutely necessary.

There may be a local company that can give you advice on things you can do in a cost efficient, least headache manner. Whatever you undertake though is probably going to be an expense, so check with your local state / county and see if they have any energy efficiency improvement programs. I just used one to improve windows and attic / crawl space insulation in my mother's home.

Good luck

I've lived in two 50's houses where the windows were replaced with double pane. Both window replacements were mediocre at best. Replacement windows are a bit smaller than the original windows so there is a gap between the house framing and the window frame. In neither house did the installer do an adequate job of sealing that gap. On one window, I could even see daylight through the gap. I had to remove the inside trim and spray in foam.

That sucks, a poorly installed window definitely defeats the benefits.

In a perfect world, you'd be able to build the perfect wall:

* https://buildingscience.com/documents/insights/bsi-001-the-p...

What you should worry about in renovations may depend on which climate zone you are in:

* https://www.ecohome.net/guides/3521/climate-zones-map-usa-ca...

* https://basc.pnnl.gov/images/iecc-climate-zone-map

> Can I improve insulation without causing moisture and mold at the boundary? Can I upgrade my furnace to a heatpump without first improving insulation and air tightness? Which of the several ways I've read about is the best to condition my crawl space? And now I'm reading that I shouldn't seal up the drafts in my home without one of these air exchangers? Etc etc

If you're serious about this, then hiring a consultant / company who specializes in this would be a first good step:

* https://www.youtube.com/@HomePerformance/videos

* https://www.youtube.com/watch?v=t-GIzX6bLeU

The money you pay upfront for a plan may save you cash down the road to make sure you don't do things in the 'wrong' order or buy incorrect equipment (type or size). The above two presenters are a good start (and do remote consulting AFAICT), but looking at ResNet-certified folks (in your area?) is a broad good start.

Generally, for indoor air quality (IAQ), you want to go air tightness (even without extra insulation) and then get a ERV/HRV. If your current furnace/AC is working fine then letting it run for a few more years won't harm anything, and changing it won't help IAQ or comfort. For crawl spaces, making it conditioned is a good start: insulation and a 10+ mille ("mill") poly tarp so stop moisture drive would be a good start.

P.S. If you think you have problems, I grew up a house from the 1890s.

Dealing with the same but a 1960s house. Make sure to air seal and insulate it well. Most insulation contractors skip the air sealing but that’s very important!

I empathize with you, as I am in the same boat.

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