General overview & priority areas for an energy efficient home
Whenever I tell people that I work in home performance & energy efficiency their mind somehow always jumps to solar. Home solar is great, and if that's what you're looking for, you have my support, but I am definitely not the guy to help you.
We work in efficiency & home performance. That means making homes work better, helping to prevent air leaks so that the air you cool (or heat) stays in your home, making your home more comfortable and healthier. It means you will pay less for energy bills (and need less solar when you do get around to it). It means your air quality will be better and you'll have less indoor pollutants.
So once we get there, the next question is "How much do windows matter for energy efficiency?"
Windows are very important to the efficiency of a home. Think about it this way: there is a hole in your wall. There isn't insulation there, and the only thing that prevents that hole from being a source of leakage is the window and how its sealed.
So, yes, windows matter quite a bit for energy efficiency.
But windows are also very expensive. So my recommendation looks like this:
- If you are building a new home, opt for high-efficiency windows. They will cost more upfront, but they work better. Go double or triple paned, go argon filled, get a low-e window. Estimates say you can save up to $288 each year, and so over the course of your mortgage they are a great investment. (https://modernize.com/windows/energy-efficient)
- If you are replacing windows anyways, 100% opt for high-efficiency windows. See above.
- If you have single-pane windows in your home, oh yeah, go for high-efficiency windows. Single-pane windows are way behind the curve in performance, and it's time to update whenever you can.
- If you already have double-pane (or better) windows, and you haven't made any other efficiency upgrades, let's grab some low-hanging fruit first.
So there are my general thoughts on windows. But do I think that should be your first focus area? No. Below I list out the four spots I would pay attention to first (and immediately) in order to save money and be more comfortable.
Air sealing (caulk is your friend)
All homes have some air leaks in them. That's just the truth, and its ok. The question is just how much. The ideal is to minimize the air leaks and then incorporate a controlled ventilation system. After all, we do want fresh air in...but the air outside isn't necessarily fresh.
Air leaks can mean super humid air (humidity = moisture and moisture leads to mold). It also means any pollutants in the air outside are now in your home.
Air sealing your home is the cheapest, and one of the most effective, ways to improve air quality and energy efficiency. You'll stop conditioning the air only to have it leak outside, and you'll stop letting unconditioned air into the home.
There are some common areas to target, such as canned lights, plugs & switches, around doors and windows, etc. In order to really pinpoint the leaks, an energy auditor can come through and use a variety of tests and tools to know exactly how leaky your home is and where you need to seal.
LED lights are lightyears ahead of the competition
LED lights are, in the most general terms possible, the best light bulbs you can get. Now, of course people will have different opinions, and they are entitled to them. I like to make decisions based off numbers and data, so that's where we're going to look.
LED lights, once prohibitively expensive, are now only a few dollars more than either an incandescent bulb or a CFL bulb. They last longer and use less energy than either other option, though.
That's right. You spend a little more up front, and now you A) go to the store to replace bulbs less often, B) buy fewer bulbs, and C) use less energy to run those bulbs.
An LED light bulb lasts between 3 and 21 times longer than CFLs and incandescents. That is a ton. You're also looking at up to 6 times less energy used. That can be a saving of hundreds of dollars.
And the technology keeps getting better. Dimming capability, change the color of the light, soften the light, etc. LEDs are the better product.
Your attic is a leaky sauna
Here in Tennessee, most people do not have finished attics, and they don't include the attics in the thermal envelope (aka the well insulated, sealed, and conditioned space). This means that in the summertime your attic turns into a sauna because air is super heated by the sun, and it doesn't get vented out well.
The real problem with this, though, comes in that if your home isn't air sealed well between the attic and your top floor, that hot air is going to work its way into your home. Its true that hot air rises, but air leakage is the main reason why your second floor is way hotter than your bottom floor.
In order to prevent this, there are a few steps you can take, but it depends on the construction and styling of your home. A radiant barrier is almost always going to be a good choice. Beyond that, you can consider attic fans, increased natural ventilation, or putting in sill/wind baffles (we've seen a LOT of homes in Tennessee that have baffles installed completely incorrectly, which makes them 100% useless).
Air seal your lights
Remember a second ago when I said that super heated air in the attic leaks into your top floor? The main cause of this is canned lights that aren't air sealed. This should be one of your top priorities, and on the scale of difficulty, its fairly easy.
Generally, you'll also see super leaky lights between the first and second floors (for the same reason: they were never air sealed) but in the grand scheme of things this makes much less of a difference. Prioritize the lights that go to your attic or roof. If you've got the time, then go through the rest of your canned lights.
Great news: there are products out there that will knock out a few of these tasks all at once. Yes, there are light kits that automatically air seal as they're put in place (no caulk needed), and they are LED lights, which meets point number two above.
Another important consideration, not for energy efficiency, but for safety, is to check that your lights are rated so that they can be in contact with insulation. If they aren't there needs to be some sort of protective system to hold the insulation back from the light fixture or else you have a major fire hazard risk.
The long and short of it
If you want new windows then dangit you should get new windows.
If you're getting new windows, do yourself a favor and get energy efficient ones...you'll be more comfortable and use less energy to heat/cool your house.
If you want to make your home more comfortable, lower energy bills and make your home healthier, then start with the list above. It will cost you a lot less money to actually take care of, and you'll probably see bigger returns faster.