I have a house built in the 90s that's two stories with a basement, totaling 3700 sq ft. I've noticed that my heating and cooling costs are pretty high, and after an energy audit, I found out we have about 3 air changes per hour, which is reasonably tight. They didn't suggest many improvements, just sealing the lighting receptacles in the attic. However, there's still around a 5-degree temperature difference between the upstairs and the main floor, and about 10 degrees between the upstairs and basement.
I received a quote of around $6,000 to remove the current fiberglass insulation (which has an R-value of 43 but has compacted over 30 years), air seal, and blow in cellulose to reach the code requirement of R50. If I'm doing the math, it looks like I'd need to save about $200 annually on heating and cooling to break even over 30 years. So I'm wondering: is it really worth it to improve comfort and reduce the stack effect? From a return on investment standpoint, I'm not so sure.
3 Answers
If the energy audit says your house is in good shape, you might not need to spend that much on insulation. It could be better to focus on sealing rather than a full insulation overhaul if your ROI looks low.
You might want to check if you qualify for any rebates or tax credits—they can help a lot! You don’t necessarily need to remove the old fiberglass if it's still in decent shape; you can just blow cellulose on top of it. This can save you some money on labor costs. It's also worth considering that energy costs are likely to rise over time; that can impact your ROI. I did something similar and found it really improved comfort in our home, plus the cellulose helped with noise reduction and made sleeping a lot better!
Honestly, if you’re just trying to deal with the physics of temperature differences, it might not be worth the money. The warm air goes up and the cold settles in the basement naturally, so don’t expect insulation to totally fix that. It might be better to look at additional AC units for better air distribution instead of just adding more insulation.
I have just one AC unit that services all three floors, and it keeps up but there’s definitely an uneven airflow. I was hoping improved air sealing would help with the stack effect.
That’s exactly what I heard! They mentioned they could blow cellulose right over the fiberglass, which might make things easier on the wallet.