Improving Indoor Air Quality & Comfort
I have a ~2,900 sq ft house built in 2000 in the Washington DC metro area with a Carrier Infinity compressor (model: 24ANB724A300) and 2 indoor evaporators (model: CNPVP2414AL). The house layout is a bit unusual (see floor plan). In 2019 I had a blower door test done that indicated an ACH of 16, so I had the swiss cheese batt insulation on the floor of the multi-section attic removed and replaced with 2″ of closed cell spray foam and 14″ of blown cellulose. Our gas heating bill went down about $1,000/year so the ROI on that particular ~$6,000 investment seems pretty good.
Unfortunately, we still have some indoor air quality and comfort issues in the house. Specifically:
1. The 2 upstairs rooms (Kids’ BR#1&2) tend to be uncomfortably hot compared to the rest of the house (even compared to the landing area outside the utility closet which itself is often unbelievably hot despite having a louvre door), and the air in the bedrooms is often stale/stuffy.
2. CO2 levels in multiple rooms in the house are usually between 1,000-1,500 ppm. My understanding is that well-ventilated buildings are half that.
3. Thermal imaging indicates air leakage at the 1st floor powder room (see blue line in floor plan), which is no surprise because the floor of that bathroom and the under-stair storage space are both freezing in the winter. Is a few holes in the interior wall and spraying the cavity with a froth pak the cheapest/safest way to address this? I am an ABAA level 3 installer, so I know the proper way to detail a wall from the outside, but I suspect that opening everything up to do it right will cost way more than can be reasonably justified by utilities savings or comfort.
I would like some help prioritizing investing in solutions, whether that’s retrofitting an ERV, mini-splits, re-doing ductwork, etc. I am willing to pay for such help, but unfortunately most of the knowledgeable professionals I’ve found in this area seem to focus exclusively on commercial, multi-family, or new construction. I spoke to an executive at one company who mainly does volume new construction and he said that they could help me, but that it would likely be $1,000 for the inspection and another ~$4,000 to design the hvac/ventilation system based on the inspection, plus hiring a 3rd party HVAC contractor to implement the new system. I’m willing to spend some money, but $5,000 just to figure out what to do seems excessive.
Does anybody have any suggestions? Alternatively, is there a professional in the DC market you would recommend I hire?
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Replies
sure thing! so you’ve got a pretty sweet setup with your Carrier system and the recent attic insulation upgrade. 😊 sounds like it’s paid off on the heating bills, which is awesome. but those hot rooms upstairs and the high CO2 levels are definitely a bummer. 😕 for the upstairs rooms, it could be an airflow issue. the ducts might be too small or getting squished somewhere, not letting enough cool air through. or maybe the insulation isn't as tight as in other parts of the house. now, the CO2 problem is a bit trickier. that usually means you’re not getting enough fresh air exchange. ERVs are great for this since they bring in fresh air without losing a lot of the temp-controlled air you’ve already paid to heat or cool. the thermal imaging leak on your 1st floor, since you're an ABAA level 3, you probably already know that spraying foam in the wall could be a quick fix. but yeah, tearing down walls for a perfect seal is gonna cost a pretty penny. 😬 for the priority list, I'd say tackle the comfort and air quality first. maybe start with a cheaper indoor air quality monitor to confirm those CO2 levels. if they're consistently high, an ERV might be the way to go. for the hot rooms, before you think about mini-splits or new ducts, have you tried balancing the system? like adjusting vents or dampers to redirect more air upstairs? I get not wanting to drop a ton of cash on just diagnosing the problem. $5k is steep if you're not even fixing anything yet! 😓 have you tried reaching out to any local HVAC pros? sometimes, the smaller shops can give you more attention and better prices than the big guys, especially if you explain you’ve got some know-how and you’re not starting from scratch. and hey, maybe someone in the neighborhood has a go-to guy they trust. word of mouth can be golden. check out local forums or neighborhood apps, and you might snag someone good who’s up for a challenge. good luck, and hope you get those temps and CO2 levels down soon! 👍