Air sealing effects
I have a very leaky home and am contemplating having air sealing done as well as some improvements to the insulation. While I know this will help improve energy efficiency, I was wondering a couple of things:
1) Once the air sealing is complete and the house is tighter, will indoor air quality be affected? That is, less air exchanges with the outside. If so, should I look at installing mechanical ventilation (i.e. HRV, ERV)?
2) We had borderline Radon levels when we bought our home and had a sub-slab depressurization system put in which brought the levels way down. If we go through with air sealing and tightening up the home will the radon levels rise again? Or will air sealing in the attic and basement help reduce the stack effect thus leaving the radon levels the same or perhaps even lower?
Thanks in advance for all your thoughts and advice…
Daniel
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Replies
1) You need to know the ventilation requirements for your house, based on whichever ASHRAE standards you want to use, and you need to have mechanical ventilation that meets the need. Chances are that you already have installed bath/laundry room exhaust fans that meet part or all of the need. Ideally you measure fan flows and find out what you already have, then plan for whatever else is needed.
2) Seems to me that you should check radon levels after you do air-sealing. IMO the effects of air-sealing are unpredictable, at least in terms of where you will gain tightness, and how much. In theory a tighter house would let in less radon, but you'll never know what's really happening unless you do radon monitoring.