Deep energy retrofit questions
Finally, I am buying a home after 30 years. It’s a wreck of a foreclosure, which means I’m doing a deep energy retrofit, and want to do it right!
1250 sf. 1930s 2-story with unconditioned basement. Halfway between NYC and Albany. Existing ductwork has supplies upstairs, but no returns. We’re taking it to studs.
1) I’m planning 4″ dense pack cellulose plus an R8+ foam sheathing on the exterior. ** Is sheathing rot a problem under foam board if there’s not enough R value on the foam? Any rule of thumb ‘not worth it’ for foamboard over well-insulated dense pack walls?
2) Triple pane windows on upstairs for sound attenuation and design considerations. ** Opinions if triples are worth it, particularly for skylights? ($100 or so more per 8 sf skylight)
3) We’re doing air source heat pump and I’m assuming the house will be well within the air tightness range of needing an HRV/ERV. There are several returns on the first floor, and I’m thinking of putting some on the second, and then using the ASHP fan to circulate the ERV supply. ** Are any particular variable speed ASHP fans up to that task – to run low, often, and quietly? Aside from a switch from the ERV for the handler to turn on, are there any other common considerations? Not sure we can run separate ducting to the rooms unless we go with a fan assisted small diameter tubes.
4) Other pitfalls for converting from an old oil furnace to an ASHP using existing ducting? Any leads for info for me to understand air flow needs better?
Tons of questions. Thank you so much for your time!
GBA Detail Library
A collection of one thousand construction details organized by climate and house part