What’s the break-even for ERV?
I’m in the design stage of a new construction house and I just got the Manual J from my mechanical engineer. He has assumed an ACH50 of 5, and has calculated that infiltration will provide 62% of the necessary ventilation in winter and 36% in summer.
My thinking is to make the house tighter, which means that more of the ventilation comes from mechanical ventilation. I’m also thinking of using an ERV to capture the embodied energy in the conditioned air that exhausted. Obviously there’s going to be a point of diminishing returns, a bigger ERV costs more and requires bigger ductwork, and improving the sealing of the house becomes more expensive as the house becomes tighter.
I’m just curious if people have a ballpark idea of where the break-even point lies, where we should be shooting for.
The house is in Washington DC, climate zone 4.
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