Ventilation in Tight Homes where an ERV isn’t appropriate
Some of the common posters may have seen by now that my M.O. is rebuilding century homes and making them more energy efficient. It’s a good market in my location and people appreciate the “green-ness.”
That being said, I feel like there are cases where an ERV/HRV isn’t appropriate. Sometimes it’s a budget issue, sometimes floor plan makes it challenging, but I’ve also seen some people “turned off” by houses they perceive to be complicated.
In a tight home (and I only build tight homes), obviously we need some kind of mechanical ventilation. Balancing the right amount to have enough fresh air while taking the energy penalty into account is relatively straight forward I guess – but I’ve been mulling over the idea of “blasting” the home with fresh air with ventilation on a timer rather than consistently trickling X amount of CFM in and/or out. No such thing as a free lunch, but I’m wondering if a rapid air exchange might be better for the hvac to offset rather than consistently running slightly more.
Just an idea, open to input on supply only, exhaust only, balanced mechanical with a non-HRV setup. Location is Kansas City, KS.
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I don't see any advantage to an intermittent blast vs. a steady trickle.
In warm enough climate, an argument can be made for a venting ducted dehumidifier. The extra energy cost for running this is not enough to offset the additional cost of an ERV.
P.S. I've had good luck with Pansonic's WhisperComfor ERV. Only a bit more than a good bathroom fan and very simple install.
I would say in a damp enough climate. A dehumidifier is a very efficient space heater, the latent heat that it removes from the air is dumped inside the building envelope at a high COP. If you are in a cooling climate you're better off running AC.
The exception is when the latent load overwhelms the sensible load -- your HVAC can't produce a low enough SHR. This would happen when it is humid but not hot. Ideal circumstances for a dehumidifier are when you need a little bit of heating and a lot of dehumidification -- say if the outside air is 60F and 100% relative humidity. In that situation you're essentially getting free heat.