Sizing an ERV for a larger home and optimal vs code minimum ventilation
I’m in the process of specifying a full remodel for our house in the San Francisco Bay Area (Climate Zone 3).
As we remodel (back to the studs) the house (c. 5800 sq ft) we’re working hard to ensure that we’ll dramatically improve the air tightness of the envelope (fully adhered house wrap, attention to continuity of the water and air control layer and sealing at the foundation etc).
We’d rather avoid lots of separate bath fan perforations in the envelope and prefer the idea of balanced valuation; and not venting all our often (expensively) cooled air to the outside; reason one for the HRV/ERV.
Secondly we rented a house in the UK which (we found out later was super well sealed and had a Zehnder ERV and) both my wife and I noticed have never had such a clear head and good nights sleep as we did staying there.
Anyhow, while ASHRAE 62.2 etc., set a minimum (e.g. 0.35 ACH which will equate to c.300 cfm), clearly this is a ‘code minimum’, and we’re trying to figure out what would be optimum (family of 5, often socially hosting others). We’re thinking there’s a ‘standby, no one home’, a ‘normal’ and a boost (e.g entertaining, perhaps during/after the morning shower routines) level that we should target.
Does anyone have good insight/data/sources?
Also recommendations for manufacturers at this end 300cfm capacity range; also at this range would folks recommend zoning and multiple systems or one large system?
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