[Greenbuilding] ERV's

[Tedd Weyman]

I recently decided against using a spot ERV for a 5 room, 1200' sq cottage 
(radiant heat) because the local wind pressures and stack effects make the 
pressure drives on the exterior just too overwhelming for a light weight, 
low-CFM, ERV. If your heat recovery and air exchange are not from a central 
system (i.e. powerful enough to take over the buildings climate, 
including ducting to all rooms), its unlikely a small ERV will be able to 
overcome the external environmental forces on the building your describing 
(i.e small apartments or condos).

A normal kitchen exhaust (if its externally vented and not just an internal 
filter - has 400 to 1000 CFM) and your bathroom exhaust (120+ CFM) are more 
(locally) powerful than a full sized, let alone a spot ERV and probably 
perfectly adequate to meet all the air exchange needs in small and medium sized 
living units. Timer controlled fresh air supply might be needed to 
complement/supplement the exhaust of a timed bathroom exhaust and during the 
cooking cycles of the kitchen exhaust.  Your under-door fresh air supply 
(allegedly fresh air) will defeat the spot HRV's performance (its not just a 
question of volume of air per minute, its the flow rate and pressures).

If you live in a apt/condo, under-the-door positive pressure from the hallway 
brings is ugly.  Give me independent air such as the trickle-vent or a 
coordinated (with exhaust) timed fresh air supply any day over the stale smells 
and particulates of fried fish, cigarettes, cat hair and marijuana smoke from 
the neighbours.  


I bet there are half a dozen other things you can do per unit for the same price 
(investment) as the spot ERV that will more constructively affect living 
climate, improve the air quality, and conserve/recycle/reduce energy waste. 


TW

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