[Greenbuilding] Exhaust Only Passive Inlet Ventilation

[John Straube]

The IRC and CMHC have done a number of studies on this. You can do the work to look these up.
The exhaust only passive inlet system can work even in cold climates, BUT, requires more careful design and does not usually offer mixing of the supply air and the interior air. I have this system in my 5 storey apartment building and it works well. Requires a specially designed air inlet in each room that does not have an exhaust fan.
Builders often screw up the EOPIVS by applying it to non compartmentalized multistorey buildings and houses and not providing inlets that allow sufficient air into each room for the pressure differences to be expected.
This is still acceptable in code, but that does not mean it is the best system and many code approved things may not work if they are done correctly. EIPIVS is a perfect example.
If you have a forced air heating system, it is much better to use a return side air inlet combined with a FanCycler to ensure good mixing and avoid over ventilation.
HRVs often cost more electric fan energy and do no better for air quality than the return side air inlet with controller but they cost a lot more and demand better maintainance.
For large airflows like commercial buildings, schools, etc. an HRV is essentially always the most economical in paybacks of 1 to 5 years or so depending on the situation.

John



Nick Pine wrote:
> "Robert Tom" <ArchiLogic at yahoo.ca> wrote:
> 
>> If by "simpler exhaust fan" you mean exhaust-only, passive-inlet 
>> ventilation strategies (EOPIVS) ... testing done about 10 or 15 years 
>> ago here in Canada showed that EOPIVS do not work in all but the most 
>> mild Banana Belt locations in Canada, do not work in multi-storey 
>> homes and do not work in homes over ~1600 sf.
> 
> Why not? What were the problems? Got any references? IIRC, an exhaust 
> fan qualifies as a "mechanical ventilation system" in Canadian codes.
> > 

-- 
Dr John Straube, P.Eng.
Associate Professor
Dept of Civil Engineering & School of Architecture
University of Waterloo
Waterloo, ON Canada