1. What feedback information is most important to give the occupant so they
can make better decisions about changing ventilation settings?
2. What kind of ventilation feedback and control strategy is most cost
effective (ie you can convince the typical occupant to pay for the
installation without losing the job or losing money)?
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Several years ago I was part of a research project on new manufactured homes
that had whole-house ventilation systems and the vast majority were
disconnected (partially because of noisy fans used at the time). They also
felt that the fan running was "wasting" electricity and the had blocked the
window inlet vents to keep cooler air out. (in the eastern part of the state
where it is high desert much dust blew thru those vents as well.) Washington
State Enegy Office has reported on their research on residential ventilation
systems several years ago and found that most people didn't understand the
purpose of their systems. As a result Bonneville Power Administration
prepared a pamphlet and hired Iris Communications in Eugene Oregon to
produced a short video on whole house ventilation that is provided with each
new home. Most are never watched, I'm sure.
Please pay attention to Andy Persily's comments about CO2. It's used an
indicator, not a pollutant at the levels being discussed for control in
office buildings. There has been research on using CO2 as a control strategy
in homes but my recollection is the levels rarely get high enough to trigger
the system.
I've seen RH used to control bath fans successfully (dehumidistats in place
of wall switches and the new Broan and Nutone models). These have the
advantage of keeping the fan running a LONG TIME needed to get the humidity
down, not just the fog off the mirror. I also recall seeing study about
using RH to control whole-house vent systems but I believe the problem is the
moisture storage of a house is so huge that it takes forever before the
system kicks on (this may be a problem with the crude sensor technology).
The Swedes have probably done more work on this than anyone.
The Tamarack Air Minder switch is probably the best thing on the market right
now. I remember the old Vent Axia exhaust fans had a great big honking
control box with a "boost" position on it. I love that. What I'd suggest to
someone is that they turn up your system to "boost" when there's sweating on
the windows or the air seems stale. There should not be any OFF position on
the control except at the breaker panel!
Dave Brook
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