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Re: GBlist: Air Vented Windows



I had this valuable little piece of research by Cameron Duncan filed
away for a rainy day, hope he doesn't mind my reposting it here - I had
thought of custom manuf. a similar window for our own purposes but felt
a little hesitant. I was more interested in single pane interior glazing
with  passive air flow to the interior i.e. that the windows would not
be mechanically vented but that the building itself would be on
continuous exhaust. The obvious concern is condensation which could be
manually controlled by adding a top exterior vent and making the
interior vent closable or I thought it might be possible to minimize
condensation problems by creating a proportionally smaller interior
bottom vent or scoop to slightly warm incoming air. I had also thought
that it would not be difficult to reverse the process for minimizing
heat gain by pressurizing the building from an alternate air source.
I'm still interested in testing a practical application and was hoping
to be able to do something different for our next project.

John Salmen
TERRAIN E.D.S.
Willmar Windows:
Willmar windows prepared some prototype windows, test marketed them in
the 
Montreal area, and poor sales led to their demise. Solplan  Review
claimed 
"...the dynamic window could be important for multifamily ventilation in 
milder climates...Combining the window with the ventilation systems
seems 
like an idea that should be pursued."
(Re: "What Ever Happened To...Dynamic Windows," R. Kadulski, Solplan
Review, 
(No. ) p. 7, April/May 1994.)

I just sent them a fax to see what I can find out about their project. 
Perhaps more on that later.
     References:
        Canadian Windows and Doors Assn.
        (613) 233-6205

        Willmar Windows
        485 Watt St.
        Winnipeg, MN R2L 2A5
        Phone: (204) 668-8230
        Fax:       (204) 663-1072
......
Research:
I also found that information describing research conducted in
Scandanavian 
countries (Finland, Norway) an Canada on "Supply-Air windows" (summary
of 
Canadian info. below):
"...studies in Finland  have shown the possibility of such supply-air 
windowsÉ providing ventilation air sufficiently preheated to recover
most of 
the heat transfer through the window. A Norwegian study  has shown that
a 
double-pane, supply-air window could be built with a U value of 0.5
W/m2.K 
(R-10)."
NRC of CanadaÉs IRC testing:
Specs:
   6.4mm interpane airspace, airtight, double-glazed window with
single-pane 
glazing 66mm outside other assembly.
   3 25mm frame holes (584mm wide section) in bottom of single-pane and
top 
of double-pane assembly (top holes lined with rigid conduit)
   Fans used to extract air at 11.5 L/s (~0.5 ACH)
Results:
   Window air temp rise ~ 50% of DT (44% nighttime, 58% daytime due to
solar 
heating effect)
   Ventilation air temp rise ~ 50% to heat it to room temp (contributes
to 
overheating on sunny days)
   Heat flow of inner panes lost to outside ~ 20% of std. triple-glazed 
window (most of the heat was recovered through the air flow)
   Supply-air window U-Value: 0.45 W/m2.K
   Energy consumption comparison: supply-air window 25% less than 
double-paned window control
               20% est. less than triple-paned window
Considerations:
   Inside pane temp is lowered (thermal comfort & condensation issue)
   Window must be integrated into the ventilation system
   Maintenance/cleaning issues
(Re: "Thermal Performance of a Supply-Air Window Tested," S. A. Barakat 
(Instutute of Research in Construction, National Research Council of 
Canada), Solar Today, (2:1) pp. 10-11, January/February 1988.)
......
Integral Window Ventilating System/Device manufacturers:
BTW, does anyone know any Integral Window Ventilating System/Device 
manufacturers, such as trickle ventilators, other than Titon Inc.?
(Titon Inc., P. O. Box 6164, South Bend,  IN 466660, (219) 271-9699: 
Glazed-in, Slot, & Surface Mounted)

Cameron Duncan
(800) 363-3732 (US)
(703) 287-8391 (Intl)
cameron.duncan@nciicn.com
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