ASHRAE Journal - August 2022 - 34

COLUMN BUILDING SCIENCES
FIGURE 10 (left) Dropped Ceilings. Supply and returns could be located in a hallway/corridor dropped ceiling.
IGUR
(left) Dropped Ceilings. Supply and returns could be located in a hallway/corridor dropped ceiling. FIGURE 11(right) More Dropped Ceilings. The returns are " passive " -
IGUR
transfer grilles into the dropped ceiling and a large ceiling register in ttransfer grilles into the dropped ceiling and a large ceiling register in the corridor dropped ceiling, connecting the dropped ceiling to the corridor. The supplies are " active " hard
ducted. ducted.
he corridor dropped ceiling, connecting the dropped ceiling to the corridor. The supplies are " active " hard
(right) More Dropped Ceilings. The returns are " passive " -
same wall (Photo 10).
Still not done. With " fabulous "
windows we can get rid of the supply
return ducts altogether (Photo 11).
Having said that, we will still need
some means of distributing ventilation
air. Fully ducted HRVs and ERVs
are more than up to the task.
There has to be some issue with
all of this. Yup. Lousy windows
saved old buildings with lousy walls.
They acted as " dehumidifiers " and
prevented high levels of interior
moisture (Photo 12). Lousy windows
were the first condensing surface in
a building in a cold climate. When
we got better windows, we moved
the condensing surface to the interior
sur‑face of the exterior sheathing.
And better windows allowed
higher levels of interior moisture.
The higher levels of interior moisture
messed up our walls. We had
to get better walls. Better windows
made us get better walls.
Having pointed that out, we are
Countercloc Counterclockwise from left:wise from left: PHOTO 8O 8 Dropped Ceiling. Dropped Ceiling.
Duct Ductwork located in a hallway/corridor dropped ceiling.work located in a hallway/corridor dropped ceiling.
The supply and returns are in the same dropped ceiling.he supply and returns are in the same dropped ceiling.
PHOTO 9O 9 More Dropped Ceiling. The returns are " pasMore
Dropped Ceiling. The returns are " passive " -transfer
grilles into the dropped ceiling and a largesive " -transfer grilles into the dropped ceiling and a large
ceiling register in the corridor dropped ceiling connect- ceiling register in the corridor dropped ceiling connecting
the dropped ceiling to the corridor. Ting the dropped ceiling to the corridor. The supplies arehe supplies are
" active " hard ducted. " active " hard ducted. PHOTO 10O 1 Still More Dropped Still More Dropped
Ceiling. T Ceiling. The supply grilles and return grilles share thehe supply grilles and return grilles share the
same wall. same wall.
Photo 11 (left1 (left) F) Fabulous Windows. With " fabulous "
window
Photo 1
abulous Windows. With " fabulous
windows we can get rid of the supply return ducts alls we can get rid of the supply return ducts all
t together. Having said that, we will still need some means
ogether. Having said that, we will still need some means
of dist of distributing ventilation air. Fributing ventilation air. Fulully ducted Hly ducted HRV's and
ERV's are more than up to the task. Photo 12 (right)
V's an
V's are more than up to the task. Photo 12 (right
Lousy Window Lousy Windows. " Dehumidifiers " that prevented highs. " Dehumidifiers " that prevented high
levels of interior moisture. levels of interior moisture.
beginning to get even better windows.
Fabulous windows, actually.
This will allow even higher levels of
interior relative humidity in cold
climates. It will allow COVID levels
of interior relative humidity. Yes. We
were here before, not that long ago
( " Covert COVID Thoughts, " ASHRAE
Journal, February 2022). Guess what,
that means we are going to have to
get fabulous walls. Fabulous windows
are making us get fabulous
walls. Odd, indeed.
34
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ASHRAE Journal - August 2022

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