ASHRAE Journal - August 2022 - 29

COLUMN BUILDING SCIENCES
From left:rom left: PHOTO 1O 1 High Supply Registers. As window thermal performance improved, we learned to " throw " the air across the
ceiling, get to a window, be cooled, fall to the fl ceiling, get to a window, be cooled, fall to the fl oor, fl ow across the fl oor and be picked up by a return register located at the botr
room from registers located high on interior walls.
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Furniture no longer interfered with airfl ow.
As window thermal performance
improved, we learned to " throw "
the air across the room from registers
located high on interior walls
(Photo 1). The air would " fl ow " across
the ceiling, get to a window, be
cooled, fall to the fl oor, fl ow across
the fl oor and be picked up by a return
register located at the bottom of the
wall on interior walls (Figure 4).
Better windows also meant smaller
ducts. Ducts could easily fi t in interior
walls (Photo 2). Not done yet. It
got even better with better windows.
The return at the bottom of the wall
in Figure 4 could be moved to the top
of the wall (Figure 5). What was nice
urniture no longer interfered with airfl ow.
about Figure 5 is that furniture did
not interfere with airfl ow. Let me
repeat-furniture did not interfere
with airfl ow. Yeah! Can't tell you
how much interior designers interfered
with ductwork layout.
The supply duct and the return
duct could be located up high on
the same wall a couple of feet apart
(Photo 3). Short circuiting of fl ows
did not occur because the supply air
was " thrown " with a high positive
pressure, whereas the return had a
small negative pressure. With wellinsulated
walls and ceilings and real
good windows, Figure 5 worked in all
climates.
At left, countercloc At left, counterclockwise from left.wise from left. PHOTO 3O 3 No Short Circuiting. The
one side, low on the opposite side to control light and noise transfer.
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well to act as the return system.well to act as the return system.
Photo 5: TPhoto 5: Transom Vents. " Sound attenuated " by being
internally internally baffl ed.
ransom Vents. " Sound attenuated " by being
baffl ed.
†I had a lot of fun in Minneapolis in the late
'90s with the code folks. They said they
were never going to allow the approach.
No way. I said how about letting me build
a couple of houses with both approaches
in each house. Run them one week one
way and one week the other way through
the winter and summer. At the end of the
year you tell me which way you will allow,
and I will convert the houses to that way.
It helped that I had a big-time builder
who had my back-Bill Pulte I miss you
big-time. The houses had real families in
them- " friends of Bill.. " They were instrumented
" up the wazzou. " " Wazzou " is a
metric term. It is two " ying-yangs. "
A U G U S T 2 0 2 2 ashrae.o rg ASHRAE JOURNAL
29
No Short Circuiting. The
supply duct and the return duct could be located up high on the same
O 4 Transfer Grilles. Grransfer Grilles. Grille high onille high on
supply duct and the return duct could be located up high on the same
wall a couple of wall a couple of feet apar feet apart.t. PHOTO 4
one side, low on the opposite side to control light and noise transfer.
FIGURE 6 Transfer Grilles. This approach allowed the hallway and stairransfer
Grilles. This approach allowed the hallway and stairWhile
all of this was going on, we
started to really look at return systems.
Did we in fact need them in
each room? We discovered " transfer
grilles " (Photo 4 and Figure 6) and
" sound attenuated " transom vents
that were baffl ed (Photo 5) that
allowed the hallway and stairwell
to act as the return system with a
single return hard ducted to the air
handler. What? Folks freaked out. A
single return-and on the main fl oor
of a two story house-no way that will
ever work. But it did.†
All kinds of
options. Figure 7, Photo 6 and Photo 7
show a basement air handler with a
single return at the main fl oor level.
High Supply Registers. As window thermal performance improved, we learned to " throw " the air across the
. " Throwing the Air. " With good windows, air could " fl ow " across the
IGUR
oor, fl ow across the fl oor and be picked up by a return register located at the botSmall
Ducts. Better windows also meant smaller ducts. Ducts could easily fi t in interior
oom from registers located high on interior walls. FIGURE 4. " Throwing the Air. " With good windows, air could " fl ow " across the
tom of the wall on interior walls.tom of the wall on interior walls. PHOTO 2O 2 Small Ducts. Better windows also meant smaller ducts. Ducts could easily fi t in interior
More Good Windows. The return at the bottom of the wall in Figure 4 could be moved to the top of the wall.
wal walls.ls. FIGURE 5 More Good Windows. The return at the bottom of the wall in Figure 4 could be moved to the top of the wall.
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ASHRAE Journal - August 2022

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