Page 18 - Summer_2019

ArchDC Summer 2019.qxp_Spring 2019 5/22/19 2:54 PM Page 16

Fresh Air

When ISTUDIO started the survey of the existing buildings, the
architects noticed some unexpected vents in the 1929 building,
long closed off. Intrigued, they explored further and discovered
that the vents were at the ends of ducts leading to the attic level,
where they joined and discharged at the bottom of the cupola.
With the right breezes and open windows, this could provide
noticeable cooling to the rooms. “It was amazing,” said Schneider.
“We discovered a solar chimney, somewhat primitive but doubtless
able to provide a decent amount of cooling, before air conditioning!”
Solar chimneys rely on two basic scientific principles: First,
hot air rises, and second, Nature abhors a vacuum. In the original
Powell building, windows in the cupola let in sunlight, which heated
the air inside. The heated air would rise, exiting via louvers in the
top and creating a vacuum below. When vents in the classrooms
were opened, air from the classrooms was pulled in to equalize
pressure. The classroom air was then replaced by cooler air entering
through north-facing windows.
During the renovation of the 1929 building, this passive
ventilation system was brought back on line. It also served as
inspiration for the eye-catching modern solar chimneys in the new
west wing, which were engineered for top performance, as well as
for a less elaborate version worked into the east wing’s renovation.
All the rooms served by these passive ventilation systems have
notification lights that flash green when a weather station on the
roof determines that the conditions are right. Aside from a
damper—“the simplest of mechanical devices,” said Schneider—
no mechanical equipment is required.
Schneider emphasized that the solar chimneys are meant to
work only in the shoulder seasons at either end of summer. However,
he averred, the students know what the green light means and
have become “invested” in the building’s functioning; they are not
simply passive customers of whatever HVAC system happens to
be running.
Daylighting

Operable windows are a necessary part of the solar chimney’s air
flow, but of course they also offer daylighting and views. The
pre-existing 1929 and 1959 wings at Powell had fairly large windows
that were retained in the renovations, but the new wings incorporate
much larger areas of glass that take on different forms such as the
high clerestories in the library and the big skylight in the atrium.
Views to the outside are emphasized—the downside of potential
student distraction is regarded as minimal compared with the upside
At grade level, a small playground for younger children is
of stimulation and a sense of a school community connected to one
tucked away at the eastern side, with a large playground for the rest
another and to the neighborhood.
of the children at the west side, embraced by the glass walls and
dramatic white sunscreens of the new wings. Although protected
Outdoor Program by a tall fence, the large playground opens to 14th Street and the
community. At the upper roof level are “teaching gardens,”
Powell’s site is rather tight for a 90,000-square-foot school plus
reached by outdoor stairways that are also intended for student
necessary playgrounds and (unfortunately equally necessary)
and staff use going from floor to floor. (For inclement weather,
surface parking lot for the staff, so ISTUDIO had to make the most of
interior stair connections are of course available, but the hope is to
every square foot. (The space squeeze, in fact, forced the relocation
incentivize contact with the outdoors. In almost any other school
of a community garden, which became a spinoff project for
building, all the stairs would be interior.) There is also a modest
ISTUDIO: the Twin Oaks Community Garden featured elsewhere
balcony off the library, where one can be surrounded by a vegetated
in this issue of ARCHITECTUREDC magazine.)
roof and overlook the larger playground.
16 BREATH OF FRESH AIR