ASHRAE Journal - August 2022 - 49

Basement Thermal Labyrinth
Proves Key to Project Success
BY RAYMOND D. SCHOUWEILER, P.E., MEMBER ASHRAE
F
rom the beginning, the 1801 J Street project
was envisioned as an energy effi cient, net
zero project that would provide a healthy
working environment, be fossil free and reduce
environmental impacts. An additional goal was to
create a " Living Lab " that would allow visitors and
new employees to visualize the components that
make up a building.
The renovation is of an existing 28,833 ft2
(2679 m2) single and partial two-story building and
a 5,692 ft2 (529 m2) second-story addition to the
single-story portion of the building. The building
renovation included 15,272 ft2 (1419 m2) of offi ce
tenant improvements for a general contractor (and
building owner/developer) on the second fl oor, a
1,936 ft2 (180 m2) entry and a 582 ft2 (54 m2) fi tness
area on the fi rst fl oor. The remainder of the ground
fl oor is a future lease space.
Innovation
A unique opportunity was created with the renovation
of the existing building. An existing basement
area was scheduled for demolition due to
current building code exiting requirements. Rather
than incurring the cost of fi lling in the area, it was
repurposed as a thermal labyrinth to precool the
building's ventilation air.
Computational fl uid dynamics (CFD) modeling
was performed on the thermal labyrinth to
evaluate effectiveness and several confi gurational
options. Two of the options evaluated included
the effectiveness of adding walls within the labyrinth
to create more surface area and the value
of including a nighttime charging sequence. The
results of these studies showed little benefi t from
the additional walls, but the nighttime charging
cycle provided an additional value. The modeling
also predicted a peak of 14°F (7.8°C) ventilation air
1801 J Street.
temperature reduction in the summer and a peak
temperature increase of 12°F (6.7°C) during the
winter. The actual performance of the labyrinth has
been tracking closely to the predicted performance.
The actual performance of the thermal labyrinth
is continuously monitored and is available for the
public to view at https://buildingos.com/s/dpr/
Sacramento/?chapterId=57433.
Energy Effi ciency
A variable refrigerant fl ow (VRF) system was
selected for the building because of the system's
inherent heat recovery capabilities and its ability
to heat the building without the use of fossil fuels.
Ventilation for the building is provided by a dedicated
outdoor air unit, which draws air from the
thermal labyrinth. The unit also includes a heat
wheel to capture the heat of the building exhaust
stream.
To further increase the energy effi ciency of the
mechanical system, when a zone is within its
temperature dead band (no call for heating or
cooling), the fan in the fan coil is cycled off, reducing
fan energy consumption. Backdraft dampers
are included at the return air plenums of the fan
coils, directing the ventilation air through the fan
coil to the occupied space via the supply air duct
and grilles. Densely occupied spaces include CO2
Raymond D. Schouweiler, P.E., is a senior mechanical engineer at Lawson Mechanical Contractors, Sacramento, Calif.
A U G U S T 2 0 2 2 ashrae.o rg ASHRAE JOURNAL
49
2022 ASHRAE Technology Awards | Honorable Mention
ARCHITEM_MAXIMEBROUILLET

https://buildingos.com/s/dpr/Sacramento/?chapterId=57433 https://buildingos.com/s/dpr/Sacramento/?chapterId=57433 http://ashrae.org

ASHRAE Journal - August 2022

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