ASHRAE Journal - May 2014 - 74

2014 ASHRAE TEcHnology AwARd cASE STudiES

ventilation only when the towers cannot provide sufficient fresh air.

Figure 1 Cooling by displacement ventilation (cool weather).

Energy-Efficient Design Features

Hot Air Rises

For Passive
OUSD-LEEC is intended to be a
Relief
showcase green project, so miniCool Air Enters
The Room at
mizing energy use is a key priority.
Low Velocity &
Cascades
Strategies employed include:
Along Floor
* Classroom cooling strategy is
based on thermal mass, natural and
mixed mode ventilation, and ceiling
Figure 2 Cooling by automatic ceiling fan (warm weather).
fans rather than compressors.
* Cool towers provide as much as
50,000 cfm (24 L/s) and 90 tons (317
kW) of cooling without fans or coils
Ceiling Fan
on hot days, and natural ventilation
Operates at
Warm Air Enters
High Speed
the Room at Low
on mild days.
For Comfort
Velocity. Airflow
Cooling
Is Ventilation
* Ceiling fans use efficient direct
Minimum.
drive electronically commutated
(EC) motors, drawing 80 W to provide 4°F (2°C) of perceived cooling.
Figure 3 Heating with automatic ceiling fan assistance (cold weather).
* AHUs use high-efficiency variable-speed fan arrays, with demandbased static pressure setpoint reset
to minimize fan energy.
Ceiling Fan
Operates at
* FP-VAV boxes use efficient variHeated Supply
Low Speed
Air Enters the
To Destratify
able-speed EC motors.
Room at Low
Room
Velocity and
* VAV-reheat boxes use dualRises Toward
maximum control sequences and
The Ceiling
supply air temperature control, with
demand-based supply air and static
pressure resets to minimize reheat
* Solar hot water panels provide hot water for the
and fan energy.
* Data center AHUs have digital scroll compressors
kitchen and bathrooms.
and custom control programming to maximize airflow
* Classrooms and offices are designed for daylighting:
when economizer is available, and minimize fan energy, oriented for southern exposures with overhangs and
favoring DX cooling, when economizer is locked out. The daylighting windows, orientation specific glazing, and
system is 100% redundant with both units running to
automatic dimming controls.
minimize fan power.
* The design easily beats Title 24, with EnergyPro mod* Kitchen exhaust hood uses a variable-speed fan conels showing savings of 29.9% in TDV energy use. When
trolled by heat and smoke sensors to minimize exhaust
modeled according to CA-CHPS rules, which permit
when not actively cooking.
the inclusion of on site renewable energy, savings were
* Heating hot water is by condensing boilers with vari48.5% TDV energy and 55.6% energy cost relative to a
able-speed pumping, with supply water temperature
baseline building.
reset to maximize condensing operation.
* The data center was modeled separately, for a util* A 203 kW photovoltaic array provides an estimated
ity rebate program. Third-party analysis showed 72%
280,000 kWh per year.
energy savings relative to baseline.
74

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ASHRAE Journal - May 2014

Table of Contents for the Digital Edition of ASHRAE Journal - May 2014