ASHRAE Journal - May 2020 - 53

2020 ASHRAE TECHNOLOGY AWARD CASE STUDIES

TOP The building's energy efﬁcient LED lighting was
designed to mimic the pattern of the canopy ceiling at the
student entry.
BOTTOM Each classroom has a "green button" as part of
the lighting controls to minimize energy consumption. The
teachers or students can select this button, which resets
the classroom lighting levels and temperatures.

remainder of the construction. This
trial-and-error method of testing
and adjusting a small portion of the
building allowed the entire building to pressure test to just 0.152
cfm/ft2 (0.772 L/s·m2) of building
envelope at project completion. The
standard testing allows a maximum
of 0.25 cfm/ft2 (1.3 L/s·m2)of building envelope, which
would have allowed a total additional inﬁltration of over
46,000 cfm (21 710 L/s) to the building. The rigorous
testing procedure undertaken resulted in a 34% reduction in air inﬁltration. This process also ensured that the
design team properly met ASHRAE Standard 55-2010
thermal comfort requirements.

Cost Effectiveness
The cost of this energy-efﬁcient school was $206/ft2
($2217/m2), which is within the average range for this
area. The utility cost for the past 12 months has been
$0.58/ft2 ($6.24/m2), which is the lowest cost of any
Fayette County Public Schools high school. The outside
air, LED lighting, and window glazing systems were
some of the design options that the design team took
into consideration to ensure initial cost and utility costs
were minimized. Some choices had a higher initial cost
but resulted in a lower life-cycle cost (Figure 2). The outside air system consists of a single external air unit with
air distributed throughout the entire building rather
than multiple outdoor air units, which increased the
initial cost. Individual CO2 sensors were used to control
the appropriate amount of outside air being conditioned. Illuminating with LED light ﬁxtures cost more
initially, but there is also an offset since the HVAC system
can be sized for the reduced heat output. The choice to
use LED lighting allowed for a designed lighting load
of 0.6 W/ft2 (6.5 W/m2), a 50% decrease from the 2012
International Energy Conservation Code allowance of
1.2 W/ft2 (13 W/m2). The cafeteria had vast expanses
of west-facing glass that could have caused signiﬁcant
heat gain from the late-afternoon sun, so blinds were

installed. East- and west-facing glazing were minimized,
but where deemed architecturally necessary, as in the
large cafeteria, the windows were equipped with motorized shades to allow the occupants to shield the space
from the heat during evening hours.

Environmental Impact
Traditionally, Fayette County Public Schools utilized
variable refrigerant ﬂow (VRF) systems for heating and
cooling in all their buildings. The design team's selection
of a geothermal system instead of a VRF system reduced
the total amount of refrigerant in the building. If the
HVAC system utilized VRF equipment, there would be
approximately 3,400 lb (1542 kg) of refrigerant in use for
the building. The total refrigerant in all heat pumps in
the geothermal system is approximately 970 lb (440 kg),
a reduction of 2,430 lb (1102 kg) of refrigerant. Utilizing
a central geothermal plant instead of cooling towers also
eliminated the use of any process water
for mechanical cooling.
The reduced energy use at Frederick
Douglass High School saves approxihttps://bit.ly/2V8P31I
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mately 582 metric tons of CO2 annually.
M AY 2020

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