ASHRAE Journal - June 2024 - 63

2024 ASHRAE TECHNOLOGY AWARDS CASE STUDY
rooftop heat pump units. Ceiling fans help avoid
stratification and increase thermal comfort in these
large spaces. Zone comfort in classrooms and lower
density spaces is controlled mainly by the zone's heat
pumps, but additional strategies help ensure students'
areas are as comfortable as possible. Self-shading glass
reduces glare and solar heat gains while still providing
natural light and views of outside.
In order to comply with ASHRAE Standard 90.1-2013
lighting control requirements, a lighting control strategy
was used. Each fixture is connected with an individual
sensor and can be controlled individually or networked
together, allowing better performance of daylighting
controls and giving school staff customizable control
over the lighting in their spaces.
Innovation In Education and Long-Term Climate Planning
Sustainable building systems were translated into
interactive points of learning for visitors and students.
These learning installations highlight the natural energy
resources and allow students to monitor the building's
energy performance. The design team worked diligently
to translate the extensive amount of energy metering
and controls monitoring data into a form digestible to
young students.
" Students in our district get to learn about net zero
and geothermal, which is a unique opportunity, so it's
of great value to our students, " notes Kerri Modjeski, the
principal at Forest Edge.
A ground-source heat exchanger, on-site energy
generation, battery storage and microgrid system all
provide the school with resilience against continuing
climate change effects. Using the geothermal loop to
provide heating and cooling help protect the building
systems from changes in future weather conditions since
ground temperatures are less susceptible to weather
changes than air temperatures. On-site solar allows the
building to produce its own renewable energy.
Excess solar energy can also be fed back into the main
power grid system, making Forest Edge's impact reach
beyond its own walls. If there are larger scale power
interruptions or outages, the battery storage system
and microgrid can be used to power the facility using
the generated solar energy and supplemented with
excess solar energy stored during peak production
times. The building systems are adaptive and ramp
down with the remaining battery capacity.
Operations and Maintenance
A key component in the selection of the GSHP system
was that the maintenance associated with this system
was inherently light. By removing the need for central
equipment like boilers and chillers and contracting
service of the zone heat pumps through a third party, the
school is now able to allocate its maintenance resources
elsewhere to better serve students.
A significant commissioning effort was undertaken
by the design team to ensure the smooth operation of
these building systems. In addition to confirming that
equipment was operating properly, the team worked
through verifying the extensive monitoring systems
throughout the building. These systems monitor
energy usage, generation and storage as necessary to
show that the building is performing within net zero
energy parameters.
Cost Effectiveness
A battery storage system helps the building
avoid peak charges from the utility company and
increases self-consumption during peak solar
generation. Alongside the geothermal system, the
original analysis of this battery storage system showed
a payback of 16 years. Since the building has been in
operation, the buyback utility rates have increased
and improved the payback to less than 10 years. The
Oregon School District's dedication to investing in
this renewable energy strategy has saved the district
over $60,000 a year since the building's completion
in July 2020.
Environmental Impact
Forest Edge Elementary School is the first net zero
energy school in the State of Wisconsin and at the time
of certification, the largest net zero energy certified
educational building in North America and has become
a great model for other schools looking to embody
sustainability. It has eliminated its natural gas bill
by fully electrifying the building and turned back
the meter on its electricity bill with a solar PV system.
The last year of operation has resulted in a
operational carbon emissions reduction of 80% from
the code baseline of 20.7 CO2e/ft2·yr, equivalent to
the electrical use of 96.4 homes; 1,403,553 miles
driven by an average passenger vehicle and 623,249 lb
(282,701 kg) of coal burned. 
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63
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ASHRAE Journal - June 2024

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