ASHRAE Journal - July 2023 - 37

HONORABLE MENTION 2023 ASHRAE TECHNOLOGY AWARDS
Energy Efficiency
The all-electric design of the restaurant achieves
greater than 105% net-positive energy through twelve
consecutive months in operation using an energy efficient
building and systems, incorporating cutting edge
cooking and refrigeration technology, as well as an
innovative use of two types of solar PV panels.
This building replaced an existing one that was demolished
and consumed on average 1,079,114 kWh/yr (141
EUI) of electricity. The new restaurant consumes 38%
less electricity (666,454 kWh/yr; 87 EUI) and generates
705,000 kWh through roof-mounted solar PV panels.
A majority (66%) of the annual energy consumption
is from kitchen equipment. While process loads aren't
regulated, the project incorporated a technology not
used before on previous restaurants that allows an
entire cooking line to go into an energy efficient standby
mode of operation. A significant innovation that will
impact future restaurants, the technology significantly
reduces passive energy consumption and allows any one
of three lines to return to operating mode instantly to
address demand. Normally all three lines would remain
at full cooking ready 24 hours per day in a typical quick
service setting.
This project incorporated air-cooled, heat recovery
variable refrigerant flow (VRF) units to condition both
the dining and kitchen areas. Ventilation is provided to
the dining area by a dedicated outdoor air system with
carbon dioxide (CO2) demand control ventilation. A
variable speed makeup air unit with a desiccant energy
recovery wheel (using general building exhaust) provides
replacement air to the kitchen. Kitchen exhaust
fans are demand controlled to adjust the volume of air
based on cooking load and are connected to the makeup
air handling unit to control pressurization.
Operable windows line the exterior of the dining room
and are opened and closed based on outdoor temperature,
humidity, enthalpy and wind speed for natural
ventilation. When the louvers open, the dining room
DOAS and VRF units serving the area are shut down.
Indoor Air Quality
A typical restaurant would include a multiple rooftop
unit design with kitchen makeup air to offset the
cooking exhaust. With the VRF comfort design in this
CASE STUDY
building, 100% outside air ventilation systems were
designed for not only the kitchen exhaust, but also the
dining room.
Within the restaurant, the dining area is maintained
slightly positive to the kitchen area so that air is transferred
from the dining area to the kitchen to ensure
cooking odors and contaminants are fully captured.
Kitchen exhaust operates variably based on cooking
demand while the dining room DOAS unit tracks CO2.
All mechanical ventilation equipment has MERV-13
filtration.
The entire perimeter windows at the occupied level of
the dining room are operable louvers that open to provide
natural ventilation. When the louvers are activated,
the VRF units and DOAS serving the dining area are shut
off. With a 24 hour restaurant, an operative temperature
range of 68ºF to 78ºF (20°C to 26°C) in a typical year
is greatly expanded with approximately 3,800 hours of
8,760 (43%.) The natural ventilation system even operates
during summer months.
Innovation
The PV system implemented in the project was innovative.
A typical monocrystalline array covers the roof
of the building and produces up to 379 kW. The exterior
dining area is covered with a custom designed glass
with amorphous silicon PV panels that generates up
to 51 kW. While not as common because of production
costs and less energy generation than monocrystalline,
in-operation the amorphous silicon panels have
outperformed predicted energy generation by nearly
200% over weather normalized levels. In addition to the
unexpected performance, the panels provide a stunning
visual to consumers as well as a much needed shade
from the sun.
The service water heating for the kitchen and bathrooms
is provided by an air-cooled heat pump water
heater that rejects cool air during peak dish cleaning
periods, reducing HVAC loads in the kitchen.
Freezers and coolers feature a new refrigeration compressor
technology, providing much higher efficiency.
Permanent sub-metering on each breaker in the building
serves as a monitoring-based commissioning tool,
allowing for real-time control adjustments to be made
based on actual energy performance data.
Jason Robbins, P.E., is manager, IOS - Building Systems, at McDonald's Corp in Chicago, Ill. Benjamin Skelton, P.E., is president of Cyclone Energy Group in Chicago, Ill. Francis Kohout, P.E., BCxP, is director
of engineering at Cyclone Energy Group in Chicago, Ill.
J U LY 2023 ashrae.o rg ASHRAE JOURNAL
37

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