Avoiding service contracts helps to
minimize life-cycle costs. This project
does not require service contracts for
chillers, cooling towers, boilers, and
chemical treatment. The geothermal
system uses water without an antifreeze
solution as the heat transfer fluid.
The design-build project delivery
method allowed a high performance,
net zero energy building to be delivered within the owner’s construction
budget. From the initial charrette
meetings and throughout the schematic and design development phases,
the focus was on designing the most
energy-efficient building in a cost
The key design strategy for any successful NZE project is drastic energy
reduction. This project prioritized
energy-efficiency strategies which
have significant effect on both the
annual and lifetime energy savings of
an NZE project. The team quantified
the annual cost savings for both the
energy reduction and PV generation
for equipment life of 20 years.
A police station is occupied
365/24/7 so the energy intensity
of these buildings is higher than
typical buildings. The latest CBECS
data for police stations indicates an
average EUI of 79.4 kBtu/ft²·yr. The
new CD3PS is operating at an EUI
of 26. 7 kBtu/ft2·yr, which is one-third the energy usage of the average
CBECS station. The first year energy
reduction savings is $36,900, and the
total 20-year savings is $991,516.
The 329 kW solar PV system
produces 403,500 k Wh annually.
Revenue is received from selling all
electricity back to the utility provider
in a “net metered” arrangement.
Additionally, revenue is realized
by the selling of the solar renew-
able energy credits or “SRECs.” In
Ohio SRECs are marketable and, as
of September 2016, can be sold for
year, only five work orders have been
filed—all for minor repairs.
The majority of the building’s
HVAC system features a decentralized plant which allows maintenance
engineers the ability to avoid HVAC
system shutdowns. Any centralized
equipment has n+ 1 redundancy for
maintenance or failures. Also, all
equipment is manufactured with
components that are easy to obtain
and exhibit low downtimes.
All equipment is tied into a building automation system that allows the
building to be monitored, adjusted,
and diagnosed remotely prior to dispatching a service technician and
eliminates the need for onsite personnel. The building also features an
energy management system, which
allows maintenance personnel the
ability to ensure the building is operating at peak performance.
Operation and Maintenance
Through careful design and collaboration, the CD3PS was able
to achieve incredible sustainable
performance without sacrificing operability, serviceability, or maintenance
life-cycle costs. During the design
process, the design team, the City of
Cincinnati and the commissioning
authority worked collaboratively to
ensure this was achieved. The owner
tracks work orders, and in the past
TOP The second floor mechanical room
houses geothermal heat pumps, the geothermal domestic hot water system, and
hot water storage tanks.
BOTTOM LEFT The CD3PS uses a distributive pumping system, eliminating the need
for a full system shutdown when repairs
BOTTOM RIGHT The ventilation system for
the building consists of one outdoor air
unit to provide dedicated outdoor air to the
building distributed via variable air volume
boxes directly to occupied spaces or to the
return air ductwork of heat pump units.