ASHRAE Journal - December 2013 - 36

2013 ASHRAE TEcHnology AwARd cASE STudiES

IAQ and Thermal Comfort
A dedicated, 100% outdoor air, ventilation system is
used in conjunction with natural and displacement
ventilation strategies to reduce the demand on the central plant, while improving ventilation distribution and
occupant comfort. The natural ventilation strategies
include operable windows at all perimeter spaces and
a three-story central atrium that was design to act as
a thermal chimney. At the top of the thermal chimney
36

ASHRAE JouRnAl

ashrae.org

D ecem ber 2013

ASHRAE 90.1 Baseline
Proposed Building
Actual Building

2,500
2,000
Total Consumption (GJ)

equivalent to 59 kBtu/ft2 (186 kWh/m2) for the building
over the first year of operation. In comparison, the energy
simulation for the proposed design had a predicted
energy intensity of 38 kBtu/ft2 (119 kWh/m2) per year.
Several possible reasons exist for the discrepancies
between the total energy consumption data, including
inaccurate assumptions about the operating conditions
of the building during the creation of the energy model,
unusual weather conditions during the study period
or operational troubleshooting during the first-year of
post-occupancy commissioning.
Preliminary examination of the utility bills and the
control trend logs show that the gas use for the building is higher than expected. The utility bills include the
consumption of the whole building, including the commercial kitchen and the science labs. However, these are
both considered process loads, and as per LEED guidelines, were not included in the energy simulation.
During the design process, VIU stressed the importance of continued energy monitoring and verification
to allow optimization of the building's annual energy
and water consumption. Continuous metering devices
with BACnet protocol were installed on the water, gas
and electricity services, including separate meters for
the lighting systems, plug loads, mechanical loads and
the boilers. These meters are all connected into the central energy monitoring and control system where data is
collected and trend logged, providing a valuable tool for
troubleshooting and correcting the deviations from the
anticipated building performance.
The recommended next step for the Cowichan
Campus building is to carefully examine the recent
trend logs, especially the boiler gas loads, to understand
any significant fluctuations in energy consumption or
to identify any potential opportunities to save energy. In
addition to the utility meters, Btu meters were installed
on the major equipment and systems, which will allow
verification of the operating efficiencies.

1,500
1,000
500
0

Electricity

Natural Gas

Figure 1 First year energy consumption.

there is a heat recovery coil to capture any waste heat in
the exhaust airstream, which is injected directly back
into the central water loop.
To reduce the heating load on the central plant, only the
minimum ventilation required by the Ventilation Rate
Procedure defined in ASHRAE Standard 62.1-2004 is delivered to the spaces. Further energy savings are achieved by
occupancy sensors that are installed in all classrooms, labs
and offices, which shut down the individual zone VAV box
to provide zero ventilation when the space is unoccupied.
Variable speed drives on the fan motors in the central air
handling units are used to maximize the energy savings.
Displacement ventilation is used in the 120-seat lecture theatre. Cool, low velocity air is distributed at the
floor level, which then rises up when it encounters a
heat source, i.e. an occupant, and is exhausted via ceiling grilles. This strategy allows the clean ventilation
air to be directly supplied at the occupied level that
improves the ventilation effectiveness of the system. To
avoid drafts at the occupant's feet, the supply air is delivered at low velocity and at a minimum of 65°F (18°C),
which is not as cold as a traditional overhead supply system and, therefore, provides additional energy savings
on the mechanical plant.
The original design brief required full cooling
throughout the new campus building. However, thermal analysis confirmed this was not possible via natural
ventilation strategies alone. A mechanical cooling system, via the in-floor radiant piping system, was used. A
typical radiant system can only provide a maximum of
approximately 15 Btu/ft2 (47 W/m2) of sensible cooling;
therefore careful consideration of the building envelope
was required during the early design stages.

ASHRAE Journal - December 2013

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