ASHRAE Journal - December 2014 - 50

2014 ASHRAE TECHNOLOGY AWARD CASE STUDIES

FIGURE 1 Ventilation systems.

FIGURE 2 Chilled and heating water systems.

Fresh Air Supply Fan

Fresh
Air
16,000 cfm
Exhaust
Air
Exhaust
Fan
Heat
Recovery
Wheel

Fan Coil for Building
Envelope Load
(6 Per Floor)
Occupied
Zone

3,200 cfm

Occupied
Zone

Condenser
Evaporator

3,200 cfm

Occupied
Zone

Heating Water
Bypass Valve
150 gpm

Cooling Coil

80 Tons
Each

Condenser

150 gpm

Evaporator

3,200 cfm

Occupied
Zone

3,200 cfm

Ventilation System Occupied Zone
(1 Per Floor)

Ventilation System
Of Occupied Zone
(5 Total)
General
Exhaust

Energy Efficiency
To evaluate the energy savings, a computer model of
the base case building was made using the EE4 simulation software (this base case building must meet
Canadian energy codes or ASHRAE/IES Standard 90.1).
Table 1 shows the real energy consumption and cost
(before taxes) in Canadian dollars of the building from
January to December 2011. Please note that this energy
consumption includes the tenant consumption with an
average occupancy level of 70%.
Figure 3 shows the simulation results along with the
real energy consumption of the building from January to
December 2011.
The total energy (which is 100% electric) consumption
of the building is 1,141,800 kWh per year, which translates to 9.7 kWh/ft2 (104 kWh/m2) per year. The energy
consumption of the model was 1,906,400 kWh per year,
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Fan Coils for Building
Envelope Load
Quantity: ±30

Sanitary
Exhaust

air it supplies to its given zone according to the load.
The systems use chilled or hot water and treat the air
with the same coil. Every coil is connected to the cooling
and heating water loops and switches on the appropriate loop using automatic control three-way valves. All
pumps are equipped with variable frequency drives and
modulate their flow according to the coil demands of
each loop. Figure 2 shows the chilled and heating water
systems.

150 gpm
150 gpm

3,200 cfm

Occupied
Zone

Chilled Water
Bypass Valve

D ECEM BER 2014

±26 Bore holes of 500 ft Deep

or 16 kWh/ft2 (172 kWh/m2) per year, which is relatively
low. The total energy consumption was thus reduced by
40% compared with the model, which roughly sums to
$62,000 CAN$ per year. Figure 3 also indicates the impact
of heating with recovered energy only: the average savings during the winter period is 50% compared to the
model.
In this project, the total HVAC system costs were
$1,880,000 CAN$. For a 117,000 ft2 building, this capital cost represents $16/ft2. If more common mechanical systems had been installed (ventilation units, no
ground-source boreholes, cooling towers and boilers),
the mechanical costs would have been equal or higher.
Indeed, if no heat recovery wheel had been installed, the
chillers would have been bigger because of higher fresh
air cooling load. If the building envelope were less high
performing, the summer cooling load would have been
higher, requiring bigger chillers, and the winter heating
load would have increased, probably requiring energy
from hot water boilers.
From the beginning of the project, the engineers and
architects worked together to design a high performance
building envelope to reduce the quantity and size of the
mechanical systems and thus reduce capital costs. This

ASHRAE Journal - December 2014

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