ASHRAE Journal - April 2015 - 79

2015 ASHRAE TECHNOLOGY AWARD CASE STUDIES

the key element in the commissioning process, especially the fine-tuning of the chiller operation and performance as well as the optimization of the gas/electric final
stage of hot water heating. Operation and maintenance
costs were considerably reduced due to the automation
and the capital upgrade of main mechanical systems
(boilers, storage tanks, control system, heat exchangers,
and pump motors). The concept of using the underground
concrete tanks as a condenser of the new chiller saved the
operational costs of maintaining the cooling tower and
eliminated the necessary water chemical treatments. It
also saved the cost of several water quality tests per year.

Energy & Economic Benefits
This project, which is a mix of a construction of an
efficient radiology clinic and the retrofit of an existing
domestic water network, cuts the complex's energy cost
by $139,634/year and saved the cost of installing a new
cooling tower worth $250,000. The selection of the type of
chiller (water to water + heat recovery) was the subject of
a life-cycle cost analysis of 20 years. Table 1 (Page 75) shows
the resultant energy and cost savings of the project as calculated prior to project implementation. The energy savings
calculation was based on the measurement of key parameters such as the domestic hot water daily consumption and
the amperage and power demand of the booster pumps.
The overall payback of the project is 3.6 years.
However, if we consider the avoided cost ($250,000) of
the cooling tower and the maintenance savings ($5,000/
year), the payback goes down to 1.7 years.
Table 2 (Page 75) shows the energy consumption of SW1
before and after the project. The energy consumption data
shown in this table are rough data as taken from the utility
bills and haven't been corrected to take into consideration
weather normalization and/or base year adjustments (such
as the implementation of the new 18,000 ft2 clinic).

Environmental Impact
The project has avoided the emission of over 92 tons
of CO2 into the atmosphere, which is the equivalent of
planting 464 trees or removing 18 medium cars from the
road. This avoided emission is associated with the gas
energy savings. However, the electrical energy savings,
which represent 77% of the total energy savings, have no
direct avoided emissions in Quebec since electricity is
mostly produced by hydro-electrical plants.
In addition to avoided GHG emissions, the project

saved 929,261 gallons of water that could have been consumed by the cooling tower, not to mention the chemical
products that go with it.
The project resulted in other intangible benefits such as:
* The preservation of the living environment in the
complex.
* GHG reductions associated with the manufacture
and transport of the avoided cooling tower.
* Recuperation of the two concrete tanks.

Conclusion
The combination of the medical radiology clinic and
the domestic water network retrofit allowed SW1 to
implement advanced energy efficiency standards while
respecting highly demanding healthcare requirements,
cutting installation and operation costs, and preserving
the complex's green and aesthetics aspects.
The successful implementation and operation of a water
cooled chiller with existing condensing tanks instead of
a cooling tower demonstrated that there is always a way to
be creative and innovative in every HVAC project.

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APRI L 2015

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ASHRAE Journal - April 2015

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