Volume 20, number 1, june 2006

Richard J. Renaud Pavilion at Concordia University – a good example of energy efficiency

Concordia University, formed from the union of two institutions – Sir George Williams University and Loyola College–has been in existence since 1974. It welcomes more than 30,000 students each year on its two campuses, George Williams and Loyola.

In recent years, the need for space and for high-performance appliances on campus has greatly increased, and a project to enlarge the Richard J. Renaud Pavilion
was conceived. The project calls for adding 345,000 sq. ft., including 150,000 sq. ft. of laboratories. The inclusion of laboratories has an enormous influence on the energy performance of the building, since the major energy load is for ventilating the labs. This constraint enabled the project designers to innovate and to make the new pavilion extremely energy efficient. In fact, on average, it consumes only 673.5 kWh/m2 annually.

Laboratories fitted with hoods with variable exhaust flow rates in the Richard J. Renaud Pavilion at Concordia University.

Ventilation needs

The various appliances in the laboratories exhaust a total of 174,062 CFM. The number of extractors and exhaust hoods differs from one laboratory to another, and not all of them function simultaneously. In order to simulate the energy consumption potential of these appliances, a diversity factor was determined, based on the number of hoods per laboratory.

The following table illustrates the energy needs of a base building with and without processes. The operation of the hoods was first set at 10 air changes per hour, 24 hours per day.As the table shows, the exhaust appliances have an enormous impact on the building’s energy consumption.

Laboratories fitted with hoods with variable exhaust flow rates in the Richard J. Renaud Pavilion at Concordia University.

 

Analysis of impact of hoods on the reference building in kWh/m2

  Base Without hoods With hoods
  Without processes With processes
processes N/A 88.2 88.2
lighting 56.4 56.4 56.4
appliances 38.8 38.8 74.9
heating 39.3 39.3 704.4
cooling 30.3 30.3 59.0
pumps 39.8 39.8 63.8
ventilator 31.0 31.0 166.9
total 235.6 323.8 1,213.6

Energy savings

Several suggestions were proposed and implemented in order to improve energy performance, for example:

  • the flow of air to the laboratories was reduced from 10 to 3 air changes per hour at night and the suction was configured to vary depending on the hood opening;
  • movement detectors were installed in the 381 laboratories in order to optimize the use of the HVAC and lighting systems;
  • a glycol recuperation loop was installed on the stale air exhaust.

For heating, the designers opted for a low-temperature system, thus making it possible to recuperate heat from the cooling unit condensers and to install a direct-contact economizer. Lastly, the office and laboratory systems were combined.

Unit cost method

The project was analyzed taking into account the costs of investment, operation and maintenance. The unit cost method also allowed the designers to choose different appliances that would be cost-effective for the client even after 5, 10 or 15 years of use. To evaluate the energy costs of the Richard J. Renaud Pavilion, the borrowing rate was set at 6.75% for 5 years, for a cost of $0.23568 per dollar of investment per year. The electricity rates were set at $0.06/kWh, and the equivalent for natural gas set at $0.05/kWh.
The following table shows some unit costs of the appliances or systems:

Unit costs

System, appliance Investment ($) Operation/maintenance ($)
glycol loop 4.45/l/s 0.15/l/s
boiler 250/HP 8/HP
perimetric water heating 43/m2 0.43/m2
recuperator, direct-contact hot-water heater 400/HP 20/HP

Performance

As an example, reducing the exhaust flow rate at night represents, annually:

  • an investment of $132,128,
  • an annual operation and maintenance cost of $7,928,

for a total of $140,056. The annual savings in natural gas and electricity total $703,732. So, reducing the exhaust flow
is an investment with a rate of return of 402% (!) per year:

The implementation of all these solutions led to annual savings equal to 12,240,600 kWh in natural gas and 3,844,720 kWh in electricity, or $842,713 per year (for the useful life of the appliances). These investments have a return of 138% per year. In the first year of operation, savings were $888,566, higher than forecasted.

The final table shows the potential consumption of the building simulated with the hoods and the energy savings measures in place.

The unit cost method and the energy simulation turned out to be exceptional tools for optimizing the operation of such a building. While they were useful, the implementation of innovative and high-performance technologies would not have been possible without the vision and openness of the client.

Consumption in kWh/m2

  Without hoods With hoods With all the energy savings measures suggested
processes 88.2 88.2 88.2
lighting 56.4 56.4 43.1
appliances 38.8 74.9 74.9
heating 39.3 704.4 322.3
cooling 30.3 59.0 40.6
pumps 39.8 63.8 26.4
ventilator 31.0 166.9 78.0
total 323.8 1,213.6 673.5

Marie-Joëlle Lainé, eng.
Technical consultant
DATECH Group