©2013 This excerpt taken from the article of the same name which appeared in ASHRAE Journal, vol. 55, no. 11, November 2013.
By Richard Perry, C.Eng., P.Eng., Member ASHRAE and Tom Ren, P.Eng., Member ASHRAE
About the Authors
Richard Perry, C.Eng., P.Eng., is senior engineer emeritus, and Tom Ren, P.Eng., is project engineer for alternative energy at DEC Engineering in New Westminster, BC, Canada. Both are members of ASHRAE's British Columbia Chapter.
The Whistler Athletes Village in Whistler, BC, Canada, was originally constructed to house athletes competing at the 2010 Winter Olympic Games. The buildings in Phase 1 have been converted for residential use and have operated for more than two years, during which the connected systems have been monitored on an hourly basis and the results documented.
The primary energy source for heating, cooling and domestic hot water is the district energy sharing system (DESS), which takes low-temperature energy from the existing Whistler Village Sewage Treatment Plant and uses it for heating and cooling the buildings. The DESS is designed with capacity for an eventual community of 400 residential units and their ancillary services.
Treated sewage is pumped from the existing treatment plant to an adjacent mechanical plant room, where it is filtered before passing through a bank of heat exchangers. A two-pipe, reversed return, closed-loop system around the Athlete’s Village supplies the energy required for all of the heat pumps in Phase 1 of the project.
Water from the heat exchangers in the mechanical plant room is pumped through high density polyethylene piping, around the distribution loops, providing the energy source for the heat pumps within each of the Village buildings. There are no circulating pumps or control valves between the connected building supply and the return to the DESS. Control is entirely governed by the pressure difference between the supply and return mains.
The heat pumps in each unit were selected to provide 60% of the peak capacity for heating and/or cooling, with electric heating elements installed in each building as backup. The largest pipe at the discharge from in the system mechanical room is 14 in. (356 mm) in diameter. Phase 1 flow from the mechanical room is maintained at 1,600 gpm (101 L/s). Flow rate for the completed system will be 2,400 gpm (152 L/s). Space has been reserved for a future heat exchanger and pump. Two gas-fired standby boilers are located in the mechanical room.
The innovative aspects of this project rest completely in the DESS. The system is unique in that it is providing heating, cooling and domestic hot water to a very large development using the energy that is reclaimed from the sewage treatment plant. The first year’s operation of the system is producing an energy savings of almost 50% compared to the energy use for comparable buildings. As the system is expanded and the operation is refined, it is expected that this figure will rise to a 60% savings.
Designing the Whistler system was complex because of the variability of the energy source and the residential demands. Further complicating matters was the need for the system to perform in a cold climate. The distribution piping creates a thermal storage that is used by the building heat pumps, functioning in either heating or cooling modes.
The use of a non-freezing compound in the system was not considered necessary because of the temperatures maintained in the DESS. It is estimated that the design life of the system will be at least 50 years, will require a minimum of maintenance, and will be inexpensive to operate, as demonstrated by the first year’s operation.
It is projected that the system, when completed, will have provided a 70% reduction in greenhouse gasses, over a comparable district heating system, and up to 3,200 MWh of building energy per year, using the energy that would otherwise be wasted.
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