Schreyer Award -South Interlake Recreation Centre

The South Interlake Recreation Centre in Warren, Manitoba has operational and energy costs less than half those of conventional ice hockey arenas built over the past 80 years or so in Canada.

As prime consultant and project manager for the $2.6-million new centre, Tower Engineering was able to achieve the energy savings by applying new technologies and integrating different systems. The project is a successful integration of several fields of building science to produce a highly efficient building; it orchestrates earth sciences (geothermal systems), building envelope technology, refrigeration, HVAC systems, and electrical demand and control systems.

Warren is a picturesque community about 40 kilometres northwest of Winnipeg. The important role that the recreation centre serves in Warren as in many other small communities in Canada cannot be overstated. For the town of 1,000 people it is the social and recreational hub of the community and replacing the old arena was vital. A volunteer committee, however, realized that the community’s small size and limited resources could not sustain a conventional arena with high operating costs. In the end, however, the energy efficient design reduced the arena’s operating costs and it also made the 2,790-m2 project eligible for government and utility grants, enabling it to be constructed within the town’s budget.

For the design, Tower Engineering had to “pull out all the stops.”

Modular refrigeration units

First, modular refrigeration units (heat pumps) were used as opposed to large unloading brine systems for the hydronic systems. Also, smaller circulation pumps were used instead of fewer large pumps. Although larger equipment would be more efficient at full loads, full load conditions are rarely attained. Modular units allow on/ off operation, and the ability to shut off some refrigeration units results in efficiencies at part-load operations.

Ice plant used for HVAC

Next, energy for the building HVAC systems is generated by the same Ice Kube units that make the ice for the rink, thereby saving energy. There is no energy simultaneously used to produce ice as well as to heat or cool the occupied spaces. Low-grade 95F heat recovered from the condensers is used in the in-floor hydronic heating, while high grade 130F super- heat recovered from the ice-making process is used to heat water for ice flooding and showers.

In addition, heat recovery ventilators (HRVs) are used to recover heating and air-conditioned ventilation energy from the air. These, coupled with the energy recovered from the ice plant, virtually eliminate the need for any additional energy to heat the make-up air and ventilation air.

Lighting

A conventional arena would typically have only one lighting level –all lights either on or off. The South Interlake Arena incorporates three levels of lighting control over the ice surface and uses full lighting only during important events or games. This approach saves energy thanks to the lights themselves being turned off, and also because less cooling energy is required to counteract radiant heat from the lamps.

Ground Energy Sinks

Energy storage buffers serve to trim the building’s peak loads and decrease its energy demand. The entire structure is built over a man-made heating and cooling sink. The area below the building was excavated and a gravel-clay storage medium was laid under the stands and apron floors at 1 ft. (0.3m) deep. It was completely insulated.

For heating, this buffer medium stores approximately 35 BTU per cubic foot, which adds up to 18,000,000 BTU or 4,600 kWhr of energy storage under the warm dressing rooms and lobby. The buffer is maintained at 15F above the required dressing rooms/lobby temperature. The stored energy can keep the building warm for up to 15 days without any additional energy use.

A similar buffer was installed under the ice surface slab. For cooling, the buffer stores up to 6,000,000 BTU or 500 tons of refrigeration under the ice when the buffer is frozen to 5F below the ice temperature. The buffer helps to keep the ice harder during heavy use periods and keeps the ice frozen for many hours upon a power failure.

Geothermal system

An open geothermal system consisting of a supply well and a return well provides the primary source of energy. Submersible pumps circulate water from the supply well through a heat exchanger and down the return well. The energy is then transferred to the heat pumps. The open well system has the advantage of providing consistent 41F water temperatures summer and winter. The temperatures in a closed loop system would fluctuate between 80F in summer and down to freezing (or even lower) in winter.

To prove the building’s efficiency, Natural Resources Canada (NRCan) required that an energy model be provided using their EE Wizard Software specifically designed for arenas in Canada. The software predicted that a conventional arena of similar size would use $85,000 worth of power per year, whereas this geothermal arena would use about $28,000 per year. These projected energy savings qualified the arena for the maximum $60,000 CBIP grant from NRCan.

When constructed, the arena produced an actual annual energy bill of $31,000.

Project: South Interlake Recreation Centre, Warren, Manitoba

Award-winning firm: prime consultants, mechanical, electrical, project management: Tower Engineering Group Greg Jorgensen, P. Eng., Jack Abiusi, P. Eng., Guenter Schaub, P. Eng., Thai Tonthat, P. Eng., Mike Houvardas, P. Eng.

Owner: South Interlake Recreation Centre

Other key players: Road Architecture (architect), Laverne Draward & Assoc. (structural), Parkwest Projects (contractor)