Specialized Concrete Pipe That Can Pay for Itself-Used to Heat and Cool Net Zero Building

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The recently completed Coniston Seniors housing complex located in the greater Sudbury area provides affordable housing to seniors in the local Coniston area. In addition, the 56,000-square-foot apartment complex is designed as a net zero energy building.

The project was designed by Sheena Sharp from Coolearth Architects, and the General Contractor was Ron Belanger Construction.

A key component of this project attaining a net zero energy target was the addition of an innovative heat recovery system that captures effluent heat by utilizing specialized reinforced concrete pipe. The technology for extracting and injecting heat into a wastewater line is called geo-exchange. The patented @Source-Energy Pipe consists of a heat exchanger encased in a concrete sewer pipe. The pipe and surrounding ground become a thermal battery. Rainbow Concrete, a local Sudbury concrete pipe and precast concrete producer, has been licensed by Renewable Resources Recovery Corp. to produce the specialized pipe in Ontario that allows for a heat recovery system to be utilized. Lafarge Pipe is also licensed to produce this pipe for the Prairie provinces.

Rainbow Concrete worked with Renewable Resource Recovery Corp. to develop a manufacturing process that ensures the specialized pipes meet the heat exchanges system pressure requirements and provide the structural capacity required to meet the live and dead loads that will be applied to the pipe installed. The @Source-Energy Pipe meets both the D-Load and hydrostatic testing stipulated in CSA A257.

During cold weather, using a ground source heat pump, the @Source-Energy Pipe captures waste thermal energy from the sewage effluent and from the ground around the pipe. This is used to heat the building and provide hot water. During warm weather, heat is removed from the building with the same heat pump and rejected with the effluent and stored in the wall of the pipe and the ground around it. Since the heat exchanger is embedded in the wall of the pipe, it does not come into contact with or handle any sewage.

Maintenance is only required for the heat pumps to control the system, distribute heat, or remove heat from the building. Because the heat recovery system is embedded within the pipe walls, a contiguous system can be developed along the entire sewage pipe system forming a district thermal energy system.

The installation of the concrete sewer pipe follows the traditional method. Providing proper bedding and compacting the backfill in 200 mm lift as per the standard practices found in OPS for gravity pipe installations. Connecting/fusing the heat exchanger to a header and return line is accomplished using the same techniques as in a conventional geothermal installation.

Concordia University is monitoring this innovative heat recovery system with two Ph.D. students. The students have developed and implemented a data monitoring system that includes sensors, data acquisition systems and communications protocols. Once the data has been collected, it will be analyzed and evaluated. A final report will be produced that will provide information on system performance and recommendations regarding control strategies to improve system performance.

I would like to extend my thanks to Rainbow Concrete for helping produce a specialized reinforced concrete pipe with an embedded heat exchange coil that meets both the structural requirements as well providing a heat recovery component that has allowed for the Coniston Seniors apartment complex to reach a net zero energy rating.

For more information, please visit:
Source Energy
RCIL -Resource Center for Independent Living
Lafarge Canada

Les Lisk
Vice President
Renewable Resource Recovery
Corporation
Precast Producer: Rainbow Concrete
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