by Cheryl Mah
Climate change and the need to reduce greenhouse gas emissions (GHG) have led many municipalities to explore district energy systems (DES) as a solution. District energy is a proven technology that is in use in communities around the world. Efficient, resilient, community-based energy systems, fuelled mostly by renewables, are increasingly becoming an important tool to transform energy infrastructure and to make cities more sustainable.
The City of Prince George approved a DES in 2010 to provide carbon neutral green energy and improve the air quality in the community. More than $4 million was invested in the piping for the biomass-based system, which was fully commissioned in 2012. It currently reduces annual CO2 emissions by approximately 1,900 tons a year. In 2013, use of the DES reduced the city’s natural gas consumption by 17,000 gigajoules, enough to supply heat for 110 homes annually.
Fuelled mainly by sawmill residuals from the Lakeland Mills sawmill, the DES generates hot water used for domestic hot water and space heating in several key downtown civic buildings including city hall, Prince George Public Library, the RCMP building and the Wood Innovation and Design Centre.
The Prince George Law Courts, located on George Street, is the most recent building to connect to the system. According to the city, a connection to the DES will not only reduce GHG emissions but also capital and operational costs. Local contractor RH Jones and Son Mechanical completed the 2.5 month job in September 2017.
“We’ve done the bulk of the work connecting buildings to the system and the DES building itself. This is our ninth building,” says project manager Paul Baylis, noting the company is currently working on connecting Plaza 400 which will complete later this year.
A MCABC member since 1979 when the company was founded, RH Jones and Son Mechanical has been serving northern B.C. for almost 40 years, specializing in plumbing, heating, HVAC, fire protection and sheet metal fabrication.
For this project, the contractor had to install six-inch diameter steel pipes from the parkade up through to the mechanical rooms on the second and fifth floors of the Law Courts to tie into the DES. Heat exchangers transfer thermal energy from the DES to the building system. This interface system installed within the building is called an Energy Transfer System (ETS). The new system replaces old gas boilers.
The first step was to get the holes cored through the floors to get the exact location of piping in the mechanical rooms, notes Baylis. The first mechanical room was on the second floor which was used for the main DES heating, housing the pumps and exchangers. The fifth floor mechanical room was used for domestic piping which was mostly copper. Veiga propress was used for all connections.
“Trying to get large diameter steel piping into an existing building and up several floors through existing offices and mechanical rooms was a big challenge,” says Baylis. “The majority of the lay down was also offsite so we had to truck all the materials including 20-to 40-foot pipes just in time for installation.”
With the Law Courts remaining fully operational during the project, most of the work had to be done at night.
“Safety was very important and we had welding to do which means smoke and smells. We also had to go through several floors of 12-to 14-inch concrete to get the pipe up through,” says Baylis, who had a crew of two plus subtrades working 10-hour night shifts.
The completion of the project is a continuation of the city’s efforts to reduce its carbon footprint and another step towards achieving the goal of being carbon neutral.
Cheryl Mah is managing editor of MCABC Plumbing & Mechanical magazine