This past March, one of the largest residential properties in downtown Montreal, YUL Condominiums, gained some additional distinction when it won the Énergir prize for better use of natural gas at the 35th Domus Awards gala.
The honour recognizes the use of an innovative central natural gas heating system in the project’s first 38-storey tower. A second tower at the site, which has been developed in partnership by the Brivia Group and the Tianco Group, is currently under construction.
Given Montreal can experience extreme cold in the winter season, each unit is also equipped with electric baseboard heaters connected to individual meters.
The single-pipe vertical loop system used for heating and cooling in the building connects to a thermal pump in each unit, where residents have the flexibility to adjust temperatures based on their heating and cooling requirements.
The entire system runs off two condensing boilers.
”Doing this centrally also allows us to provide heating and cooling to the entire building at the lowest possible cost,” says Nicolas Lemire of Pageau Morel.
Another advantage of a centralized system was that it would require as little intervention as possible, says Fernando Bucci of the Briva Group.
”There are checks and balances throughout the building, so we are able to enjoy energy efficiency with as little maintenance as possible. The only thing unit holders have to do is change the filters on the pumps.”
Bucci says few builders have gone down the alley he and his partner firms have for the YUL project because the upfront costs are higher.
”The real cost savings in doing this are found in the annual recurring energy efficiency,” he explains. ”We wanted to provide a long-term product that made more sense.”
As a result of the system they chose, the builders were able to mitigate some of the extra costs through grants from energy providers, such as Énergir (formerly Gaz Métro), but the ongoing savings were the primary driver for the developers.
While inexpensive electricity is in plentiful supply in the province, according to Fernando Bucci, vice-president of operations for the Brivia Group, natural gas offered more long-term benefits in terms of efficiency and savings for this project.
”We were looking for an energy efficient system that would capitalize on the efficiencies of commonality. In this case, the water is tempered and therefore always balanced to have enough cooling or heating energy,” Bucci explains, adding that natural gas provided a better opportunity to temper that water efficiently and quickly.
At the heart of the tower’s mechanicals is a centralized boiler system that uses a mitigated single-pipe water loop system.
”With a common boiler system, we can provide heating, cooling and domestic hot water to the unit owners for the same flat rate. We could have opted to do independent heating and cooling and charge tenants on a pay per use basis but we believed this was the smarter use of energy into the future,” he says.
Nicolas Lemire, president of Pageau Morel, the mechanical and electrical engineering firm on the project, cites energy use and efficiency as being a very important consideration since the earliest design stages of the tower
”We wanted to find a way to share energy for the whole building as much as possible,” he says. ”That’s not common in condos, where it’s usually autonomous for the residents. This approach is not only more efficient, it saves energy costs.”
Two make-up air units located on the roof deliver fresh air to the building and units, with the exception of the corridors. ”There are systems that blow fresh air into the corridors, but we chose not to do that,” says Bucci.
As an added efficiency booster, the heat rejected from the cooling loop is extracted to heat the swimming pools in summer.
Natural gas is also used to heat the snow melt system, using an independent gas-fired boiler and a part glycol/part water loop. ”We found it extremely efficient to use natural gas for the two large driveways in front,” Bucci says.
Plans are to install a similar system in the second tower, but with some modifications. In this case the central water loop will feed into a horizontal system on each floor.
”In that way we don’t have to install thermal pumps in every unit,” says Bucci. ”Instead we are having one per floor and using evaporators in the units. That increases the energy efficiency a bit and makes it even better.” The revised design also reduces the installation time.
”We learned in Phase I that the installation was a bit longer than we would have wished for. In Phase II instead of 400 compressors, we will only have 39 to worry about,” he adds.
Lemire admits the piping for these projects is more extensive than a standard installation.
”If we compare some buildings that have the typical unit-by-unit piping design, each unit would have their own domestic hot water tank and own system for electric heating and some kind of cooling unit,” he says. ”In this design, we used bigger piping for the centralized heating, cooling and domestic hot water. All in all that took more than 50 per cent more piping. At the same time each unit does not need a hot water tank.” That’s something he says would need to be replaced every 10 years.