Designing HVAC systems for large, mixed-use facilities is never easy, but imagine if that design had to meet the diverse needs of both a university and a community center all within the same building.
That was the challenge faced by MCW Consultants Ltd. when the engineering firm was asked to design the HVAC systems for a satellite campus of Trinity Western University (TWU) and the new City Centre Community Centre in Richmond, British Columbia, Canada. The community center would occupy the first two floors of the four-story building, and the university would occupy the two floors directly overhead. The rooftop would be visible from neighboring buildings, including upscale residential high-rises and commercial real estate, all situated in an area conceived to showcase an urban lifestyle, culture, and sustainability. The decision to pursue LEED Gold certification for the community center ramped up the challenge even further.
A decentralized heat pump system was provided as part of the base building mechanicals and would meet all of the facility’s heating and cooling needs as well as the required individualized control. For ventilation, MCW searched for an efficient, nonobtrusive solution. Their search led them to Systemair’s Topvex Energy Recovery Unit (ERV).
Determined to maintain a high aesthetic standard, the architects ruled out any rooftop equipment. Interior mechanical space was limited, especially given the 60 heat pumps installed throughout the building. Multiple ERVs had to be tucked away in small places, above ceilings, and in random pockets of spaces throughout the structure. Some of those spaces were in offices or next to classrooms, making noise a concern.
MCW was on the hunt for a slim-lined ERV that could fit within these nooks. They also wanted variable-flow capability and electronically commutated motors (ECMs) for more quiet operation, enhanced performance, and demand-controlled ventilation. Such features don’t ordinarily come in a small box — at least not with the cfm requirement of a high-occupancy public space — but they do with the Topvex.
“The Topvex offers a lot of features, like airflow options, variable flow, a high-efficienc`y energy wheel, easy access points, economizer options, sensor options, data points, etc.,” said Raymond Cho, project engineer for MCW. “You don’t typically see all that in a packaged unit like this.”
The community center and TWU each occupy about 28,000 square feet within a new living and cultural development in downtown Richmond. The community center features a large living room, multipurpose spaces, a fitness center and change rooms, aerobics and dance studios, meeting rooms, a lounge, a kitchen, an art studio, and music rooms. Directly above are TWU classrooms, faculty offices, seminar rooms, a resource center, and other spaces typical of an academic facility. Thus, at any given time, TWU students could be listening to a lecture while a class of preschoolers practice ballet in a room below.
“Because this was a decentralized system, we knew from the beginning that noise would be a concern,” Cho said. “And we did not have the space to put equipment in any loud spaces like the fitness center. So [the ERVs] had to be put in hidden spaces, like in office closets.”
Fortunately, the largest ERV selected for the project occupied a space no larger than 97-by-70-by-36 inches, and, depending on the location, some units were specified with factory-installed silencers.
Maintaining seamless communication between the ERVs and the building management system (BMS) was another hurdle for MCW.
“We’ve had a lot of issues with BACnet integration between base building DDCs and OEM control modules,” Cho said. “Most of the time we have issues getting the two systems to talk to each other.”
Luckily, that wasn’t the case at the TWU/Civic Centre facility. The control signals matched perfectly between the field-installed control and the factory-installed Corrigo E controls on the ERVs, so the integration was much smoother than expected.
A total of 11 Topvex ERVs with capacities ranging from 1,150-3,800 cfm were chosen for energy recovery and fresh air delivery. The units supply 100% outdoor air while recovering up to 73% of energy from the air exhausted from bathrooms, showers, and other interior spaces.
Meanwhile, 60 water-source heat pumps are the primary source for heating and cooling. A closed-circuit cooler and condenser water loop serve as the heat rejection and absorption source for the heat pumps. The closed-circuit cooler and several condensing boilers work together as needed to keep the condenser water loop within the heat pumps’ operating range.
The ERVs minimize the load on the heat pumps year-round and can operate in full economizing mode when outdoor temperatures allow. Fresh outdoor air passes through the ERV where it is preconditioned with building return air via the energy recovery wheel. After exiting the ERV, the fresh, preconditioned air enters the individual heat pumps where it is further heated or cooled depending on demand. Some ERVs are equipped with an electric preheat coil to heat outdoor air as needed to keep the internal heat wheel from freezing during extremely cold periods. Operating parameters are preprogrammed into the onboard controls, which can be monitored and adjusted via the BMS.
Duane Goderis, project manager for GML Mechanical, the installing contractor, credits the Topvex design and controls package as well as Systemair support for streamlining the installation and startup process.
“The units were very easy to hang,” Goderis said. “There are only six connection points with the brackets, which the manufacturer includes. Also, these units have good doors that swing open from the bottom, so changing filters is easy, with no side access required.”
Most importantly, according to Goderis, the client was happy, and GML was able to meet the project’s stringent deadline.
“The experience I had working with Systemair was great,” he said. “It isn’t always this easy.”