Fisher Towers

When engineers were tasked with retrofitting Fisher Towers, a set of 22-floor apartment buildings just outside downtown Ottawa, their mandate was to upgrade the building envelope, add cooling and replace the existing baseboard electrical heating system with a new energy-efficient system.

To provide heating and cooling throughout the 850 units originally built in the early 1970s, engineers initially specified 650 Briza 12s for a decentralized cooling approach. That approach would require a single fan coil in each room: a one-bedroom apartment would have one emitter in the bedroom and another one in the living space. However, they quickly discovered that to retrofit the electric building, the existing concrete slabs would need to be modified to accommodate additional piping.

Lacking any original drawings to identify the location of steel rebars in the slab located in the old buildings, the project cost quickly escalated. The higher number of fan coil units would also increase installation costs, which can be double or triple the cost of the original unit. They needed a better solution.

The Briza-22 Offers Flexibility and Savings

Engineers found that a centralized system would accomplish the same goals of providing heating and cooling while also substantially reducing energy consumption. This would require a single fan coil unit in each apartment that would be ducted into each room. Jaga’s Briza 22 unit offered the key to the solution.

“The product that made this project viable was the Jaga fan coil product line,” said Ryan Leonard, Senior Associate Mechanical Engineer for GWAL. “The high-performance heat exchanger provided outstanding heating and cooling performance at very low flow rates, as well as very low heating temperatures. This allowed the operating efficiency of the natural gas boiler plant to run at peak efficiency by continuously operating at high condensing mode.”

“The low water flow rates required allowed smaller pipe sizing and risers, helping with project costs and space constraints,” he continued. “The fan coils themselves are very compact, which was necessary for retrofitting an existing space previously served by electric baseboards only.”

The fan coils were installed in the ceilings of existing closets, maintaining the existing footprint, and not decreasing the available square footage of each apartment unlike a traditional wall-mounted fan coil. In addition to providing heating and cooling in the bedroom, the 220mm( 8 ¾” ) deep fan coil unit was ducted to also feed the living room.

The centralized solution required approximately half the original number of fan coils originally specified—only 347 units were required. In addition to reducing the overall cost of the emitters, it also substantially reduced installation costs, showing the viability of centralized solutions for a retrofit scenario. Over the long-term, the system will substantially reduce energy use over the previous baseboard system, achieving the required mandate.

“I would not hesitate to use Jaga again,” added Leonard.