Built in the mid-’70s, this expansive site underwent a deep energy retrofit from 2015 to 2018, addressing inefficiencies caused by aging HVAC and lighting equipment. By achieving reductions of 31% in energy use, 26% in energy bills and 57% in greenhouse gas (GHG) emissions, the project went on to win first place in the existing public assembly category of the 2019 American Society of Heating, Refrigerating and Air-conditioning Engineers (ASHRAE) Technology Awards.
The Montreal Olympic Park is a source of national pride with the Olympic Stadium, 541 foot (165 meters) observation tower and The Biodome. Built for the 1976 Summer Olympics, the Stadium is now used for sporting events, concerts and other activities. The park is attended by three million visitors each year. With its more than 2,500 jobs and as an international symbol of Montreal, the Olympic Park is an important engine of economic and tourist development.
Montreal Olympic Park began what ended up being a $6.5 Million energy retrofit that reduced that reduces the energy bill by $ 1.55 Million. The work lasted three years and four major projects were on the program:
Led by Quebec-based design-build firm Ecosystem, the project relied on a whole-system approach to simultaneously address all energy-related issues.
“We didn’t specify a lot of equipment,” explains Dominic Desjardins, energy manager at Olympic Park. “All the companies took about six months to do their own designs and after that we selected the best solution with the best payback.”
Ecosystem implemented numerous measures to deliver this payback, the vast majority of which focused on the site’s HVAC system. For example, the waste created by the facility’s steam heating network was addressed by a conversion to hot water.
“The steam to hot water conversion reduced energy waste in the distribution network,” says Olivier Matte, technical communications director at Ecosystem. “Also, you have higher efficiency, because obviously if you’re heating water rather than producing steam, your boilers are working at a lower temperature, hence they are reducing the flue gas temperature and waste.”
Three steam boilers at the site’s main plant underwent this conversion, as did the primary steam heating loop. However, stand-alone steam-producing generators are still used to provide humidification.
“Taking out the steam from this building yielded more savings than we expected,” says André-Benoit Allard, project director with Ecosystem. “A lot of the steam wasn’t providing any services to the building; it was just there to keep the system warm.”
Heat recovery pumps were also introduced as an alternative to heat exchangers, boosting the efficiency of hot water production and minimizing heat loss by providing hot water directly to the secondary loops. Sized to assume the building’s full cooling load in winter and full heating load in summer, the pumps return a small amount of heat to the hot water loop during the cold months. In summer, they are used to partially recover the cooling load.“
The heat pumps and the conversion from steam to hot water are really working hand-in-hand here,” says Matte. “Looking at the whole system rather than one piece of equipment at a time has allowed us to integrate all this together in an optimal design.”
The chillers, in turn, were resized to expand their cooling load range, offering increased flexibility for Olympic Park’s varied events. Additionally, one of the four was moved away from its counterparts. This distinct placement, along with the downgrading of the gas boilers from 60 to 45 MBTU/h, reduced the once-constant supervision requirements for these systems, which now need to be monitored only one hour of the day.
An electric boiler has also been added to reduce reliance on natural gas. This, combined with the electric heat pumps, allows the facility to operate virtually GHG-free in summer. Also, thanks to the prioritization of electricity over gas, subsidies were granted to Olympic Park by the provincial government (through an emissions reduction program and through Hydro-Quebec) and the gas supplier. Operating the boiler during off-peak hours also helps drive down costs.
Maurice Landry, Olympic Park’s vice-president (VP) of construction and maintenance, reports significant improvements in the facility’s annual energy bills.
“Before the project, we were spending about $6.5 million in energy,” he says. “Now, we’re down to about $5 million.”
Two new 200 ton (703 kW) heat recovery chillers were installed to take advantage of Quebec's clean and inexpensive hydroelectricity rates. The heat pumps supply a low-temperature heating network with 130°F (54°C) water that heats five pools including the Olympic diving, swimming and synchronized swimming pools, and provides air heating in the sports center. This network also preheats the various domestic hot water heating loads. In addition, a new ENERVEX VHX6400-66 flue gas heat recovery system from ENERVEX was installed on the stack of the primary boiler (Photo 4), boosting the boiler's efficiency to 89%. ENERVEX also supplied an integrated mechanical draft control system. It is estimated the ENERVEX system recovers 4,300MBH of energy off a single 45,000MBH boiler.
Carly Midgley is a freelance writer and editor based near Toronto. She has covered numerous aspects of the architectural and engineering industries in her work, drafting technical articles for various trade publications. This article originally appeared in the March 2019 issue of Energy Manager Canada.