Commercial buildings designed under the C2000 green buildings program have been around for a number of years, but the first C2000 retail store opened just last summer. The Mountain Equipment Coop stor...
Commercial buildings designed under the C2000 green buildings program have been around for a number of years, but the first C2000 retail store opened just last summer. The Mountain Equipment Coop store in Westboro, Ottawa is the kind of building we might expect from the Vancouver-based retailer, which has earned a reputation for its ethical business policies.
Almost every part of the store has been designed with an environmental approach. Over half of the building materials are recycled, such as the posts, beams, concrete blocks and steel posts that were taken from the building that was originally on the site. Indeed, 75% of that original building was re-used or recycled. The new structure has a strawbale wall and a rock wall made of material excavated on the site. Much of the building has been built with panels and screws so that it can be easily disassembled at the end of its life.
Energy management was very important. With help from the Commercial Buildings Incentive Program, another NRCan environmental program, the project team honed their design to produce a building that is expected to use less than 50 per cent of the energy used by a standard equivalent building. As a result the store is expected to save $22,500 per year.
Leslie Jones & Associates of Ottawa was in charge of the mechanical and electrical design and energy modelling. A veteran of 30 years in the energy management field, Jones recalls that one of his first assignments when he left engineering school in England was coincidentally related to this type of retail project: measuring the economics of daylight as opposed to electrical lighting in a supermarket.
The Mountain Equipment Coop store has a large central skylight that brings in daylight, and artificial lighting that dims automatically when not needed. The lighting system of the entire building is orchestrated by a VCI central energy management system (NCX200 protocol) using occupancy sensors and other tools. Light levels in the merchandising areas, for example, are set at one level when the staff are stocking shelves, another level when the store is open to customers, and another during store closing hours. The range for lighting power density in the merchandising space is 15.70 to 20.01 W/m2, almost half that given in Canada’s Model National Energy Code for Buildings.
While this is not the kind of “intelligent building” that we associate with futuristic electronic devices, it is carefully tuned to respond to the varied occupancy levels and changes of use that occur over the course of a day. “Most of the technologies have been around for a while,” Jones says. “A lot of engineers might just pick up on one or two [green technologies] for a building. But this one was special. Every piece of equipment that used energy came under scrutiny. You had to forget how you had always done things, go back to first principles and ask: How is energy used in this piece of equipment, and how can we minimize it?”
Jones emphasizes that it was the design team’s holistic approach that made the difference. “To me, the most important thing was the way the design process worked. I was involved in trying to set the building shape — I didn’t just come along and add a heating ventilating system to a preconceived idea of a building. We did modelling early on to look at various shapes, whether it should be a one or two storey structure.” The team chose a two-storey structure, with triple-glazed, low-e argon filled windows on the north, and double-glazed windows with exterior louver sunshades on the south and west.
Since the overall building design reduced the energy loads, Jones was able to reduce the size of the mechanical systems. At the same time, the engineers did introduce some relatively new HVAC technologies. One is the use of carbon dioxide (CO2) detectors to modulate the ventilation levels. When there are few people in the store, carbon dioxide levels are lower, and sensors tell the energy management system to reduce the outdoor air supply. According to Jones, the CO2 detection system saves “a lot” of energy.
Highlights of the heating/cooling system are the use of R-407C (HFC type) refrigerant, which is non-ozone depleting, and the use of custom high-efficiency rooftop units providing heating (natural gas) and cooling (electricity) for the forced air system. Unlike most heating/cooling equipment, these units work more efficiently at part load, i.e. when the heating or cooling demand is not extreme, which is the majority of the time (82% efficiency at full load, 86% efficiency at 20% load). A condensing boiler that provides supplementary heat works at above 90% efficiency and has low NOx emissions. The designers also concentrated the zones requiring domestic hot water in one area, a strategy that economized on the amount of pipe, and minimized heat loss through the pipe.
Myriad other features and strategies — from high insulation levels, to water saving devices, to rainwater collection — seem to make this an exemplary environmental building. The store opened last June, and Corin Flood, project manager at Mountain Equipment Coop, reports that so far the building is working well.CCE
Owner: Mountain Equipment Co-op
Mechanical & electrical, energy modelling: Leslie Jones & Associates, Ottawa (Leslie Jones, P.Eng.)
Structural: Cleland Jardine Engineering
Architect: Linda Chapman & Christopher Simmonds
C-2000 facilitator: Enermodal Engineering