October 27, 2008

Collaborative Structures introduces Canada’s first LEED-CS certified building

DAN O’REILLY

correspondent

Paying special attention to the building envelope has paid major dividends for contractor Collaborative Structures Limited and the consultants who designed and built its new Cambridge headquarters.

The new 24,000-square-foot building became the first LEED-CS (Core and Shell) certified building in Canada.

“The office is a demonstration of environmental responsibility that offers significant operational savings, increased workplace productivity, and community sensitivity,” said Stephen Carpenter, president of the Waterloo Ontario-based Enermodal Engineering Limited, the LEED consultant.

Architectural design was by Tacoma Engineers Inc. of Guelph, while Collaborative Structures was its own design/build contractor.

LEED-CS is distinguished from LEED-NC by a number of factors.

Even though a LEED-CS building is an entirely new structure, the developer does not occupy the entire building and therefore cannot ensure LEED standards for the interior will be met by tenants in the leased space.

For LEED-CS (Core and Shell) certification, the core and shell of the building achieves LEED, but the whole interior may or may not.

While CSL will occupy 45 per cent of the building, the rest of the space will be rented out, said Carpenter.

However, because the building represents an opportunity for owner and tenants to work together on building fit-out and operations, CSL created a landlord-tenant agreement with guidelines that cover topics such as light pollution, low-toxicity building materials and cleaning products, recycling and construction waste management, he said. The certification was obtained through a variety of energy and water safety features and, in particular, using insulated concrete forms for the perimeter walls.

“We (Enermodal) are a big fan of ICF, it’s a real tremendous technology,” he said.

High insulation levels that can reach an R25 rating can be achieved with the use of insulated concrete forms.

That’s an important consideration for owners and designers pursuing LEED certification, which requires 25-per-cent energy savings over the Model National Energy Code, said Carpenter.

And constructing a building with insulated concrete forms is fairly straightforward.

Instead of a conventional wood concrete form, the polystyrene modular units are locked together somewhat like Lego blocks and concrete is poured into the cavity from the top.

In effect, the concrete wall is sandwiched between layers of insulation.

Not only are the materials and labour savings significant compared to erecting a traditional framed wall, but the result is a very airtight and highly insulated building.

“It’s very hard for air to blow through concrete,” he said.

Although insulated concrete forms don’t work well when there is a continuous band of windows such as all glass towers, it is becoming a popular material for the construction of apartment buildings in the Kitchener/Waterloo area, said Carpenter.

The effective building envelope on the CSL building, combined with its state-of-the art mechanical system, reduces energy consumption by 41 per cent annually.

This is in addition to the 56 per cent potable water savings from water conserving fixtures such as low flush fixtures.

Comprised of high efficiency gas heating/cooling rooftop units, an energy recovery system captures heat and humidity from exhaust air for pre-heating ventilation air during the winter.

In the summer the same system removes heat and humidity from in coming air before it is conditioned for indoor ventilation.

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