LEED certification ensures building envelope durability

Durability is becoming an increasingly more important element in building envelope construction today as the green trend, especially LEED, deepens.

“We are being asked to work on that framework, which we like, because we are really looking at long-term solutions,” said Douglas Watts, an architect and engineer in the building sciences division of Read Jones Christoffersen.

“What we are seeing, on the buildings where there is a LEED status requirement for durability, is that the developers are choosing to buy better materials up front.”

Durability — ensuring the longer life of a structure — has often been a design issue with architects and engineers in an industry where developers want to build at the lowest cost, and owners often look to redevelop in a 25-year cycle.

But as more buildings are looking for the LEED certification, developers are being faced with the issue of durability.

In Canada, projects can receive a durable building credit which accounts for one in a possible 70 credits, with accredited projects only requiring 26.

The LEED Durable Building Credit MR8 references the Canadian Standard Association (CSA) standard S478-95 – Guideline on Durability in Buildings.

It requires the expected service life of components to equal or exceed the design service life of the building.

“Better quality material selection is extending the building’s life which, in turn, is really reshaping perspectives on building,” said Watt.

The durability issue is impacting all areas of the building envelope, such as masonry, cladding and glazing systems.

“For example, if it’s a marine environment, rather than opt for coated fasteners, we are seeing clients going for stainless steel,” he said, adding that there is more focus now on providing structures that will last 100 years and a cladding that will last 50 years.

The end result is a doubling of the life span of the building structure and envelope.

The LEED standard is really a slam dunk for contractors, Watts said, adding that initially there is resistance to this new method of looking at construction.

However, after the first experience, contractors see how clean their site is and how material allocations and waste disposal can simplify the workplace.

“They say, ‘We will do it again, doesn’t matter whether it is LEED or not’,” he said.

One of the impacts of building more durable is that there is less waste going to the landfill for renovations or demolitions.

“The figures are something like 60 per cent of the waste stream is related to construction activity,” Watts said.

“There is no question that it (the green movement) has had a dramatic effect,” agreed Don Brown, architect, with Jensen Architects in Victoria, B.C. The architect designing the building envelope is now called in earlier as part of the integrated design process, which includes all members of the design team that will impact the building’s design and environment.

This process knits together design team members both from the interior and exterior of the building and ensures that the objectives of the owners are met.

“This is now happening at a much earlier stage,” said Brown, adding that it would eventually happen downstream.

But, when the internal components are met, they have to be expressed in the technical exterior requirements.

“The question may be whether the curtain wall is the most suitable for a building with that orientation and in the climate,” he explained.

Brown said the largest change when designing building envelopes has come from the building owner, who are now more open to pursuing durability as a design goal.

“They are coming to the table with their own demands and how green they want the building to be,” he said, adding that building owners now recognize the market potential of marketing a green, if not LEED, structure.

Iredale Group of Architect’s Graham Coleman agrees there is a shift in attitude.

“Sustainability is becoming embedded in the building envelope community,” he said, adding that when a building envelope remediation is occurring, the clients are now using that as an opportunity to examine the environmental performance of the building.

For example, he said, if the roof and wall is upgraded to be thermal resistant, the client becomes more open to using other products that add to that such as window systems, alternative insulation, and low-VOC caulking.