November 18, 2009

Building envelope commissioning lagging in Ontario

Vancouver building code already requires it

DON PROCTER

correspondent

Building envelope commissioning has been around for decades in Canada, but ask any two builders what it is and you are likely to hear two very different answers.

In an ideal situation a building envelope consultant has input from the design stage of a building right through to its construction.

The goal is to achieve optimum environmental separation.

“Wall cladding systems are complex and a consultant should be brought on early in the design stage to review and provide comments on items such as the compatibility of materials, the continuity of the air/vapour barrier, drainage and material-component interface details,” said Ted Katsoris, manager and associate of the building and facilities division of Morrison Hershfield Limited’s Toronto office.

The problem is that building envelopment specialists often aren’t retained until the construction stage.

However, by this time it may be too late for the consultant to correct errors in the envelope design. It doesn’t mean changes can’t be made, added Katsoris, but the changes can be costly and result in project delays.

Morrison Hershfield Katsoris has been involved in several projects, reviewing wall cladding and design details, followed by random field reviews to ensure the envelope conforms to the design and contract documents.

One current project involves the review of the cladding and roofing details of a new church.

“The wall design and details are intricate and quite complex,” the consultant pointed out.

“The project is in the initial stages, which is beneficial to all parties, as any potential problems can be sorted out before they become costly, either during construction or once the facility is in use four or five years after occupancy, where repairs can be very expensive.”

While envelope commissioning is not new in Canada, it is hardly common in Toronto, Ontario or most other provinces and cities.

Things are different in Vancouver.

That city’s building code requires building envelope professionals to review the design and inspect construction of multi-residential frame structures.

Furthermore, third party warranty coverage on building envelopes is mandatory, said Mark Lawton, senior building science specialist out of Morrison Hershfield Limited’s office in Vancouver.

In Toronto it is project specific and in many cases client driven, pointed out Katsoris.

Laverne Dalgleish, principal of Winnipeg-based Building Professionals, said he thinks envelope commissioning requires a single definition and the provinces should get involved in its enforcement through legislation.

That definition should stipulate that consultants be retained early on in the design process because the time to change a mistake is at the design stage, not once a building is under construction, he said.

Kevin Day of Toronto-based Halsall Associates Limited, said that although it is best to retain a building science expert during the design, once a building is under construction there are things an expert can do.

For example, he said, testing walls/windows/roofing, thermographic scanning and installing a monitoring system in key areas of the envelope where performance is critical.

Once a building is completed a consultant might be retained to make quarterly visits to measure localized temperatures of the building assembly and identify condensation if thermal bridges are an issue.

Day pointed to an example where Halsall designed a dual-barrier roofing system for the Credit Valley Hospital in Mississauga.

By monitoring the thermal efficiency of the membrane, the consultant demonstrated that keeping the insulation dry in a protected membrane roof was more thermally efficient than a conventional protected membrane system.

Both Day and Dalgleish agreed that envelope commissioning is not widespread for any type of buildings in Toronto or many parts of Canada outside B.C.

“There are design/architectural firms commissioning it in all of their designs, but I don’t think we can say that Toronto or elsewhere is doing it in all their buildings or curtainwall buildings,” explained Day.

He said he doesn’t see any significant change in the near future unless envelope commissioning becomes a popular LEED point for new building construction.

The Canada Green Building Council (CaGBC) has indicated it may add a LEED point.

While envelope commissioning is a relatively new concept to the U.S., Lawton said Canada’s uniformly cold climate is why building scientists started first looking into it 20 or so years ago.

Envelope (sometimes referred to as enclosure) commissioning evolved out of the late 1980s and early 1990s.

It evolved partly as a result of moisture-related problems developing in buildings that had been heavily insulated during the 1970s energy crisis.

Back then, Public Works Canada was one of the chief drivers of the movement because it needed to control the humidity in its buildings.

Experts realized that if air flow wasn’t controlled through a heavily insulated building, the resulting moisture build-up would cause problems.

At the time, the industry learned that the key to an envelope’s success was to be able to validate the performance during the design and construction stages of a project.

Waiting for the building to be completed would be too late.

Lawton said that while some proponents of envelope commissioning — particularly in the United States— market it as a means of improving the energy efficiency of a building, it is not its prime objective.

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