October 24, 2008

B.C. Building Envelope Council

Expert offers tactics for designing carbon-neutral buildings

Brian Martin

correspondent

The design professions are facing a pretty stiff challenge to meet government targets for carbon neutral buildings, according to Stephen Pope.

Pope is a sustainable building design specialist with National Resources Canada.

He spoke recently to the annual convention of the B.C. Building Envelope Council held in Vancouver.

The aim is to create buildings that by 2030 emit no greenhouse gases, otherwise known as carbon neutral.

To meet the target, the fossil fuel use must be reduced by 60 per cent in 2010 and be reduced by 10 per cent every five years.

By 2030 the carbon neutral standard kicks in and will apply to new construction and major renovations.

Pope said that the targets will be achieved through a combination of conservation, on-site renewable generation, offsets and/or purchasing renewable energy (up to 20 per cent).

He outlined a series of design tactics for conservation including: controlling the window to wall ratio; reducing lighting requirements and using daylight dimming controls; improving window performance by using the highest U-value affordable; separating ventilation air supply from heating and cooling; using heat recovery on exhaust or relief air; using demand controlled ventilation; installing condensing space heating boilers; increasing wall and roof insulation.

He also said it may be necessary to concentrate occupancy and suggested it may have to double.

Of all the subjects he addressed, Pope said that the window to wall ratio is the single most important building envelope issue.

“Energy efficiency and carbon emission reductions are a design issue more than a technology issue,” he said.

“Building location and transportation factors cannot be ignored.”

He also noted that the 2015 performance target is technically feasible now with off-the-shelf technology.

Later in the day, the group heard from Mark Blamey, a managing partner with Cobalt Engineering in Vancouver.

Blamey emphasized the need to bring all the players to the table from the very beginning and to employ an integrated design process.

“It might not be an approach you’d expect from a building systems design firm, but it’s one that you’ll grow to value,” states the company website.

“With our creative input at the start of a project we can help to develop fresh ways to satisfy the needs of clients and occupants, enhance environmental sustainability and keep a tight reign on budgets and timelines.”

Blamey expanded on the theme during his address to the building envelope delegates.

There are many ways both mechanical and electrical systems can impact the design of a building – and many ways the design impacts the mechanical and electrical systems, he said.

It reinforces the need for all parties to work together from the start.

In preparing a preliminary building concept, he said, there is an array of items to be considered including window and wall treatment to limit heat gain, heat loss, lighting and power systems.

Daylight renewable systems and alternative energy should be priorities.

He said it is also important to consider the location of the building and be aware of micro climates.

His firm will often do a micro climate analysis because Environment Canada is often too general.

They will set up their own weather station on the site where a building is being planned.

He noted that it is possible for a properly designed building to function for much of the year without any mechanical cooling or heating.

He used the Hesquiaht School on Vancouver Island as an example.

The design incorporated the prevailing winds and there is almost no need for heating or cooling.

Blamey maintained that low tech solutions can play an important role.

“If there is a single thing you can do to minimize your mechanical requirements, it is window shading,” he said.

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