June 17, 2009

The Aldo Leopold Legacy Center in Wisconsin is just one of the eight documented institutional or commercial carbon-neutral buildings in the U.S.

Green Building

Carbon-neutral design requires new approach

PATRICIA WILLIAMS

staff writer

The leap to carbon-neutral design requires a shift in mindset on the part of design professionals, says Terri Meyer Boake, associate director of the school of architecture at the University of Waterloo.

“Designing to zero-carbon standards requires a modified approach to current sustainable and high-performance design methods,” said Boake, also president of the Society of Building Science Educators.

Speaking at the Ontario Association of Architects’ (OAA) recent annual conference, Boake said green, sustainable and high-performance buildings are not going far enough, quickly enough in reducing their negative impact on the environment.

The Architecture 2030 organization has urged that all new buildings be carbon-neutral by 2030, using no fossil-fuel, greenhouse gas-emitting energy to operate.

The OAA has endorsed the 2030 challenge.

While sustainable design is a holistic way of designing buildings to minimize their environmental impact, Boake said carbon neutrality focuses on the relationship between all aspects of building and carbon dioxide emissions.

A carbon-neutral building derives 100-per-cent of its energy from non fossil-fuel-based renewable energy sources.

At the moment, there are only eight documented institutional or commercial carbon-neutral buildings in the United States, Boake said.

One example is the Aldo Leopold Legacy Center in Baraboo, Wis.

The 11,900-square-foot centre is a carbon-neutral, net-zero energy building.

Boake, who teaches environmental design courses at Waterloo and is a member of the OAA’s committee for a sustainable built environment, said a sustainable building does not equate a carbon-neutral one.

She said four key strategies are required to design to a state of carbon neutrality.

• Reduce energy loads/demand first through such measures as conservation, passive heating and cooling strategies, daylighting, shading and building orientation.

• Meet loads efficiently and effectively through energy-efficient lighting, high-efficiency MEP (mechanical, electrical and plumbing) equipment and controls.

• Use renewable sources such as photovoltaics, solar hot water systems and wind energy, to meet energy needs.

• Use purchased offsets only as a last resort when all other means have been looked at on site or where the scope of building exceeds the site-available resources.

“As the way that buildings interact with carbon is highly complex, the first aim is to reduce operating energy as it is the most significant (factor) and easiest to control,” Boake said.

The leap to zero carbon design has implications on a number of fronts, in addition to incorporation of measures to reduce energy requirements.

Increased attention must be paid to building orientation, siting and site treatment, both during and after construction.

Choice of materials also comes into play, Boake said.

The scope of acceptable materials is narrower.

Materials can help reduce a building’s carbon footprint.

“Wood from certified renewable sources, wood harvested from your property or wood salvaged from demolition and saved from the landfill can often be considered net carbon sinks,” she said.

Planting new trees can help compensate for the carbon released during the transport of essential materials, while incorporating green roofs and living walls can assist in carbon sequestration. By the same token, Boake said, reuse of a building, part of a building or its elements reduces the carbon impact by avoiding using new materials.

Design for disassembly and eventual reuse will offset future carbon use.

Designing to zero-carbon standards imposes a greater need for an integrated design process and co-ordination with consultants from the very outset of a project.

“Carbon neutral cannot be done without the highest level of early and continued co-operation amongst the client, architect and engineers,” Boake said.

The Society of Building Educators has set up a website dedicated to explaining carbon-neutral design, examining building case studies and exploring carbon calculation tools and software.

The initiative is being funded by the American Institute of Architects.

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