March 1, 2008
By John Souleles, Aaa
Sustainability as it relates to building design evolves as we undergo societal, economic, and political change. In particular, civic and public structures become a rather candid and raw reflection of ...
Sustainability as it relates to building design evolves as we undergo societal, economic, and political change. In particular, civic and public structures become a rather candid and raw reflection of the collective consciousness at the time of their design.
For officials in the town of Canmore in Alberta, the design of their civic centre in 2002 was a chance to integrate the majestic natural context of the town with a unique culture and quality of life. Situated about 120 kilometres west of Calgary against the backdrop of the Rocky Mountains, Canmore has evolved from a coal-mining town to an internationally recognized mountain resort community that espouses notions of health, sport and respite. It is this legacy that the town wanted to incorporate in the new Canmore Civic Centre. Green design was a natural extension of their philosophy.
The economic arguments for green design are well understood. They are applied through budgets, life-cycle analysis and asset management. The requirement for fiscal restraint and responsibility is pervasive, but more and more stakeholders have become advocates for increasing the front-end capital expenditure on buildings. Building owners and designers recognize the potential to reduce the cost of long-term operations with a reasonable return on investment. It’s not just about saving the world but it is about saving the budget as well.
The Canmore Civic Centre was designed with the above objectives in mind. By redeveloping a brownfield site near Main Street, the town was able to integrate existing parkland and a plaza to create a true town centre. The design of the two-storey, 2,500 square metre facility was started in 2002, with construction beginning in 2003.
Not without controversy, the town directed that the building be registered and certified for LEED (Leadership in Energy and Environmental Design), the green building rating system. In 2005 the centre became the first building in Alberta to be certified as LEED Silver.
Among the civic centre’s sustainable design features are its innovative massing to maximize solar access, a tempered interior street that serves as an atrium and cultural space, high efficiency boilers, and a diligent focus on materials, resources and indoor air quality. The integrated design team included Marshall Tittemore Architects with Stantec Consulting for mechanical-electrical engineering, and Cascade Engineering for structural engineering.
How does it perform?
As progressive as the town of Canmore was in embarking on a sustainable project in the heart of conservative Alberta, the town was also pragmatic. How the building actually performed was foremost in the minds of the administrators, whose purpose was to apply the model to other facilities within the town inventory.
Therefore, in April 2007, the town of Canmore in conjunction with Marshall Tittemore Architects and Stantec Consulting conducted an energy consumption study of the civic centre. The study’s purpose was to evaluate the building’s actual performance.
At the time of design and construction there was no budget for additional commissioning or supplementary metering. Consequently, the study was limited to the evaluation of gas and electrical billing from June 2004 to June 2006. The assessment compared the original projection according to NRCan’s Commercial Buildings Incentive Program (CBIP), with the actual numbers posted by two years of operation.
To find energy savings, the client and consultant team had targeted mechanical systems more than the electrical design of the complex. This approach was based on cost and priorities set out by the steering and consultant committee.
With a business-as-usual approach, the CBIP reference building anticipated a nominal consumption of 1,157,374 MJ of electricity and 2,583,674 MJ in gas. This consumption would have cost the town $52,800 per year for gas and electricity combined.
The CBIP design model had projected 1,052,695 MJ and 1,203,660 MJ of electrical and gas consumption respectively. While the CBIP model predicted a halving of the gas consumption, we anticipated the electrical design to be on par with the baseline building. Five of 10 points were achieved under the “Optimizing Energy Performance” category within LEED. The model anticipated a 39% decrease in combined energy consumption.
The real building performance used an average of 1,192,489 MJ and 1,532,410 MJ of electrical and gas consumption respectively. Although the electrical consumption has increased from the CBIP model, the value is well within the software’s margin of error and effectively matches the modeled value.
The actual gas consumption is also higher than the modeled number, by 328,750 MJ. It is, however, still well below (59%) the gas consumption in the reference building.
On a combined electricity/gas level, compared to the reference building, the civic centre has exhibited a 26% decrease in energy consumption over the first two years, based heavily on its gas consumption. With a 25% reduction in year one (2004-5), and 27% in year two (2005-6), the civic centre performance seems to be improving as the facility is managed and operated more efficiently.
Why the discrepancy between the design model and the reality? As with any predictions that involve complex variables, energy models are only as good as the assumptions. In our case, for example, the CBIP model excluded energy consumption incurred by exterior site lighting.
And, among other items, the model assumed an average winter temperature, a nominal electrical plug load, and a generic occupant load and hours of operation. All these variables affect the predictions and forecasts. Ultimately, building models are merely an approximate interpretation and representation of reality.
However, for the town of Canmore, the actual results are more tangible and profound. The civic centre has saved an average of 1,016,146 MJ of combined energy over two years. This figure roughly translates to a reduction of 25 tonnes of carbon dioxide emissions per year, and monetary savings of at least 25% annually in the purchase of gas and electricity.
High-efficiency boilers pay back
One of the more contentious, yet triumphant choices for expenditure in the project was the purchase of high efficiency condensing boilers. An initial life cycle analysis showed a 25-year payback for the equipment. In the two years of operation, with the boilers’ exemplary performance and low operating costs — even though energy costs outpaced the original assumption — the payback period has been drastically reduced to 12 years. It is expected that associated monetary savings over the life of the boilers will be in excess of $100,000.
Finally, the most important metric of a successful sustainable design lies with the users and operators of the facility. The building operators attest that the civic centre functions with ease and not at the expense of human comfort. Additionally, in a social environment that is fraught with a high cost of living and a cyclical resort-town economy, Canmore has had difficulties in the past with staff retention and satisfaction. Administrators have noted a marked positive change in the spirits and outlook of staff. The staff are proud of their facility, which means the Canmore Civic Centre attracts and keeps talented employees.
With LEED-certified Silver becoming the minimum building standard of many municipalities in Canada, the bar is being raised continually for more innovative, more ambitious projects. It is our hope that buildings will continue to evolve with more ecologically friendly designs.
John Souleles, AAA, MRAIC, is an architect with Marshall Tittemore Architects of Calgary.