Note: See the digital edition, page 54, to see the table included in this article: Current Climate Design Parameters and Consolidated Opinion and Collective Prediction of Change. Table compiled by GRG Building Consultants.
Building design has traditionally relied to a considerable extent on accumulated historic climate data to provide design criteria for building components, such as the structure, cladding, windows, site drainage and HVAC systems.
There are indications, however, that our climate may be beginning to change. Putting aside the question about what may be the cause, if our climate is indeed changing as many experts believe, this historic data may no longer best serve us for designing buildings to have a long service life.
Over the next 40 years, if buildings do experience different environmental loads (temperature, relative humidity, rainfall, snowfall, wind pressures, and UV radiation), these changes could have a significant impact on our building stock.
Engineers Canada and its Public Infrastructure Engineering Vulnerability Committee (PIEVC] have developed several models for studying the potential effects of climate change on buildings and infrastructure.
The PIEVC committee has been overseeing the execution of climate change vulnerability assessments on four key asset categories. In addition to looking at public and multi-unit residential buildings, PIEVC is assessing transportation assets, storm/waste water treatment/collection and water resource systems (www.pievc.ca).
Following is a summary of the five-step protocol used to assess the effects of climate change on buildings and the risks to their components.
PIEVC Climate Change Assessment Protocol
The assessment protocol established by PIEVC includes a rigorous review of climatic parameters that are expected to change over the next 40 years, along with assessments of the impact these changes may have on buildings.
The protocol steps include determining the most important building components, identifying the climate change parameters and values, the probability of occurrence (extreme or otherwise), and a risk assessment. In most cases, recommendations on specific building systems as well as on their operations and maintenance can then be derived.
As applied to a sample building selected from the residential high-rise stock in downtown Toronto, the process proceeded as follows:
Step 1 | Project Definition. This step developed a description of the building, including location, age, infrastructure details, historical climate loads, and other relevant factors. It also included developing a component inventory, a time horizon (40-50 years), relevant climate parameters, and a baseline and determination of the cumulative effects of climate change.
Step 2 | Data Collection. This step identified which building components were to be assessed and climate factors to be considered. The climate projection information was derived from a variety of sources, including the Canadian Climate Change Scenarios web site and peer-reviewed studies applicable to Ontario cities. See www.cccsn.ca
Components were sorted by major building systems and then into sub-systems grouped under the following headings: site, structure, building envelope, HVAC, plumbing and drainage, electrical, vertical transportation, life safety and finishes.
Step 3 | Risk Assessment. This step involved identifying how vulnerable building components may be and the consequence on a particular building component based on specific aspects of climate change. A key aspect was the input from a facilitated focus group, including designers, owners, property managers, insurers of property, building repair and maintenance people, and climate change specialists.
Step 4 | Engineering Analysis. Some risk assessments may require an analysis of various climate impact scenarios to determine the level of vulnerability. The sample study identified gaps in assessment protocols and made recommendations.
Step 5 | Recommendations and Conclusions. Based on the results of Steps 1 to 4, the Step 5 recommendations included: action to upgrade the infrastructure; management action to accommodate changes to building capacity; performance monitoring; and recommendations for additional research and analysis.
Components at risk
After completing Steps 1 to 4, a preliminary analysis suggested that the components of the building that were considered at “medium risk” to climate change included:
• the building envelope, particularly with respect to moisture management and heat/cooling losses.
• the mechanical drainage systems, at risk of inducing flooding.
• the emergency electrical supply systems associated with capacity to deal with power outages.
• the grounds and site, deemed to be at risk. However these are addressed by other PIEVC studies.
Reports and presentations from case studies using the PIEVC protocol are available for download at www.pievc.cacce
Gerald R. Genge, P.Eng., is principal of GRG Building Consultants of Toronto and Newmarket. He is a past president of the Ontario Building Envelope Council. www.grgbuilding.com. Brian Burton is with Award Bid Management Services, specializing in technical business writing. http://award-bid-management-services.com