Designing buildings for climate change

by Katie Daniel | July 7, 2015 10:30 am

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By Gerald R. Genge, P.Eng., and Brian Burton
Canada’s building codes have historically been formulated, at least in part, based on accumulated historic climate data that ultimately provides the essential criteria for most key building component performance characteristics. However, there are indications climate may be beginning to change. If buildings do, in fact, experience different environmental conditions over the next 40 years, these changes could potentially have a significant impact on our building stock.

Some experts also believe this apparent warming trend may have the potential to destabilize weather patterns, possibly increasing both the frequency and intensity of severe weather-related events. As a result, this accumulated historic climate data may no longer best serve us in providing the criteria for designing buildings that will have an extended service life.

This ongoing debate calls into question whether the Canadian construction and codes communities should continue to use historic data for designing buildings that are expected to provide an effective service life of 30, 40, or 50 years or more, without examining the issue closely.

In response to the perceived risk, the Public Infrastructure Engineering Vulnerability Committee, (PIEVC), established by Engineers Canada has been directing the completion of climate change vulnerability assessments on four key asset categories. (In addition to buildings, the committee has also been overseeing the formal assessment of transportation assets, storm/waste water treatment/collection and water resource systems.)

The PIEVC website details its purpose, objectives, and vision, while also providing a valuable glossary of terms and definitions, as well as a definition of climate change and detailed fact sheets.

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Climate change assessment protocols
The assessment protocols for buildings established by PIEVC includes a rigorous review of climatic parameters expected to change over the next 40 years, along with assessments of the impact these changes may have on buildings and other assets as mentioned. The assessment protocols include:

• determining the identity of what are the most important building components;
• identifying the climatic parameters and values;
• the probability of occurrence (whether 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 formulated. The process typically proceeds as follows.

Step 1: Project definition
This step involves preparing a detailed description of the building, including location, infrastructure details, historical climate loads, age, and other relevant factors. This initial step also includes developing a component inventory, a time horizon (e.g. 40 to 50 years), relevant climate parameters and baseline, and determination of the cumulative effects of climate change.

Step 2: Data collection
This second step identifies the building components to be assessed and the climate factors to be considered. The climate projection information is derived from various sources, including the Canadian climate change scenarios website[3] and peer-reviewed studies applicable to Ontario cities.

Components are 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; and
• life safety elements and finishes.

Step 3: Risk assessment
This third step involves 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 of this step typically includes input from facilitated focus groups including designers, property managers, insurers of property, owners, and building repair and maintenance professionals and climate change specialists.

Step 4: Engineering analysis
Some risk assessments may require analysis of various climate impact scenarios to determine the level of vulnerability. Sample studies identify gaps in assessment protocols and make recommendations.

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Step 5: Recommendations and conclusions
Based on the results of the first four steps, recommendations may include:

• action to upgrade the infrastructure;
• management action to accommodate changes to building capacity;
• performance monitoring; and
• recommendations for any additional research and analysis.

GRG Building Consultants conducted one such study[5] on an existing building in Toronto. It was the focus of this case study assessment was one of close to 2000 high-rise residential towers in the Greater Toronto Area (GTA) region, which were constructed when Ontario experienced a sustained building boom that corresponded to rapid urbanization in the 1960s and extended into the ’70s.

Aside from determining the important building components that may be at risk of significant impact due to climate change, the protocol specifically identifies environmental load parameters and values, the probability of occurrence, and the potential changes to those loads. After a thorough digestion of numerous studies by climatologists around the globe, recommendations on design parameters, as well as specific building systems could be summarized.

Components at risk
Analysis suggested building components considered at ‘medium risk’ to climate change included:

• building envelope, particularly with respect to moisture management and heat/cooling losses;
• mechanical drainage systems at risk of inducing flooding; and
• emergency electrical supply systems associated with capacity to deal with power outages.

Grounds and site were also deemed to be at risk, but these elements were addressed specifically by other PIEVC studies.

Environmental loads that could change
Figure 1 is a summary of the current environmental loads based on historic data and the anticipated change to these loads based on the ensemble projections from numerous climatologists that are referenced in the complete study. The data is summarized into three primary environmental loads: temperature, precipitation, and wind. While these predictions are based on climate models and remain to be proven, prudent designers may wish to consider the best available information when designing buildings that are to remain serviceable into the middle of the 21^st century.

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It is noteworthy that while average temperature is predicted to increase by only a few degrees in winter and in summer conditions, designers should consider the impact of those conditions on for example, heating and cooling loads both in the present and in the future.

For instance, while climate in 2050 is expected to place a lighter heating load on the building, those same systems will be in use in the years prior and should also be expected to accommodate the loads experienced in those prior years. Similarly, cooling load is expected to increase by approximately 70 per cent, but it may not be efficient to include capacity for 2050 loads in buildings constructed in the next few years. As a result, designers may wish to consider building adaptability into HVAC systems.

Taking precipitation into account, there may be a greater number of wet days, but also more consecutive dry days. Irrigation and greywater systems relying on rain may be flooded at times and dry at others. Stormwater collection and dispersion system design may also need modification to deal with the anticipated increase in extreme rain.

Periods of highest wind gust load is also expected to increase nearly doubling the occurrence of 90-km/h (56-mph) and greater winds. Wind-driven rain is likely increasing as well.

Potential impact and risks of climate change
Given the size, value, and importance of Canada’s building stock and infrastructure, it is important the issue of climate change be monitored, and the efforts of Engineers Canada and its Public Infrastructure Engineering Vulnerability Committee be maintained.

It is also apparent funding, research, and general attention to the topic must be increased, particularly in respect to adaptation of design and construction codes and standards, to develop a more forward-looking paradigm.

Overall, while the risks to the built environment appear to be increasing, the probable impact of climate change on a broader scale will doubtless move beyond what was once considered an environmental concern to include long-term political and financial issues that could eventually impact energy production, agriculture, industry, transportation, and other primary industries.

In the building sector, some professionals are suggesting these changes will also challenge architects, engineers, technologists, building scientists, and other building professionals with regard to the development of remedial procedures to upgrade the Canada’s substantial portfolio of existing buildings.

In many ways, adopting a proactive approach to the potential impact of climate change also represents an opportunity for building professionals to take a leadership role in advancing design and construction codes and standards as well as adopting a forward-looking, building adaptability, approach.

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Summary of potential impact and risks
There is concern regarding the increasing health and safety risks for occupants caused by a reduction in the overall quality and ability to maintain effective control of the indoor environment. There are also some fears related to the risk of premature or accelerated deterioration, and the reduction of design safety margins.

Reduced service life and functionality of components and systems may be a consideration. Increased risk for catastrophic failure may also represent a risk factor.

Costs for repair, maintenance, reserve fund contingencies, and energy may increase in the long term. There may also be an increase in service disruptions and emergencies, along with liability as a result of premature ageing or deterioration.

Looking ahead
Designing buildings to anticipated future loads is not a current building code requirement; but perhaps it should be. Clearly, there is work to be done to better understand how we need to prepare our buildings for the changes ahead. Regulations will doubtless wish to address the issue somehow in the next 10 or 15 years; in all likelihood, there will be pushback or resistance from groups that do not acknowledge that we should be looking ahead rather than in the rear-view mirror when designing buildings.

Obviously, Canada invests significant resources and capital in buildings and infrastructure. Practitioners in this country have proven to be innovative in adapting domestic buildings to the severe climate. Hopefully, they will be equally competent in addressing the code issues relating to climate change.

Further Considerations for Concrete and Masonry

Climate change on concrete and masonry structures over the next 30 to 50 years will increase the durability needs for those buildings—particularly in relation to freeze-thaw and wetting and drying response. This means masonry buildings constructed in the last 30 years or so that were not subject to current durability standards may be more susceptible to damage due to increased cycling of freezing and thawing. The additional stress placed on the exterior façade of older buildings using masonry may make them good candidates for over-cladding with additional insulation and a durable exterior finish. This is also in keeping with the need to be more concerned about energy use and buildings and as such as a collateral benefit. Additionally, concrete exposed to freezing and thawing will also receive increased cycles and increases opportunity for deterioration. This would involve exposed concrete curbs, sidewalks, and pavements, along with structural building components subjected to wetting and freeze-thaw cycles. With increased intensity of rainfall, the wind pressures on the building envelope are also expected to increase. For instance, window systems that would have been acceptable for high-rise buildings may require greater water penetration resistance. This is not to say Canadian designers have to learn new design procedures—rather, it means architects, engineers, and contractors must adapt current procedures to different exposure conditions. While some design standards may change, it is anticipated knowledge about new exposure conditions will also evolve. Of course, becoming better informed for the future also involves having the political will to invest in the requisite knowledge base.

 

[9]Gerald R. Genge, P.Eng., is a principal of GRG Building Consultants of Toronto and Newmarket, Ont. He has directed more than 3000 investigations of building performance problems and completed over 2000 design and construction review assignments. Genge is a past-president of the Ontario Building Envelope Council (OBEC), and chaired the 2014 Canadian Conference on Building Science and Technology (CCBST). He can be reached at jgenge@grgbuilding.com[10].

[11]Brian Burton served on the committee that prepared the Canadian Standards Association’s (CSA’s) Certification Program for Fenestration Installation Technicians, which ensures the skills and abilities of individuals who install fenestration components in buildings. He is also involved with Award Bid Management Services, a firm specializing in technical business writing. Burton can be contacted via e-mail at brianburton1995@gmail.com[12].

Source URL: https://www.constructioncanada.net/designing-buildings-for-climate-change/

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