Heat island

Urban Heat Island Mitigation Strategies: 2021 Update

  • This literature review covers measures to mitigate urban heat islands that decision-makers and public and private property managers, municipal stakeholders, non-profit organizations, and other project designers can implement in Québec to ensure healthy, comfortable living environments.
  • Urban spread, the loss of crown cover, soil sealing, the use of heat-retaining materials, heat and greenhouse gas emissions stemming from human activities, and urban morphology with dense neighbourhoods and narrow streets are causal factors in urban heat islands. Rising temperatures and more frequent heat waves against a backdrop of climate change are likely to exacerbate their impact.
  • Urban heat islands can have detrimental environmental impacts such as the deterioration of air quality and adversely affect human health and well-being. Certain factors for increased vulnerability to heat such as age and chronic diseases warrant paying particular attention to certain populatio…

Greening cities for public health

  • Greening is taking place in cities, primarily to adapt to climate change and its effects, like heat islands. This literature review describes the impacts of green spaces on health. Some observations are also put forward for optimal green space use and design.
  • Green spaces are beneficial for physical health, particularly because they provide opportunities for physical activity. Green spaces might also have positive effects for reducing numbers of obese and overweight people, linked to morbidity. Lastly, neighbourhood green spaces reduce the mortality associated with certain diseases.
  • Green spaces also provide benefits for mental health, such as reducing symptoms of depression and reducing stress. They can have positive effects on mental well-being, feeling of recovery, good humour and vitality.
  • For seniors, these green spaces are a better place for walking and reduce the risks of chronic health problems.
  • For children, they have a positiv…

Life cycle assessment of the environmental impacts resulting from the implementation of urban heat island mitigation measures

The Institut national de santé public du Québec (INSPQ) decided to draw on the expertise of the CIRAIG to conduct a life cycle assessment (LCA) of ten urban heat island mitigation (UHI) measures applicable to the residential sector. The goal was not to compare or evaluate the effectiveness of these measures, but rather to assess the other potential environmental impacts that result from their implementation and maintenance during a specified period. The options were therefore analyzed on an individual basis (implementation of a particular measure), without taking into account their temperature reduction potential.

This assessment was intended to:

  • Make it possible to individually compare the UHI mitigation measures applicable to the residential sector with a baseline situation, which corresponds to the status quo (i.e. taking no action).
  • Permit, if possible, a ranking of certain comparable measures according to their potential overall environme…

Urban Heat Island Mitigation Strategies

According to the Intergovernmental Panel on Climate Change (IPCC), eleven of the hottest twelve years ever observed were recorded since 1995 and are attributable to rising levels of greenhouse gases in the atmosphere. North American cities “that currently experience heat waves are expected to be further challenged by an increased number, intensity and duration of heat waves”.

In Québec, the hottest ten years of the century have been recorded since the 1980s (Natural Resources Canada, 2004). Forecasts indicate that average temperatures will continue to rise in the coming decades.

This observed and forecast constant increase in temperature will accentuate a problem with which we are already familiar: the urban heat island effect. This phenomenon is characterized by higher summer temperatures in urban environments than in surrounding rural areas. According to observations, this temperature difference, which is primarily attributable to the urban built environment, range…