Reducing the urban heat island effect

Urban heat islands can be described as urban areas that are hotter than surrounding, more rural areas. The urban heat island effect is what happens as a combination of increasing temperatures due to climate change and the growth of sprawling urban areas. Our cities comprise of buildings, roads and parking lots that are generally dark in their appearance and they therefore take in the sun’s radiation and emit it back out, heating up both surface and air temperatures. What results is an increase in the intensity and frequency of heat waves.


This raises big concerns as urban heat islands pose significant threats to human health and particularly those that are most vulnerable to prolonged heat exposure. This is in no way a new phenomenon; deaths resulting from extreme heat events in Canada were recorded in BC in 2009 and Quebec in 2010 and 2018 to name just two and by 2050, the number of dangerously hot days in parts of Canada is predicted to double.


Mitigating the impact of urban developments


Climate sensitive planning, design and development of our urban areas is fundamental to minimize the urban heat island effect. Ironically, many of the initiatives that guard against extreme temperatures are those natural things that were lost with development - water, greenery and trees. So how can buildings be adapted to work hand-in-hand with planning measures and offset their impact?


  • Minimize waste heat emissions through improved use of insulation, smart technology and energy efficient appliances. Insulation can be incorporated in all elements of the envelope of a building including the floor, roof and wall and this helps to retain energy inside of the building. Smart buildings not only help to appeal to the needs of prospective tenants, they use lighting and sensor technology to automate routine processes that would normally be open to human error or omission resulting in unnecessary energy usage.

  • Using reflective materials and surfaces to the exterior of properties which reflect heat rather than absorb it and light-colored, reflective pavements are all choices which can reduce the heat a building generates. A ‘cool roof’ is a well-known option for a reflective surface and although they’re often white in color, they are now available in a variety of colors and materials.Reducing the temperature of a building ultimately reduces air con usage and makes for more comfortable conditions for occupants.

  • Although the upfront cost will be more than a traditional roof, green roofs are much more durable and can be expected to last for 50 years when installed correctly. A green roof not only offers direct and ambient cooling effects, it helps to reduce heat island effects by absorbing pollutants and on average, it pays for itself within a couple of years.

  • Integrating naturally-inspired design choices such as trees, water features and greenery into the landscaping can reduce surface and air temperatures and ensure moisture is put back into the air. According to ecoRI, trees are particularly effective at reducing surface temperature, sometimes up to a massive 35℉ and air temperatures by 2-9℉.

  • Ensure designs incorporate adequate ventilation corridors, allowing air to move freely between buildings, rooms and communal spaces. This allows the inside air temperature of a building to cool down in the evenings when the temperature drops rather than the hot daytime air remaining trapped. Some structures are naturally cooling to other parts of the same building; an atrium or courtyard for example has an internal shaded area providing a cooling effect to the rooms and pedestrian areas surrounding it and induces airflow.


In existing buildings, thermal imaging systems can be used by facility owners and managers to identify energy losses and address them retrospectively to take advantage of cost-savings.


What are the industry benefits of heat resilient development?


At all stages of a project, from development to completion and also operationally, cost-savings and profits may be gleaned in many areas;




Reducing UHI effect requires widespread adoption


A comprehensive report by the ‘Urban Land Institute’ stated that without widespread adoption of mitigation strategies by the real estate industry, temperatures in cities could grow by 5-10℉ as opposed to a much more manageable 1-2. It’s difficult to be indifferent with that sort of statistic.


Now that the world seems to be coming to some sort of unity on addressing the effects of climate change, the real estate industry will likely see more mandates rather than recommendations around urban planning as governments attempt to reduce the urban heat island effect for the greater good. Regulatory measures in the future could enforce the retro-fit of heat-mitigation measures to both buildings and landscapes which could prove more costly. Initiatives such as the Seattle Green Factor (SGF), where the development has to meet a certain score by choosing from a menu of ‘green’ landscaping options, will no doubt become more commonplace.


Regardless of any initiatives mandated for new developments, without real estate addressing the issue of extreme heat in our cities as part of their customary processes, many of the implications of climate change could impact the net present value (NPV) of new projects and deem them unviable. It’s in the industry’s best interests to seek out strategies to mitigate heat-related risks and assess how they can future-proof their portfolios and projects against future risks.


LandSec, one of the biggest developers in the UK are already taking the initiative and have assessed the possible effects of climate change on their entire portfolio for two time periods up to the year 2100. Their approach is to protect customers and properties from the impacts of climate change by building resilience now rather than risking future failure.


For developments that recognize the importance of reducing urban heat island effect, the payoff comes by way of long-term competitive advantage and financial success - it’s simply a case of who is going to take the baton.


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