COOLING THE CITY - THE BATTLE AGAINST URBAN HEAT
BY JUSTIN HAUAD & MARC COTE
Cities are heating up at an unprecedented rate. As urban areas expand, dense infrastructure and heat-retaining materials are amplifying temperatures, making public spaces less inviting and, in extreme cases, uninhabitable. The Urban Heat Island (UHI) effect is forcing cities to rethink how they design outdoor environments.
For Landscape Architects, this presents both a challenge and an opportunity. It is a chance to transform urban spaces into climate-responsive landscapes that prioritize cooling, comfort, and sustainability. In regions like Toronto (our home city), and Singapore, where we’ve recently opened an office, city policies are now pushing for integrated cooling strategies in urban design. Landscape Architects are at the forefront of this shift.
How can water features contribute to this movement? And what role do design, technology, and policy play in shaping cooler cities? Let’s explore.
A. UNDERSTANDING URBAN HEATING
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WHY URBAN COOLING CAN'T BE IGNORED
The Urban Heat Island (UHI) effect is making cities 4°C to 7°C hotter than their surroundings as hardscape materials trap heat (BMJ, 2022). By 2050, global cooling demand is projected to surge by 300%, increasing carbon emissions and energy dependence (The Economic Times, 2018).
As temperatures rise, public spaces are emptying out. A Harvard study found that excessive heat reduces pedestrian activity, changing outdoor behavior and cutting engagement with public areas (Harvard, 2022). In Germany, a survey of 2,253 residents after the 2022 summer heatwave showed fewer than 20% visited green spaces on hot days, despite their cooling potential (GHHiN, 2023).
Urban heat mitigation is no longer an afterthought; it is an essential design priority shaping the future of cities. Water features can be a critical tool in this effort, not just for their visual appeal but for their ability to actively lower temperatures and enhance public well-being.
HOW CITIES ARE RESPONDING - POLICIES DRIVE CHANGE
Governments worldwide are embedding urban cooling into policy, recognizing the urgency of mitigating rising temperatures in public spaces. In Toronto, the Toronto Green Standard (TGS) mandates Landscape Architects to incorporate sustainable site design. This mandate requires increased tree canopy coverage, reflective paving, and promotion of various shade strategies to combat urban heat (City of Toronto, 2022). The city is also expanding cool pavement initiatives, lowering surface temperatures in high-traffic public pedestrian zones.
Internationally, policies are being implemented as well. In Singapore, policies like the Landscape Replacement Policy ensure that lost green space is compensated through rooftop gardens, vertical greenery, and climate-adaptive infrastructure. The Landscaping for Urban Spaces and High-Rises (LUSH) program promotes water-integrated cooling strategies, seen in developments like Gardens by the Bay, where misting systems and shaded reflecting pools help regulate temperatures.
These policies set a new standard for public space design.
B. WATER FEATURES AS A COOLING STRATEGY
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Water plays a crucial role in cooling urban microclimates, particularly within dense city environments. Through evaporation and convection, the presence and movement of water generates a noticeable cooling effect on surrounding spaces.
EVAPORATION
Evaporative cooling occurs as water absorbs heat from the air, lowering ambient temperatures. This effect intensifies with increased water movement. Turbulent and aerated water effects expose a greater surface area to the air, accelerating evaporation and enhancing cooling efficiency.
CONVECTION
In addition to evaporation, moving water promotes convective cooling by disrupting stagnant warm air layers and replacing them with cooler air. The increased air circulation generated by water movement further enhances the cooling effect, making nearby spaces more comfortable.
C. WHAT WORKS BEST? WATER FEATURE IDEAS FOR URBAN COOLING
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FOG SYSTEMS
Evaporative cooling can take many forms in urban water features, offering a highly effective solution for mitigating the Urban Heat Island (UHI) effect. Cities worldwide have begun integrating misting systems into public spaces to enhance thermal comfort. This approach is especially useful in transit hubs, where misting corridors provide cooling relief to large numbers of pedestrians without leaving them wet. When paired with shade structures, misting systems become even more efficient by reducing evaporation rates and maximizing their cooling effects.
Project example – Atlantic Station, Atlanta, Georgia, USA
INTERACTIVE WATER FEATURES
Interactive water features offer both direct and passive cooling. Through physical interaction, visitors experience immediate relief from heat, while passive cooling occurs as water evaporates, absorbing heat from the surrounding air and naturally lowering ambient temperatures. These features not only engage users but also contribute to creating more comfortable and livable spaces.
Project example – Domino Park, Brooklyn, New York, USA
AERATED WATER ELEMENTS
Aerated water elements, such as cascades, waterfalls, water walls, and rain curtains are particularly effective for promoting evaporation, convective cooling, and air circulation. Their versatility allows them to fit seamlessly into various urban environments. Linear ground-level installations work well in transit-heavy areas, while vertical water walls are ideal for dense urban spaces with limited footprints, adding both functionality and visual impact.
Project example – Bell Tower Green, Salisbury, NC, USA and Crown Fountain at Millenium Park, Chicago, IL, USA
SHALLOW STREAMS & CHANNELS
Shallow, narrow streams and channels that wind through urban parks or plazas introduce a gentle cooling effect. The continuous movement of water encourages evaporation and convective cooling, while textured stone surfaces along the channels help dissipate heat further. These elements can be both functional and beautiful, blending natural cooling with urban aesthetics.
Project example – Daytona Beach Riverfront Esplanade, Daytona Beach, FL, USA
Each of these strategies can be adapted to the unique context of a city’s urban fabric. Thoughtfully integrating water features in the right locations can transform transit hubs, gathering spaces, and green corridors into comfortable, engaging environments that benefit entire communities.
Connect with Justin Hauad by clicking the button below, to explore how water features can transform your next project. Whether designing urban oases, integrating low-flow systems, enhancing patron engagement, or achieving precise lighting and colour matching, select your area of interest and submit your details. Justin will reach out to discuss tailored solutions that align with your vision.
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