Urban cooling in dry climates

In the first of a series of internal presentations designed to collect and share our knowledge of regenerative design, Michael Rowlands, Studio Director at ASPECT Studios in Perth, drew on the team’s experiences to explain what a regenerative approach means in hot, dry climates. This condensed version captures insights from the Perth studio and their collaborations with teams in Dubai, London and Melbourne, highlighting lessons from designing in arid environments that the rest of the world needs to pay attention to.

Our studios work in some of the world’s driest regions: Perth, the Pilbara, India, Saudi Arabia and the UAE. The challenges vary in intensity. Perth might experience five or six days a year above 40 degrees, while in Riyadh, that kind of heat is the daily norm for four months of the year, with regular temperatures during the summer reaching 45 to 47 degrees and occasional peaks exceeding 50 degrees.

What these climates share are high levels of solar radiation and surface temperature. That distinguishes them from humid climates, where the challenge is compounded by moisture in the air and low airflow. Strategies that work in one setting often don’t work in the other. For example, introducing moisture into a humid climate can worsen discomfort, while in dry climates, it can have a cooling effect.

Although many of the approaches we use were developed for dry zones, they are increasingly relevant elsewhere. Climate change is pushing temperate cities like Melbourne, Sydney and Brisbane toward more frequent extreme heat and prolonged dry periods. Strategies for dry climates are no longer niche. They are part of the global design toolkit.

The urban heat island effect is caused by an imbalance between heat gained from the sun and heat lost from the built environment. Buildings, roads and hard surfaces absorb solar heat. Dense, non-porous materials retain that heat, while limited airflow in built-up areas prevents it from escaping. As a result, urban temperatures can be 2 to 12 degrees hotter than surrounding rural areas.

As climate change accelerates, extreme heat events are becoming more frequent, longer and more intense. According to KPMG, heat is Australia's deadliest natural hazard, claiming over 3,000 lives each year. Vulnerable communities - older people, children and those without access to shade or air conditioning - are disproportionately impacted. Left unaddressed, the heat island effect threatens fundamental urban values: comfort, safety, social connection, biodiversity and identity.

Extreme heat affects people directly. When temperatures exceed 36 to 38 degrees, the human body begins to struggle to self-regulate. This can lead to fatigue, dehydration, heat exhaustion and, in severe cases, heatstroke. Mental performance also declines. Productivity and focus drop in uncomfortable conditions. Thermal discomfort becomes noticeable when mean radiant temperatures reach 32 to 34 degrees, or when the Universal Thermal Climate Index (UTCI) hits 28 to 30 degrees.

Heat also affects how we use space. It pushes people indoors, limits physical activity and changes how communities engage with streets, parks and public places. It compounds social inequality. Without access to shade, greenery or cooling infrastructure, many people are excluded from public life. But the good news is that even small interventions (trees, water and shade) can transform experiences, regardless of the air temperature.

Materiality is one of the most direct ways we influence temperature at ground level. We actively avoid dark, heat-retaining materials like black asphalt or dark concrete. Instead, we prioritise high-albedo materials that reflect heat, such as pale pavers, light-coloured stone and permeable surfaces.

At the Hope Street project in Fremantle, for example, we used light-toned paving and permeable driveways to reduce surface temperatures while supporting water-sensitive design.

Vegetation is equally vital. Beyond providing shade, plants cool their surroundings through evapotranspiration. We integrate both deciduous and evergreen species where possible to support seasonal comfort. In Riyadh, we have seen how even modest green spaces—like Richard Bödecker Park in the Diplomatic Quarter by Bödeker—can provide meaningful respite from extreme conditions through thoughtful planting and materials.

In more extreme environments, we sometimes incorporate active or semi-active cooling systems. Misting, for instance, can reduce ambient temperatures by 2 to 5 degrees. At Kalgoorlie City Centre, we integrated misting into a large shade structure to provide relief and increase usability. Water use was carefully calibrated to ensure efficiency and avoid waste.

Our work on the Abu Dhabi Lake and Sports Park is another example. There, we partnered with Buro Happold to model thermal comfort across the site. By layering modular shade structures, trees, light materials and water features, we were able to significantly improve comfort by up to 60 percent in some areas according to UTCI modelling.