Urban cooling in dry climates

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.

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.

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.

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.

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.