123Fab #104

1 topic, 2 key figures, 3 startups to draw inspiration from

Urban areas face rising temperatures from the combined effects of climate change and the “urban heat island” phenomenon. Concrete and asphalt trap heat, creating hotter cities, escalating energy demands, and endangering vulnerable populations. To mitigate these effects, solutions must address the problem across all scales: city, neighborhood, street, building, and individual levels.

City-Level Strategies

At the city scale, urban planning focuses on creating cooler environments by improving airflow, increasing plant cover, and reducing heat-retaining surfaces:

• Urban Planning and Cool Corridors: Designing open spaces and cool corridors encourages air circulation and reduces heat concentration.
• Increasing Plant Cover: Initiatives like Paris’ Oasis Project transform schoolyards into green spaces, doubling as cool islands and heat refuges.
• Low-Emission Zones (ZFE): Reducing vehicular traffic in cities cuts emissions, indirectly lowering heat retention.
• Urban Water Management: Large-scale rainwater management systems and urban basins help infiltrate water into the soil. This not only prevents flooding but also encourages evaporation, naturally cooling the air during heatwaves.

Neighborhood-Level Strategies

Neighborhood interventions tackle heat through surface treatments, targeted greenery, and smart solutions:

• High-Albedo Materials: Reflective materials reduce heat absorption, like those used in Paris’ “cool islands.” High-albedo materials are surfaces that reflect more sunlight than they absorb, helping to lower surface temperatures.
• Vegetation and Cool Islands: Projects like Urban Canopée integrate vegetation into neighborhoods, while ENGIE Lab Crigen’s Skycooling panels provide shade-based cooling.
• Water Permeation: Soil desilting and localized rainwater infiltration enhance evaporation, which cools the surrounding air naturally. Incorporating small water features like ponds or fountains within neighborhoods can amplify these cooling effects.

Street-Level Strategies

Streets act as heat hotspots, but targeted solutions can reduce their thermal footprint:

• Draining Pavements: Products like Holcim’s concrete, a permeable concrete Hydromedia, allow rainwater to infiltrate the soil, supporting evaporation and natural cooling.
• Green Walls and Photovoltaic Shades: Vegetated walls and shaded walkways lower street temperatures while improving aesthetics and functionality.
• Localized Water Features: Incorporating fountains, small basins, or artificial streams along streets can provide significant localized cooling effects.

Building-Level Strategies

Buildings are central to urban cooling, as they represent a significant proportion of heat storage:

• Green Roofs: Vegetative layers provide natural insulation and cooling, reducing the heat stored by buildings.
• Reflective Paint: Products like Cool Roof reduce heat absorption, keeping interiors cooler.
• Advanced Insulation: Aerogels, a cutting-edge material known for their lightweight properties and high thermal resistance, can significantly reduce heating and cooling costs by providing superior insulation compared to traditional materials.
• Bio-Reactive Facades: Innovations like XTU Architects’ microalgae facades actively regulate temperature by producing oxygen and absorbing heat.
• Rainwater Harvesting: Buildings can integrate systems to collect rainwater, which can then be used for evaporative cooling or irrigation for rooftop and vertical gardens, further reducing heat buildup.

Individual Actions

Individual behaviors also play a vital role in reducing urban heat:

• Soft Mobility: Walking, cycling, and using public transport help reduce vehicular emissions and heat contributions.
• Urban Greening: Individuals can plant greenery at home, install small water features in gardens, or volunteer for local tree-planting initiatives to enhance cooling.
• Water Stewardship: Households can promote cooling by managing rainwater infiltration with permeable garden designs, rain barrels, or bioswales to ensure water is available for natural evaporation processes.

Cooling urban environments requires a multifaceted approach across different scales. From city-wide planning and water management to individual actions like soft mobility, these strategies not only provide immediate relief from heat but also promote the long-term sustainability of urban life. Addressing the urban heat island effect is a pressing necessity as cities prepare for increasingly extreme temperatures in the decades ahead.

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2 Key Figures

4

Temperatures can be 1 to 4°C higher than surrounding rural areas due to the presence of heat-retaining infrastructures like concrete and asphalt.

15%

A 10% increase in tree cover in cities reduces surface temperatures and lower energy consumption needs for cooling by around 15%.

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3 startups to draw inspiration from

CoolRoof

French-based startup specialized in reflective coatings for rooftops and pavements to reduce heat absorption in cities, lowering temperatures and energy consumption.

SolCold

A materials startup from Israel that creates innovative coatings which cool buildings by converting heat into light, reflecting sunlight to reduce urban temperatures.

Green City Solutions

German startup that develops urban green spaces using “CityTree,” a smart, air-purifying moss wall that cools and cleans the air in densely populated areas through IoT integration.

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