How Design Can Help Mitigate Extreme Heat

This year, the world experienced the hottest summer on record with temperatures in July, August, and September reaching up to one degree Fahrenheit higher than prior years. If our own heat wave experiences aren’t enough to convince us of how dire the situation is, the Intergovernmental Panel on Climate Change has reported that some areas of the globe have already crossed the threshold climate scientists refer to as “the point of no return” in the global warming crisis. Research indicates that extreme heat scenarios will continue to worsen in the coming years. 

‘Extreme heat’ does not have a one-size-fits-all definition or reference point. It is characterized by summertime temperatures that are much hotter and/or more humid than average and depend on location. Extreme heat is classified differently based on a location’s natural and built environment factors, and even the average temperatures that local residents are used to. 

Places with certain climates, geography, and terrain, including those near the equator, desert regions, and areas of high solar exposure with little naturally shading vegetation, can be more prone to extreme heat. Urban areas are also likely to have higher ambient temperatures due to high density, dark surfaces such as asphalt roads, and materials with considerable mass like concrete and stone that absorb heat and release it over time. 

Communities worldwide are poorly equipped to handle extreme heat, in part because of its variable nature. Tolerance to heat and thermal comfort is different from person to person and place to place—populations in colder climates are not as acclimated to heat as those in warmer locations. Access and financial issues related to electricity grid overload plague cities during periods of extreme heat and, in many locations, temporary cooling centers are needed to help people survive. 

Creating resilient buildings 

As designers, we understand there’s no doubt that buildings can exacerbate extreme heat. It is a byproduct of increased carbon emissions warming the globe, a large percentage of which come from building operations and construction activities. The long-term impacts and feedback loop of extreme heat is simply illustrated: as we use more air conditioning to cool buildings, more carbon dioxide enters the atmosphere, stemming from both the process of manufacturing HVAC equipment as well as energy consumption when it is put into operation. Architects and designers—and building owners and operators—can make choices that reduce the amount of carbon that enters the atmosphere. 

As the global population continues to rise and the planet gets warmer, we’ll need more buildings and better cooling, and we’ll face bigger, more unpredictable weather events. How can we create sustainable solutions to adapt to and mitigate extreme heat through design? 

On the individual building scale, ‘passive design’ provides a big opportunity for a climate-responsive future. Passive design elements such as cross-ventilation, stack ventilation, shading, and glazing can increase natural air flow, decrease humidity, limit direct heat, and provide the feeling of comfort without air conditioning. Often implemented in tandem with HVAC systems, passive design solutions can afford buildings the ability to operate successfully with or without air conditioning, limiting energy use and allowing them to provide shelter and comfort to people during emergencies or power failures in addition to daily use.

An excellent example of a time-tested, passive solution is a windcatcher, traditionally used in the vernacular architecture of desert regions in the Middle East. These systems collect air from higher elevations and send it into buildings to cool and ventilate naturally without using electricity. By taking cues from such systems and incorporating high-performance technology, we can advance the utility of passive design strategies. 

Thoughtful consideration of a structure’s exterior and immediate surroundings can also impact a design’s ability to mitigate extreme heat. Using materials and surfaces with high albedo that reflect more sunlight is a simple design intervention that can reduce direct heat, as can structures and building forms that create shade throughout the day both inside and outside. Ecological solutions such as vegetated landscapes, green roofs, and natural, local building materials resistant to climate-specific heat challenges also help. 

Helping cities and communities thrive 

Holisti,c community-oriented urban planning solutions can create impact across all scales, from individual spaces to entire cities, as we collectively seek to navigate periods of extreme heat and prevent them from worsening.  

Developing and designing more green spaces and parks is imperative. Native, climate-responsive trees and vegetation in our cities and communities can clean the air by absorbing carbon dioxide in the atmosphere. They can also provide shade and moments of respite for people, which in turn reduces the amount of time spent indoors with air conditioning running. Smart urban planning strategies like concentrating high-density development in specific, compact areas will ensure that green open spaces are preserved, thus reducing heat absorption. Green belts serve not only as natural barriers, but also offer enhanced filtration of heat and pollutants. 

Planning and design can help mitigate climate impacts when we leverage strategies that embody both the vernacular of a place and its ecosystems with performance-based goals and outcomes. Urban geometry design that considers street layout and building orientations to maximize natural ventilation can help dissipate heat. Improving transportation systems, redeveloping under-utilized infrastructure such as parking lots and former industrial areas, and transforming them into vibrant places that serve the community can help stave off the effects of social and health crises that are often a result of extreme weather events. 

Many global, national, and local organizations and governments are taking extreme heat seriously and attempting to enact meaningful change to mitigate it. The United Nations (UN) Sustainable Development Goal 13 outlines the dire need for climate action to reduce the impacts of events like heat waves, while cities like New York and Miami have developed extreme heat plans. Design industry organizations including Architecture 2030 and the American Institute of Architects (AIA) consistently publish research and resources including the AIA Resilience Design Toolkit, co-created with our firm, HKS. As designers, we are energized by HKS’ carbon neutrality commitment, UN Global Compact involvement, and drive to create more livable cities and communities through sustainable design.

We believe designing for resilience is key to enabling our communities to thrive and survive during times of extreme heat. Together, through design that prioritizes people and the planet, we can help make that happen. 

Sheba Ross is Global Practice Director, Cities and Communities, and a Partner at HKS. Sheba, a highly engaged member of Atlanta’s Urban Land Institute, combines the power of creativity and the joy of collaboration to create tangible project outcomes.

Sammy Shams is a Sustainable Design Professional at HKS. His responsibilities include Nature of Place studies, LEED & WELL certifications, early phase energy modeling and life cycle analyses.