Thought Leadership

Urban Planners Can Leverage Microclimate & Thermal Comfort for Outdoor Spaces

Creating world-class cities of the future means that city planners will need to incorporate thoughtful design to create cities that are both a delight to be in and live in, but also that are resilient to climate and global challenges. 

The quality of shared outdoor spaces is becoming increasingly important, especially during climate change and post-COVID lockdowns. Global temperatures and weather patterns are changing so resident comfort in outdoor spaces has recently attracted considerable attention for the sustainable design of cities.Furthermore, keeping outdoor spaces comfortable has also become increasingly important post-COVID as more urban residents seek escape from the confines of their residences to outdoor spaces. 

Luckily, outdoor spaces can be optimized through microclimate assessments and a concept known as thermal comfort. 

What is Thermal Comfort? 

Often thermal comfort is associated with indoors spaces like homes and offices. Here, we apply the idea to public outdoor spaces. Thermal comfort is finding a perfect balance when people in outdoor spaces aren’t too cold, too warm, and when it's neither too sunny, too cold, nor too windy for pedestrians.  

Outdoor public park in front of building with people in New York City

Public parks, outdoor malls, open-air sport stadiums, cafes and outdoor restaurants can all be thoughtfully designed to maximize the comfort of those using these spaces. Building design, for instance, is one key element of thermal comfort. That is because building can affect its surroundings in many ways, from reflecting or limiting sunlight to altering wind patterns, ultimately impacting pedestrians and public spaces around the building. Understanding the impacts and accounting for them in the design process, can help achieve acceptable comfort levels around them. 

Challenges to creating thermal comfort for all

The challenge to creating a consistent concept of thermal comfort is that it is incredibly subjective and based on context. Thermal comfort is impacted by different personal and environmental factors including temperature, humidity, wind, solar, clothing people wear, or an individual’s activity level, among others. 

Different cities would have different thermal comfort requirements at different times of the year. Miami and Stockholm, for example, have vastly different environmental factors. But even individuals occupying the same space could have different perceptions on how the space impacts their personal thermal comfort. Consider the spectators and players in an open-air sports stadium: each group would have different thermal comfort expectations that would be impacted by the clothing they are wearing and their activity level. Adjustments to the shape or positioning of a stadium can balance sun, shade, and wind to keep both patrons and athletes comfortable during more of the game or match—and for more of the season. Your expectations of the built environment could also impact your thermal comfort. For instance, it would be a shock to move from an air-conditioned interior at 20°C to full sun at 40°C. Ideally, great design would gradually reacclimatize people as they move to the outside. 

With so much to consider, how do you consistently design outdoor spaces that are comfortable for all to use?

How microclimate assessments provide a holistic view of pedestrian comfort & safety

Many major metropolitan cities require a planning application for each tall building, which typically includes various environmental assessments like a wind assessment. However, often wind, sunlight, and overshadowing have been considered separately, limiting a planner’s ability to evaluate the combined impacts of different environmental factors. Undertaking a thermal comfort or microclimate assessment provides exceptional insight into the combination of unique factors that impact a person’s comfort, including temperature, humidity, wind, solar, and how the space will be used. 

Diagram showing the impact of sunlight, humidity, temperature, and wind on microclimate and pedestrian thermal comfort in urban outdoor public spaces

When design teams are equipped with the right data from the beginning - allowing them to understand the microclimate of a building before it is built - such effects can not only be mitigated, but also harnessed into sustainable, efficient opportunities for the area, its users, and the city as a whole. 

How cohesive wind and microclimate guidelines can unify building approaches and methodologies

Cities can standardize thermal comfort by creating guidelines to keep assessing and measuring thermal comfort consistent. Recently, the City of London developed thermal comfort guidelines in partnership with RWDI, making it the first city in the United Kingdom and one of the first globally to implement such guidelines. Thermal comfort guidelines will set the standard for thermal comfort for the City’s urban outdoor spaces, improving the lives of residents and visitors alike.  

Cover of thermal comfort guidelines document for City of London

RWDI has spent several years collaborating with the City of London to develop pioneering guidelines aimed at better evaluating new building designs and the impact they may have on their surroundings. Our award-winning guidelines formalizing the methodology around pedestrian wind microclimate assessments were launched in August 2019, followed closely by the publication of guidelines for thermal comfort in December 2020. 

These guidelines represent a significant move forward in urban planning for the same reasons that our wind studies were so important: major developments in dense urban centers mean a more thoughtful approach to design is needed, with more consideration for the surroundings and people in and around these new buildings and developments. 

Learn more about thermal comfort guidelines

Learn more about pedestrian thermal comfort and microclimate assessments