Driven first by public health objectives and later by an insatiable desire for daylight and broad views, outdoor spaces are largely celebrated for the ways in which they maximize access to light. Unobstructed rays became synonymous with urban progress and yet, as temperatures rise every year, our sun-drenched streets and public spaces are becoming less and less comfortable (and less safe for our skin). According to the U.N., life-threatening heat is expected to impact more than half the global population by 2100. Cities will be exposed to double the level of heat stress compared to rural surroundings.
In light of these accelerating thermal changes, there is a need to reexamine the critical relationship between sun and shade. Many cities have long grappled with extreme heat and recognize the vital and democratizing role that shade plays: it offers shelter and relief; it creates new places to gather safely; and it is an unintended choreographer mapping and remapping cool corridors for safe travel. Even in Toronto, within a country known for cold winters, extreme heat events are expected to rise from 20 days per year now to 66 by 2050, leading to increased risk of illnesses and mortality. The Bentway’s summer 2025 program “Sun/Shade” brought together artists, designers, and researchers to deploy the sun and shade as creative tools, revealing how new thinking about familiar resources can improve public space. The program was inspired and informed by the City of Toronto’s new Thermal Comfort Guidelines, which are re-shaping the way we plan and build public space.
Meanwhile, Boston recently completed its Shadow Study, a pioneering effort to understand the interplay between urban development, sunlight, and the vitality of historic parklands. With Boston’s skyline evolving, especially in neighborhoods surrounding the Back Bay Fens and the Riverway, the study addresses how growing vertical development interacts with the needs of plants, pollinators, birds, and people. The research underscores sunlight as both an ecological necessity and vital to human comfort, as well as critical for vegetation growth, biodiversity, mental health, and physical wellness. At the same time, the study explores the nuanced duality of shadow: as a source of cooling in summer and hazard in winter, as both respite and limitation for community use. The result is a robust model and reporting of the impacts of shade and shadow on park spaces in the City, and several key insights that are universally applicable to growing cities.
Support is provided by the Robert Wood Johnson Foundation. The views expressed here do not necessarily reflect the views of the Foundation.
