Hotter New Year: Policymakers Will Need to Invest in Smarter Solutions for Hotter Days
How cities manage the sun and rain that fall on them in the immediate future has a huge impact on city resilience and on residents’ health and quality of life.
Kats & Glassbrook | a Smart Surfaces feature
How cities manage the sun and rain that fall on them has a huge impact on city resilience and on residents’ health and quality of life. That will be hugely significant in the immediate future as the most important event of 2024 awaits all of us on the horizon: The threat of more ecological collapse and literal melt from a year of climate crisis-induced heat that’s already resulted in the warmest January on record ….
Some cities have established programs supporting adoption of cool roofs, solar PV (photovoltaic) or reflective pavements, while others promote expansion of green roofs and trees. More, and ideally all, need to do this. But even in a city like Washington, D.C., which is a national leader in urban sustainability, or in Philadelphia, which is a leader in water management, adoption of these measures is still too fragmented and limited for the hotter days we have ahead of us. There is very limited data and analysis to date on the costs and benefits of these solutions.
City leaders, planners and developers lack the data and tools needed to understand and quantify the costs and benefits of technologies such as cool roofs, green roofs and porous pavements that could allow them to manage their city’s rain and sun far more effectively and cost-effectively. As a result, cities mismanage their two greatest natural gifts: sunshine and rain. This mismanagement costs billions of dollars in unnecessary health, energy, and stormwater-related costs each year, while degrading city comfort, decreasing livability and resilience, and contributing to climate crisis.
The costs are greatest in low-income areas, characterized by little greenery and dark impervious surfaces that result in excess summer heat and air pollution, excess respiratory illness, heat stress, and high health costs.
There are large physical disadvantages of low-income neighborhoods relative to cities as a whole. This typically includes more paved areas, fewer trees, and lower albedo (reflectivity), all of which means that more sunlight is absorbed, creating additional heat and heat stress and increased smog formation, and in turn worsening health. A broad review published in Environmental Health Perspectives examined heat risk–related land cover and found that, in U.S. cities, African Americans and Hispanics are 51 percent and 21 percent more likely, respectively, to live in high heat risk urban areas than non-Hispanic White Americans. The report found that the “extent of impervious surface is greater in neighborhoods with low socioeconomic status and a high proportion of minority residents”, and cites multiple studies of extreme heat that show large racial disparities in heat-related deaths. This systematic structural inequity appears endemic to many US cities.
Even a modest city step such as adoption of a cool roof procurement policy for affordable housing would generate substantial net benefits. For example, changing a square foot of dark, low albedo roof to a higher albedo generates nearly $4/ft 2 in net energy and health benefits. Residents of these buildings benefit from lower energy bills and improved health due to better air quality, lower heat stress and cooler indoor conditions.
As summarized below, the calculated city-wide net present value (NPV) of city-wide adoption of these technologies ranges from $538 million for El Paso to $1.8 billion for Washington, D.C., and $3.6 billion for Philadelphia. If we include the estimated avoided summer tourism losses the expected NPV from city-wide adoption by our nation’s capital rises to $4.9 billion, and for Philadelphia it rises to $8.4 billion.
Policymakers, especially in cities, will need to look at technologies from the air, as it were, all city surfaces and how they manage - or fail to manage – their sun and rain through their choice of surfaces. One strategy that clusters and analyzes, for the first time, a set of technologies that are applied to the surfaces of cities - from roofs and roads to parking lots and sidewalks - is described collectively with a new term: “smart surfaces.” These technologies of climate management for the future works because they cover surfaces and because they are engineered to deliver a range of measurable if sometimes complex benefits and enhancements relative to conventional surfaces. The large majority of these “smart surfaces” for most cities deliver positive net present value. The process smart surfaces have developed to understand, quantify and compare these “smart surface” choices also demonstrates that these are, overwhelmingly, smarter choices than conventional design.
It is also clear that the urban heat island reduction strategies such as cool and green roofs and cool pavements if applied city-wide can have large cooling benefits both within the city but also on areas that are downwind in the summers. At the scale of cooling application envisaged - with smart surfaces adopted as baseline standard practice rather than in current limited applications - this downwind cooling impact is cumulative and can be large, potentially doubling peak cooling benefits. This concept is a new one and is potentially very large and so merits a new term - we call it “downwind cooling.”
Cities suffer from worse air pollution and higher summer temperatures than surrounding suburban and rural areas. The impacts of air pollution and higher summer temperatures are particularly acute in low-income urban areas, where residents tend to live in inefficient buildings (sometimes without air conditioning) and disproportionately suffer from respiratory and other health problems exacerbated by poor air quality. The last few decades have seen the emergence of a set of surface solutions that could contribute towards reducing these environmental, health, and energy costs. These smart surface solutions include cool (reflective) roofs to cool the urban environment and decrease energy bills, green (vegetated) roofs to reduce stormwater runoff, cool the urban environment, and decrease energy bills; and rooftop solar photovoltaics (PV) to generate electricity and reduce air pollution. Urban trees, though commonly seen as a way to beautify cities, are increasingly becoming recognized for their ability to help manage stormwater, cool the urban environment, reduce pollution, and decrease energy bills. Cool (reflective) pavements, a technology still in its infancy, can also be used to cool the urban environment.
These solutions are deployed in pilot and subsidized programs by cities, developers, affordable housing organizations, and others to reduce the cost of stormwater treatment, cut utility bills, lower summer ambient air temperatures, improve air quality, and reduce CO 2 emissions. However, these initiatives tend to be standalone or pilot projects.
This has to change. Cities can increase resilience, improve health and comfort, expand jobs and slow global warming through smart surface strategies - such as cool and green roofs – while also achieving hundreds of millions of dollars in net financial benefits at a city level, and potentially deliver half a trillion dollars in net financial benefits from urban deployment nationally.
GREG KATS is CEO of the Smart Surfaces Coalition. KEITH GLASSBROOK is Director of Future of Heat Strategy Activation at the National Grid.
