Urban Heat Islands

August 4, 2023

Hands-up: Who nerded out about urban heat islands (UHIs) before? My hand stayed down until recently, when a founder I work closely with asked me: 'Have you looked deeper into UHIs?'

Hands-up: Who nerded out about urban heat islands (UHIs) before ?

My hand stayed down until recently, when a founder I work closely with asked me:

“Have you looked deeper into UHIs?”

And to my shame, I had to confess I hadn’t.

Until now. That time’s over, ladies and gentlemen.

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What are Urban Heat Islands (UHIs)

A poetic description reads:

Amidst the towering skyscrapers and bustling streets of modern cities lies a hidden menace that threatens the very fabric of urban life – Urban Heat Islands (UHIs). These heat-trapping zones are far from the idyllic tropical islands we envision; instead, they are urban areas that experience significantly higher temperatures than their surrounding rural regions.

In other words:

Cities emit heat (people, cooling/heating buildings and devices, transportation fumes)

Construction materials used in many cities absorb and retain heat

We rarely used any materials or devices with heat-reducing properties

There you go: your personal Urban Heat Island

Data first

MIT Climate Portal says that UHI’s can on average be 5-7 °F warmer than the surrounding countryside.

Sounds like not much ?

Well, consider this:

1 degree is the difference between water being in its liquid phase and frozen phase

the earth’s climate is changing due to less than that difference

7 °F can be the difference between your body feeling just fatigued or having a sunstroke


Why UHIs exist

UHIs exist because of the concrete and asphalt that dominate the cityscape (for good reasons, because they still are among the most scalable building materials known to mankind).

But these surfaces absorb and retain heat, creating microclimates within urban areas that can be several degrees Celsius higher than their rural counterparts. The soaring temperatures in UHIs have far-reaching consequences that impact various aspects of urban life.

Health issues

As the urban thermometer climbs, vulnerable populations face more and more risks of heat-related illnesses. Elderly people, younger folk, and persons with pre-existing health conditions are extra susceptible to heatstroke and dehydration. Moreover, the relentless heat can exacerbate air pollution, worsen respiratory issues, and pose a serious threat to the well-being of city residents.

Energy consumption death spiral

What’s the immediate reaction to urban heat? You got it. Air conditioning. In a desperate bid to beat the heat, residents in urban heat islands (have to) resort to artificial cooling in buildings, homes, and transportation.

Thing is: This surge in energy consumption strains power grids and exacerbates greenhouse gas emissions, amplifying the impacts of climate change. The vicious cycle of UHIs and increased energy demands place cities at the forefront of the battle against global warming.

UHI >> disrupted weather >> more wear and tear in cities

What’s more is that the man-made disruption of the natural thermal balance within UHIs seems to have adverse effects on weather patterns, which would exacerbate the urban heat spiral.

If we continue lacking sufficient green spaces in cities, our urban environments will struggle to counteract rising temperatures through natural cooling mechanisms. And that scorching reality of UHIs places additional stress on city infrastructure, accelerating deterioration and increasing maintenance costs.

Wanted: Cool-er materials

Cities will be forced to take proactive measures to tackle UHIs and create resilient urban environments. Implementing green infrastructure, such as rooftop gardens, urban forests, and green corridors, can help cool cities by providing shade and increasing natural cooling through evapotranspiration.

Moreover, promoting the use of cool-er materials for building surfaces, along with energy-efficient design and construction practices, can help mitigate the urban heat trap.

What’s more is that reducing the heat island effect can enhance outdoor comfort, promote physical activity, and foster a sense of community cohesion.

Let’s not forget: Better transportation

Local governments can play a crucial role in combating UHIs by investing in sustainable transportation infrastructure, promoting public transportation, and encouraging active commuting methods like walking and cycling. If you look for examples where it works, I suggest you start your search with the Netherlands.

Such measures not only reduce the heat island effect but also mitigate traffic-related emissions and improve air quality.

Venture-backable opportunities

The UHI space is neither easy nor obvious for the traditional venture-backed founding opportunity. Replacing physical infrastructure – as in pavings, materials of existing buildings, transportation infrastructure – does not operate on a zero-marginal cost model (faaaaaaaaaaaaar from it) and also not on the short timelines ventures like to operate in.

Practically, it has sales cycles measured in decades, not days.

Just think how some of the most modern cities are not built “in situ” but from scratch (case in point: Neom), for that same reason that replacing legacy physical infrastructure is just a first-principles nightmare.

That said, I do suspect there exist venture-backable opportunities.

Just one example to leave with you all here:

Provision and maintenance of repeatable plant-matter for cities. The tech-enabled aspect here is the city planning, extremely efficient supply chain to standardize, procure, remove waste and install the plant matter, as well as a supply chain (skilled labor!) play to maintain it. Think: tech-enabled landscaper on city scale.

Would love to hear from you which other venture-backable opportunities you are seeing in the Urban Heat Island arena.

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