Urban heat islands
Why is it hotter in the city than in the countryside? How can overdeveloped sites increase the heat across Cambridge and beyond?
We’ve mentioned urban heat maps a few times. Here are ten points to know with links on what an urban heat map or island means and why it needs to form part of your concerns about current and future development in Cambridge.
UHI means urban heat island. In city centres and urban areas scientists have found evidence that there is an increase in ground and air temperatures compared to the outskirts.
The differences between an urban area and its surroundings can reach 10 °C.
Studying them and using this evidence to create sustainable developments can help to lower temperatures and retain the biodiversity of cities.
A sustainable development might pay attention to building materials (glass outputs more heat to the landscape around it), height which can create heated areas and prevent nature growing at ground level, trees and canopies to create shade, effective water use so that the development doesn’t create drought or water shortages.
Tarmaced spaces such as parking areas, storage facilities and streets store energy during the day and release it at night in the form of heat. Whilst the current Beehive site has bad UHI, the new plans are no better.
Lack of trees and shade can affect the use of spaces. Poor UHI can lead to poverty
Heat islands are created by poor development of urban environments and they are man-made warming. This means that they can be prevented if developers engage and we raise neglect of UHI and biodiversity in our comments and objections.
UHI can have negative consequences for humans as well as the environment. Risks to health, threats to biodiversity, feelings of discomfort are among the issues posed by urban heat islands.
Facilities that help people inside a building to feel comfortable such as air conditioning accentuate the heat by sending it outside.
Narrow streets will not aid air circulation so it sits still on a clear day, increasing the heat effect. Large waterproofed surfaces have higher surface temperatures than smaller surfaces of the same nature - materials also matter in reducing heat.
If you do not live in the city or close to large scale developments, you’ll be affected. People living in Ditton Fields or Newnham would all feel the total UHI of the Beehive, for example, if it was to be built as planning with unsufficent attention to the impact on UHI.
And the good news
The Greater Cambridge Partnership impressed us with their attention to the science and are in discussions about adding this to the next local plan for Cambridge. There are already indicators in the current local plan about this and it’s been recognised as a problem that needs to be solved. This can be an opportunity for change if we all act on this.
What can you do right now?
Keep objecting and cite your worries about the UHI and lack of biodiversity in large scale planning application like the Beehive or Grafton Centre.
Tell your councillors (but not if they are on planning as we’re not allowed to lobby them). Here’s where to find your local councillor.
Read more about UHI and biodiversity in our links below
Each person over 16 in your home can write their own unique letter of objection.
Talk about it and spread the word as it’s new to us, and we need to learn more with you.
Find us on Facebook
Further reading
Climate Central on building design
University of London on reducing urban energy consumption
Professor Marialena Nikolopoulou whose talk we listened to in November on changes that developers can make to reduce urban heat
The BBC on urban heat maps
National Geographic’s Encyclopaedia entry
Take away
Developers seem intent on making the most money from sites but that's not being a good long term neighbour if it leaves behind a legacy of poverty and a city in which people can’t live or use the site they have building making it long term ineffective. The UHI matters. You do have a voice in this. You absolutely do not have to use fancy words to object or raise a concern. You might wish to state that you believe the development isn’t sustainable and you have worries about the resulting urban heat map because of it’s height, lack of trees, the material used and/our the poor use of water.
The Addenbrookes development means that Nine Wells is drying up and it’s lost it’s SSI status. Let’s not kill the diversity we already have by letting poor development be the most important thing. Our planet is.