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Some time ago I found myself chasing after Roger Madelin, who sets a brisk walking pace when he’s not leading the redevelopment of British Land’s £4bn Canada Water scheme in south-east London.
Lem Bingley, PW editor
The site merits the name, given all the water around the place. As we strode along Brunswick Quay next to the broad Greenland Dock, we discussed the role of open water in urban development.
Besides aesthetic value, water can fight the heat-island effect that blights urban sites – a steadily rising concern given global warming.
A large body of water is not simply somewhere to dip your toes. As Madelin explained, with a quick basic physics lesson, the latent heat effect comes into play. For those a bit hazy on the topic, latent heat is the slug of energy required to turn a liquid into a gas, including water into vapour. As the dock’s surface water slowly evaporates on a hot day, it sucks up energy to fuel the transition, cooling the air above. The result is a big, natural air conditioner.
The cooling effect of evaporation is one of the lessons I remember most vividly from my schooldays. ‘Making ice by the evaporation of ether’, as the experiment was called, involved blowing bubbles of air through a beaker of volatile liquid, standing in a saucer of water. This was a scientific breakthrough in icemaking about 300 years ago.
Water can fight the heat-island effect on urban sites – a rising concern given global warming
The bubbles increase surface area, speeding up evaporation. This sucks up energy, the beaker cools rapidly and the water in the saucer freezes.
This lesson was memorable not for the physics but for teacher Mr Holland’s demonstration. He decided to create bubbles not with an air pump but with a drinking straw. He would have failed biology, given the famous role of ether in anaesthesia.
Moments into the experiment, blowing bubbles in a cloud of ether vapour, Mr Holland keeled over. I can’t remember if he made any ice, but he knocked himself out cold. His class found this hilarious.
Today, the same physics underpins refrigerators, freezers, air conditioners and heat pumps. Evaporation and its reverse, condensation, is the basic principle at play in all these devices. As done routinely by heat pumps, you can – counter-intuitively – move energy from the cold outdoors to the warm indoors.
I mention all this to applaud the vision and ingenuity of SmartParc and SEGRO. As we highlight this week in our I&L supplement, the pair have created a logistics park in Derby dedicated to food production. The site employs heat pumps at industrial scale to move energy from food preparation areas that need to be kept chilled into office areas that need to be kept warm.
It’s a highly efficient process. SmartParc Europe chief operating officer Phil Lovell says the site can achieve 3kW of cooling and 4kW of heating from every 1kW of energy used by the heat pumps. The result for occupier HelloFresh is a 20% saving on energy costs – a significant sum when your fridge-freezer is the size of a warehouse.
All things considered, I reckon that’s pretty cool.