How technological innovations can reduce urban temperatures

Below a cloud­less, blue­ber­ry-blue sky, where the sun blazes fierce­ly and gleams from Lon­don land­marks, a mul­ti-per­son mass of liquify­ing limbs smoul­ders. The cap­tion for Zoom Rockman’s Pri­vate Eye car­toon reads: “I love Lon­don; it’s such a melt­ing pot.”

But few peo­ple were laugh­ing when, on 19 July, the UK tem­per­a­ture exceed­ed 40C for the first time, accord­ing to the Met Office, and the city’s infra­struc­ture melt­ed – lit­er­al­ly. Half of the six areas to sur­pass that lev­el were in and around the cap­i­tal: St James’s Park, Kew Gar­dens and Northolt. 

With glob­al warm­ing an increas­ing­ly hot top­ic and res­i­dents fig­u­ra­tive­ly melt­ing, the heat is being turned up on politi­cians, plan­ners and oth­er key stake­hold­ers to keep cities cool.

Just days after the record high tem­per­a­ture, the may­or of Lon­don, Sadiq Khan, loos­ened purse strings. He award­ed £2.85m from the Green and Healthy Streets fund to 19 projects, includ­ing rain gar­dens, tree pits and sus­tain­able drainage areas. Fur­ther, a £1m grant will sup­port “inno­v­a­tive and exem­plary projects” on the Trans­port for Lon­don Road Net­work, and £150,000 was released to improve walk­ing routes con­nect­ing green spaces.

“We can­not shy away from it: the cli­mate cri­sis is on our doorstep,” wrote Khan on LinkedIn in ear­ly August, announc­ing the fund­ing deci­sions. “We’re tak­ing action before time runs out and invest­ing £4m … to make Lon­don more resilient to heat­waves.” 

He added: “Work­ing with Lon­don bor­oughs and TfL, these projects will make Lon­don more resilient against extreme weath­er, plus make our streets more green and pleas­ant for Lon­don­ers. It’s a win-win.”

Col­lab­o­ra­tion and long-term plan­ning are para­mount to reduc­ing the impact of extreme heat in cities. And invest­ing in inno­v­a­tive tech­nol­o­gy solu­tions can accel­er­ate the vir­tu­ous cir­cle to which Khan allud­ed.

Beware the heat island effect

Indeed, embrac­ing an approach to build­ing that keeps nature in mind, rather than seek­ing to dom­i­nate it, will lead to bet­ter urban spaces for both peo­ple and the plan­et. So says Chris Ben­nett, co-founder and man­ag­ing direc­tor of sus­tain­abil­i­ty ser­vices at Evo­ra Glob­al, a Lon­don-head­quar­tered real asset con­sul­tan­cy. 

“Our urban envi­ron­ments are dom­i­nat­ed by dense­ly grouped build­ings made of reflec­tive mate­ri­als cre­at­ing a ‘heat island effect’,” he explains. “This is why it’s often hot­ter in cities than rur­al areas.”

Ben­nett believes sim­ple tech and nature-based solu­tions will make a big dif­fer­ence. “Reduc­ing hard reflec­tive sur­faces such as road pave­ments would help to low­er tem­per­a­tures,” he says. “Re-engi­neer­ing pave­ments to be per­me­able blocks, instead of con­crete or Tar­mac, would allow water to flow through the pavers in wet con­di­tions and evap­o­rate when the heat ris­es, cre­at­ing a cool­ing effect.

“Also, incor­po­rat­ing trees and plants reduces the reflec­tive nature of the streetscape, pro­vides habi­tats for wildlife and offers shel­ter from harsh ultra­vi­o­let radi­a­tion and solar heat dur­ing sum­mer.” 

Iron­i­cal­ly, it is part­ly due to tech­nol­o­gy that we find our­selves in this sticky sit­u­a­tion. Since the 1960s, planes, trains and auto­mo­biles have heav­i­ly con­tributed to glob­al warm­ing, and cities have evolved to accom­mo­date gas-guz­zling vehi­cles. So it’s time for a swift U‑turn, says Ben­nett.

“In Lon­don, we are blessed with many urban parks and squares cre­at­ed by the Geor­gians and Vic­to­ri­ans. But many of the city’s trees have been lost to pro­vide car park­ing spaces,” he says. “Plant­i­ng street trees will increase pro­tec­tion from the cli­mate by reduc­ing heat stress and lim­it­ing the degra­da­tion of the urban con­struc­tion mate­ri­als, mak­ing build­ings last longer.”

Appropriate early-stage design 

Anoth­er expert urg­ing cross-indus­try action is Håvard Hauke­land, co-founder of Space­mak­er AI. His com­pa­ny pro­vides ear­ly-stage analy­sis for archi­tects and urban plan­ners and enables build­ings to be designed with the local micro­cli­mate in mind to min­imise urban heat islands. 

“The way our cities have been designed is no longer appro­pri­ate for mod­ern times,” he says. “As tem­per­a­tures rise due to cli­mate change, the design choic­es pre­vi­ous­ly made either due to tra­di­tion or prac­ti­cal con­sid­er­a­tions around ener­gy effi­cien­cy are mak­ing our cities even hot­ter.”

Hauke­land con­tends that archi­tects and urban plan­ners need to step up. “While solu­tions such as addi­tion­al green­ery or reflec­tive roofs can help keep things a lit­tle cool­er, the real­i­ty is the most impact­ful solu­tions are done at the ear­ly stage when new devel­op­ments are being built,” he con­tin­ues. 

Design adap­ta­tions – includ­ing rotat­ing struc­tures to “open up” for wind or even alter­ing the shape of a build­ing – can make “the biggest dif­fer­ence to micro­cli­mates”, Hauke­land says. Although these solu­tions are “much hard­er to imple­ment”, he asserts that design­ers “must con­sid­er micro­cli­mates at the out­set”.

That may be so, but how should cities upgrade old­er infra­struc­ture to make it bet­ter able to with­stand extreme heat? “This is the crit­i­cal ques­tion when you think about the num­ber of her­itage and old­er build­ings we have in the UK,” says Ian Ellis, smart build­ings expert at Siemens Smart Infra­struc­ture. Sen­sors that cap­ture data and allow deep analy­sis of how peo­ple use build­ings – espe­cial­ly as hybrid-work­ing strate­gies are firmed up – could be the answer.

“This tech­nol­o­gy is already being used in build­ings across the UK, where it can pro­vide usage data on the flow of peo­ple through a build­ing, where they con­gre­gate and how they use it,” says Ellis. “Data like this pro­vides invalu­able insights in opti­mis­ing oth­er tech­nolo­gies like heat­ing and ven­ti­la­tion sys­tems.”

Sensors, shade and sewage

Sebas­t­ian Peck, a part­ner at Kom­pas – an ear­ly-stage ven­ture cap­i­tal firm focused on trans­form­ing the built envi­ron­ment – lists some pio­neer­ing solu­tions to cool cities. “Ver­ti­cal Field is installing sen­sor-con­trolled smart planters to puri­fy the air from car­bon diox­ide and, when mount­ed to build­ings, they help insu­late them from the sun,” he says. 

Mean­while, Lumi­weave has devel­oped an inno­v­a­tive fab­ric that pro­vides shade dur­ing the day and har­vests the sun’s ener­gy to illu­mi­nate itself and its sur­round­ings at night. “And,” Peck con­tin­ues, “Tree­Tube has a patent­ed mod­u­lar sys­tem of tubes that lets tree roots grow safe­ly in a tun­nel with­out dis­rupt­ing their sur­round­ings.”

Peter Hogg, UK cities direc­tor at glob­al design, engi­neer­ing and man­age­ment con­sult­ing com­pa­ny Arcadis, offers a more prac­ti­cal but pongy exam­ple. “We are look­ing at using efflu­ent as a heat exchang­er that allows you to extract ener­gy used for cool­ing with min­i­mal car­bon impact. Imag­ine the poten­tial in a city the size of Lon­don, which hous­es 8.5 mil­lion peo­ple.”

At this stage, no idea should be flushed away. And while there is much work to do, the will­ing­ness to force change – and think up unusu­al solu­tions – is final­ly evi­dent, sug­gests Hogg. “The pan­dem­ic was a water­shed,” he says. “There is a col­lec­tive under­stand­ing that this sit­u­a­tion must be addressed. Today, build­ing plans that fail to con­sid­er the cli­mate chal­lenge won’t attract investors. 

“Before the coro­n­avirus cri­sis, you would have to go to the Nether­lands or the Nordics to find peo­ple tak­ing this seri­ous­ly. We now acknowl­edge that sig­nif­i­cant behav­iour­al and struc­tur­al changes are required, and quick­ly.”

Peck con­cludes that enough tech­nolo­gies are avail­able to cool cities but to har­ness their pow­er, lead­ers must be bold. 

“The dif­fi­cul­ty is that urban plan­ners need to rethink our cities, make them green­er and ensure water is put to good use,” he says. “But chang­ing and build­ing back exist­ing urban infra­struc­ture is expen­sive. Cities are under pres­sure to demon­strate to the pub­lic that their scarce resources are well invest­ed.

“In oth­er words, cool­ing our cities is not a tech­no­log­i­cal chal­lenge, but a polit­i­cal one.”