How climate change will affect our energy consumption

As a gen­er­al rule, a warmer cli­mate means low­er heat­ing require­ments. How­ev­er, this gen­er­al obser­va­tion con­ceals a num­ber of dis­par­i­ties, which vary from region to region and from sea­son to sea­son. Demand is par­tic­u­lar­ly high dur­ing cold spells. France, for exam­ple, is a spe­cial case because of the exten­sive elec­tri­fi­ca­tion of its heat­ing sys­tem. Though we will always expe­ri­ence cold snaps, they will occur less fre­quent­ly. And yet our heat­ing needs will, on aver­age, decrease with cli­mate change. As a result, elec­tric­i­ty con­sump­tion will become increas­ing­ly frag­ment­ed, with high­er and high­er peaks. This could make it more dif­fi­cult for the elec­tric­i­ty sys­tem to manage.

In France, the elec­tri­cal grid is designed to cope with peaks in demand, and the grid oper­a­tors are sub­ject to severe con­straints in terms of their abil­i­ty to sup­ply ener­gy. But even this high degree of vari­abil­i­ty in con­sump­tion does not improve the prob­lems asso­ci­at­ed with the vari­abil­i­ty of renew­able ener­gy pro­duc­tion. All oth­er things being equal, cli­mate change brings an addi­tion­al con­straint that could lead to the sys­tem becom­ing oversized.

Cli­mat change is affect­ing air con­di­tion­ing require­ments. The prob­a­bil­i­ty of exceed­ing a tem­per­a­ture thresh­old requir­ing air con­di­tion­ing increas­es with cli­mate change. The trop­i­cal belt is the region most at risk from extreme heat. But beware: these ener­gy require­ments do not nec­es­sar­i­ly trans­late into ener­gy con­sump­tion: will the impact of cli­mate change real­ly result in the instal­la­tion of more air con­di­tion­ing units? It’s very dif­fi­cult to say.

The dynam­ics behind the adop­tion of air con­di­tion­ing vary great­ly: for exam­ple, it is very wide­spread in the Unit­ed States, but much less so in Europe. The type of air con­di­tion­ing used also varies. With my col­leagues André Mounier and Louis-Gaë­tan Giraudet from CIRED, we are final­is­ing an as yet unpub­lished study illus­trat­ing the dif­fer­ences in adop­tion dynam­ics between fixed and portable air con­di­tion­ers. The lat­ter are only half as ener­gy-effi­cient, with poten­tial­ly sig­nif­i­cant con­se­quences for ener­gy con­sump­tion. While ris­ing tem­per­a­tures appear to be the main rea­son for the pur­chase of fixed air con­di­tion­ers, heat­waves, which occur more fre­quent­ly, appear to be the main rea­son for the pur­chase of portable air conditioners.

Ener­gy con­sump­tion is not just about the cli­mate; it is also about the choic­es we make as a soci­ety. There are a num­ber of ways of com­bat­ing heat peaks: repaint­ing build­ings, insu­lat­ing, plant­i­ng veg­e­ta­tion, installing air con­di­tion­ers, etc. A team led by French researcher Vin­cent Vigu­ié has shown⁴ that adap­ta­tion mea­sures oth­er than air con­di­tion­ing are use­ful for improv­ing the ther­mal com­fort of res­i­dents and reduc­ing ener­gy con­sump­tion in the Île-de-France region. When opti­mised, they can reduce out­side air tem­per­a­ture by up to 4.2°C at night. How­ev­er, they can­not total­ly replace air conditioning.

Con­vert­ing a require­ment into ener­gy is not straight­for­ward. It depends on the dynam­ics of adop­tion, which are linked more to eco­nom­ic devel­op­ment than to cli­mate change. In the case of France, mod­el­ling heat­ing needs is fair­ly easy, because the tech­nolo­gies are already well-known. Cool­ing, on the oth­er hand, is more com­pli­cat­ed. Air con­di­tion­ing is not wide­spread, so we have lit­tle data. But his­tor­i­cal data is essen­tial for any simulation.

Mod­els based sole­ly on demand, inde­pen­dent of actu­al use, show that this is indeed the case on a glob­al scale (see box). We have car­ried out sim­u­la­tions for France that also include sce­nar­ios for the instal­la­tion of air con­di­tion­ing units. We have shown that ener­gy con­sump­tion in the region should fall, and that con­sump­tion linked to air con­di­tion­ing should only exceed the fall in heat­ing in sce­nar­ios involv­ing mas­sive use of air con­di­tion­ing. On a region­al scale, as in the south of France, how­ev­er, it is much more like­ly that elec­tric­i­ty con­sump­tion from air con­di­tion­ing will exceed that from heating.

Anaïs Marechal