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