COOL ACs ARE NOT SO COOL

Down to Earth - - EDITOR’S PAGE - PS: Go to www.csein­dia.org to down­load the study . @suni­ta­nar

THE NOW in­creas­ingly ubiq­ui­tous air-con­di­tioner (AC) in our houses would eas­ily make it to the list of the top en­vi­ron­men­tal crim­i­nals. Why? Just con­sider these facts. In Delhi, a mere 1°C drop in tem­per­a­ture leads to a 400 MW drop in de­mand for elec­tric­ity. This is be­cause ACs ac­count for some 30 per cent of Delhi’s elec­tric­ity de­mand and over 60 per cent of its peak de­mand, ac­cord­ing to the data of the Bureau of En­ergy Ef­fi­ciency ( bee). In fact, the peak de­mand hour for elec­tric­ity is chang­ing. Now in­stead of evening—tra­di­tion­ally this is when peo­ple reach home and switch on lights—it is late af­ter­noon. This is when the house­hold and com­mer­cial elec­tric­ity-us­age hour is co­in­cid­ing. So it is ACs that de­ter­mine elec­tric­ity de­mand and will de­ter­mine en­ergy ef­fi­ciency and se­cu­rity.

So how ef­fi­cient are the ACs sold in In­dia? More im­por­tantly, if they are rated to be en­ergy-ef­fi­cient do they per­form as ef­fi­ciently? My col­leagues at the Cen­tre for Science and En­vi­ron­ment ( cse) de­cided to find out by get­ting branded ACs rated five-star by bee tested for per­for­mance. The tests re­veal that there was a dip of 2.5 per cent in en­ergy ef­fi­ciency for ev­ery de­gree rise in tem­per­a­ture. In this way, a fives­tar AC per­formed worse than a one-star AC when tem­per­a­ture was 45°C. Why does this hap­pen?

Quite sim­ply be­cause we have adopted test stan­dards that do not suit our tem­per­a­tures. The In­ter­na­tional Or­ga­ni­za­tion for Stan­dard­iza­tion has three dif­fer­ent stan­dards for test­ing the per­for­mance of ACs: mild, cold and hot weather con­di­tions. In­dia’s isi stan­dard has been de­rived from this, but by adopt­ing mild weather con­di­tions. This means ACs are rated for en­ergy ef­fi­ciency based on their per­for­mance in 35°C am­bi­ent tem­per­a­ture and 27°C in­side. The same ma­chine is also tested un­der max­i­mum (46°C) con­di­tions, but this is not to de­ter­mine its en­ergy ef­fi­ciency. In this way, when you buy your AC, re­mem­ber bee/bis, which sets the stan­dard, has only cer­ti­fied that it will work with cer­tain ef­fi­ciency when the tem­per­a­ture out­side is 35°C.

This is when the Na­tional Build­ing Code ( nbc) data shows that out of the 60 cities sur­veyed, 41 cities, in­clud­ing Delhi, had tem­per­a­tures over 35°C for 175 hours in a year—these are hours that de­ter­mine peak loads. This is bound to in­crease, with heat is­lands grow­ing in cities be­cause of con­crete and mi­cro-cli­matic changes. Clearly, the test­ing method needs to be changed.

But this is not all that de­ter­mines the en­ergy ef­fi­ciency of ACs. In 2006, bee started its en­ergy stan­dards and la­belling pro­gramme. In 2010, en­ergy-ef­fi­ciency stan­dards for ACs, set in terms of the en- ergy-ef­fi­ciency ra­tio, were made manda­tory and the last re­vi­sion was in 2014. What is shock­ing is that In­dian AC stan­dards re­main way be­low global bench­marks. The specious ar­gu­ment is that we are a poor coun­try, and so, I as­sume, we should con­tinue to be swamped with out­dated tech­nolo­gies by In­dian and multi­na­tional com­pa­nies. Last heard bee was “re­vis­ing” these stan­dards up­wards but the re­vi­sion is de­layed. So the AC en­ergy-ef­fi­ciency stan­dard, which was to ex­pire in 2016, is now no­ti­fied by bee to con­tinue till 2018.

Worse, when bee “cer­ti­fies” that an AC is star-rated, it does this based on the man­u­fac­turer’s self or third party ef­fi­ciency re­port. Amaz­ing trust! Amaz­ing reg­u­la­tions!

This is not all in the AC story. The us­age of these ma­chines has to do with us and our idea of com­fort. Ac­cord­ing to nbc, ther­mal com­fort lies in the tem­per­a­ture zone be­tween 25°C and 30°C, with op­ti­mal con­di­tions at 27.5°C. What is never told is what will hap­pen to the en­ergy ef­fi­ciency of our ma­chines and their op­er­at­ing cost if we crank down tem­per­a­tures. cse’s study found that run­ning ACs at low tem­per­a­tures of 20°C has huge en­ergy penal­ties—2 per cent drop in the en­ergy ef­fi­ciency ra­tio for ev­ery de­gree tem­per­a­ture low­ered be­low the 27.5°C op­ti­mal com­fort level. In this way, the per­for­mance of a five-star AC be­comes equal to that of a two- or three-star AC when we run it at 20°C, nor­mal for most of us. This is also be­cause com­fort is de­ter­mined, not just by what we set AC tem­per­a­ture at, but also by the amount of ven­ti­la­tion we have and, of course, the clothes we wear. If you work your air-con­di­tioner with a con­ven­tional room fan your com­fort goes up, sim­ply be­cause there is more breeze, hence more ther­mal com­fort. But who de­signs mod­ern build­ings with ven­ti­la­tion? This is the age of sealed and cen­trally air-con­di­tioned build­ings. Fans are con­sid­ered notso-cool. In life­styles we have been sold as mod­ern, it is the wow fac­tor that works and we over-cool our spa­ces and then wear cli­mate-in­ap­pro­pri­ate clothes—suits and ties in sum­mers.

If we are re­ally cool then let’s get AC maths and our clothes right. That is the real en­ergy game-changer.

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