Why Modi Govt’s Plan for a 24°C Default for ACs Is a Great Idea

There was outrage about a nanny state, but here’s the real deal.

Launching a campaign to promote energy efficiency last week, power minister RK Singh said the government would likely mandate 24°C as the power-on default for air-conditioners in India.

The news report was promptly criticised, misunderstood, debated, then aggressively defended by a troll pack confused about its weekend to-do list – whether to viciously attack Sushma Swaraj, or valiantly support a technical setting they didn’t really understand so well themselves.

It didn’t help that the PTI report had added that temperature settings in ACs would henceforth be in the range of 24°C to 26°C. There was outrage about a nanny state, and outrage and abuse aimed at those outraging.

One female TV anchor faced three days of trolling and abuse over her question on this issue. Overall, a normal weekend on Twitter.

While the minister said this could save 20 billion units of electricity in a year, this is extreme optimism. This mandate isn’t kicking in till 2019, and it will affect only new ACs.

What Will a 24°C Default Setting Do?

Let’s get three little things out of the way first.

• A 24°C power-on default temperature is an excellent idea. It means that at first power on, or when settings are reset, the AC should start up at 24°C, instead of 18°C as many ACs tend to do. A 24°C setting is far better for us humans, who are at 37°C, apart from saving lots of energy. More on this in a bit.
• Yes, you will be able to set the AC temperature up or down, after power on. The government won’t stop you. I would have been happier if they implemented a 5-minute delay before letting you lower the temperature. Some nannies are good. But no, you’re free to jump to 18°C or 29°C after power-on. Though, as the minister tweeted later, an AC set to 18°C does not cool any faster than an AC set to 24°C.
• This may not actually make a big difference, on its own. That’s because most ACs use digital remotes, which store settings. Like Japan’s offices, I keep my home ACs at 28°C. When I power off, and power on later, they simply re-use my last settings of temperature, mode, fan speed. My ACs don’t do this, but the remotes do.

Manufacturers will need additional complex logic to tackle this. A remote could be set to ‘remember’ only temperatures above 24°C, so if it was at 28°C when I powered off, it should come back on at 28°C the next time. But if I had stepped down to 19°C, the remote should power the AC back on at 24°C. But this is logic that will be up to vendors to implement, not the government to prescribe.

The “allowed range of 24 to 26 degrees Celsius” was a misquote in news reports. There’s no such restriction. The power minister was likely saying that setting your AC at 24°C will give you a room temperature of between 24°C and 26°C.

What’s a Good Setting? Japan Says 28°C

It depends on whether you’re using a ceiling fan or not. At home in Gurgaon, I set daytime aircon temperature to 27-28°C, and 29°C at night, with fans on slow. Outside, it’s a sweltering 40°C, with a relative humidity of 45 percent. Inside, it’s a pleasant 27°C at 25-30 percent humidity, fan on slow. In my Delhi home, a TERI GRIHA green building, we often don’t use the aircon at all.

It also depends on whether you use a quilt or cover at night. If you do, in summer, you’re wasting energy. I know some people get a kick out of sleeping in 18°C with a thick quilt. They also like bathtubs, or running a hot shower for 10 minutes while they’re away shaving.

Don’t use a quilt, and you’ll find 29°C with a fan perfect, or 27°C without a fan.

Our Gurugram condo tower’s main lobbies used to be set to 18°C. I had them reset to 29°C. Comfortable, when you step in from 44°C. It’s unhealthy, if you’re moving from summer outdoors to 18°C for two minutes, en route to the lifts.

What about offices, with no fans? That’s where around 26°C of actual temperature is considered perfect. Japan has chosen 28°C though.

Japan is a nation that went from energy surplus to a severe crisis, and used aggressive energy management to bring down its power demand by 12 percent in the summer of 2011. It moved to LEDs from tungsten (almost bypassing CFL/fluourescent bulbs). And it changed the average temperature in office buildings from 26°C to 27.6°C in 2011.

After its Fukushima nuclear plant core meltdown following the 2011 tsunami, Japan took its nuclear power plants offline, causing a hit of 30 percent to its national power grid. Even today, only 8 of 42 functional reactors are in operation, in five power plants.

Since 2015, Tokyo has been promoting its ‘Cool-Biz’ campaign, asking firms to set cooling temperature at 28°C, and wear light cottons in summer instead of suits. This has been controversial.

Academics have pointed out that 26°C is an optimal temperature, 28°C is a maximum, and that efficiency of workers at 28°C declined by 6 percent compared 25°C (in a call centre), resulting in worker overtime.

India’s choice of 24°C for power-on default does not affect what offices, hotels, homes or trains are set to. They can still choose to set 18°C and freeze your butts off. But if they do set thermostats to 24°C, which would usually mean that a well-designed office building would remain in the 24-26°C range, that’s a comfortable range.

And picking 27-29°C at home can save you a load of energy and money, while you refocus your energy and outrage on other real issues, like Aadhaar, privacy and the nanny state.

(Prasanto K Roy (@prasanto) is a technology policy professional whose South Delhi house was the first certified TERI GRIHA green home in India. This is an opinion piece and the views expressed in this article are that of the writer. The Quint does not endorse nor is responsible for the same.)