India’s Thermostat War: The Surprising Science and Strategy Behind the 24°C AC Mandate 

India’s push to standardize air conditioner temperatures at 24°C is a strategic response to its exploding AC market, which saw a record 14 million units sold in 2024. This policy, led by the Bureau of Energy Efficiency, is a compromise aimed at reducing the significant 25-30% share of peak energy demand attributed to cooling. While the “magic number” is based on an estimated 4-6% energy saving per degree and is politically acceptable, it faces challenges due to India’s diverse climate.

High humidity in coastal regions can make 24°C feel uncomfortable and force ACs to work harder as dehumidifiers, undermining efficiency. The mandate also battles a cultural tendency to overcool, seen as a status symbol. Ultimately, this rule is a key part of India’s broader climate strategy, including the India Cooling Action Plan, to ease grid stress and cut carbon emissions, but it must be complemented by better building design and a shift to renewable energy for a sustainable cooling future.

India’s Thermostat War: The Surprising Science and Strategy Behind the 24°C AC Mandate 

As the Indian summer relentlessly pushes mercury levels past 45°C, a silent battle is being waged over a few degrees on a thermostat. In homes, offices, and public spaces across the nation, a new mantra is being promoted: 24°C. This isn’t just a random suggestion; it’s a calculated policy at the heart of India’s ambitious climate and energy security goals. 

The numbers are staggering. In 2024, a record 14 million air conditioning units were sold in India. By 2030, this figure is projected to more than double. This explosive growth places an immense strain on the national power grid, with cooling alone accounting for a staggering 25-30% of India’s peak energy load. In a country where only 8-10% of households currently own an AC, this represents both a massive challenge and a looming crisis as affordability and accessibility increase. 

The Union government’s push to standardize AC temperatures, most recently through guidelines proposed by Power Minister Manohar Lal Khattar, is more than a nudge—it’s a critical strategy to keep the lights on and advance the Net Zero by 2070 mission. But why this specific number? The answer is a fascinating blend of human physiology, engineering, political pragmatism, and a nation’s fight against a warming planet. 

The Art of the Possible: A Policy Forged in Compromise 

The Bureau of Energy Efficiency (BEE) first mandated 24°C as the default setting for new star-rated ACs in 2020. The recent proposal to hardwire a range (20-28°C) into all new units is a reinforcement of this policy. 

Ajay Mathur, a former director general of the BEE, reveals the candid truth behind the choice: “We chose 24°C because it was technically viable and politically acceptable. We would have pushed our heels in and said 26°C, but 24°C was something everyone could agree on.” 

This admission highlights the delicate balancing act of policy-making. The science of energy savings provided a clear framework. Manufacturers indicated that energy consumption spikes by roughly 6% for every degree lowered below 22°C. The savings become less dramatic at higher temperatures. By anchoring the default at 24°C—a midpoint—policymakers aimed for a significant energy saving of 4-6% per degree, without triggering widespread consumer rebellion against a setting that might feel too warm. 

The Myth of the “Magic Number”: It’s Not Just About Temperature 

The most common misconception is that thermal comfort is solely dictated by the temperature on the thermostat. In reality, the human body’s perception of comfort is a complex equation involving four key factors: 

• Air Temperature: The reading on the thermostat. 

• Humidity: The amount of moisture in the air. 

• Air Velocity: The speed of moving air (from fans or AC vents). 

• Mean Radiant Temperature: The temperature of surrounding surfaces (like sun-heated walls). 

“Asking someone to maintain four parameters is very impractical,” explains Professor Rajan Rawal of CEPT University, whose team developed the India Model for Adaptive Comfort (IMAC). “So we use ‘operative temperature,’ which accounts for all four.” 

This is where the 24°C guideline faces its toughest test: India’s incredible climatic diversity. 

In the dry, scorching heat of Rajasthan, a well-ventilated room at 28°C might feel perfectly comfortable. However, in the humid coastal climates of Kolkata or Chennai, where relative humidity can hover near 100%, even 24°C can feel clammy and uncomfortable. Here, the AC isn’t just cooling the air; it’s working overtime as a dehumidifier. This extra latent load keeps the compressor running longer, increasing energy consumption even at the same temperature setting. 

“When humidity is high, the same 24°C can feel very different than in dry heat,” notes Satish Kumar of the Alliance for an Energy Efficient Economy (AEEE). 

This diversity exposes a research gap. Sumedha Malaviya from WRI India points out, “A lot of these [comfort] studies have been done for North Indian climates. There is a need for more research on temperature ranges for thermal comfort in the South and eastern parts of the country.” A one-size-fits-all policy, while necessary for broad implementation, inevitably has limitations at the local level. 

Cold Culture: The Psychology of Overcooling in India 

Beyond climate and science lies a powerful behavioral hurdle: a deeply ingrained cultural association between powerful air conditioning and luxury, status, and effectiveness. 

• Thiagarajan, Managing Director of Blue Star, identifies a key issue: “Many users set the temperature far lower than necessary.” This often happens because installers leave units at 18-19°C after testing, or because consumers believe a lower setting will cool the room faster—a misconception, as the AC cools at the same rate until it reaches the set point.

This leads to the absurd yet common sight of people wearing jackets and using blankets in movie theatres, malls, and offices during peak summer. This wasteful overcooling is a direct contributor to the nation’s energy peak and a symbol of inefficient cooling culture. 

The Stakes: Grid Stability, Emissions, and a Sustainable Future 

The push for 24°C is not an abstract exercise in comfort; it has direct, measurable consequences for India’s future. 

• Grid Stability: With peak demand already touching 250 GW, an additional 60-75 GW is sucked up by cooling. Unchecked AC growth could push cooling-related demand to nearly 100 GW by 2030, risking blackouts and necessitating massive, costly investments in power infrastructure. 

• Carbon Emissions: India’s grid still relies heavily on coal, emitting approximately 727 grams of CO₂ for every kilowatt-hour of electricity generated. The BEE estimated in 2018 that shifting from 20°C to 24°C could save 20 billion units of electricity annually, preventing 16-18 million tonnes of CO₂ emissions. In the context of the **India Cooling Action Plan (ICAP)**—which aims to reduce cooling demand by 20-25% by 2037-38—these savings are critical. 

Beyond the Thermostat: A Holistic Cooling Strategy 

Informed experts agree that fiddling with the thermostat alone is not a silver bullet. The truly sustainable path forward involves a multi-pronged approach: 

• Passive Cooling Design: The best watt is the one you never need to use. Architects and builders are emphasizing features like cross-ventilation, green roofs, reflective coatings, and better insulation to naturally keep buildings cooler and reduce the dependency on ACs in the first place. 

• Super-Efficient Technology: Continued innovation in inverter ACs, and the development of newer, greener refrigerants are essential to ensure that the millions of new units sold are as efficient as possible. 

• Renewable Energy Integration: Ultimately, decarbonizing the grid itself by shifting to solar, wind, and other renewables will break the link between cooling and carbon emissions. 

As Professor Rajan Rawal puts it, “Access to cooling is a must for health and productivity, but consumption has to be responsible… The solutions are always somewhere in the middle, not at the extremes.” 

The 24°C mandate is a pragmatic first step in a much longer journey. It’s a symbol of a nation reconciling its right to development and comfort with the pressing realities of a climate crisis it did little to create. It’s a signal that in India’s quest to stay cool, efficiency and responsibility must become the new status symbols. The goal is not to shiver indoors, but to be comfortable wisely, ensuring that the pursuit of personal comfort doesn’t collectively heat the planet beyond repair.