Science behind right AC temperature

Key Highlights:

• The Ministry of Power is considering fixing the temperature range for new ACs between 20°C and 28°C.
• A default setting of 24°C has been previously proposed to improve energy efficiency.
• Every 1°C increase in AC setting can reduce electricity consumption by 6%.
• The vapour-compression cycle of ACs operates most efficiently within a specific temperature range.
• The International Energy Agency (IEA) estimated over 2 billion ACs in use globally as of 2022.
• The WHO recommends 18°C as a safe lower indoor temperature, especially in colder regions.

Detailed Insights:

• The initiative is aimed at achieving dual goals of energy efficiency and public health protection.
• Previous government efforts sought to raise public awareness and promote voluntary adoption of 24°C as the default setting.
• According to the Bureau of Energy Efficiency (BEE), if widely adopted, 24°C could result in 20 billion units of electricity saved annually.
• Prolonged exposure to indoor temperatures below 18°C has been linked to increased risks of hypertension, asthma, and respiratory infections.
• Mental health concerns have also been observed, with colder homes associated with a higher incidence of anxiety and depression.
• The proposed policy aligns with international thermal comfort standards such as ASHRAE-55 and ISO 7730, which balance thermal comfort and energy use.
• The policy seeks to reduce strain on the national power grid, especially during peak summer demand.

Scientific/Technical Concepts Involved:

• Vapour-Compression Cycle: The refrigeration process used in ACs involving evaporation, compression, condensation, and expansion of a refrigerant.
• Predicted Mean Vote (PMV): A metric used to assess thermal comfort in a space based on occupant feedback.
• Thermoregulation: The body’s physiological process to maintain stable internal temperature.
• ASHRAE-55 & ISO 7730: International standards for defining acceptable indoor thermal conditions and comfort zones.

Mains Mock Question:
Discuss the rationale behind regulating air conditioner temperature settings in India. Evaluate the implications for energy policy, public health, and environmental sustainability.