CONTEXT

• Rising temperatures have led to increased air conditioner (AC) usage across India, especially in cities like Patna.
• The Union Ministry of Power is considering regulations to cap AC temperature settings between 20°C to 28°C.
• Aim: Balance energy efficiency, public health, and comfort standards in AC usage.

CONCEPT

• Working Principle of AC:
  • Based on the vapour-compression cycle using refrigerants.
  • Heat is absorbed by the evaporator, compressed, and released via the condenser.
  • The compressor stage consumes the most energy.
• Thermodynamic Efficiency:
  • ACs operate most efficiently within a specific temperature band where refrigerants optimally absorb and release heat.
  • Power consumption increases when pushing room temperatures too low.
• Energy-Saving Science:
  • Every 1°C increase in AC temperature saves 6% electricity.
  • Setting ACs at 24°C could save 20 billion units of power annually (Bureau of Energy Efficiency).
• Health Implications of low temperatures (<18°C):
  • Increases risk of hypertension, vasoconstriction, and respiratory infections.
  • Can lead to sympathetic nervous system overactivation and systolic pressure spikes (6-8 mm Hg).
  • Studies link cold indoor temps to higher cholesterol, low vitamin D, and weakened immunity.
• Comfort Standards:
  • ASHRAE-55 and ISO 7730 define comfort based on mean skin and core temperature stability.
  • 20–24°C is ideal for heat dissipation in lightly clothed individuals without sweating.
  • WHO recommends 18°C as the minimum safe indoor temperature in cooler climates.

CURRENT

• Policy Proposal: Temperature cap of 20–28°C for new AC units in homes, cars, and hotels.
• Past Attempts: In 2018 and 2021, govt. proposed default setting at 24°C with public awareness campaigns.
• Research Support:
  • Japan, UK, NZ studies show better respiratory health and sleep quality at 18°C+.
  • UK 2022 study: Cold homes linked to 2x risk of depression/anxiety, even after income adjustment.
• IEA Data: 2 billion ACs globally (2022); Asia-Pacific cooling demand growing.

MAINS QUESTION

1. What is the scientific principle behind the working of air conditioners, and how does thermodynamic efficiency impact energy consumption?
2. Discuss the health implications of setting AC temperatures too low (<18°C) and the benefits of optimal temperature settings.