A step in the right direction – says CSE of power ministry’s move to fix starting temperature of room air conditioners at 24oC and not lower to save energy

June 25, 2018

This measure needs to be taken forward for both room ACs and centralised cooling systems in commercial and residential buildings to lower energy costs while meeting the optimum comfort level

  • According to power ministry, this move can save 20 billion kilowatt hours of electricity in one year -- only if adopted by ALL consumers. With a 1 degree drop in temperature set point of ACs, energy consumption increases by 6 per cent. This can upset the household and national energy budget and undermine energy security 

  • According to the National Building Code, in India’s climatic condition people are comfortable between 24 degree C and 30 degree C. Unnecessary lowering of AC temperatures can increase electricity consumption significantly and must be regulated

  • ACs are energy-intensive and high emitters of heat-trapping CO2. Unregulated usage can undermine energy insecure and aggravating environmental costs.

  • The next steps should be to set a similar temperature setting for commercial buildings with centralized cooling facilities. But combine this strategy with energy efficiency measures of cooling down buildings with shading, ventilation and appropriate insulation and also moderate the demand for cooling with effectively priced consumption-based billing

June 25, 2018: Centre for Science and Environment (CSE) says the new proposal of the Ministry of Power to fix the starting temperature of room air conditioners (RAC) at 24 degree C is a step in the right direction, as the current popular practice of fixing the starting temperature or switch ON temperature at 18-20 degree C increases electricity guzzling. Comfort targets can be met at a higher temperature setting and at lower electricity consumption.

According to the estimates of the power ministry, this new move can save 20 billion kilowatt hours of electricity in one year only if adopted by all consumers. At this stage this is only an advisory to make people aware of high energy penalty associated with operating ACs at lower temperatures. The Ministry has stated in its release that it may consider making this mandatory at a later stage.

This new move basically means that new RACs, when switched on, will start running at 24 degree C temperature unless changed by the consumer. Currently, manufacturers are free to set the default temperature at any level and often this can be lower than 20 degree C or even 18 degree C. This new step will make users more aware of the energy penalty associated with unnecessary lowering of AC temperature settings.

Says Anumita Roychowdhury, executive director-research and advocacy, CSE: “This is, however, only a small part of the larger reform of the air-conditioning manufacturing, labeling and usage management sector that CSE has been asking for -- but this is a move in the right direction.”

While the new proposal has finally got the AC industry’s nod, the initial attempts since 2016 to get the industry to agree with default temperature setting for ACs has faced resistance. Publicly available minutes of an earlier meeting of the Bureau of Energy Efficiency (BEE) have shown the industry’s reluctance to accept such moves. In fact, the BEE’s proposal of default set temperature of all air conditioners while switching ON at 27°C (which is in line with the testing temperature defined in IS 1391) was contested. Manufacturers had argued that if the ACs are programmed for default set temperature while switching ON, it will lead to discomfort to the user and it will always restart at 27°C instead of the set point preferred by the consumer.

To balance energy conservation and consumer comfort, the industry even suggested that a rider be added in the product user manual to state that “comfort zone for humans is 24-27°C, hence to conserve electricity and for comfort conditioning, air conditioner should be used between 24-27°C”. Industry did not want this to be mandated, but has now agreed to temperature set points for RACs.

It is also encouraging that the new release from the Power Ministry has mentioned that a similar temperature setting will be adopted for centralised cooling system for commercial buildings that will include airports, hotels, shopping malls, official and government buildings (ministries and attached offices, state government and public sector undertakings etc. CSE would urge the government to expedite the process.

Comfort is possible without freezing temperatures
In India, the National Building Code (NBC) defines and regulates indoor comfort standards for all buildings in the country. This has been in place since 1970s and the latest revision was issued in 2016. It says centrally air conditioned buildings need to maintain temperatures in the range of 23.5-25.5 degree C, while buildings with RAC it can be comfortable at temperatures up to 29 degree C and naturally ventilated buildings can be comfortable even at 34 degree C. While there can be arguments against segmented definition of comfort, the bottom line is that it is deemed uncomfortable for all building types to have indoor temperature lower than 23-24 degree C during summer. There certainly cannot be any justification for RACs to be used for cooling down to 16-18 degree C.

It may be noted that the NBC has already introduced adaptive comfort standards for buildings that use RACs intermittently to optimize energy efficiency and human comfort. This may guide further action on RACs.

Consistent with global good practice
Those who are doubtful about the government’s role in setting temperatures for ACs and cooling systems should know that globally, indoor temperature settings are regulated as part of indoor health and comfort standards.

Japan’s environment ministry has been running a successful ‘cool biz’ campaign since 2005, seeking commercial establishments and households to voluntarily set their indoor temperature at 28°C during summer and recommending people to adopt comfortable and season-appropriate dress codes. Japan recommends 28°C as default setting even for RACs: the overall approach is to target attaining the optimum ambient room temperature of 28°C. It is expected that mechanical cooling devices will deliver on that target running at that range of thermostat setting. Even in Hong Kong, the indoor temperature requirement is set at 25.5°C. 

California, as part of its Standard Operating Efficiency Procedures, mandates that “the temperature set point should be no higher than 68°F (20°C) in winter and no lower than 78°F (25.6°C) in summer, unless such a temperature in a particular job or occupation may expose employees to a health and safety risk”.

Similarly, Harvard University has introduced a temperature policy mandating set points should range from 74-78°F (23.3-25.6°C) during summer. London School of Economics (LSE) has mandated 24 ± 1°C at all its facilities for summer. Its website sternly states: “This provides for an optimum comfort vs. environmental benefit. … we cannot accommodate personal preferences that fall outside the above parameters.”

India needs to act, too
Such interventions to reduce energy intensity of AC usage have become necessary, as even at low market penetration, the impact of ACs on energy demand is immense. ACs can use up 80 per cent of the household electricity budget. A recent CSE study has shown that almost up to 50 per cent of electricity used during summer months in Delhi is consumed only for cooling. This quantum is so big that it can power nine cities the size of Chandigarh during summer months. Night-time peak demand for electricity can be higher than the day-time peak demand because of residential use of ACs. Such uncontrolled energy guzzling has enormous environmental and equity impacts.

A previous CSE study had also found that 5-star ACs consume -- on an average -- 20 per cent more energy than their labeling when outdoor temperatures hit 45°C, a common occurrence in northern India. It also noted that their cooling capacity dropped by 13-15 per cent. Said Roychowdhury: “We also tested ACs to run at 20°C indoor setting instead of standard requirement of 27°C and found that it led to a drop in energy efficiency by 15 per cent and cooling capacity by a staggering 20 per cent.” These tests were done independently and it is certain that if these conditions co-exist (which they do regularly), the performance of an AC will be exponentially worse.

Cooling is not about refrigerating ourselves, but about feeling comfortable. And comfort levels of buildings can be improved in many different ways other than setting RACs at low temperature levels. Proper shading, ventilation, air circulation, and appropriate insulation is needed to cool down a building. Fans can bring greater comfort at lower energy cost if used with RAC at optimal temperature. But new AC-friendly building designs are eliminating fans.

The intensity and duration of AC use can be reduced substantially if buildings are designed more sensibly to reduce heat gain. Summer heat gets trapped by climate-insensitive construction and a highly concretized urban-scape. Inappropriate architectural design and material used in the country -- such as glass-dominant structures, predominant use of concrete, and inadequate shading etc -- traps a lot of heat. Even though the nights are cooler, buildings cannot release heat effectively, and hence require active cooling.

The way forward
Mandate temperature set points for RACs and centralised cooling systems in commercial and residential buildings, aligning with NBC-recommended optimum comfort level of 26+ 2° C.

Adopt effective energy consumption-based billing to discourage excessive and prolonged use of RACs

Tighten AC standards and make AC labeling more effective and climate-sensitive.

Adopt a summer cooling action plan. For example, refer to international best practices such as requiring establishments to operate ACs at 26oC or above (as the one adopted by Japan and California). 

Adopt effective fiscal measures including more effective electricity pricing based on consumption to discourage indiscriminate usage.

Create policy opportunities for use of natural ventilation, shading and day lighting to improve thermal comfort and reduce mechanical cooling of spaces.

For more details, please contact:

Parul Tewari, The CSE Media Resource Centre, parul@cseindia.org / 9891838367.