As manufacturers the world over struggle to find energy efficient refrigerant replacements for R22 and R410A at high ambients, a report by the Centre for Science and Environment (CSE), a research and advocacy organisation based in New Delhi, has shown that current, supposedly top-performing, air conditioners in India can show efficiency drops of 30% when the temperature heats up.
In Delhi, air conditioning accounts for about 28% of the total monthly electricity consumption during the hottest months. According to the BEE, ACs are responsible for almost 60% of Delhi’s peak electricity demand.
As the world’s fastest growing economy India is a huge market for air conditioning. It currently operates a system of a 1-star rating for air conditioners with a minimum EER of 2.7 up to 3.5 as the minimum EER for a 5-star rating.
According to the CSE, a current 5-star-rated split AC becomes energy-inefficient as soon as the temperature soars over 40ºC. In fact, it becomes worse than a 2- or 1-star rated AC. At above 45ºC, it is worse than a 1-star RAC.
The Indian Bureau of Energy Efficiency (BEE) claims that a 5-star RAC will save 20-22% of energy costs compared to a 1-star RAC. But the CSE study shows in peak summers, when temperatures are in the 40-50ºC range, a 5-star RAC can start consuming 10-28% more power than its declared capacity
Energy efficiency further deteriorates when users lower the room temperature artificially to levels below 27ºC.
The CSE has called on the Bureau of Indian Standards (BIS) and BEE to tighten energy efficiency standards and test procedures to reduce the margin of deterioration in the real world. It also notes that India’s energy efficiency standards are below those of many other countries including Australia, Brazil, Canada, China, EU, Japan, Korea, South Africa and the USA.
“We wanted to find out how AC units perform under different outdoor temperature conditions and how that affects the energy savings from the star labeling programme of the Bureau of Energy Efficiency (BEE),” said Anumita Roychowdhury, CSE’s executive director-research and advocacy.
CSE commissioned an independent NABL-accredited laboratory to test the RAC units. Three popular 5-star split models – from Voltas, LG and Godrej – were bought from the market and tested for their energy efficiency and cooling performances using the balanced ambient calorimeter method. These three brands are said to account for about 50% of the Indian RAC market. The tests looked at the effect of high external temperature on real world energy performance; the effect of lower internal room temperature on energy performance; and the effect of higher external relative humidity conditions.
Split air conditioners represent the largest growing sector in India, accounting for 61% of the market.
The test found that the EER of an air conditioner drops by an average 2.5% for every degree rise in external ambient temperature above 35ºC. Power consumption also increases as outdoor temperature goes up – on average by 1.9% for every degree rise in external ambient temperature above 35ºC. At the same time, cooling capacity drops by 1.4% for every degree rise in external temperature above 35ºC. Overall, an 8-21% drop was measured at 40-50ºC from the models’ declared cooling capacities.
Lowering the room temperature below 27.5°C – considered the optimum temperature by India’s National Building Code, also has an enormous effect on energy consumption. EER’s were shown to drop by around 2.19% for every degree of lowering of internal temperature below 27ºC.
India has adopted ISO test procedures for mild climate for its energy efficiency ratings – which is 35ºC outside and 27ºC inside. Additionally, a system reliability test is done at a maximum temperature of 46ºC. These ranges are lower than the ISO’s testing requirements for hot climate of 46ºC outside and 32ºC inside and a maximum temperature at 52ºC.
“The BIS should review and adopt additional tests at a higher and multiple temperature range appropriate for India for testing of energy performance of ACs,” said Anumita Roychowdhury.
Other countries with harsh summers have adopted multiple temperature ranges for testing RACs. Saudi Arabia has adopted both ISO mild and hot climate testing requirements. Bahrain adopted the Saudi model in 2016. Australia has a more stringent star rating system based on an annual efficiency calculation.