CFCs, HCFCs, & HFCs
Used in cooling appliances like Air Conditioners and fridges, CFCs are a type of refrigerant. The Montreal Protocol, an action mandated by the UN, was designed to protect the ozone layer by phasing out substances responsible for its depletion like CFCs.
CFCs were succeeded by HCFCs or hydrochlorofluorocarbons, which were not free from ozone depletion either. HCFCs were ultimately succeeded by HFCs which had no impact on the ozone. The new breed of ACs and fridges have only HFCs. However, not all manufacturers comply with these standards.
The conundrum of HFCs is, while they have no ozone impact, they have a global warming potential 1000-2000x that of carbon dioxide.
Coming to the question of what makes an air conditioner environment-friendly.
Criterion 1: Refrigerant selection
Environment friendliness of a refrigerant is a relative measure, and also a new one. There’s constant research to determine better alternatives. However, nothing can yet be declared environment-friendly in an absolute sense. While considering air conditioners, there are 2 things that place the final verdict on its environmental impact.
1. Refrigerant used
2. Energy efficiency.
According to research done by Drawdown, refrigerant management has the potential of avoiding emissions equivalent to 89.7 gigatons of carbon dioxide in the next few decades.
So what exactly is a refrigerant?
A refrigerant is a substance used to cool a heat source. It passes through the heat source, takes up the energy and then dumps it into a system with lower temperature. This is then cooled down again so the cycle can repeat itself.
Not all refrigerants are equal. Even amongst the ozone free ones, there are some that are much less harmful than others. This is decided by their Global Warming Potential (GWP).
GWP is an indicator of how a refrigerant compares to carbon dioxide. The most commonly used refrigerant in the market today is R410a. While it is ozone-free, it has a GWP of 1700. This means it contributes to global warming 1700 times more than CO2. Clearly not the ideal option, but definitely better than its predecessor R22 – which not only has a higher GWP but also depleted ozone. Here’s a table to show which refrigerant is the better one:
Criterion 2: Energy Efficiency
A. Star Label
There are many ways to check if your air conditioner is energy efficient. The first and most obvious way is to check its the Star Label. 4-5 Star rating for the current year is the best option.
B. Condenser/Coil Material
ACs subtract heat from indoor air and transfers it outside. That transfer takes place in the coils usually made of copper and sometimes of aluminium. Copper has a heat transfer coefficient higher than aluminium. That means, copper is a better heat exchanger than aluminium and improves the efficiency of the air conditioner. AC with a copper coil is a more energy-efficient choice.
C. Room Size
The required cooling capacity for a room air conditioner depends on the size of the room. Many people buy an air conditioner that is too large, thinking it will provide better cooling. An oversized air conditioner may actually be less effective — and wastes energy at the same time. Same holds true for the reverse, a unit with lower tonnage than is suited to the room, may take longer than normal to cool, leading to lower efficiency, higher operational costs and short life.
D. Other factors
Other factors like the presence of an eco-mode will make the compressor run at higher efficiency, but lower cooling capacity. These are useful when the outside weather is not searing. In sleep mode, the air conditioner increases the temperature by half a degree every hour for four hours reducing the power consumed.