By now, Singaporeans are no strangers to rising electricity prices in recent years due to the perfect storm of global factors such as the pandemic and the Ukraine war. Without a doubt, the use of air-conditioning is the main reason why my utilities bill has stubbornly refused to budge despite my best efforts to reduce the use of electricity. In earlier and crazier days, the highest we have clocked is 700 kWh in a month which is mind-boggling for just the two of us. These days, we’re aiming for around 400 kWh which is a tad higher the national average (oops) if I’m not wrong. Coupled with the fact that my Mitsubishi Electric Inverter air-conditioning system is fast approaching twelve years of age, it is now far from being the most efficient machine that it used to be when it was brand new. I have a Mitsubishi System 4 aircon installed with one larger BTU...