In the domestic electricity consumption, out of the total (say) 20 units per day consumption, more than 10 units are consumed by the Air Conditioning System (AC). If the same is monitored by just retrofitting a single phase static watt-hour meter costing around Rs 400, then we can have day to day control on consumption of electricity for the purpose of air conditioning in domestic and commercial segments. That will prevent us from receiving annoying over inflated electricity bill after each month.

Need for monitoring AC systems

Energy measurement is the first step towards the energy management. Whether logging of consumption should be done on daily or weekly or monthly basis that depends on the usage of AC, as well as how an individual responds proactively. While using an AC, we must know the energy consumption for running it daily. Also, we should compare that with the total consumption per day in the domestic or commercial environment.

If more than one AC system is running in the premises, ‘relative condition monitoring’ of daily kWH of each of them will make the consumer think why the daily kWH difference is occurring among the AC systems operating in the same premises? The difference in kWH in daily readings will promptly draw attention of the energy conscious consumer to conserve energy.

Earlier, I advocated that each existing AC system should be fitted externally with an hour meter costing Rs 400/. But addition of hour meter inside the new generation (already installed) AC systems is cumbersome. But for old window and split AC, this hour meter can be easily added on to the compressor thermostat circuit indoor.

Also, I suggest that AC OEMs can add this hour meter as an integral part of the indoor AC system. This will show an AC machine’s total run-hours, and the AC compressor’s cut-in/cut-out hours – to indicate the AC user how effectively he uses his AC system in his premises.

When we buy star-rated AC systems for Rs 20,000 or more, they (AC system manufacturers) must integrate this hour meter in their indoor units. In AC usage, everyone is accountable to local and global warming. As the energy-inefficient AC users contribute to reduce energy consumption and global warming potential, the government should offer tax reduction on the 5-star-rated AC systems and similar other electrical gadgets.

Because of the fall in price of the kWH meters from Rs 1000 to Rs 400, these days it is much more easy for the AC consumer to assess his AC system’s health by monitoring its daily consumption for the same given run hours. However, it is always better to assess an AC system’s health by knowing the parameters like AC compressor’s run-hours, AC machine’s run-hours and the total consumption in the run-hours. This will give the clear picture of the AC machine’s efficiency.

Reasons behind day-to-day varying power consumptions of the AC machines

Even if the same AC machine runs for nearly the fixed hours each day, its power consumption varies each day due to many factors. Following is a list of some of them:

  • AC indoor temperature settings are generally set from 20 to 26oC. But it varies depending on every individual’s need
  • Clogging in the AC evaporator filter goes unnoticed (it needs to be cleaned once in two weeks)
  • Condenser coils getting choked over a period of few months to years
  • AC outdoor unit can be torched under the sun or we can comfort the same by weather roofing
  • The refrigerant leaks minutely over a period when not noticed; AC runs more hours to cool
  • The AC compressor run-hours vary due to operating for more hours or more people inside
  • The conditioned air when leaking out of premises, forces the AC compressor run fully
  • When heat sources like fridge, deep freezer come inside premises, they increase the AC run hours
  • Higher ambient outside and solar heat ingress from the roof increase the AC run hours.

Practical way of daily monitoring

Please find below, the technical details of Rs 400 rated Static Watt-hour Meter as taken from The consumer can choose any similar branded meter of this type near this price to suit to his needs.

  • 1 phase, 2 wire, Accuracy Class: 1.0
  • Conformation with IS:13779, original ISI rated
  • Current: 5 to 30 Ampere AC as load current
  • Reference voltage: 240 Volts, Reference frequency: 50 Hz
  • Display: Electromechanical counter with one decimal
  • Surge resistant and tamper proof with magnetic shielding
  • Sustained accuracy over long period of time
  • Low power consumption
  • High insulation and dielectric strength
  • LED indication for current reversal tampering and phase availability
  • Durable polycarbonate enclosure, which is UV protected, flame retardant.

How is this meter hooked up?

This kWH meter needs to be fixed between the MCB isolator to the AC stabiliser inside the conditioned area. Or, if the user has only one AC, the same can be fixed near the EB mains distribution board from where, the user has run a heavy conductor cable to match the AC load. In offices, IT, ITES work spaces where individual machines are working, this can be fixed near the indoor unit at a readable level from the floor.

Applications of relative monitoring

  • Relative condition monitoring of air conditioners (if more than one fixed) inside premises
  • When the AC is serviced, the daily kWH reduction before and after the service done
  • When ACs are serviced, to give more attention to service to excess power consuming AC system
  • Same area cabins and same size AC why still the varying kWH consumption can be studied
  • KWH reduction can be noticed instantly on every AC: in-house efficiency improvement
  • In case of overcharging, kWH consumption increases first to show impending breakdown
  • If the stabiliser malfunctions or due to heavy voltage variations, the kWH varies • If two AC systems at the same premises are of 3-star and 5-star respectively, the 5-star savings can be confirmed by monitoring.

Govt to mandate the ‘monitor to target energy reduction’ programme

  • The govt has taken the initiatives to the AC system conservation. Through the ‘star labelling programme,’ it has spread the AC energy consumption awareness. But the govt gave the carrot only till now to the consumer and not the carrot & stick to them. It has promoted 5-Star ratings in AC; and year after year, BEE is changing the AC star ratings now, improving the 5-Star efficiency ratings
  • Showcasing the energy conservation is the first thing. But prompting the AC user with kWH meter is more of ‘DO IT YOURSELF TO CONFIRM YOUR ACHIEVED SAVINGS.’ We have to catalyse the energy efficiency practices by forcing the consumer to practice
  • The proof of pudding is in the eating. The govt has showcased the AC efficiency norms. But same govt must mandate each of the AC consumers to verify with this type of affordable kWH meter to his existing AC. On condition monitoring his AC daily, weekly and monthly, each consumer will start saving electricity in his AC. The same consumer will showcase his savings to his neighbours, friends around him; this attitude will multiply and improve the energy efficient people culture
  • So, to cultivate the energy efficient people culture among AC users, the govt has to make it compulsory to fix kWH meter in each and every existing AC system. Then each AC user will monitor his AC consumption to target reduction in his existing AC first. Later he will automatically switch over to 5-star rated AC
  • The energy experts in BEE and in the ministry said in 2012, that energy-efficient electrical appliances (majority is AC only) used in household and commercial establishments can save about 20,000 MW (Mega Watt) of power per year, resulting in savings of Rs 1.2 lakh crore in capital investment on new power plants. India spent ` 23,000 crore in clean energy programmes till 2011. BEE says in 2012, that around 1.15 crore labeled air conditioners have been sold across the country during the past five years
  • When the new AC consumer is buying his AC system, he must be mandated to buy this kWH meter along with AC to fix during installation. It is similar to the agriculture segment, the farmer is mandated to buy capacitor along with his new purchase of motor. This gives saving to him and reduction in T & D loss in rural sector
  • When the consumer has decided to spend Rs 20,000 + towards his new AC; over the counter, he can be convinced to buy this static kWH low cost meter for the sake of monitoring
  • What will happen to the AC system user after installing this retrofit kWH meter to his AC after a few months /years of run?
  1. He’ll be 1st shocked to find his AC’s guzzling power use all these years
  2. Next, he will find relief in implementing in his AC, the zero cost energy efficient running practices
  3. Next, he will be delighted to see more savings after implementing low cost ECON measures to his AC
  4. Later, the consumer will be happy to share and showcase his kWH savings achieved in his AC to others.

All the above govt suggestions will become a reality practically today, if this one step is enforced by the govt to promote consumer’s existing and new AC efficiency in domestic and commercial segments.