• Cooling India
  • Oct 15, 2017

Minimizing Air Conditioner Usage

The optimization of air circulation inside the premises is that to ensure adequate but mild air changes inside the premises, and not air blast by the old ceiling fans. This enables you to minimize the air conditioner settings from 22* C to 27 * C first thus comforting you mildly with air conditioning + air circulation around you. Automatically, this will reduce the running AC hours, less AC KWH units consumed per day now…

- Ashok Sethuraman

 Air conditioner usage makes everyone of us accountable to local & global warming. First the AC user, as electricity consumer, and next the AC OEM who had given previously, yester-year-starred AC but now poorly rated, and last but not the least, the Govt, which needs to promote mandatorily, the energy conservation in AC, AC run hour & KWH monitoring, Star rated AC promotion and sales tax reduction in star rated AC & other energy saving & monitoring gadgets.

  The optimization of air circulation inside the premises is that to ensure adequate but mild air changes inside the premises, and not air blast by the old ceiling fans. This enables you to minimize the air conditioner settings from 22* C to 27* C first, thus comforting you mildly with air conditioning + air circulation around you. Automatically, this will reduce the running AC hours, less AC KWH units consumed per day now.

Human Body Comfort Temperature for Cooling Air & Hot Water

  India’s climate suited the human peak hour productivity per day because of the ambient temperature near to our body temperature at 37 degrees C Plus / Minus 5* degrees C, that is 32 to 42 degrees C with comforting RH of around 55 percent. Human is comforted by the temperature, that is 10 *C less than 37 *C, the human body temperature. Hence, raise the AC setting to 27*C from 22 *C and this gives minimum of 10 % electricity savings. And storage water heater set at 47 –50 band in*C gives power savings. Ultimately, 10*C above & below cooling and heating is better for the human body medically than higher settings.

Govt Initiatives to Promote Air Conditioner Related Savings

  The energy savings in air conditioner can be achieved in three ways:

1. Improving generation efficiency in air conditioners – Low cost to High cost ECON measures, possible.
2. Improving the distribution efficiency in AC air – Zero cost to Low cost ECON measure, possible.
3. Reducing the Air conditioner settings and usage – zero cost to low cost ECON measures possible.

  The Govt plans now for the zero cost measure to ask the AC users to set to 24 *C minimum as the AC lower digital cut-off set point. The government has taken the right step on the AC usage aspects to raise the settings from 18* to 24 * C in AC remote hand set. They are planning to instruct the AC OEM to keep the AC digital settings at 24 * as lower cut-off from 18*C presently. Air conditioners sold in the country currently have a fixed lowest minimum temperature of 18°C. The government has to approve and implement few more measures, listed below to achieve energy savings in air conditioners and thus, a step towards reducing electricity supply –demand gap in the national grid by air conditioner loads in summer months.

Figure 1: Non-Invertor AC short cycles more after the first cycle and could maintain wider AC temperature band only

What AC OEMs Can Offer?

  Also the Government can simultaneously promote the combo schemes to monitor AC consumption and target towards reduction.

1. When an AC vendor sells one AC, the government can guide to sell along with, one BLDC fan for mild air circulation.
2. AC user can be advised to have one KWH meter, one run hour meter and AC OEM can provide in their AC indoor.
3. Latest automatic voltage stabilizer with output settings at 220 Volts +/- 5 % as ratings. (Now it is 10 % volts).
4. User can go for Optional Aircon Saver to trim down his power bills in new or existing AC room temperature settings.
5. One spare AC air intake filter to keep as active spare routinely cleanable by the user himself.
6. All the above measures can reduce AC energy by more than 30 % in power & run hours from the existing full load consumption.

Optimize Air Velocity & Circulation

  According to researchers of Toyohashi University of Technology in Japan, airflow from an AC stimulates the human body while sleeping and impacts on sleep conditions even if the mean airflow velocity is lower than an insensible level. In this study, a comparison was made on the influence of two types of airflow, mean velocity of 0.14 m/s (general AC) and 0.04 m/s (customized AC), both at a room temperature of 26 degree C.

  The participants felt cooler with the higher airflow velocity during wakefulness and sleep. However, no significant difference was observed in the feeling of comfort, length of sleep depth, skin temperature, rectal temperature or sense of warmth or coolness in each subject before sleeping. The result is useful clue as to how to configure the airflow velocity of an AC to create a comfortable sleeping environment.

  Now to improve air circulation, the user can install a BLDC ceiling fan and operate the same at mid position thus consuming 10 Watts only, and effectively air is circulated from top to bottom only, and not scattering to outside. This practice increases the human comfort because of mild cool air breeze circulated around our human body.

  Referring to Figure 1 now, let us work towards flattening the same compressor duty cycle curves first and approach to narrow down the AC temperature settings in non-inverter AC bought now instead of switching over to buy a new inverter AC.

Figure 2: Choked window Netlon PVC mesh and the removed Dirt

Figure 3: Split AC Indoor Air filter choked with dust

Figure 4: Building ventilation in CO2 ppm and limits to maintain.

Energy Saving Possible By AC Users

  Air conditioning consumes 20 times more power than the power consumed for air circulation by ceiling or fresh air fans. Let us live by adhering to the nature surrounding us, at the same time mildly comforting ourselves first by air circulation only, then only by air cooling utilizing the ambient wet bulb temperature characteristics. The ceiling fan is comforting the man by two ways namely by Evaporative Cooling and by air circulation. To achieve both the functions, the fan has to breathe in more from its top area under the ceiling. The ceiling fan especially the BLDC type needs to be mandatorily fitted in AC room or hall application.

  Based on the above and the image below, the intelligent air conditioner today, runs on high speed on the first cooling cycle, and then run at slow speed between cut-in & cut-out temperature settings. AC without room fan will make the cooled air throw at one area and hot pockets in other areas in the room are not medically good to us. Practically felt, it is really the light weight bladed ceiling fan + AC, is comforting the humans now.

  Referring to Figure 2, Netlon PVC mesh window cleaned once in six months yields heavy dirt and dust. Figure 3 shows choked-split-AC filter in hospital, once a month. So, wherever windows are provided now, better to retrofit the routinely but frequently cleanable window PVC mesh screens. Dust spreads in choked window air filter screens are blocking air way passages and results in poor fresh air circulation. Domestic or any building needs first and primary Netlon type PVC window filter. In a non-AC premises or partly-used AC premises, fresh air circulation needs to be ensured first for free positive cross air flow through windows, doors, openings, vents.

  In 24 x 7 humans-occupancy halls or buildings, indoor air quality IAQ parameters as described in Fig 4 by portable & in-situ monitoring is becoming mandatory for the OHS, the Occupational Health & Safety of the staff working inside the building. If this is monitored and controlled within the norms, this will lead to less health hazards arising out of poor IAQ. Respirable Suspended Particulate Matter is one of the air pollutants in the surrounding ambient air. But CO2 is also a factor towards poor IAQ which causes mental fatigue syndrome in prolonged working hours in In-door. And, CO2 is measureable easily and is one symptom of ventilation efficiency. (Courtesy: Inputs from ISHRAE)
Now, many existing AC users are using retrofit electronic gadget costing only few thousand rupees to their AC so that the gadget’s sensor-driven software algorithms are designed to detect the AC compressor’s thermodynamic saturation and optimizes the same. In fact, this retrofit is a sensible move taken by the AC user and this gives around 20 % savings in the existing rated AC. Instead of going for new inverter duty AC, this is a low cost option available to you in between, to optimize your AC running cost. Referring the image, the main idea is to smoothen ups & down of AC room temperature.

Monitor AC kWh Consumption Daily To Target Reduction

  Thus, AC OEM can help consumer to monitor AC and its compressor run hours in usage. This is what BEE says “Monitor your energy usage to target the reduction of the same.” The consumer will be made aware of the AC kWh consumption per hour in its total run hours, and relatively compare his AC efficiency with others around for the given same application like bedroom, office cabin, computer room, etc.

  In the residential electricity consumption, out of total say 20 units per day consumption, and more than 10 units is consumed by the AC. If the same AC is monitored by just retrofitting single phase Static Watt-hour meter costing just Rs 400/-(ISI branded static Watt-hour single phase rated 5 to 30 amps), then we can have, day to day control of AC electricity consumption in domestic and commercial buildings, instead of annoying over inflated monthly EB bills, coming later.


  Thinking and acting on conservation measures catalyzes our social responsibility, caring for others and sacrificing our selfish comforts. When we are safe and healthy, conservation prevails. If safety fails, conservation fails and pollution starts. So, comfort our AC machines to get more input power savings, first target the input power to appliances, and reduce the same, monitor the individual energy consumption & optimize the same, thus, paving for greener environment.

If you want to share thoughts or feedback then please leave a comment below.