Energy Efficiency - Air Conditioning - Comfort Cooling

What is Comfort Cooling?

Typically, Comfort Cooling system uses principle of ‘two stage evaporative cooling’. Evaporative cooling uses the principle of cooling air by evaporating water. Comfort Conditioning system uses fresh air, unlike conventional air conditioning systems (where the in-take of fresh air is limited). They are eco-friendly & energy efficient compared to conventional air conditioning systems because they do not require a compressor/condenser/refrigerant and, therefore, do emit GHGs/CFCs.

Evaporative cooling can be either direct (which leads to the addition of moisture) or indirect (so called sensible cooling which does not lead to the addition of moisture). Evaporative cooling can also be a two step process where indirect evaporative cooling is used in the first phase and then followed by direct evaporative cooling.

What are the applications of Comfort Cooling?

Comfort Cooling can be used in common areas in commercial buildings or in industries where rooms need to be cooled but cannot or need not be air conditioned.

Commercial/Industrial Area where comfort cooling can be used
Hotels Lobby areas, corridors, gyms, employee cafeteria, kitchen, laundry.
Hospitals Corridors, cafeteria, waiting rooms.
Educational institutes Multi-function hall, class rooms, laboratories, etc.
What are the geographical areas in India where Comfort cooling can be used?

In India, Comfort cooling can be used in all areas except for coastal areas (cities and towns such as Chennai, Kolkata, Mumbai, Vizag,). In coastal areas, where the humidity level is on the higher side throughout the year, Comfort conditioning using evaporative cooling does not reduce air temperatures significantly.

Can Comfort cooling be used throughout the year in non-coastal areas?

In most non-coastal areas of India, hot & dry climate prevails for most of the months. Comfort conditioning works well in many parts of India for the entire summer and winter months. In the monsoon months of high humidity, the two stage evaporative cooling works by switching off the second direct evaporative stage and having only the first direct evaporative stage work. This switch on/off function can be controlled by the humidity percentage of the ambient air.

How is the capacity of a Comfort cooling system specified?

The capacity of a Comfort cooling system specified in terms of volume of fresh air flow: cubic feet per minute (CFM).

A small size system is 10,000 CFM and is adequate for cooling a space of 2000 sq. feet. On the other hand, a relatively large size system is 30,000 CFM which is adequate for cooling an area of 6,000 sq. feet. However, heat load & application area where Comfort Conditioning system is to be installed should be considered to arrive at suitable machine capacity (CFM).

What are the costs and benefits of installing a Comfort cooling system?

The comfort conditioning system, when compared to an existing air conditioning system, uses less power. The example below reflects a typical example:

Comfort Cooling system Air Conditioning system
Area 5000 sq. feet 5000 sq. feet
Capacity required @ 120 sft/TR=42 TR @5cfm/sq. feet =25,000 CFM
Power consumption 46.20 kW (@1.1 kWh/TR) 12.118 kW
Diversity* 70% 90%
Actual consumption 32.34 kW 10.91 kW
Average working hours/day 10 10
Consumption/day 323.4 kWhr 109.1 kWhr
Number of working days 300 300
Consumption/year 97,020 kWhr 32,719 kWhr
Capital Cost Rs. 8,00,000 depends on type of AC. The costs of a packaged AC are similar to that of a comfort cooling systems. The costs of a window/split AC could be smaller
Savings in the annual operational costs of a comfort cooling system (at Rs. 8 /kwhr) Rs. 5,14,408

*Diversity is a measure of how many times/hours does an air conditioning system “come on”. This arises because the systems are thermostatically controlled.

As a potential customer, what are some of the questions that I should be asking?

Q. Is Comfort cooling a substitute to air conditioning?

Comfort cooling performs many of the functions of air conditioning. It reduces the air temperature in rooms so as to increase human productivity. The difference with conventional AC systems lies in the degree of control on temperature and humidity. In conventional AC systems, the indoor room temperature & humidity can be precisely controlled throughout the year whereas the performance of Comfort conditioning system depends on ambient air conditions.

Q. Can Comfort cooling be used in areas where the indoor humidity needs to be controlled?

Comfort cooling is not recommended in applications where the indoor humidity needs to be carefully controlled. Comfort cooling systems will not reduce the humidity. However, if application demands 100% fresh air with controlled conditions, then the two stage process can be used with indirect evaporative cooling followed by conventional air conditioning. This can substantially reduce the load on the conventional air conditioning systems.

Q. What are the health benefits of Comfort cooling?

Comfort cooling uses fresh air, unlike conventional air conditioning systems where the intake of fresh air is limited to 10 to 20%. The re-circulated air in air-conditioned systems is often high in carbon dioxide and in disease causing bacteria. Comfort conditioning solves some of these problems.

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