The main motive of this project, is to maintain cabin temperature to 25 ˚C by optimizing A.C. operation through continuous inside and outside Shelter/cabin temperature monitoring. And according to the temperature difference, Air Conditioner and Air damper will be controlled through controller. Here, Air damper mechanism is used to inject outside air in the cabin to maintain inside temperature to reduce energy consumption.

Free Cooling System Arrangements:

Fig. 01: Pictorial view of Free Air Cooling System

As shown in fig.01, there will be two air damper arrangement containing, Air filter, Fan and motorized damper. These two air dampers are controlled trough smart controller as per temperature difference conditions inside and outside the shelter/Cabin. The orientation of the air dampers is such that, one is situated at lower corner (FAN-1) and another is at opposite upper corner (FAN-2) of the cabin. This orientation will help to evacuate upper hot air accumulation effectively. Here Air filter are used to filter out external dust entering the shelter.

Working and Operation:

Before further description, let’s have a look on monthly average temperature profile for Year 2016-17 and few days of hourly temperature profile for Indore region shown in Fig.02 and Fig.03 respectively.

Fig.02: The average monthly Temperature Profile for year 2016-17

The above graph (Fig.02) depicts average monthly max. and min. temperature trends. Through this trend, it is easy to understand that, even on the peak summer months (from march to July) we get minimum temperature up to 25˚C which is usually occurs at mid night, during 2:00 AM to 7:00 AM. So, this time can be utilize for free cooling using air dampers without using air conditioner.

Fig.03: Hourly Temperature Profile from 7th to 10th April 2017

For more macroscopic understanding, hourly temperature profile for three consecutive days has been plotted, as shown in figure (Fig.02.). Here, 25˚C is inside set temperature and wavy profile shows outside temperature. Through this profile, it is easy to understand that, at the month of April we can use free cooling, during 12 AM to 8 AM. And even at the peak June month, we could probably get minimum 4-5 hours for free cooling per day.

Note: Above mentioned Temperature profile may vary according to different geographical regions!! And according to that, inside temperature setting can be done manually.

Operating Conditions:

Controller output Operation according to different temperature conditions for inside and outside of the shelter are shown in Table.01. Inside Temperature setting can be done manually as per requirement. Here, 25˚C temperature is considered for analysis and Saving calculations.
Note: ±2˚C temperature difference with respect to set temperature, will generate control signals…

Energy Saving Calculation:

Energy saving calculations are done for Air Conditioner and Free Cooling system at different operating hour combination within 24 Hours, are shown in Table.02. Calculations were done by considering power rating of Air Conditioner and Fans as mentioned below:

From Table.02, it is understood that, as increase in Free cooling hours, there will be huge savings. As per yearly temperature profile observation (refer Fig.02), we found that, few days at June reached minimum temperature near to 25˚C, but beside that, we found at least 4-5 hours for free cooling per day. And throughout the year free cooling hours can reach maximum up to 20-22 also. Therefore, the estimated Average Annual minimum saving can be 62397 Rs. (Considering 10 Rs./Unit Commercial E.B. charge).

Fig.02: Graphical analysis at different Operating Hours V/S Energy Savings


  • Implementation of Free Cooling System with Air conditioner can deliver huge energy savings as compared with conventional operational practice. considering the month of “September-February” and “March-August” the minimum average free cooling hours obtained will be 12 hours with 57,597 Rs. savings and 6 hours with 28,799 Rs. savings respectively. 
  • And the estimated average annual minimum savings can be 62397 Rs. (@ 10 Rs./Unit commercial E.B. charge).
  • According to the obtained savings, the estimated Return of Investment period will be approx. 7 months (@ 10 per unit E.B. cost and 35,000 Rs. product cost).