Metro Train Simulation

Air Conditioning Simulation for Home / Room

Air Conditioner Rating and Energy Consumption Calculation for Home / Room :

An air conditioner is basically a heat pump; it pumps heat from the inside area of the room/hall/building (cold regions) to outside atmosphere (warm regions). Naturally, heat flows from warm regions to cold regions. To reverse this natural flow of heat, the air conditioner unit takes energy from electric supply source and pump the heat from cold regions to warm region. Ideally, refrigeration of 1 ton for 24hr is equal to the cooling effect of one short ton of ice ( i.e. 907kg ) melting in 24hr period. To neutralize the effect on 1 ton cooling, a heater of 3.517kW will be required in the same room. That's why, Wikipedia / google search engine shows 1 ton of refrigeration is equivalent to 3.517 kW or 12,000 BTU/hr. Whereas, during actual operation of 1 ton Air Conditioner unit, it takes approximately 1.1kW power ( depend on the star rating of AC ). Therefore, which one is right? If both are right, what are the differences between them? Actually, both are right. It means that Air Conditioner of 1 ton capacity removes heat equivalent to 3.517kW heater from building inside area to outside atmosphere and to complete this job, Air Conditioner unit of 1 ton takes power of approximately 1.1kW from electric supply source.
The tonnage capacity required to control the room temperature and humidity depends on several factors like room size, outside atmosphere temperature and humidity, number of persons in room, power rating of electrical appliances used in room, area of doors and windows, number of walls and window facing the sunlight, air conditioner thermostat set temperature, insulation of walls, infiltration losses (depends on the doors opening frequency for passage, air leakage through window/cracks), fresh air circulating / exhaust fan capacity, number of things/stuff kept inside the room, window curtains colour etc. An oversized air conditioner is not good because it may reduce the temperature much fast but can not control the moisture/humidity level inside the room perfectly. The compressor of oversized AC unit may switch 'ON' and 'OFF' frequently, without running long enough to dehumidify the room properly or cool the space uniformly. The frequent starting and stopping of compressor, relay etc. can lead to shorter life span of the equipment. An oversized air conditioner unit will have both a higher initial cost and a higher operating cost. On the other side, an undersized AC unit will not be able to cool the room properly in extremely hot weather.
A well designed air conditioning system has duty cycle of 80 to 90 % during peak loading conditions. Duty cycle is the percentage of the ratio of compressor 'ON' time to the total period (i.e. compressor 'ON' time + 'OFF' time). Thus, a 80% duty cycle means the compressor of AC is on 80% of the time but off 20% of the time. Therefore, the optimum size of the air conditioner for given peak loading conditions may be finalised based on the value of compressor duty cycle obtained from the simulation results, considering operating time from 01:00 PM to 05:00 PM.


Sunlight falls on the roof Sunlight do not fall on the roof
Basement or Ground Floor First or Higher Floor
Window Air Conditioner Split Air Conditioner
During Day Time During Night

#Note: Please read Para 'Limitations of online Air Conditioning Simulation tool for Home / Room'. This is an online demo simulation tool and results of online Air Conditioning simulation tool may have some error due to these limitations. However, our offline software tools do not have such limitations and provide much accurate simulation results. For detailed simulation of Building / Train HVAC system, write us.

Important facts regarding Air Conditioning System:

1. Water vapour holding capacity of air depends on its temperature and increases with increase in the air temperature. Relative humidity or % humidity is defined as the ratio of the actual amount of water vapour in the moist air at any temperature to the maximum amount of water vapour, that the air can hold at that particular temperature and pressure. Thus, if the temperature of a closed room is increased, the water vapour holding capacity of air will increase but the content of water vapour in the room air will remain same (because room is closed) which results into reduction in % humidity and vice-versa. The relative humidity is 100% if the air is saturated with water vapour. Absolute humidity is defined as the mass of water vapour present in a unit volume of moist air.

2. Thermal comfort is defined as “that condition of mind which expresses satisfaction with the thermal environment”. Important factors which affect thermal comfort are the age, sex, health, activity, clothing, air temperature, % humidity and air velocity. It should be noted that since so many factors are involved, many combinations of the above conditions provide comfort. A range of recommended temperature and humidity for comfort zone is given below:
Summer : 23°C - 26.6°C and 40 - 60% RH
Winter : 20°C - 24°C and 30 - 50% RH

3. If compressor of air conditioner unit turns 'ON' and 'OFF' frequently, it indicates an oversized air conditioning system. A well designed air conditioning system has duty cycle of 80 to 90 % during peak hot weather conditions. An oversized HVAC system will have both a higher initial cost and a higher cost of operation.

4. Cooling capacity of air conditioning system reduces with increase in atmosphere temperature. As per Indian Standards 1391: Room Air Conditioners; the rating of air conditioner unit mentioned on nameplate is tested at outside atmosphere of 35 degree Celsius. Therefore, for atmosphere temperature more than 35 degree Celsius, the effective tonnage capacity of air conditioner unit will be less.

5. Co-efficient of Performance (COP) or Energy Efficiency Ratio (EER) of air conditioner unit is the ratio of heating or cooling provided by AC to the input electric power consumed by AC in watts. 1 ton of refrigeration is equivalent to 3517 watts or 12,000 BTU/hr. Higher the EER or COP, higher the efficiency of the air conditioner unit. Air conditioners with 5 star BEE rating have higher value of COP or EER as compared to lower star BEE rating. A 5 star split air conditioner has the value of COP or EER more than 3.5, while a 2 star split air conditioner has the value of COP or EER in the range of 2.9 to 3.09. The value of COP or EER may be used to compare the performance of two models of same tonnage rating. Air conditioner having higher value of COP or EER, indicates its better performance and efficiency.

6. Split air conditioners have higher EER value as compared to window air conditioners for same BEE star rating and tonnage capacity. Split AC is lot more energy efficient, silent in operation as compared to window AC and looks aesthetically pleasing, but is relatively more complicated to install and has higher initial cost as compared to window air conditioner.

7. Regular cleaning of air filters, heat-transfer coils and fins increases the air quality, cooling capacity, efficiency, life of air conditioning system and save electric energy. Energy-efficient lights like LEDs and CFLs emit a smaller amount of heat as compared to normal incandescent bulbs/halogen bulbs for same illumination level. Thus, normal incandescent bulbs/halogen bulbs should be replaced with LEDs / CFLs to reduce the cooling load on air conditioner systems and save the energy.

8. If the room is facing east or west, additional capacity is needed as it will be exposed to the morning and evening sun compared to a room that faces north or south.

9. Maximum temperature of the day occurs during 2.00 to 4.00pm while the minimum temperature occurs in the early morning. The density of dry air is more than the density of humid air.

10. If your requirement for a room/hall is 3 ton, it is advised to use two unit of 1.5 ton.

11. Air conditioner with inverter technology has capability to adjust the tonnage capacity by varying the compressor motor speed to maintain the desired temperature with minimal fluctuation to ensure that your comfort is not compromised. However, in conventional air conditioners, the compressor will operate at maximum speed to reach the desired temperature quickly. Once the desired temperature is achieved, the compressor turns 'ON' and 'OFF' on a regular basis to maintain the room temperature near the set value.

Limitations of online AC System Simulation :

1. Infiltration losses (depends on the doors opening frequency for passage, air leakage through window/cracks) is considered 2 ft3/minutes.

2. In this simulation, the compressor of air conditioner unit will be turn 'OFF' , if the room temperature goes below the set temperature - 1.5 degree Celsius limit and air conditioner unit will be turn 'ON' , if the room temperature goes above the set temperature + 1 degree Celsius limit.

3. Constant atmosphere temperature is considered during the complete simulation however the value of atmosphere temperature vary with time. Atmosphere pressure is considered 760 mmHg.

4. User can not input the value of sensible and latent heat of passenger, heat transfer coefficient of walls, roof, floor, windows etc.

5. The % humidity of outside atmosphere is also considered for % humidity inside the room.