Wednesday, April 19, 2017

Air conditioners ISEER rating; Power consumption calculations from ISEER rating

ISEER Rating you often spotted on Commercial advertisements for air conditioners and every company is claiming that they are giving highest ISEER rating and rating is also mentioned for the same. They also even claim that their product consumes very low electricity. Now it becomes very important to know about what is ISEER rating? How it is very important parameter before buying a product. In this article we will study about ISEER rating.
With everyday new inventions in air conditioning it becomes important for BEE to introduce methodology for measuring efficiency of air conditioners. With invention of inverter air conditioners, it was thought that it may not be successful but inverter air conditioners become very successful. But they were introduced without any star label which becomes very important factor while buying any electrical/ electronic product. So people want star rating of inverter air conditioners. To overcome this problem ISEER was introduced. 
Earlier for measuring performance of Traditional air conditioners EER was introduced.
EER - Energy efficiency ratio also known as coefficient of performance
EER is measured as ratio of output wattage (i.e. cooling capacity) and Input power taken by air conditioner.
EER= Output Wattage (Cooling capacity)
         Input Power taken by Air conditioner

From formula Stated above Traditional air conditioners efficiency can be ascertained, this efficiency can be further divided into 5 groups named according to star rating of air conditioners. This star rating works very well for Traditional air conditioners.
For Inverter air conditioners this formula doesn’t work as both cooling capacity and Input power taken by air conditioner vary.
SEER was introduced known as Seasonal Energy efficiency ratio. In every season temperature will not be constant and keeps on varying. So working principle behind SEER is that temperature will not remain constant throughput the year. So as there are variations in temperature so are the cooling requirements vary e.g. cooling requirements will be different to cool a particular space at 40 degree , 45 degree and 35 degree so as operating hours of air conditioners.
SEER has taken care of all these factors i.e. temperature variations throughout year and air conditioners usage pattern. So SEER will different in different countries as temperature profile will be different. Now what BEE has done that they had defined ISEER i.e. Indian Seasonal energy efficiency ratio.
ISEER = Total annual amount of heat Air conditioner can remove from the indoor when operated at active mode
                                   Total annual amount of energy consumed by the Air conditioner

Thus ISEER is the ratio of heat removed to total energy consumed.


A complete guide for right rating selection and installation guide for air conditioners:-
This is best used when there are two air conditioners compared and also there usage will be same, but as usage may be different so electricity consumption may be different.

When you are going to compare Star ratings of different types of air conditioners, Window, Split and inverter,  it becomes quite difficult to compare air conditioners . Standards defined are even provide detailed information for the same. Although with introduction of EER for fixed speed air conditioners (Split and Window)  and ISEER for inverter air conditioners help in selection of air conditioners a lot and compare them also.
As per national weather records temperature distribution and operating hrs of air conditioner are as below, Data taken from BEESTARLABEL.COM:-


In above Temperature range is shown in 1st Row.
In Second row are Average Annual Hrs which indicates temperature remains for no. of Hrs.
In 3rd row is Fraction which is fraction of total no. of Hrs for which temperature remains
In 4th Row is No. of operating Hrs of Air conditioners- In 4th row total Hrs are also selected as 1600 hrs.  
Now BEE has made ISEER rating according to star rating of air conditioner but this is not mandatory and it was introduced in 29/06/2015 and will remains valid until 31/12/2017.  According to this star rating and corresponding ISEER rating is below:-
1 Star – Minimum ISEER rating should be 3.10 and Maximum ISEER rating should be 3.29.
2 Star- Minimum ISEER rating should be 3.30 and Maximum ISEER rating should be 3.49
3 Star - Minimum ISEER rating should be 3.50 and Maximum ISEER rating should be 3.99
4 Star- Minimum ISEER rating should be 4.00 and Maximum ISEER rating should be 4.49
5 Star- Above 4.50

BEE is making mandatory from year 2018 will be valid up-to Dec’19 onwards that for Star rating and corresponding ISEER rating, e.g. for
1 Star – Minimum ISEER rating should be 3.10 and Maximum ISEER rating should be 3.29.
2 Star- Minimum ISEER rating should be 3.30 and Maximum ISEER rating should be 3.49
3 Star - Minimum ISEER rating should be 3.50 and Maximum ISEER rating should be 3.99
4 Star- Minimum ISEER rating should be 4.00 and Maximum ISEER rating should be 4.49
5 Star- Above 4.50
Rating are same but BEE has made it mandatory from 2018.

Now days you have seen that Air conditioners are coming with ISEER rating of 5.8 even.
With recent launches in air conditioning it was found that dual inverter AC will save 834 units in-comparison to 5 star split air conditioner.
Air conditioners with having capacity of 1 ton will be capable for disposing off heat  of 12000 BTU (British Thermal Units)
Why Air conditioner’s capacity is measured in Ton:-
Air conditioners 1 Ton doesn’t indicates that it’s weight is 1 ton. Actually this indicates amount of heat that air conditioner is capable of removing from house in one hour. 1 ton of air conditioner will be capable of removing 12000 BTU/Hour heat from house. But still question remains why Ton is unit of measurement for air conditioner capacity.
Before invention of air conditioners people used ice for cooling purpose. They take that ice from frozen lakes or rivers. Now for melting 1 pound of ice 143 BTU are required at 32 degree Celsius, this means that if you have 1 ton equivalent to 2000 pounds of ice then 28600 BTU are required to melt the same. If this ice block is melted uniformly throughout the day than 11917 BTU/ Hour will be required which is rounded up to 12000 BTU/ Hour, which was the methodology adopted for arriving out at 1 ton AC capacity.

How Power consumption is related to ISEER rating of Air conditioners:-
12000 BTU/ Hour 3517 Watt/hour  power
Now for Assuming the ac to be a 3 star rated, its ISEER=3.5
For 2 ton AC ,power consumption of ac =cooling capacity/ISEER
                                                                            =2*3.517/3.5
=2.00 kWh.
In Split and Inverter air conditioners there are two units , Indoor unit is known as evaporator and outdoor unit is known as compressor. Most of power is consumed by outdoor unit only i.e. compressor only. Compressor get started only when indoor temperature is more than desired temperature. So you can assume that compressor will remains ON only for 60-70% of time so power consumed will be 60-70% of 2 KWH.
So from above you will see that more will be ISEER , lesser will be the power consumed by air conditioner per hour.

A complete guide for right rating selection and installation guide for air conditioners:-
http://electrialstandards.blogspot.com/2017/04/air-conditioner-complete-selection-and.html