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3 Simple Steps to Choosing the Right Size Office Air Conditioning System

Posted by Tim Foster on 18-Apr-2018 15:27:04

3 Simple Steps to Choosing the Right Size Office Air Conditioning System - NEW1

Heated discussions in the office are great for the business process as long as the employees are not sweating their socks off. A good, correctly sized office air conditioning system is one of the key factors which make staff and visitors comfortable. Without physical comfort, it’s hard to strive for optimum service delivery.

How do you choose the right size office air conditioning system without boosting your energy bills? Below we look at basic rule of thumb calculations to indicate the correct capacity system for your needs. We strongly recommend you get your local company in to carry out a full technical survey so a much more in-depth heat load calculation can be carried out, rather than relying on rule of thumb calculations.

Step 1: Calculate The Size Of Your Office

Measuring the office size is vital to choosing the right capacity office air conditioner. Depending on how your office is designed, you may need one or several units.

  • Open plan area’s – this is the simplest office space to evaluate. All you need to do is measure the length and width.
  • Smaller Offices – It’s more energy efficient to cool the smaller offices individually than the whole office space. That’s why it’s enough to measure the office length and width to install a smaller air conditioner.
  • Hallways, corridors, reception – These areas are generally not occupied by office workers so you may want to save on cooling those. However, if your staff still suffer from heat, you may consider calculating the size of the largest hallway and place an air conditioner there, or make sure the system cools the front of house area for the comfort of guests.

Step 2: Calculate Required Cooling Capacity In kW Or BTU’s

The output of your office air conditioning system should suit the size of your room(s). Even the most expensive unit designed for a 10m² room won’t cool a 50 m² facility.

Office Size (m²) Output
10 1.5 kW – 3 kW
15 2.5 kW – 3.5 kW
20 3 kW – 4 kW
25 3.5 kW – 4.5 kW
30 3.5 kW – 5 kW
40 4.8 kW – 6.2 kW
50 5.2 kW – 7.2 kW
60 6.8 kW – 8 kW
70 8 kW – 10.5 kW


You can also take advantage of a variety of cooling calculators available online for free. At ACE Services, we can carry out in depth heat load calculations to ensure we calculate the capacity of your office air conditioning correctly based on all factors, we will then offer you several cost-effective options to consider. The size and type of the office air conditioning system may vary depending on the individual company requirements.

If you prefer to work in Square feet and BTU’s please use the table below.

Square Feet BTUs
0 - 150 5,000
150 - 200 6,000
200 - 250 7,000
250 - 300 8,000
300 - 350 10,000
350 - 400 12,000
400 - 450 14,000
450 - 500 15,00
500 - 600 18,000
600 - 700 20,000
700 – 800 22,000
800 - 900 25,000


Step 3 : Choose The Office Air Conditioning System Type

There are several different types of air conditioning system you can use to cool your office. Some may be more appropriate than others based on your budget and building layout.

  • Split systems – consist of a single fan coil and single condensing unit. The fan coil unit is installed indoors and the condensing unit is mounted outdoors. The heat is removed from the room and rejected to atmosphere via vapour compression cycle.
  • Multi-Split Systems – the operation scheme is the same as for a regular single split system but you can have up to six indoor units connected to one condensing unit.
  • Variable Refrigerant Flow (VRF) systems – These systems are available in heat pump or heat recovery models and can connect up to 50 fan coils to one condensing unit. VRF systems are very energy efficient and suited to larger scale applications.
  • Portable air conditioners – Portable units that dispose of air through a hose, which runs through a window.

Find Out More

Speak to one of our air conditioning specialists today on 01296 428783 to find out more about choosing the right air conditioning system for your office building. You can also email us for more information at sales@aceservices.uk.com

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