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How to design an air conditioning system for a room?

Nowadays, air conditioning has become essential.  It is a refrigeration-based appliance that is commonplace in homes and businesses throughout the developed world.

An air conditioner provides comfort to you, your family and your co-workers.  It also contributes to the preservation of health, especially for people living in countries with extreme weather.

However, air conditioning design and installation is not easy.  You need to have professional knowledge and experience behind it and consider some key factors in order to implement it effectively.

Engineers discussing plans

What you should take into consideration?

When designing, air conditioning engineers and technicians typically focus on 3 main areas: health, comfort and energy-saving.


Firstly, it’s essential to make sure that the resulting air condition is clean, pure, and does not damage your health in any way.

Remember that a good air conditioning system can help provide cleaner air as filters can reduce mould, bacteria and air pollution in circulation.


The main goal with an air conditioner is to provide a solution for the occupants of the house or business in terms of providing a comfortable indoor environment.

This is why when designing an aircon system, you have to consider what type of air conditioning units suit best for the area served.

Energy Saving

People around the world are becoming more conscious when it comes to preserving the environment.  This is certainly the case when it comes to air conditioners too.

The type and size of the refrigerant system, as well as many other factors, affects energy efficiency and therefore contributes to energy savings.  By saving energy you will not only be saving money on a routine basis, but you will also be helping the planet.

It is also important to consider the bigger picture, such as housing design and adherence to government-specified heating and cooling energy load limits.

Woman saving energy

What are the First Steps when designing an Air Conditioning System?

Cooling Load

First of all, the heat or cooling load of the space has to be calculated in order to select adequate design conditions.  You, the occupant, are just once source of cooling or heat load.
For one room, size could easily be measured with a measuring tape.  However, if designing aircon for multiple rooms then it is better to look at the construction or house plans.

To calculate the cooling or heat load, you can use the base of 120W per square meter.  When the ceiling is high, the volume of the space has to be measured and considered also.  Otherwise you can just work on the square meters.

Building Characteristics

Particularities of a house or building have to be determined based on detailed information and the climate.

Also, the building materials, colours, insulation and forms related to the construction will all need to be taken into consideration.

Working blueprints

External Building Characteristics

Appropriate climate information will need to be specified in order to have a clear exterior design context.  This information can be found in a meteorological study of the house or commercial premises location where the AC is going to be installed.

What else to consider?

Anything that may affect the heating or cooling load of an area has to be taken into consideration.  Heat transfer through windows, walls, doors or even the ceiling should be accounted for.  For example, any sun rays entering the air conditioned space must be factored in.

The cool or heat load will be determined based on the size of area to be conditioned, number of people that will occupy the space, covering, size and position of windows and doors, type and location of lighting, and the presence of appliances, machinery and equipment.

How to Design an Air Conditioning System?

Make a Detailed Site Survey

In this first step, you may need to draw up an architectural plan if one doesn’t already exist.  This is needed to interpret the size and conditions of all areas that the AC will cover.

Calculate the Cooling or Heating Load

You can then perform a thermal balance of all the areas that you will air condition.  This will depend on the size of the rooms, the windows and the construction itself.

Also, you will have to analyse and compare partial heat loads that evolve during the day.

Air conditioner in housing project

Identify the Best Type of Air Conditioner

You have to narrow down the choices and select the best aircon system for your needs.   This could mean one that gives you the greatest versatility, fits within your budget of how much you want to invest, has suitable ongoing maintenance requirements and/or suitable energy consumption.

Remember that those options should also align with the required capacity for the area to be air conditioned.

Ducted Air Conditioning vs Split System

You have many choices regarding air conditioning systems; you can choose from ducted, wall splits, multi-head, cassette, box, package units, or any combination of these.

A ducted air conditioner is perfect for air conditioning and heating large buildings or to heat and cool your entire home.  It can be installed in your ceiling or under floor so it won’t be visible, except for ducted air outlets in the each room.

On the other hand, split systems were made to heat up or cool down individual rooms.  They are installed in the one specific room and don’t need any air ducts.  They are often referred to as ductless aircons as a result.

Choose Position for the Wall Unit

The best option is to install your air conditioner unit over where you sit or sleep.  By doing this, you don’t have to wait for the whole room to cool down or warm up before you start feeling the effects.

Also, you should find a high, clear location where you could install the indoor unit so your room will cool down or heat up more evenly as nothing will get in the way.

If you choose to install just one wall split air conditioner, you have to choose the room carefully for it to be most useful.  For example, it would make sense to install it in a room where you spend most of the time (e.g. living room) or require the most comfort (e.g. bedroom).