How to Calculate Air-conditioning Capacity in m³

In commercial environments such as offices and hotels, suitable air conditioning capacity is the main factor in providing comfort. With special types such as clinics, childcare facilities, and nursing homes, It is also very important in ensuring health.

This article will guide you through understanding the importance of air-conditioning capacity, how to accurately calculate air-conditioning capacity in m³ for commercial spaces, and the factors that influence your calculations.

Whether you’re installing a new system or renovating an existing one, this article will help you make the right decisions at every step.

● What is cooling capacity?
● A standard formula for quick calculation
● What factors affect cooling requirements in commercial spaces?
- Internal heatload
- Occupancy
- Building characteristics
● Detailed guide to calculating accurate cooling capacity
● How to choose the right air conditioner
- AC type
- Correct capacity
● Practical tips for implementation
- Consult air-conditioning professionals
● Conclusion

Cooling capacity – measured in watts – refers to an air-conditioning system’s ability to remove a certain amount of heat from a space.

In commercial environments, the AC capacity requirement is significantly higher compared to residential areas due to factors like large number of people, longer operational hours, and the additional heat generated from machine.

Understanding the cooling capacity needed for a specific space is key when choosing air-conditioning systems. You need systems that can handle these increased demands without wastage of resources.

So where do you start? First, you need to get a preliminary estimate of the cooling capacity required for a space. To do this, you can apply a basic rule of thumb: Typically, 70 watts of cooling power is needed per cubic metre of room volume.

For example, a room with a 100 m² floor space and a ceiling height of 3 metres equates to a volume of 300 m³. Therefore, the initial calculation for cooling capacity would be:
● Volume: 300 m³
● Required cooling capacity: 300 m³ x 70 watts/ m³ = 21,000 watts
This simple estimation gives you a straightforward starting point to gauge the air-conditioning needs of a space.

Appliances, lighting, and electronics can emit a significant amount of heat, which impacts the overall cooling needs of a room. A simplified approach suggests that you can increase the cooling capacity by approximately 10-20% for rooms with major heat-generating sources, like older lighting or large appliances.

However, with the use of more energy-efficient devices like LED lighting, the heat load from electricity may be much lower in some cases. For a more precise calculation, it’s recommended to refer to ASHRAE guidelines and other sources, which provide detailed heat load data for specific electrical appliances. This allows for a more accurate estimate of how much heat these appliances add to the space.

To convert these values into a heat load per cubic meter (m³) for your room, you’ll need to perform some additional calculations. For users seeking a more accurate heat load calculation, it’s important to understand that this article provides a simplified method to give a general idea, but referring to more detailed sources will give better accuracy.

A good approach for advanced users is to calculate the heat load per appliance as proposed by ASHRAE and others, rather than just estimating based on room volume.

Each person can emit as much heat as a 100-watt light bulb – even more in active or crowded spaces. You can add about 117 watts per person to your initial cooling calculation to account for human heat in occupied spaces.

It’s also crucial to consider the materials used in the building. If the room is made from heat-absorbing materials (like cement mortar) and the building is non-insulated, it will retain even more heat. In such cases, you may need to increase cooling capacity even further to compensate for both the heat from appliances and the heat-absorbing materials.

For example, buildings with a lot of glass, which absorb heat easily, can have higher indoor temperatures, requiring more cooling efforts. Checking whether your building has a lot of glass, and the direction of the sun, can help you determine the cooling capacity needed.

You can choose between centralised and split air conditioning systems – but the choice largely depends on the size, layout, and specific cooling requirements of the commercial space.

Centralised systems are ideal for larger commercial spaces such as shopping centres, large offices, or entire buildings where consistent cooling across multiple rooms or areas is required. Centralised systems are more complex and generally involve more extensive installation and maintenance, but they offer efficient cooling and can be easier to manage once they’re in place.

Split systems are suitable for smaller commercial spaces or for buildings where individual rooms require different temperature settings. Split systems consist of an outdoor unit and one or more indoor units, offering flexibility in cooling specific areas independently. They are typically easier and less expensive to install compared to centralised systems and can be scaled by adding more units as needed.

Accurate sizing of the air-conditioning unit is important. If it’s too large it won’t remove humidity effectively, and if it’s too small it will be inefficient for cooling the entire space.

Going too big
An oversized unit cools the room quickly but does not efficiently remove humidity, leading to a damp or clammy feeling. Additionally, it takes higher operation and maintenance costs.

Going too small
An undersized unit will struggle to cool the space adequately, running continuously and using more energy, which can drastically increase operational costs and lead to early system failure.

Always consult with professionals who can provide a comprehensive assessment based on the specific characteristics of your commercial space. They can conduct detailed load calculations, suggest the best systems for your needs, and identify potential challenges in your building’s layout or structure.

Professional installation is crucial to ensure that the system operates as intended. Regular maintenance by professionals can also prevent minor issues from turning into major problems, extending the lifespan of your system.

Consider upgrading to newer models that incorporate advanced technology for energy efficiency. Look for features such as inverter technology, which can significantly reduce energy consumption by adjusting the speed of the compressor to control the refrigerant (cooling agent) flow rate according to the need.

Understanding how to calculate the appropriate air-conditioning capacity is crucial for any commercial space who wants to enhance environmental comfort.

With this guide, businesses can approach their HVAC installations and upgrades more confidently, ensuring that their cooling systems are perfectly tailored to their needs.

Remember, professional advice is invaluable in achieving the best outcomes in air-conditioning investments.