What on earth is the cooling load?

What on earth is the cooling load?

As part of our series on HVAC basics, we’re going to introduce cooling load. This is one of the key concepts in air conditioning, so is certainly worth giving some space. In our previous article, we discussed psychrometric processes. Before defining the cooling load, we’ll review some ideas from this article. 

One of these ideas was the notion of sensible heating and cooling, which simply put, is the removal or addition of heat from the air without changing the moisture content. Meanwhile, latent heat is the heat required to convert a solid into a liquid or a liquid into a vapour without a change of temperature. 

Cooling load is the rate at which sensible and latent heat must be removed from the space to maintain constant temperature and humidity. Naturally, this is important in regard to air conditioning and building comfort. Let’s look closer at the calculations and concepts.

How to calculate cooling load

A space’s cooling load is the measure of how much an air conditioning unit needs to work to cool a room of a given size, measured in BTUs or British Thermal Units. To calculate this value, an engineer will need to determine the dimensions of the space that needs to be cooled. Often, this will be a simple procedure performed with a good old fashioned tape measure. For larger projects, the engineer will consult the building design or blueprint. 

Using these dimensions, they’ll calculate the square footage. This is multiplied by 20 to calculate the BTU cooling load of the space. This is essential to inform the client’s decision on the spec of the air conditioning unit they use to keep the room at the desired temperature.

This will, of course, depend on the room’s purpose. In hospitality or industrial settings, the air conditioning unit may need to work far harder than merely maintaining room comfort in warmer months. For example, if the engineer needs to advise on the design of a cold room in a restaurant, the space will require a more powerful unit. They also need to take into account factors like product exchange. In short, this is how much warm items like hot food will affect the temperature of the space.

Get the consultation you need

Although the cooling load might seem to be a relatively simple calculation compared to those discussed in our introduction to psychrometric processes, the variables at play demand careful consideration. The space’s purpose and other aspects of building design will impact how the air conditioning system is designed. 

Equally, your budget will play a significant role. When looking for a new air conditioning system, be sure to choose one with the highest Seasonal Energy Efficiency Ratio (SEER) rating. The higher the SEER rating, the less electricity the system will consume to cool the space. This, naturally, will have a substantial effect on your bottom line. It’ll be up to you to analyse the return on investment in regard to electricity bills.

To manage these variables, consultation is key. Click here to find out more about how to get the advice you need to ensure your unit is effective and economical. 




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