How Does Air Conditioning Work?
Demand for residential air conditioning is growing, but what is it and which is right for your home? We spoke to an expert to find out
Nearly 90% of US homes had air conditioning in 2020, reports the US Energy Information Administration with the World Economic Forum adding that this figure is steadily climbing.
These systems keep ambient temperatures and humidity in homes at a comfortable level often set by the homeowner, including using Smart systems. There are many different options, though the majority of residential properties use centrally ducted systems, portable units, or window units.
The choice depends on budget, the size of the space and the design of the property. Experts add the caveat that air conditioners can dehumidify indoor air but a dehumidifier does not cool the air to the same extent as an air conditioning unit.
Air conditioning units can also offer filters to remove impurities from the air. These pollutants can include dander from pets; spores from micro-organisms; and dust particles. You can also buy air purifiers specifically designed to do this if your air conditioning unit doesn’t have this facility.
How does air conditioning work? What you need to know
All air conditioning systems work using the same basic scientific process – heat naturally transfers from regions of higher temperature to regions of lower temperature. Kyle Gluesenkamp is the senior R&D scientist who serves as Oak Ridge National Laboratory’s subprogram manager for Thermal Energy Storage. He explains: “Using electricity, a refrigerant gas is compressed, until it’s hotter than the hot outdoors. The refrigerant is then sent outdoors and cooled down to the outdoor temperature. Then the refrigerant is depressurized, so that it becomes colder than the cool indoor air.
“The refrigerant can then absorb heat from the indoors, providing air conditioning. Next it is compressed again, repeating the cycle. In order to move heat in the opposite direction, from a cool room to a hot outside, an air conditioner consumes electricity to compress a refrigerant gas and cycle it between the indoors and outdoors. The bigger the temperature difference, the more electricity is needed.”
In basic terms – forcing a gas into a smaller volume raises its temperature, and de-pressurizing a gas lowers its temperature. He adds: “Think of how the hose of a bike pump gets hot when pumping up a tire, and how an aerosol can gets cold as it’s used. This relationship between pressure and temperature is the fundamental basis of an air conditioner.”
What different types of air conditioners are there?
The main difference between types of air conditioners is that some use ducts and others do not. If you opt for a portable, freestanding air conditioning unit, this can be deployed anywhere in your home. Window or ductless mini-split units don’t use ducts either. This is a great option if you do not have the budget to fit an entire duct system. However, warns our expert, “window units and portable AC units cost less to install, but often have much higher overall cost to own, due to the high electricity consumption.”
Central air conditioning systems do use ducts to move air around the home. They can even deploy the ducts fitted for an air furnace.
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How to choose the right air conditioning system for your home
Gluesenkamp says that what is already in a home will be the most important factor in deciding what air conditioning option to choose. If you have ducts already, for example, a central air system might be within your grasp.
You also need to consider the space that you are hoping to cool or heat. Our expert explains: “Oversizing can be one source of problems – an air conditioner too big for the space will bring the temperature down too quickly, and the short runtime causes poor dehumidification, making the rooms feel clammy due to high relative humidity.”
Whatever system you choose, make sure that you have a maintenance program in place, ideally serviced by a professional. There are regular jobs that need attending to, including the cleaning or replacing of air filters to ensure the airflow is maximized but also that the air pumped out is clean. Gluesenkamp adds: “If a return register in the home gets blocked, this can cause the system to malfunction.”
If installed professionally and maintained sensibly, air conditioning systems can have a huge impact on comfort in a space, including even improving sleep and cognitive function. With this as a potential reward, it is worth investing in the best option for your home and making sure it is kept working to its optimum.
