Can Dehumidifiers Cool a Room?

Excess levels of humidity in our homes can lead to a host of health problems as well as encouraging the growth of mold, which in itself can cause health issues.

High levels of humidity can aggravate respiratory problems and allergies, as well as impacting our sleep. But levels of humidity above 50% can also have an effect on our general levels of comfort: hot, clammy air can be stifling. It can make us feel lethargic and even faint. Other factors outside of humidity can also have a similar effect, consider an air-quality monitor to rule these out.

The University of Arizona headed up a study that revealed that office workers who found themselves in high humidity working conditions recorded higher levels of stress. Interestingly, they recorded the same when the air was too dry. There’s a balance to be found in our homes and workspaces, then.

Why does humidity make us feel hotter?

A Japanese study recorded the comfort levels of participants moving from a high to a low humidity environment, with many finding that their skin felt different. The moisture was able to evaporate off their skin in lower humidity, resulting in them feeling more alert, fresher, and less sweaty.

When warm moisture stays on our skin for longer, it makes us feel hotter. This is the reason the National Weather Service factors humidity into its reports. The Heat Index is a measure of how the heat actually feels for our bodies, combining the actual temperature with humidity levels.

Dr Payam Delgoshaei is the technology manager for the US Department of Energy’s Buildings Technologies Office’s (BTO) heating, ventilation, air conditioning, and refrigeration (HVAC&R) systems. He says: “Reducing humidity can lower energy consumption from air conditioning. Since people are more comfortable at higher temperatures with lower humidity, dehumidifying can reduce the need for air conditioning.”

Improving comfort

Note that a dehumidifier doesn’t replicate the work of an air conditioner. In our homes, using a dehumidifier can definitely make us feel more comfortable, but it isn’t actually cooling the air noticeably. Refrigerant or compressor humidifiers do pass air through a cold coil, which then causes the water in the air to condense. The air is released while the water is collected to be discarded. However, home-owners won’t notice a huge change in air temperature.

Dr Delgoshaei adds a caveat: “A stand-alone dehumidifier’s primary purpose is to remove moisture from the air. A typical conventional dehumidifier operates by cooling the air to remove moisture, but that process may generate heat that is then added to the room. Such stand-alone dehumidifiers don’t actively cool a room.”

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Use in tandem

Instead, you can use a dehumidifier to lower the humidity in your home to help your air conditioning unit generate cold air. Air conditioning units take in air, cool it, and then release it. Using a dehumidifier can ease this process.

However, having multiple devices running may not work for all households. “It depends on individual circumstances, comfort levels and the configuration and efficiency of existing equipment. When equipment is correctly selected for the climate zone, an air conditioning unit will both dehumidify and cool the air. If a heat pump unit is installed in a home, it combines cooling, heating, and dehumidifying into one unit”, explains Dr Delgoshaei.

The best chance of a cool home

The BTO recommends a number of steps to try for raising your chances of staying cool at home before you consider buying a dehumidifier.

Dr Delgoshaei states: “Improving your building’s ‘envelope’ – the walls, roofs, doors and windows that separate indoors from outdoors, and protect building occupants from undesirable outdoor conditions – is recommended before purchasing dehumidification and cooling equipment.”

He advises that you can do this by:

• Sealing gaps and cracks in walls, roofs, doors, and windows – to help keep hot, humid air outside, and cool, dry air inside homes. Focus on areas such as the attic and crawl spaces. Air sealing is the most effective home improvement to maintain comfortable temperature and humidity levels. This online calculator helps you estimate the potential energy and cost savings and reduction in moisture transfer from improvements in air sealing.

• Upgrade to higher-performance doors and windows – which can improve insulation and reduce heat transfer, improving humidity control and lowering cooling demand.

• Ensure sufficient insulation in walls, roofs, and floors – proper insulation helps maintain consistent indoor conditions and reduces overall cooling and dehumidification needs.

The health benefits of dehumidifying your home to a level of between 30-50% are well documented – and a dehumidifier with a built-in digital display will allow you to keep track of the relative humidity levels in your home. While the air may not be tangibly cooler from using a dehumidifier, it will make the air more comfortable to be in. This, alongside the health benefits, are a big tick as temperatures and humidity levels rise.