Before I start, I’m not selling or advertising anything here. There isn’t an affiliate link or banner on my website. 😉
Despite all the rain here in Ireland, it does get warm from time to time, often to the point where it is difficult to sleep at night. However, what is more surprising is that I see people using air coolers that can actually make their environment even worse, not realising how these operate! So in this basic guide, I’ll go through the types of appliances and where they work best and why air coolers are not really useful in the Irish climate.
Temperature & humidity
Everyone knows that it is uncomfortable working in a warm or sticky room, but what they may not realise is that it is not just the temperature that affects how bad it feels. The humidity plays a major role also, just like the great outdoors.
Before you purchase an appliance for trying to control the temperature/comfort, it is well worth purchasing a hygrometer first, which will show the room’s temperature and relative humidity. Ideally, the room should be between 20C and 22C (18C for a bedroom) with a relative humidity of 40% to 60%.
In this example to the right, a hygrometer was placed in a room where I felt quite sticky. As the hygrometer shows, the temperature is ideal, but the relative humidity is very high. In Ireland, it is quite common to see the humidity exceed 70% indoors in the summer. In this example the weather was warm, hazy and humid outside.
How to control the room comfort
Once we establish what the temperature and relative humidity is, if either reading is outside of the ideal range, it is time to control it. This is where we choose an appliance. From here, I’ll start with the cheapest to the most expensive and explain how each is used and when to use or not use them!
Open a window!
Not really a surprise as the first tip. 😉 In many cases, simply opening a window is enough to cool the room or make it less sticky, even if it is warm outside. Like I mentioned above, it is not always the air temperature that makes the difference, but the lower outdoor humidity. Of course, this may not be an option in all cases such as if it is noisy outside, too windy or if there is no window to open.
Fan (Desk, floor-standing, etc.)
It is not really a surprise that most people use a fan to keep cool, especially since it is very effective and cheap to get hold of. A light breeze in the room typically gives the feeling of the temperature being around 2C cooler than it actually is. They also boost the effectiveness of air conditioning, for example, if an air conditioner cools the air by 5C, a blowing fan can give the impression that the room is actually 7C cooler than it was.
Air Cooler (no vent hose or outdoor unit)
An air cooler works by evaporating water to cool the air, since as heat energy is absorbed doing so, this lowers the air temperature. As a result, a portable air cooler requires water to operate and some models recommend adding ice for better effectiveness. The catch is that as they add significant humidity to the air.
Unfortunately, many people assume that as they don’t have a vent, they don’t need a window open! So what happens if an air cooler is operated with all the windows closed? Assuming the relative humidity is reasonable to start off, when the air cooler is switched on, it will do its job for a short while. Once the humidity rises up towards saturation point (around 80% RH), the cooling effect stops. With the cooling effect stopped, the temperature will gradually rise up to where it started and the room will end up feeling warm & sticky!
With the typical high humidity in Ireland, I do wonder what is the point in selling these at all here, considering how seldom it gets warm with low relative humidity. Also, as an air cooler reduces a person’s effectiveness to sweat to stay cool, they should not be used in places with intense physical activity such as while working out. E.g. if you have a home gym, don’t run an air cooler while working out!
Water Cooler (For drinking)
While this is something that does not affect the room temperature, having cool water on tap can make one feel cooler. This can also be more cost effective than running an air cooler, without its side effects either.
Dehumidifier (Portable unit)
This is an appliance typically used by builders to dry buildings, painted walls and deal with flood damage. Some people use them to control dampness. What most people don’t realise is that they are also a very effective way of controlling stickiness, especially when it is not practical to open a window.
Dehumidifiers work by condensing the moisture in the air and collecting it in a container. From my experience, most small dehumidifiers collect 2 to 4 litres per day with a room temperature of 20C and relative humidity of 60% to 70%. The only catch is that if the room is very humid (e.g. over 70%), it can warm up the room, however, personally I prefer feeling warm than sticky & sweaty. Once the room humidity drops, the dehumidifier will operate less and the temperature will return back to what it was, so ideally they should be run throughout the day for the best effect.
In the above photo example of the high humidity reading where the room was 20C and 79% relative humidity, this is where a dehumidifier works well. With a dehumidifier in this room, the temperature climbs by around 2C and the humidity level falls by around 15% to 20% after an hour of operation. After the second hour, the temperature falls back around 1C while the humidity stays around 60% to 65%, leaving the room feeling a lot more comfortable.
The catch with a dehumidifier is that it requires the windows to be closed to be effective. They are also less effective at controlling comfort in high indoor temperatures such as above 25C.
Finally, don’t try running a dehumidifier and air cooler together in the same area! First of all, most air-coolers can evaporate up to 1 litre an hour, which will overwhelm most dehumidifiers. Also, as I mentioned above, a dehumidifier releases heat energy when it condenses the moisture in the air, while an air cooler absorbs heat by evaporating water, so by running both together, this will have the effect of a complicated space heater as the room will warm up from the energy used to run both appliances, much like leaving a refrigerator door open to try cooling a room. 😉
Air conditioner (Vented portable unit)
Unlike an air cooler, an air conditioner lowers the humidity instead of raising it. This means that besides the air feeling cooler, it also eliminates the stickiness. Most air conditioners have two modes of operation – “Dehumidify” and “Cool”.
In the cool mode, the air conditioner lowers both the temperature and the humidity. This relative humidity will stop declining once the amount being extracted reaches the amount coming in the air coming in the room to replace what air has been vented out. The temperature however will continue falling for an hour or two before it bottoms out, sooner if there is a significant breeze coming in the Window opened for the vent hose.
In the dehumidify mode, the air conditioner condenses the moisture in the air like a dedicated dehumidifier, but instead of collecting it, it evaporates it out the vent along with the heat produced by its compressor. This has the advantage of lowering the room’s humidity quickly without raising the temperature, unlike what a standalone dehumidifier would. The catch is that as a window needs to be open for the vent, it costs more to run and is impractical as a dehumidifier to control dampness.
For anyone interested in running an air cooler with an air conditioner, this is one case where it will likely have some effect, since as the air conditioner extracts humidity as well as dumping the heat released from condensation outdoors, an air cooler have an effect. However, the efficiency of the air conditioner will be reduced as it will be using more energy to condense water than cooling the air, so while an air cooler may help bring cooler air to a specific area, it will likely reduce how cool the air the air conditioner puts out.