Is there such a thing as a silent portable air conditioner? Some manufacturers would have you think their machines incorporate features such as “silent technology”. However, if you take the trouble to read the fine print you will see something like “noise 53 dB” in the specification. (That’s not silent by the way.)
Noise is usually stated as a number followed by ‘dB’, an abbreviation for ‘decibels’. It’s helpful to describe different perceived noise levels on a qualitative scale. Encyclopedia Britannica and noiseawareness.org provide the following common noise level descriptions:
90 dB | Loud bus interior, very noisy restaurant |
80 dB | Food mixer, blender |
70 dB | Busy street noise, loud telephone ringing |
60 dB | Sewing machine operating, several people talking |
50 dB | Person talking quietly, quiet pedestal fan |
40 dB | Quiet room, no one talking |
The perceived noise level also depends on the surroundings. For example, noise in a room will sound louder with bare walls and floor so that sound reverberates around the room. Carpets, curtains and soft furnishing will absorb much of that noise. For simplicity, listening to someone speaking across a room is hard fr most people if the noise level is above 60 dB. Most people can sleep easily with background noise around 50 dB or less. In fact, many people find it hard to sleep without noise: they prefer some background noise to silence.
Also, the context of the noise can influence perceptions. For example, a sudden noise like a cup dropped on the floor can be very disturbing in the absence of background noise. In addition, we soon adapt to greater or lesser levels of background noise.
Some sounds have high pitch, or frequency, such as a whistle. Others have a low pitch, or low frequency, such as distant thunder. Speech has a mixture of medium frequencies. Sometimes you will see a noise rating specified as dBa or dBA. When many different frequencies make up the noise, the “A” weighting compensates for the way people hear different frequencies, so the rating is closer to the way the people will perceive sounds.
When it comes to an appliance like an air conditioner, the perceived noise level also depends on distance to the listener. Noise levels are often standardized at a distance of one metre, about three feet.
Most portable air conditioners on the market range between about 58 db and 68 db. For most people that’s too loud for a bedroom. Above 60 dB a conversation in the room may be difficult to listen to.
A few portable air conditioners are quieter, around 52 dB. Almost always, the machine noise has been reduced by using heavier components, so these machines typically weigh 70 – 80 lbs, 32-34 kg. That makes them anything but portable.
Even then, most people find it harder to sleep with sound in the bedroom above 50 dB.
One notable exception is Coolzy, a tiny portable air conditioner invented in Australia. Used correctly in a bedroom, this machine produces around 46 dB noise on its low fan speed which makes it ideal for sleeping. There’s enough background noise for people who cannot sleep in silence, and not enough to disturb most other people.
Unlike most air conditioners, Coolzy is designed to be used with open windows to ensure fresh air circulates for better health and less risk of infection. Therefore, some background noise is important so that noises from outside don’t disturb sleep.
The designers of evening breeze told us that their earliest model was too quiet. Unlike Coolzy, their machine is a fixed installation in a bedroom. It is not portable at all. Like Coolzy, it’s a low-power localised air conditioner designed to be used with windows open. The first prototype produced around 30 dB of noise, a very quiet humming noise. Unfortunately, even faint noises from outside like owls hooting would disturb sleepers, so they had to increase the noise level!
Would an old-style portable aircon be OK for daytime use, even with a noise level around 60dB? Authoritative sources such as noiseawareness.com tell us that noise levels well below limits that cause harm can still affect health and well-being. Noise contributes to stress and impaired cognitive performance. Therefore, a sensible option is to choose the quietest portable air conditioner that you can afford, not only the purchase price, but also the long term running cost.
Coolzy comes out way in front on both noise and total ownership cost.
