Are Turbines Noisy?
Information on wind turbine noise usually takes one of two forms; websites funded by energy companies or the green lobby would have you believe that they are whisper quiet. Meanwhile, anti-wind farm websites may seem to exaggerate the problems. We have to say that before we started researching this area, we had assumed that perhaps the noise issue might not be too serious. However, we have been quite shocked by the sheer amount of evidence building up on the internet that turbine noise can cause really severe distress to those living in the area.
Some of the issues involved in measuring noise are quite technical and difficult to understand. We’ve tried to explain them as simply as possible, but there is still quite a lot of information on this page. Let’s start with some quick questions and answers:
Q: Do wind turbines produce noise?
A: Yes.
Q: Will this noise disturb me? Will it keep me awake?
A: The Developers all say no. We think that it is very likely that some local residents will be disturbed both day and night. See article at the bottom of this page or Click to read more
Q: Are there any other health problems associated with wind farms?
A: Some research has suggested that noise can cause a range of health problems.
Q: Are there rules governing noise?
A: Yes, but many people have argued that these do not provide local residents with protection from noise problems.
What types of noise will there be?
Construction noise
Because the turbines are so large, they need very deep foundations. This requires very large concrete pillars to be hammered deep into the ground. This is extremely noisy, and very annoying for those living nearby, but it will only be a temporary problem.
Mechanical noise
The internal workings of the turbine, such as the gearbox and the generator, will generate some mechanical noise. However, improvements in technology mean that this noise is likely to be quite minimal, and may not be heard even if you are standing quite close to the turbine.
Blade noise
Most of the noise generated by turbines comes from the movement of the blades through the air, particularly when they pass the tower. This can produce a deep pulsing / thumping noise which has been reported to carry over long distances. This low pulsing sound may penetrate the walls of houses, and has been reported to cause severe distress to some residents, preventing them from sleeping at night.
Infrasound
Infrasound is sound that you can’t hear. Yes, we know that seems strange, but remember, the human ear has a limited range. It can’t hear very high sounds (like a dog whistle) and it can’t hear very low sounds, like the very low frequency sounds which turbines can produce. Unfortunately, this does not mean that they are harmless.
Some people near wind turbines report feeling the vibrations in their body, rather than hearing them, which keeps them awake at night. Meanwhile there is scientific evidence to suggest that certain parts of the human body may be sensitive to these very low level vibrations. This may explain why some people living near turbines seem to experience a range of health issues, often quite non-specific, such as feelings of anxiety, or generally feeling unwell. The fact that these symptoms are quite general, and therefore difficult to link conclusively to wind turbines, means that the wind turbine industry continues to deny that infrasound can affect people.
How is the noise measured?
Noise is measured in decibels (dB), and environmental noise uses a special measurement called dBA.
This system can be quite confusing at first. It’s important to remember that for every increase of 10db, the volume doubles. For example, 20db is twice as loud as 10db. 40db is eight times as loud as 10db.
Before the turbines are built, noise measurements should be taken from a variety of locations on and near the site. For example, measurements may be taken from the gardens of nearby properties. These are to work out the level of “background noise”. These measurements should be taken at a range of different wind speeds, since this can affect how much background noise there is. This level of background noise is expressed in dBA, e.g. 40dBA.
What are the guidelines about noise?
These are set out in a document called ETSU-R-97. This specifies that in general the noise generated by a wind turbine should be no louder than 5db above background noise. So for example, if the background noise is 40db, residents may hear 45db of noise including the turbines. Remember that an increase of 10db sounds like a doubling of the volume. However, in quiet areas, different rules apply. ETSU-R-97 recommends a daytime limit of between 35-40 dBA. At night however, the limit is 43dBA. Incredibly, this means that turbines are allowed to create more noise at night than during the day.
What problems are there with these guidelines?
There have been a large number of objections to ETSU-R-97. For example:
Will they keep me awake at night or disturb me? Are there any effects on health?
Developers again will say “no”. We would encourage you to have a good search around the internet, read both sides of the story, and make up your own mind. Here are some of the articles and downloads that we found useful while we were researching this page:
Measuring wind turbine noise
An interesting page from renewableenergyworld.com which explains why some people can find the noise from wind turbines annoying, even if the measurable noise isn't very high
"So if wind turbines aren't any louder than what we're already used to, why are some people complaining about them?"
Aerodynamic Modulation noise
This document, published by Sadberge Parish Council, explains why turbines can make a low thumping noise, and why the rules governing noise will not protect residents from this problem.
"The noise monitoring recommended in ETSU-R-97 is totally ineffective in protecting residents from aerodynamic modulation noise..."
Sleep disturbance and wind turbine noise
A report by Dr C. Hanning, an expert in sleep disorders, stating that wind turbines can have a negative effect on sleep and so cause other health problems. It should be noted that Dr. Hanning was commisioned to write this report by an organisation campaigning against wind turbines in his local area. However, his qualifications and experience would seem to speak for themselves.
"There can be no doubt that groups of industrial wind turbines (“wind farms”) generate sufficient noise to disturb the sleep and impair the health of those living nearby."
Are wind farms a health risk? (NHS)
This page from the NHS considers an American study which linked sleep disturbance and other health problems to nearby wind turbines. While critising the design and small-scale nature of the study, the NHS notes that further study is needed in this area. This study was also reported in The Independent and The Daily Mail.
"it is physically and biologically plausible that low frequency noise generated by wind turbines can affect people..."
MAS Environmental
A long and perhaps quite technical document which offers a detailed explanation of why the noise guidelines in ETSU-R-97 are flawed, and not appropriate in considering planning applications for large turbines.
"ETSU-R-97 is incapable of addressing the noise impact issues created by large turbines..."
Some of the issues involved in measuring noise are quite technical and difficult to understand. We’ve tried to explain them as simply as possible, but there is still quite a lot of information on this page. Let’s start with some quick questions and answers:
Q: Do wind turbines produce noise?
A: Yes.
Q: Will this noise disturb me? Will it keep me awake?
A: The Developers all say no. We think that it is very likely that some local residents will be disturbed both day and night. See article at the bottom of this page or Click to read more
Q: Are there any other health problems associated with wind farms?
A: Some research has suggested that noise can cause a range of health problems.
Q: Are there rules governing noise?
A: Yes, but many people have argued that these do not provide local residents with protection from noise problems.
What types of noise will there be?
Construction noise
Because the turbines are so large, they need very deep foundations. This requires very large concrete pillars to be hammered deep into the ground. This is extremely noisy, and very annoying for those living nearby, but it will only be a temporary problem.
Mechanical noise
The internal workings of the turbine, such as the gearbox and the generator, will generate some mechanical noise. However, improvements in technology mean that this noise is likely to be quite minimal, and may not be heard even if you are standing quite close to the turbine.
Blade noise
Most of the noise generated by turbines comes from the movement of the blades through the air, particularly when they pass the tower. This can produce a deep pulsing / thumping noise which has been reported to carry over long distances. This low pulsing sound may penetrate the walls of houses, and has been reported to cause severe distress to some residents, preventing them from sleeping at night.
Infrasound
Infrasound is sound that you can’t hear. Yes, we know that seems strange, but remember, the human ear has a limited range. It can’t hear very high sounds (like a dog whistle) and it can’t hear very low sounds, like the very low frequency sounds which turbines can produce. Unfortunately, this does not mean that they are harmless.
Some people near wind turbines report feeling the vibrations in their body, rather than hearing them, which keeps them awake at night. Meanwhile there is scientific evidence to suggest that certain parts of the human body may be sensitive to these very low level vibrations. This may explain why some people living near turbines seem to experience a range of health issues, often quite non-specific, such as feelings of anxiety, or generally feeling unwell. The fact that these symptoms are quite general, and therefore difficult to link conclusively to wind turbines, means that the wind turbine industry continues to deny that infrasound can affect people.
How is the noise measured?
Noise is measured in decibels (dB), and environmental noise uses a special measurement called dBA.
- A very quiet room might be 30 dBA
- The noise from vacuum cleaner might be 75 dBA
This system can be quite confusing at first. It’s important to remember that for every increase of 10db, the volume doubles. For example, 20db is twice as loud as 10db. 40db is eight times as loud as 10db.
Before the turbines are built, noise measurements should be taken from a variety of locations on and near the site. For example, measurements may be taken from the gardens of nearby properties. These are to work out the level of “background noise”. These measurements should be taken at a range of different wind speeds, since this can affect how much background noise there is. This level of background noise is expressed in dBA, e.g. 40dBA.
What are the guidelines about noise?
These are set out in a document called ETSU-R-97. This specifies that in general the noise generated by a wind turbine should be no louder than 5db above background noise. So for example, if the background noise is 40db, residents may hear 45db of noise including the turbines. Remember that an increase of 10db sounds like a doubling of the volume. However, in quiet areas, different rules apply. ETSU-R-97 recommends a daytime limit of between 35-40 dBA. At night however, the limit is 43dBA. Incredibly, this means that turbines are allowed to create more noise at night than during the day.
What problems are there with these guidelines?
There have been a large number of objections to ETSU-R-97. For example:
- The rules were published in 1996… but in those days turbines were much, much smaller than today.
- The rules assume that problems with noise are only caused by how loud it is… but there is no consideration given to other factors, such as the type of noise and the duration of the noise. However, we all know that some types of noise are much more irritating than others.
- The rules state that it is only necessary to measure wind speeds up to 12 metres per second… but they ignore the fact that faster wind speeds may cause turbines to generate more noise.
- The rules state that wind speed should be measured at a height of 10 metres… but modern wind turbines can be 125 metres high.
- The rules are about audible sound… but completely ignore the problem of infrasound.
- The methods used to calculate noise levels from wind turbines are not appropriate. The rules specify a special measurement called “LA90,10min” Here’s how it works: The noise levels are measured over a 10 minute period. The noisiest 90% of this time is ignored completely, leaving only the quietest 10% of the data. The noise level is then calculated as being the loudest noise in this quiet period. “the wind turbines could be making a noise like a jet plane taking off in next door's garden for nine out of every ten minutes. LA90, 10min would ignore that and characterise the noise based on the remaining one quiet minute.”
- The rules recommend that noise limits are set in relation to the nearest properties… but some types of noise are actually difficult to measure close to wind farms, and more noticeable a little further away, at distances of over 500 metres.
- The rules assume that background noise will help mask the noise of turbines. However, the type of noise produced by turbines is of a completely different type to normal background noise, so may not be masked.
Will they keep me awake at night or disturb me? Are there any effects on health?
Developers again will say “no”. We would encourage you to have a good search around the internet, read both sides of the story, and make up your own mind. Here are some of the articles and downloads that we found useful while we were researching this page:
Measuring wind turbine noise
An interesting page from renewableenergyworld.com which explains why some people can find the noise from wind turbines annoying, even if the measurable noise isn't very high
"So if wind turbines aren't any louder than what we're already used to, why are some people complaining about them?"
Aerodynamic Modulation noise
This document, published by Sadberge Parish Council, explains why turbines can make a low thumping noise, and why the rules governing noise will not protect residents from this problem.
"The noise monitoring recommended in ETSU-R-97 is totally ineffective in protecting residents from aerodynamic modulation noise..."
Sleep disturbance and wind turbine noise
A report by Dr C. Hanning, an expert in sleep disorders, stating that wind turbines can have a negative effect on sleep and so cause other health problems. It should be noted that Dr. Hanning was commisioned to write this report by an organisation campaigning against wind turbines in his local area. However, his qualifications and experience would seem to speak for themselves.
"There can be no doubt that groups of industrial wind turbines (“wind farms”) generate sufficient noise to disturb the sleep and impair the health of those living nearby."
Are wind farms a health risk? (NHS)
This page from the NHS considers an American study which linked sleep disturbance and other health problems to nearby wind turbines. While critising the design and small-scale nature of the study, the NHS notes that further study is needed in this area. This study was also reported in The Independent and The Daily Mail.
"it is physically and biologically plausible that low frequency noise generated by wind turbines can affect people..."
MAS Environmental
A long and perhaps quite technical document which offers a detailed explanation of why the noise guidelines in ETSU-R-97 are flawed, and not appropriate in considering planning applications for large turbines.
"ETSU-R-97 is incapable of addressing the noise impact issues created by large turbines..."
Noise Torture! How the sound changes at different times of the day & Night!
"The sound of high winds: the effect of atmospheric stability on wind turbine sound and microphone noise" van den Berg dissertation, University of Groningen, 2006"
This scientific study, will give you a clearer insight into the torture of living too close to turbines, I urge you to visit the site and read for yourself.
In particular for other campaigning groups- there is very valuable scientific data!
Click to read more
This scientific study, will give you a clearer insight into the torture of living too close to turbines, I urge you to visit the site and read for yourself.
In particular for other campaigning groups- there is very valuable scientific data!
Click to read more
