Noise and Health in the Built Environment - Bereco Ltd
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Welcome to noise and health in the built environment. In this CPD we will discuss the problem with noise and how to address acoustics in the built environment. Before we begin let me tell you a little bit about Bereco group, with the Ber taken from the natural renewable material timber, and then Eco taken from a deep rooted passion to eco-friendly.
Bereco was established in 2003 as a supplier of bespoke timber windows and doors. The motto was to deliver the difference and the aim was to provide sustainable source bespoke timber windows and doors, that were designed to last and wouldn't impact the environment. This value driven approach influences everything we do from product development, to our supply chain, our environmental campaigns and the way we deal with customers.
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Sustainably sourced timber windows and doors that are designed to manufacture to the highest standards and quality performance and security, were and remain to this day, our core values. We believe in designing healthy happy homes whilst protecting a natural world. This is an ethos we consider from the very start of the manufacturing process and this begins in the forest. All Bereco windows and doors are available, FSC 100% certified softwood and hardwood.
At Bereco we strongly believe that the only way to a sustainable future for our planet is to really use timber in construction and production in place of non-renewable materials such as oil using the production of PVC U. 300 billion tons of carbon are stored in our forests across the world. When harvested to make wooden windows and doors the wood retains a carbon store making them carbon negative. You can reduce your carbon footprint by 100 kilograms of CO2 for every Bereco timber window and door you buy. Our commitment to supplying sustainable products doesn't stop there. Two years ago we began working with the world land trust, a wildlife charity whose patron Sir David Attenborough. As part of their buy an acre scheme for every window and door we sell we add £1 to the world Land Trust. To date we have saved 135 acres of threatened habitat. This donation costs you the customer nothing and is a simple deduction for the margin we make which would be necessary in order to continue to satisfy our wish of making a difference. We offer an extensive range of window and door styles designed suits all property types from modern to new build to bespoke build and renovation right through to listed in heritage properties and the most architecturally sensitive projects all backed by an extensive 10 year warranty.
If you would like more information on our windows and doors after our presentation today our company profile and product overview can be found at Ribaproductselector.com. All our product sections and elevations can be found in our resource centre in both DWG and PDF.
Noise and Health in the Built Environment CPD Learning Outcomes
You will develop an understanding of the effects that noise has on our health, the detail behind the way which to design out noise, you gain knowledge of the accused performance or glazing units and an understanding of the process of acoustic testing for Windows and doors. We will cover how sound reduction is measured and how to calculate the same reduction that is required to satisfy an acoustic report.
What is Noise?
So section 1 the problem with noise in this section we'll explore the problem with noise and how this affects health and wellbeing. In order to discuss this we must first understand what noise is. Noise is derived from the Latin word nausea meaning sickness. It is said that the word noise in fact stemmed from unpleasant sounds or complaints made by seasick passengers or sailors. It is no coincidence then to find that noise actually does have the capacity to make us sick. In order to explore this further we must define the difference between sound and noise. Sound is vibrations of travel through the air or another medium such as a window and can be heard when reaching a person's ear. Noise on the other hand is a sound however it is sound but it's especially loud or unpleasant or that causes disturbance. Different sound sources produce vibration or waves at different rates. The rate of which the wave repeats itself is called the frequency. The higher the frequency the shorter wavelength is. The way for low frequency noise such as that produced by lorries repeats less often than a high frequency noise such as a whistle. The volume of sound which is measured in decibels or DB is determined by the height or aptitude in the wave. Different materials will transmit sound of varying frequency in different ways. Therefore if you are trying to reduce the amount of sound travel through something you need to consider the frequency of the source.
Typical Sound Levels
In modern life we are subjected to various types of environmental noise on a daily basis and the situation is getting worse. The perceived loudness of sound is measured in decibels often abbreviations DB. The DB sale starts at the threshold of audibility with 0DB and even at this level noise can be perceived by the human ear. The chart shows the common types of noise and the rating at which they take place. Our hearing system is complex and we have the ability to filter out background noise yet subconsciously our brains' fight on flight mechanism is prepared in response to noise that might be considered a threat to prepare for action.
At 70 DB we have a 30% chance of being awakened by a noise according to the World Health Organization. The noise policy statement for England and the World Health Organization state that noise exceeding 35 DB can unsettle a person’s healthy restorative sleep pattern. Which can have a negative impact on a person’s health and well-being. 30 DBS and below is a recommended level for the restorative process of sleep. Various studies have been conducted to investigate the effects of noise on health. These studies show a clear link between exposure to excessive noise levels and long term health issues.
Governments recognised the impacts of this and are increasingly developing policies to reduce noise levels at their source. The government has a long term vision which is set out in MPSE. They believe by controlling noise levels cited camp avoid significant adverse impacts on health and quality of life and where possible contributes to improvement of health and quality of life. We have the ability to filter out background noise yet subconsciously our brain’s fight or flight mechanism is prepared in response to noise that might be considered a threat to prepare us for action. This can happen while we sleep without us actually being aware of it. Our 24 hour society has threatened this delicately balanced mechanism particularly at night. If our fight or flight mechanism is repeatedly triggered in vain, it is not good for us.
Noise and Health
Laboratories studies have shown that the body releases stress hormones such as adrenaline in response to acute noise. This happens in response to high sound levels during the day but relatively low levels when sleep or relaxation is disturbed.
A report carried out by the World Health Organization over a 10 year period Concluded at least one million healthy years of life are lost each year in Europe alone due to noise pollution. There were reports titled burden of disease from environmental noise; it noted that thousands of people in Britain may be dying because of a lack of peace and quiet. In the second World Health Organization report night noise guidelines for Europe, it was shown that 1 in 5 exposed to noise at night could be significant damage to their health. The potential health issues are extremely varied but include mental illness, stress, headaches, dementia, high blood pressure, stroke and some heart conditions both cardiovascular and culinary. Section 2 designing out noise. It is important that we consider noise in the built environment if we are to design healthy happy buildings. In this section we explore what to consider when designing out noise and how to determine the sound reduction required to build comfortable living spaces.
Noise and Buildings
To understand noise we first need to look at how noise enters a building. Noise will enter a building through the weakest points and the acute performance of the whole building will be affected considerably by the weakest part of the building fabric. This can be demonstrated by opening a window slightly when there is noise outside. The noise levels in the room will be substantially higher due to the open window. In order to understand why this is the case you could consider the acoustic performance of a building as being similar to the ability of a sink with a hole in the bottom to hold water. The rest of the sink could be impenetrable to water, but the water will still escape. Strengthening other parts of a sink such as walls would have no impact on the overall ability for it to hold water as it would still leaki out of the bottom.
To improve their performance first you need to deal with the weakest points. Noise and regulations. The building relation relating to sound is part E which really relates to walls and prevents sound when travelling from one room to another and from adjoining buildings. Part E is split into two sections E1 and E2.
E1 looks at protection from noise from adjoining buildings such as flats, terraces or semis and E2 deals with sound transmission within the home itself. What we want to look at is sound reduction in relation to outside noise and this is where the windows are a key design element.
A noise survey and report may be required at the application stage or once planning permission has been granted. If the proposed development will be sensitive to noise and is likely to be affected by existing noise sources for example a housing development near busy road railway or commercial activity. The second one is the proposed developments will create noise which may affect nearby noise sensitive properties for example a new commercial activity near existing residential properties.
All noise reports for residential developments are governed by BS8233:2014 guidance on sound insulation and noise reduction which represents current government guidelines and compliance. This standard has combined with the World Health Organization and they both recommend the internal noise levels shown here in the chart in DB. This deals with the control of noise from outside the building.
BS8233 is regularly referred to by local authority planning departments in order to assess noise impact upon residential developments. The aim of a noise survey is to gain a baseline measurement of the noise environment within the vicinity of your proposed development. Once a noise environment has been defined the potential noise impacts on residential dwellings can be assessed.
The level of noise impact is analysed according to British standards and the World Health Organization guidelines to ensure the future occupants will not be adversely affected by noise. These standards provide guidance on acceptable levels of noise impacts on developments as well as noise thresholds that should be achieved in bedrooms, living rooms and external areas. The desirable daytime noise level for living rooms and bedrooms is 35 decibels dining rooms should be designed at no more than 40 decibels and bedrooms at night should be a maximum of 30DB.
Understanding sound reduction.
Now we have an understanding of desirable noise we will look at calculating sound reduction. The sound reduction provided by glazing may be represented by a number of different indices. The most commonly used in the UK and Ireland is there RW are weighted reduction which incorporates a correction to the ears varying sensitivity at different frequencies. This is measured in decibels.
European standards present the sound reduction as adaptation factors RW in brackets C or CTR.
RW is awaited sound reduction, C is the adaptation term for medium to high frequency such as radio or TV’s and CTR is a traffic noise reduction adaptation factor.
Where applicable the CTR value must be added to the RW to provide the CTR.
Example: the performance of a 6 12 6 inch utility glass unit is written as 33 in brackets minus 1 minus 3 equals R in brackets C comma CTR. Where RW equals 33 C equals 32 and CTR equals 30.
Determining Sound Reduction (Rw)
Let's just now look at a few examples. In the table we have an external noise at 67 decibels. In order to satisfy BS8233 we need to design the bedroom at night to be no more than 30 decibels. If you were to take a 42 decibel window the internal sound would be 25 DB, i.e. 67 take away 42 which takes this under the desirable level. However if you're looking at an area which is subject to traffic noise you need to make a correction for the CTR value. Which would in fact take the internal noise level to 30 decibels which is exactly the recommended level. Take the same example but in an area of low frequency noise and you would apply the C correction which would take the internal note to 26 DB well under the desired level.
Noise reducing windows and doors.
Let us now explore how noise reduction is achieved by windows and doors and what to look for when specifying external joinery. So how does acoustic glass work? Well it works in two ways. By reflecting the noise back towards the source and by absorbing the noise within the glass. As you can see in the example the glass unit is made up of different thickness of glass. 2 panes of 4mil glass with an acoustic interlayer which works to absorb sound, a 20 milligram filled gap followed by a 4 by 6 mil toughened pane. Glass with varying thicknesses is not of a much better acoustic performance.
It is certainly worth avoiding configuration with match panels as they share a dip in performance at the same frequencies and so allowing sound to pass through more effectively. Glass thickness should be different by at least 30% in order to minimise the risk of sympathetic residences within the units i.e. 10mil plus 6 mil or 4 mil plus 8 mil. Further benefits may be gained from including laminated glass products usually the combination of laminated glass and different thicknesses of glass reduces vibrations and noise so less sound travels through the window. The acoustic insulator between the panes works to absorb sound.
Triple glazing has long been promoted for its acoustic performance however we speak to Jack Harvey Clarke apex acoustics who explains that this is a common misconception. He says that manufacturers test data for the glass alone shows that the reduction for traffic noise for a similar configuration of double and triple glazed panes is typically similar or can even be lower. With so many discrepancies and false claims in a window industry when selecting an acoustic window you really want to be looking for a window which has been tested that the whole window and not simply the glazing and ideally a window that has been certified as this will give you assurance of the resulting sound reduction that the chosen window will comply with your acoustic report.
Assessing the overall window. Although glazing is an important factor in the sound reduction, what you want to look at is a true acoustic performance of the window or door. Some manufacturers will simplify the acoustic values of the glass whilst glass but whilst the glass is a single most important element of the window it is vital that all the windows components are taken into account including the frame design, seals and even the hardware. Experience has shown that performance characteristics for the whole window can vary dramatically between different windows systems even though they incorporate the same glass specification. To give a true indication of the performance the manufacturer should subject the entire product to an acoustic test under controlled laboratory conditions, in order to determine the awaited sounded reduction value of the product.
Window acoustic testing.
In order to determine the acoustic performance for windows this will generally be put from testing. In this section we explored approaches involved in acoustic testing and the certification process. Testing your window for sound reduction. The performance of noise reducing windows should be determined through laboratory testing. A sample windows builds, and sound reduction is measured over a range of frequencies with the result given in DB. The higher the number the more sound is reduced. Most window designs on the market will be expected to achieve around 25 decibel RW awaited sound reduction. Whereas a window that has been designed to reduce noise is likely to achieve around 40DB RW.
Acoustic testing measures the ability of the building product to reduce the transmission of sound. Where you see that the EN code for sample BS EN ISO 1040 – 2. This demonstrates that the product is being tested under laboratory conditions. Step 1. Noise generated on one side of a test sample. Step 2 noise measured on the other side of the sample to calculate sound reduction. Measurements are made using pink noise which is a controlled sound very similar to white noise. Noise is generated on one side of a test sample and measured using accurately calibrated microphones so that the level is known. It is then measured on the other side of the sample to calculate the level of sound reduction. Measurements are taken in a range of described positions with background noise and reverberation times being taken into account. The test laboratory is designed to eliminate any background noise that could affect measurements. It consists of two chambers or sorcery where noise is generated and a receiver room as used to measure reduction of noise. The test chambers are completely isolated from the floor, the ceiling and of each other. This stops noise traveling around test samples so any noise measured on the receive side can only have passed through the test specimen. Between the chambers is a wall into which a tested product is installed. The sound reduction rating of this wall is such that a sound will only travel through the test sample. The testing sample will be delivered to the acoustic testing laboratory and the product is installed in a very specific way in accordance with the British standard. The importance of certification. It is important to specify a window that has been certified as this provides assurance that the chosen window will provide compliance with the acoustic report and that the sound reduction shown has been verified by a third party. Blue skies noise ratings make it easy to choose noise reducing windows and doors only companies that have joined the blue Sky scheme for acoustic windows and doors can use this label giving you confidence that products with this rating are being checked by an independent certification company. The blue Sky label represents a noise dial with A plus plus being the best possible sound reduction and E being the least.
As a result of today's presentation:
- you will gain the following learning outcomes.
- You will have developed an understanding of the effects of health noise on health.
- You will be aware of the building regulations relating to noise and when an acoustic report is required.
- You will have an understanding of how acoustic glazing performs in terms of sound reduction.
- You will be aware of the process of sound reduction testing of windows and doors in accordance with BS EN 1040 - 2. An overview of how sound reduction is measured.
You will be aware of what's considered when specifying noise reducing windows and doors.
Thank you for your time.