59. Many householders attribute noise problems to poor building design. There is also evidence of a lack of compliance with current Building Regulations and that this lack of compliance results in complaints about poor sound insulation. This evidence supports the raising of standards of sound insulation. For all the reasons already referred to, including improvements in living standards, changes in lifestyles, rising expectations, and current Government housing policy, it is considered that to continue with the current Requirements and Approved Document is unsustainable. The 'do nothing' option would do nothing to stem the rising trend in reported noise problems. Rather than delivering benefits the 'do nothing' option would mean that the situation would probably deteriorate. A discussion of the costs of Option 1 is given in Section 8.
60. The DETR (now ODPM) has for many years adopted a policy towards sound insulation which has involved a combination of good practice guidance and minimum standard regulation. Once again, the evidence presented earlier shows that this approach has not been entirely successful. There are many BRE Reports, Digests and Information Papers available that provide good practice advice. In recent years the DETR (now ODPM) has also supported the development of two good practice guides, with industry involvement, under the Partners in Innovation Scheme. The first of these guides23 was intended to reduce the risk of poor sound insulation and the second24 is a guide to specifying enhanced sound insulation. Whilst some developers have voluntarily begun to adopt higher standards of sound insulation in the specification of new housing developments, there is little evidence available to demonstrate widespread application of good practice guidance. It appears that the guidance is only used by certain sectors of the industry and that this approach is essentially preaching to the converted.
61. A better resourced dissemination of good practice guidance might help to increase take up. However, experience with sound insulation codes of practice that have been more widely adopted shows that enforcement problems would remain. An example would be the problems in the conversion sector, where prior to 1991 there were a number of voluntary codes in common use. Many of these codes had deficiencies in the advice they gave, but most importantly they had no mechanism for ensuring compliance. The result is a legacy of poor conversions from the 1980s, regular legal actions on behalf of occupants, and continuing complaints about poor sound insulation from the occupants. The Building Regulations were extended in 1991 to specifically deal with the problems arising from an over reliance on good practice guidance in this sector.
62. Therefore it is considered that a reliance on the promotion of good practice, which would essentially be a development of the current approach, would deliver socially inequitable benefits, coupled with probable poor take up and associated problems arising from there being no mechanism for enforcement. A discussion of the costs of Option 2 is given in Section 8.
63. Adopting the Requirements and Approved Document will create a level playing field that will improve sound insulation in a socially equitable manner, which in turn will help to address the health issues associated with exposure to noise and the rising trend in reported noise problems.
64. A number of the amendments within Option 3 are cost-neutral since they involve the transfer of existing controls to Building Regulations (Requirement E4) or because they standardise current good practice. Requirement E2(a), for example is developed from a requirement of the warranty companies who cover some 90% of new dwellings. Further, some of the changes to support new Requirement E1 are revisions to the structure and content of the Approved Document in response to feedback from users, changes in construction good practice, complaints from building occupants and changes in British and European Standards. These are also considered to be cost-neutral.
Requirement E1 - Changes resulting from the extended scope of Requirement E1
65. Extending the scope of Requirement E1 to include rooms used for residential purposes is compatible with the intention of the current Requirement (see Section 4.1) and is socially more equitable in that it provides protection for a wider range of buildings where people may sleep, rest and engage in normal domestic activities. Extending the scope also ensures that Part E is more in step with the government's recent housing policy initiatives (see Section 2.2).
Requirement E1 - Measures to improve sound insulation and measures that improve compliance with the Requirements
66. These amendments are best considered in conjunction. The new performance standard and the measures to improve compliance with the Regulations together will improve the overall sound insulation performance of dwellings. The constructions included in the current version of Approved Document E are intended to meet a 'true' performance value for walls and floors of 49 dB and 48 dB respectively. However, field test data show that there is a wide range of performance for some of the constructions included in the current guidance and that examples of non-compliance occur. As explained in Section 4.1, the new minimum performance standards for the airborne sound insulation of walls and floors involve an increase of at least 3 dB and 4 dB respectively. Further, the introduction of the pre-completion testing regime will ensure these minimum standards are met.
67. As discussed in Section 5.2 Langdon et al undertook studies in flats during the early 1980s where the sound insulation performance of walls and floors was measured and then related to the occupant rating of their performance. It was found that occupant satisfaction was positively correlated with sound insulation performance despite a number of confounding factors. Data from these studies remain one of the few sources available to give some indication of the anticipated improvement in occupant rating as a result of an increase in sound insulation performance.
68. On the basis of these studies an estimate of the anticipated overall occupant satisfaction ratings for walls and floors based on the standards in the current and revised Approved Document are given in Table 2. In preparing Table 2 it has been necessary to extrapolate data outside the performance range of the original Langdon data. It must also be borne in mind that the Langdon work is over 20 years old and that improvements in living standards and changes in social attitudes and lifestyles have occurred since the interviews took place. Despite these limitations, Table 2 presents a best estimate of the likely outcome of the revised sound insulation standards.
Table 2: |
Change in occupant satisfaction ratings arising from improvement in airborne sound insulation performance of walls and floors in flats (1982 data) | ||
Proportion of occupants rating sound insulation as: | |||
Building element |
Poor or Very poor |
Good or Very good | |
Floors | |||
Current |
30% |
40% | |
Revised |
5% |
85% | |
Walls | |||
Current |
35% |
35% | |
Revised |
10% |
60% | |
69. More recently, Grimwood and Tinsdeall25 have undertaken a social survey and analysis involving the occupants of converted flats. A series of over 200 field measurements of sound insulation were conducted between 1993 and 1997 in a sample of converted and refurbished flats; occupants were subsequently interviewed during 1998. An analysis, similar to that used by Langdon, was applied to a subsample of interviews, where the remedial treatment applied to the separating floor had followed guidance in the current Approved Document E.
70. On the basis of this study the anticipated overall occupant satisfaction ratings for floors based on the standards in the current and revised Approved Document are given in Table 3.
Table 3: |
Change in occupant satisfaction ratings arising from improvement in airborne sound insulation performance of floors in converted flats (1998 data) | ||
Proportion of occupants rating sound insulation as: | |||
Building element |
Poor or Very poor |
Good or Very good | |
Floors | |||
Current |
50% |
20% | |
Revised |
40% |
30% | |
71. Support for adopting the new DnT,w + Ctr rating has come from a subjective listening experiment carried out under controlled laboratory conditions as recently reported by Wright and Fothergill26. The tests simulated the situation in which a flat is situated above a pub or bar which plays amplified music and allowed the effect of typical floor constructions and low frequency insulation performance to be investigated. Subjects were asked to provide ratings of acceptability of the level of a series of amplified music stimuli. Use of the new DnT,w + Ctr rating markedly improved the strength of the relationship between subjective acceptability and the insulation rating. An increase of 3 dB in the new rating was associated with a clear reported improvement in acceptability.
72. Tables 2 and 3 give some indication of the benefits that will result from the introduction of the revised standards. The tables indicate that the proportion of occupants rating sound insulation as either poor or very poor will fall, whilst the proportion of occupants rating sound insulation as either good or very good will rise.
73. It has to be noted that the revised standard is not intended to provide protection from unreasonable levels of noise. However, there is also some acceptance that the current standards are set close to a threshold of noise audibility where certain everyday sounds such as that from normal conversation and listening to the TV or radio at a reasonable level are only just audible. The improvements to sound insulation will help to ensure that many of these reasonable everyday sounds that might currently just be heard will become inaudible. Achieving such a step change in the audibility of everyday noises may well provide significant additional benefits.
74. Clearly, this improvement in occupant satisfaction rating may well correspond to a reduction in noise complaints and an improvement in health of a significant proportion of the population, although the precise extent is difficult to quantify on the available data.
75. The pre-completion testing regime would not only contribute to improving compliance with required standards. The testing regime would also offer an opportunity for an extensive database of sound insulation performance to be developed. The database would allow information to be fed back to the industry (both developers and enforcement bodies) in a useful manner. Ultimately, the database would allow poorly performing constructions to be identified and removed from the Approved Document, as well as providing a route whereby new and innovative constructions can prove their field performance and be added to future revisions of the Approved Document.
Requirement E2 - Protection against sound within a dwelling etc.
76. Requirement E2(a) has been developed from an existing NHBC requirement (see Section 4.2) and seeks to standardise and extend current good practice regarding the standard of sound insulation of internal walls. Requirement E2(a) will reduce disturbance for people in rooms designated as bedrooms and protect the privacy of persons using toilet facilities. Requirement E2(b) extends the principle to improve the sound insulation of all internal floors. Requirement E2 will also apply to rooms for residential purposes.
77. The benefit of these changes is that they will enable homes to provide occupants with more flexible accommodation that has a level of sound insulation more appropriate to the current extended use of bedrooms. Social changes have meant that bedrooms are increasingly being used as a 'home within a home' with a wide range of electronic equipment (e.g. stereos, televisions, computers etc.) being used, all of which can be a noise nuisance to others in the house as well as occupants in adjacent dwellings. Further, the move towards home-working has meant that bedrooms are frequently used as offices which in turn leads to the need to insulate that room from the rest of the house. It should also be noted that the concrete beam with infilling block floor construction has been included as an internal floor, rather than a separating floor, in the revised Approved Document. Use of this floor construction would provide an additional benefit in terms of improved fire resistance within dwellings.
78. The amendment helps Part E to address the Government's strategy for sustainable construction as it involves designing with more flexibility and meeting people's social needs and aspirations. The amendment also brings Part E more into line with European building standards. For example, Germany, Netherlands, Belgium and Portugal all require some level of internal sound insulation in their building codes.
Requirement E3 - Reverberation in the common internal parts of buildings containing dwellings etc.
79. Requirement E3 involves the provision of acoustically absorbent material in the common areas that give access to flats and rooms for residential purposes. The benefits are:
80. The amendment helps Part E to address current government policy initiatives on housing as set out in PPG3 and brings Part E more into line with European building standards. For example, Germany, Netherlands, Denmark and Norway all require some level of control over reverberation time in their building codes.
81. The preceding discussion has sought to present the benefits of adopting Option 3 in both a qualitative and, as far as practical, in a quantitative manner. The WHO27 advocates that cost-benefit analysis should only be applied with caution in the noise field and that it should 'never be used as the sole and overriding determinant of decisions'. Further, the WHO also state that 'there is a tendency to overestimate the cost of control action and underestimate the benefits' due to different levels of knowledge of the costs and health effects. The extent to which it is reasonable to attempt to quantify the benefits of Option 3 in financial terms is clearly debatable and the figures in the following paragraphs are speculative and should be considered in this context.
82. There appear to be very few cost-benefit studies that attempt to value the benefits of improving sound insulation between dwellings. One such study28 concluded that around 60% of the population of Sweden were willing to pay on average a 10% higher rent if the sound insulation of the dwelling could be improved. The report estimated that insufficient sound insulation cost Swedish society around 7,500 million SEK per year (about £630 million).
83. However, in the transport noise field, particularly in France, Germany, Switzerland and the Scandinavian countries there has been some research on the use of a monetary value of noise in cost-benefit analysis. In France29, for example, revealed preferences studies applied to the housing market have shown that each additional decibel of noise pollution reduces the value of real estate by about 1%. Assuming it was reasonable to apply these sort of figures to improvements in sound insulation, then the 3 dB improvement in standards for dwelling houses would correspond to 3% of the value of the attached housing stock, producing a benefit of the order of £160 million. These countries also typically account for the direct costs of noise (due to stress, annoyance etc.) by adding a further 50% to this figure - so total benefits of about £240 million would result from applying these techniques.
84. Alternatively, some of the benefits of Option 3 can be valued using the time off work and cost to the NHS that may result from noise induced cases of stress. The report 'Building Regulation and Health'10 suggests that 100,000 such cases may result each year. If we assume that the Part E changes might prevent say 20% of these cases taking 5 days off work over the course of a year and with, say, an average salary of £20K and a cost to the NHS of £500 per case then the resulting benefit would be of the order of £18 million.
85.The same report states that up to 10 people a year are killed as a result of noise problems. If it is assumed that the changes to Part E could save 2 lives a year, and adopt the valuation of a life used by the DfT for road traffic accidents, then further benefits of £1.6 million would result.
86. In a national noise attitude survey conducted in England and Wales during 1991 some 2% of householders said that they were prepared to move because of noisy neighbours. If we assume that 1% of new households in attached dwellings, i.e. about 800 households (see note to Table 4), would actually move because of noise, at a cost of £5K per move, then the annual benefit would be of the order of £4 million.
87. A different approach to estimating the financial benefits that could result from the amendments is to look at the avoided costs of the remedial treatment that is required where sound insulation problems are corrected after occupants have moved in. For example, there has recently been a block of 40 purpose built flats where remedial work to the value of £1 million was undertaken30 at an average cost per flat of £25K. More typically the additional cost of retrospective remedial work in a small flat conversion might vary between £1K - £10K per flat. This cost cannot be grossed up to provide a national figure because the required information is not available.
88. This attempt to value the benefits of Option 3 provides speculative estimates ranging from £24million (paragraphs 85, 86 and 87) to about £240 million (paragraph 84). These figures should be considered in conjunction with the qualitative and quantitative estimates of the benefits of Option 3 that are presented in Section 7.3.
23 BRE. Quiet Homes – a guide to good practice and reducing the risk of poor sound insulation between dwellings. BRE Report 358, edited by BRE and Wimtec Environmental, 1998
24 BRE. Specifying dwellings with enhanced sound insulation. BRE Report BR406, edited by Wimtec Environmental and BRE, September 2000
25 C. J. Grimwood and N. J. Tinsdeall, Occupant opinion of sound insulation in converted and refurbished dwellings in England and the implications for national Building Regulations, Proceedings Euronoise ’98, pp 705 – 710, 1998
26 P. Wright and L. Fothergill, The spectrum adaptation terms in BS EN ISO 717-1:1997, Acoustics Bulletin, Vol 23 No 6, December 1998
27 WHO. Guidelines for Community Noise, 2000
28 S. Wibe. The demand for silent dwellings (in Swedish), 1997. ISBN 91 540 5780 9
29 J. Lambert. Using monetary values of noise for transport policy decisions, Proceedings of Internoise 2000.
30 NHBC. Private communication, September 2000
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