Keep the noise down! – BS8233:2014 under consultation

Jack Park, Commercial Technical Manager

A draft consultation with amendments to BS 8233:2014 requirements was released on the 6th June. The main changes reference indoor air quality legislation & some 2018 World Health Organisation Environmental Noise Guidelines. 

Here is a summary of what’s proposed.

• • Shifting to Lden and Lnight rather than LAeq,16hr (07:00 to 23:00) and LAeq,8hr (23:00 to 07:00) – L day (07:00 to 19:00), evening (19:00 to 23:00), night (23:00 to 07:00) – so surveys will have a 24-hour result and a night-time result.
  • Given the strength of health evidence based on Lden and Lnight, there are no maximum noise events specified for transportation noise sources (instances of LAF,MAX), but may be set for other noise sources
  • There are specific (and different to road noise sources) internal noise levels to be set for rail and air noise sources. 31dB Lden railway and 22db Lden aircraft.

• • There is a minimum façade sound insulation requirement of at least 30dB nT,A,tr. For road traffic noise, internal noise levels within the house are expected to achieve less than 35dB Lden.
  • Different levels are no longer specified to living rooms, bedrooms etc. The same level applies to all habitable rooms within the house (excluding bathrooms, en-suites, stores, etc). This is to accommodate flexibility in room use, such as bedrooms being converted to offices, downstairs lounges being converted to bedrooms, etc.
  • Sound levels depending on source will be reviewed and assigned a Sound Exposure Category (SEC):

• • Table 11 informs when windows can and cannot open, and when the overheating assessment needs to inform the requirements indicated by the grey boxes

• • There are no specific criteria for external noise levels, and a greater recognition that shared or private amenity spaces are still beneficial in louder, noisy urban environments, with examples given such as flat balconies being used for drying washing or growing plants. In some louder shared amenity areas, it is recommended that green infrastructure be put in place to add positive/natural sounds to the environment rather than always considering screening in the first option in urban environments
  • Absorption methods for residential communal hallways/stairs in blocks remains the same, referring to the appendices within Approved Document E

• • Further advice is given within the document for hotel, office, industrial environments and many other unique uses
  • BS 4142 is still the point of reference and measurement criteria for commercial noise
  • CTRN guidelines for road traffic noise are still available based on traffic characteristics:

• • The CTRN method of taking a short sample (1hr or 3hr) and converting to either Laeq,16hr or Lden will be available; however, full duration survey samples will still be the preferred method if possible.
  • There is still reference to BB93 (schools), HTM-08-01 (medical) and the BCO guide for offices in terms of recommended ambient noise levels for specific non-residential room activities

• It is encouraged in all instances in environments where windows should remain closed for suitable internal noise levels that windows are still openable at the discretion of the occupant, for residents’ wellbeing, and their ability to exercise environmental control, comfort potential to connect with the outside, along with indoor air quality.

• • Part O overheating constraints are referred to review the AVO: Residential design guide
  • Good practice and design advice is given for domestic and non-domestic building services within the document