The new skool rules - OK? | Features

Changes at a glance
Key differences between the existing BB87 and the new requirements in BB93 compiled by Adrian James of Adrian James Acoustics
	BB87, 1997	BB93, 2002
Internal ambient noise levels	Previously called background noise levels, which includes noise from teaching activities in adjacent spaces in addition to the indoor ambient noise from internal and external noise sources identified in BB93	The indoor ambient noise levels in Table 1.1 of BB93 do not include noise from teaching activities in neighbouring rooms, which is addressed through specification of sound insulation. They include all other noise from internal and external noise sources except noise associated with classroom activities
Maximum indoor levels	Guidance was given that noise from aircraft and trains should not exceed 55 dB LA1 in teaching classrooms	It is now a requirement that noise from individual noisy events in certain rooms including classrooms should not regularly exceed 55 dB LA1,30mins
Sound insulation between rooms	Requirements for weighted level of difference Dw are given in terms of a matrix as a function of noise tolerance and activity noise levels	The sound insulation requirements are in some cases more onerous than in BB87. Use of doors communicating directly between classrooms is generally impracticable because these reduce sound insulation, Dw replaced by similar DnT (Tmf,max)
Sound insulation between rooms and corridors	Dw quoted between rooms and corridors, but was not reproducibly measurable in practice because of the irregular dimensions of the corridors	Requirements are given in Rw (weighted sound reduction index) for walls and doors, and there is a separate requirement for ventilators. Compliance has to be by calculation rather than measurement
Impact sound insulation	No requirements	New requirements for impact sound insulation of floors over sensitive rooms (see page 8)
Reverberation times of rooms	Definition of Tmf was mean of 500 and 1000 Hz values	Definition of Tmf changed to mean of 500, 1000 and 2000 Hz values, which means there are limited permissible increases at lower frequencies. Some changes to room descriptions and values
Absorption in corridors, entrance halls and stairwells	No requirement	Requirements in terms of areas of sound absorbent material, as defined in Section 7 of the new Approved Document E
Open-plan spaces	No requirement	Use of open-plan spaces for simultaneous teaching of several classes is strongly discouraged. If there is a real demonstrable need for such spaces, detailed acoustic modelling is needed to demonstrate that a Speech Transmission Index (STI) of 0.6 or above will be achieved
Design checks	School designers were left to self certify compliance with the standards	School designers will have to submit information to satisfy building control bodies that the designs conform to the above requirements. Alternative criteria may be considered by Building Control bodies but must be fully and formally justified
Commissioning	No requirement	It is recommended that the client should include a requirement for acoustic testing in the building contract. The Building Control body may also request such a test

Footsteps on the classroom floor:
Maximum floor-impact sound levels
Type of room	Maximum weighted BB93 standardised impact sound pressure level L'nT (Tmf,max),w dB
Nursery school playrooms	65
Nursery school quiet rooms	60
Primary school: classrooms, class bases, general teaching areas, small group rooms	60
Secondary school: classrooms, general, teaching areas, seminar rooms, tutorial rooms, language laboratories	60
Open-plan spaces
Teaching areas	60
Resource areas	60
Music rooms
Music classroom	55
Small practice/group room	55
Ensemble room	55
Performance/recital room	55
Recording studio	55
Control room for recording	55
Lecture rooms
Small (fewer than 50 people)	60
Large (more than 50 people)	55
Other rooms
Classrooms designed specifically for use by hearing impaired pupils	55
Study room (individual study, withdrawal, remedial work, teacher preparation)	60
Libraries	60
Science laboratories	65
Drama studios	55
Metalwork/woodwork classrooms, resource/light craft and practical work	65
Assembly halls, multi-purpose halls (drama, PE, audio/visual presentations, assembly, occasional music)	60
Audio-visual, video conference rooms	60
Atria, circulation spaces used by pupils	65
Indoor sports hall	65
Gymnasium	65
Dance studio	60
Swimming pool	65
Interviewing/counselling rooms, medical rooms	60
Dining rooms	65
Ancillary spaces
Kitchens*	65
Offices, staff rooms	65
Corridors, stairwells	65
Coats and changing areas*	65
Toilets*	65
* This applies only to teaching and learning spaces and is not intended to cover administration and ancillary spaces. For these areas the values are for guidance only.