It is a known fact that achieving the minimum requirements set-out by Building Regulations, does not mean that satisfactory conditions are achieved for building occupants.
A classic example is the low frequency impact noise of some timber floor constructions which, according to recent studies, can contribute towards discomfort and annoyance amongst building users, even when Building Regulations criteria is achieved.
ISO 10488 has recently been registered for formal approval and it will soon be published. The standard seeks to describe class criteria and procedures for acoustic classification of dwellings with classes reflecting different levels of acoustical comfort in new housing.
Its main purpose is to help developers to specify a standardised level of acoustic quality and for users to be informed about the acoustic quality of their buildings.
It can also help the relevant national authorities to define specific classes in Building Regulations as a required minimum.
The standard includes criteria for:
1. Airborne sound insulation;
2. Impact sound insulation;
3. Sound insulation against exterior noise (traffic, industry and other sources);
4. Noise from building services equipment;
5. Reverberation time and sound absorption in stairwells and access areas.
The classification is specified for six classes A, B, C, D, E and F for dwellings. Class A is the highest class and F the lowest class. Examples of criteria for airborne and impact sound insulation are presented in the Tables below.
Note: The tables in the final version of the standard may vary.
New parameters?
As it can be seen in the Tables above, ISO 19488 introduces not only criteria but also parameters which differ from Building Regulations Approved Document E. Regarding airborne sound insulation, it refers to the parameters DnT,50 and DnT,A and regarding impact sound insulation it refers to L’nT,50.
For ease of reference, these can be described as follows:
DnT,A - sum of the weighted standardised level difference DnT,w and the spectrum adaptation term C according to ISO 717-1 DnT,A = DnT,w + C
DnT,50 - sum of the weighted standardized level difference DnT,w and the spectrum adaptation term C50-3150 according to ISO 717-1 DnT,50 = DnT,w + C50-3150
L’nT,50 - sum of the weighted standardised impact sound pressure level L’nT,w and the spectrum adaptation term CI,50-2500 according to ISO 717-2 L’nT,50 = L’nT,w + CI,50-2500
Approved Document E vs ISO 19488
It can be complex to compare both sets of criteria in detail but to have an idea, if we consider the requirements between two adjacent living areas which form part of different dwelling units, we have the following scenario:
We can see that regarding airborne sound insulation, ADE requirements translate mainly to a Class D. However, for impact sound insulation the requirements translate to a Class E.
As mentioned in the very beginning, complying with Building Regulations does not mean that satisfactory conditions are achieved for building occupants and as such this does not come as a surprise.
An effort towards an international acoustic classification
ISO 19488 is a stepping stone for the construction and the acoustics industry and a very significant contribution towards an international acoustic classification scheme for dwellings. Provided that relevant national entities adopt its criteria, the exchange of construction experience and trade between countries, including the European region, is expected to increase.
The adaptation of the standard criteria will, without a doubt, also contribute towards sustainability in construction and our team is looking forward to work with any clients who wish to pursue its application.
References:
[1] ISO/FDIS 19488 (2018), Acoustics - Acoustic classification of dwellings. ISO, Geneve, Switzerland;
[2] J Harvie-Clark, F Larrieu, Iain Critchley; Impact sound insulation in timber frame flats: International experience and opportunities for application in the UK, Proceedings of the Institute of Acoustics, Vol. 37. Pt.2 2015
[3] Rasmussen, B., & Machimbarrena, M. (2019). Developing an international acoustic classification scheme for dwellings – From chaos & challenges to compromises & consensus? In A. Calvo-Manzano (Ed.), Proceedings of Inter-Noise 2019 : The 48th International Congress and Exhibition on Noise Control Engineering: NOISE CONTROL FOR A BETTER ENVIRONMENT (pp. 1-12). INTERNATIONAL INSTITUTE OF NOISE CONTROL ENGINEERING. Noise-Con Proceedings http://www.sea-acustica.es/fileadmin//INTERNOISE_2019/Fchrs/Proceedings/2140.pdf
[4] ISO 717:2013, Acoustics – Rating of sound insulation in buildings and of buildings elements. – Part 1: Airborne sound insulation. – Part 2: Impact sound insulation.