BREEAM Noise Assessment: Hea 05 and Pol 05 Noise and Acoustic Issues in Relation to Car Showrooms and Dealerships

19 June 2017 by Alex Priestley, Senior Consultant

Spectrum has worked with Meda International and BDB Design Build, as well as XLB Projects, on a number of car showroom developments across the country for Audi, JLR, Volvo, and Kia, being involved both at the planning stage as well as assisting with achieving BREEAM credits. In relation to noise and acoustics, credits under BREEAM sections Pol 05 and Hea 05 are often sought.

Section Pol 05 aims to reduce noise from fixed installations affecting nearby noise sensitive buildings. One credit is available under this section. In relation to car showrooms, the criteria to be met are typically less onerous that those imposed at the planning stage and are normally readily achieved.

Section Hea 05 aims to ensure that the acoustic properties of the building meet the appropriate standards for its use, and sets out criteria in terms of the indoor ambient noise level, sound insulation of internal partitions, and reverberation time. The number of credits available and the relevant criteria to be achieved under this section depend on the building category. Car showrooms fall under the Industrial, Retail, Prisons and ‘Other’ building types category.

Overview of Hea 05 credit requirements

Historically, within this category there have been two credits available. The first credit can be awarded where the criteria for both internal ambient noise levels and sound insulation of internal partitions are achieved. The second credit relates to reverberation times in spaces used for speech or performance. Where there are no spaces that are used for this purpose, and where the first credit is achieved, the second credit is awarded by default.

Credits under this section have been very difficult to achieve in car showrooms. Internal partitions typically consist of light weight demountable walls, often glazed, which offer a low acoustic performance and suffer from significant flanking noise effects. To meet the criteria, higher performance partitions would need to be specified and installed from true slab to soffit with careful consideration given to reducing acoustic flanking at each junction detail. This is generally seen as impracticable within the design and budget constraints of car showrooms.

As of the 2014 version of the BREEAM UK New Construction Technical Manual, an additional option for achieving credits within this building category has been provided. A suitably qualified acoustician is appointed to define a bespoke set of criteria for each of the three assessment areas (internal ambient noise level; sound insulation; reverberation) and one credit is awarded for each. Therefore, up to three credits are available as opposed to the two available under the first (historical) option. The issue of achieving a good standard of sound insulation between adjacent spaces remains. However, it no longer precludes achieving credits for internal ambient noise and reverberation, which may be awarded independently under the bespoke methodology.

Some further detail

It is worth noting that BS 8233 was also revised in 2014. BREEAM has not been consistent in its references to this Standard. The compliance notes in Pol 05 still refer to the old Standard from 1999, which is now withdrawn. Hea 05 now refers to the current version of the Standard published in 2014.

The BS 8233 guideline criteria for sound insulation that is referred to in Hea 05 was revised in 2014. Previously, it was advised that for acoustically sensitive rooms, the sound insulation performance of a partition (as measured in terms of Dw) should take account of the internal ambient noise level (LA) within the room such that Dw + LA > 75. This recognises that internal ambient noise can provide some useful masking of external noise breaking into a room. For rooms considered to be particularly sensitive BS 8233 advises that the sum should be greater than 85. Given the limiting criteria within Hea 05 for internal ambient noise, and the fact that a mechanical ventilation scheme is normally designed to reduce noise to below a specified level (rather than to within a small range), the requirements for sound insulation can become particularly onerous.

The current version of BS 8233 does away with these guidelines, rather, setting out a guideline matrix within Section 7.5, which can be used to determine the required sound insulation performance of a partition (now in terms of DnT,w). The matrix takes account of the degree of activity noise in the source room and the sensitivity of the receiver room. The internal ambient noise level in the receiver room is no longer considered.

In spite of these changes, typical layouts and construction types used in car showrooms still have limited potential to meet the criteria. However, the bespoke option for achieving credits under BREEAM Hea 05 for Industrial, Retail, Prisons and ‘Other’ building types means that this does not have to preclude the targeting of other available credits within the section.

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