Reverberation solution for new sustainably-designed school sports hall

The internal environment of a newly built, highly sustainable school sports hall building on the south coast of England required acoustic enhancement to ensure it could be used and enjoyed to its full potential.

The facility at the New Horizons Seaside Primary School at Lancing in West Sussex was created to provide much needed additional space for PE sessions, which had become more difficult for teachers to deliver effectively as pupil numbers have been increasing. The long term forward-thinking vision of the school to create a highly sustainable new building, rather than opt for a standard, compliance-level hall, was brought to fruition by architects Burns Guthrie and Partners.

They proposed a design with materials and features that would minimise the carbon footprint of the sports hall, both in terms of its embodied carbon and carbon emissions during its lifespan. This included using a cross laminated timber (CLT) structure rather than steel, which represented an 85% reduction in embodied carbon for this major element of the building.

In addition, windows were positioned on the eastern elevation to maximise solar gain from sunlight early in the day and underfloor heating was installed supplied by air source heat pumps. The building is also naturally ventilated, controlled automatically by the temperature and carbon dioxide levels within the hall.

Once completed and in-use, attention turned to optimising the acoustic conditions through measures to reduce reverberation. Sports halls of all types are prone to high levels of reverberation given the presence of so many hard surfaces and few materials capable of absorbing soundwaves generated through speech, music and sporting activities.

Following consultation between the architects and Hush Acoustics, a solution was proposed in the form of wall-mounted absorber panels. The technical team at Hush produced acoustic calculations based on the drawings provided by the architect, which enabled a plan to be developed showing how many absorber panels would be required and their locations within the hall.

Hush Acoustics recommended the installation of 40x Hush Absorber 50 panels in three sizes – 1200 x 1200mm, 800 x 1200mm and 600 x 1200mm – which would cover more than 43 sq. m on the hall’s four walls. These absorbers are manufactured using a specially formulated 50mm thick acoustic foam which is hand finished with interior fabric applied to the face, edges and back return to offer a visually attractive result.

The Hush team calculated that the installation of these panels would transform the acoustic environment through a significant reduction in reverberation time (RT) – that is the amount of time taken for sound to decay by 60 decibels (dB) in a closed space after the sound source stops. It would also ensure that the RT was in line with the levels specified for school refurbishment projects in BB93 (Building Bulletin 93) of between 1.67s and 2.01s.

Prior to completion of the acoustic treatment, the 1000Hz RT was calculated at 3.90s. Following the installation of the Hush Absorber 50 panels, this reduced to 1.70s. Similarly dramatic reductions were also noted in the RT for lower and higher frequency sounds at 500Hz and 2000Hz.

Now that Hush Absorber 50 sound absorber panels are installed, the New Horizons Seaside Primary School sports hall not only provides a model for sustainable development, but a high quality teaching space that is popular with teachers and pupils alike.