One Leadenhall is a 35-storey tower neighbouring the historic Grade II* listed Leadenhall Market in the City of London. The development provides 40,000m² of modern office space, 743 m² of retail and hospitality space, and a publicly accessible terrace overlooking Leadenhall Market. The building is targeting BREEAM Excellent and WELL Platinum certifications.

Sandy Brown was appointed to provide acoustic design advice from concept design through to completion. Our input focused on setting optimal acoustic performance requirements for the building envelope, ensuring effective sound insulation between internal spaces, controlling reverberation and managing noise and vibration from building services.

For the building envelope, internal noise criteria observed BREEAM, WELL and British Council for Offices (BCO) guidelines. Facade flanking sound transmission was an important consideration where lightweight cladding would separate sensitive spaces from one another or noisy areas such as plant or retail areas.

Reducing airborne and impact noise between levels was key to achieving the desired sound insulation levels. Detailed specifications for floors and partitions were provided to effectively mitigate sound transmission between office floors, plant areas and external terraces.

The building includes an emergency generator installation located at high level within the tower. This posed several acoustic design challenges including vibration isolation, internal sound insinuation and environmental noise egress control. A specialist isolated box-in-box design was developed to mitigate these issues.