The Interchange Building, Croydon

Case Study: Acoustic Improvements in an Open Plan Office

Introduction

Clarion Housing Association, located on the third floor of the Interchange Building in Croydon, London, has been experiencing significant acoustic challenges in their open plan office. Employees in the housing and repairs team, who frequently communicate with clients via telephone, reported difficulties due to poor acoustic conditions. To address these concerns, Cahill Design Consultants were engaged by 3-Space UK to conduct an acoustic assessment and propose mitigation strategies.

Site Description

The open plan office under review consists of 72 workstations arranged in a hot-desking configuration. The space features a carpeted floor and a suspended lay-in grid ceiling. Workstations are equipped with dual monitors, and employees use headsets connected to their laptops. Initial observations noted the presence of acoustic screens between some workstations, primarily those facing each other.

Acoustic Challenges

The primary acoustic challenges identified were:

1. Noise Disturbance: High levels of ambient noise affecting communication and concentration.
2. Reverberation: Prolonged reverberation times causing speech to be unclear.
3. Sound Propagation: Inefficient attenuation of sound between adjacent workstations.

Assessment Methodology

The assessment was carried out following standards such as BS ISO 22955-2021 and ISO 3382-3:2012. Key acoustic parameters measured included reverberation time (RT), spatial decay of A-weighted speech (D2S), and the A-weighted sound pressure level of speech at 4 meters (LpAS 4m).

Findings

1. Reverberation Time: The RT values were found to be within acceptable limits, indicating the ceiling’s good absorption characteristics.
2. D2S and LpAS 4m Parameters: Both parameters were outside the required values for a call center environment. D2S values were below 5 dB, and LpAS 4m values exceeded 50 dB, indicative of poor acoustic conditions.
3. Workstation Noise Levels: Noise levels during typical work activities ranged from 43 to 57 dB. Due to low occupancy (stemming from a work-from-home policy), the noise levels were not representative of a fully occupied space, which should ideally exceed 55 dB.

Proposed Mitigation Measures

To address the identified acoustic issues, the following measures were proposed:

1. Acoustic Screens: Erection of acoustic screens at least 140 cm high between all workstations. This height is necessary to interrupt direct paths of speech and reduce sound propagation.
2. Wall Absorbers: Installation of Class A absorptive materials on the non-glazed areas of the internal walls, covering at least 80% of the surface area.
3. Review Work from Home Policy: Increasing office occupancy could naturally raise ambient noise levels, potentially masking disruptive speech and improving overall acoustic conditions.
4. Headset Upgrade: Investing in higher-quality headsets with advanced noise-cancelling features to reduce vocal effort and improve communication clarity.

Conclusion

The assessment confirmed the validity of the complaints raised by the Clarion Housing Association employees regarding the poor acoustic environment. By implementing the recommended measures, it is anticipated that the acoustic conditions will significantly improve, thereby enhancing communication efficiency and overall employee productivity. The combination of physical acoustic treatments and potential policy adjustments presents a comprehensive approach to mitigating the identified issues.

This case study underscores the importance of tailored acoustic solutions in open plan office environments, especially for teams requiring clear and frequent verbal communication. The proactive steps taken by 3-Space UK and Clarion Housing Association highlight their commitment to creating a conducive work environment for their employees.

Read our article on Open-plan offices Workplace Noise Annoyance – A multifaceted issue!