Acoustics case study

The Captain Sir Tom Moore Building, Halton General Hospital – CDC Unit Extension


Kier is constructing an extension to the existing Captain Sir Tom Moore (CSTM) Building at Halton General Hospital to form a new Community Diagnostics Centre (CDC) Unit. The single-storey CDC Unit extension will house two new scanners and associated ancillary spaces, with plant located on the roof (some in the open air, some within a plant room). The scheme is targeting a BREEAM “Pass” rating.


Being a relatively small scheme in terms of hospital developments, there is a high level of focus on pragmatic and cost-effective solutions to keep costs down. Plant noise from the roof of the CDC Unit extension must be controlled to not exceed guideline internal noise levels in the existing CSTM building – some rooms have direct line of sight over the new roof plant. Vibration from construction works for the CDC Unit extension will have an impact on the existing CT and MRI scanners in the CSTM building.


We are working with Kier and the architect to develop a cost-effective acoustic design strategy for the new building which meets the HTM 08-01 design guidance. This includes:

  • building envelope and ventilation strategy to meet the indoor ambient noise level criteria
  • internal elements such as partitions, floors, doors, and glazed screens to meet the sound insulation criteria
  • room finishes to meet the reverberation time criteria
  • testing to satisfy BREEAM credit Hea05 for indoor ambient noise levels, absorption, and sound insulation
  • assessment to satisfy BREEAM credit Pol05 for controlling the level of plant noise at the nearest noise sensitive receptors

In addition to this, we have worked very closely with Kier as well as physicians and clinical staff from The Trust to determine the vibration impact of the proposed construction works on the existing CT and MRI scanners in the CSTM building. There was concern over this based on previous projects where construction vibration had caused significant damage to existing scanners.

Kier facilitated the simulation of some construction activities in the site compound using a 5-tonne excavator, and we measured the vibration caused by its various activities in the existing scanner rooms. We compared the measured vibration levels against the design thresholds for the scanners provided to see if they were exceeded. This assessment allows The Trust to more accurately determine the amount of downtime required for the scanners during construction, which in turn will help to determine to what extent they need to utilise mobile scanners or absorb the work elsewhere.