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CAT B Refurbishment

Piper Sandler, a leading investment bank and asset management firm, sought to refurbish approximately 19,160 sq ft of commercial office space on the 6th floor of 2 Gresham Street, London. The project involved upgrading the space from Cat A to Cat B standard, with a focus on partially exposed mechanical and public health services in circulation areas, break out areas, and reception. The project was completed within a tight 17-week timeframe, with a value of £2.5 million. Parkeray was the main contractor, while Proton Built Environment provided mechanical and public health services design and coordination, as well as environmental services input for BREEAM certification.

Image by Winston Tjia




The project faced several challenges, including working with the constraints of the existing base build services, which had to be retained with only minor adaptations to accommodate the new office layout. The ceiling voids were restrictive, and the requirement for partial exposure of services in certain areas posed additional design and coordination challenges. Coordination with the base build services and integration of new services within the limited space available were critical to the success of the project.


Proton Built Environment, as the mechanical and public health services designer, provided innovative solutions to address the challenges. LED feature lighting and lighting controls were carefully designed and integrated to create a visually appealing environment while meeting energy efficiency requirements. 4-pipe EC/DC fan coil units were installed to provide efficient heating and cooling to the office spaces. Central mechanical ventilation was strategically designed to ensure optimal air quality and comfort for occupants.

Proton Built Environment worked closely with SALE Group and other project stakeholders to coordinate the design and installation of the services within the limited ceiling voids and exposed areas. Detailed 3D modelling and clash detection were employed to ensure that the services were accurately coordinated with other building elements, such as structural beams and architectural features.

To achieve BREEAM certification, Proton Built Environment provided input on environmental services, including energy efficiency, water conservation, and waste management. This helped the project to meet sustainability targets and contribute towards the overall BREEAM rating.


The CAT B refurbishment project at 2 Gresham Street was successfully completed within the 17-week timeframe and met the client's requirements for partially exposed services in circulation areas, break out areas, and reception.

The upgraded office space provides a modern and functional work environment for Piper Sandler, with efficient mechanical and public health services that meet energy efficiency and sustainability standards.


The coordination efforts between Proton Built Environment, SALE Group, Parkeray, and other project stakeholders ensured a smooth execution of the project, overcoming the challenges posed by the existing base build services and limited ceiling voids. The project's successful completion further strengthened the relationship between Piper Sandler and the project team, showcasing Proton Built Environment’s expertise in mechanical and public health services design and coordination for Cat B office refurbishments.

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