Gilbert-Ash has announced that its £29 million redevelopment of Havelock House on Great Bridgewater Street, Manchester, has achieved the highly coveted 'BREEAM Outstanding' sustainability rating.

BREEAM (Building Research Establishment Environmental Assessment Method) is an internationally recognised benchmark for sustainability in building design, construction and operation. Fewer than 1% of non-domestic buildings registered in the UK attain the Outstanding classification, highlighting the significance of the achievement.

Gilbert-Ash led the design and build redevelopment of the former warehouse, transforming it into nine floors of high-spec CAT A office space, including a basement and two additional upper levels. The project's deep retrofit strategy retained the existing structural framework and implemented numerous sustainable technologies, significantly reducing the environmental footprint.


OMI Architects played a key role from the early stages, aligning the project with BRE’s Green Guide principles and ensuring responsible sourcing of products throughout the construction phase. The new façade system, selected through a whole-life carbon appraisal, preserved 2,000 CO2e of embodied carbon—equivalent to the carbon sequestered by 10,250 trees.

Offsite fabrication of the unitised façade further reduced waste and accelerated the construction timeline, while a rainwater harvesting system installed in the basement helped minimise water usage across the development.

Ray Hutchinson, Managing Director at Gilbert-Ash, said: "At Gilbert-Ash we have delivered some of the UK and Ireland’s most iconic spaces and we are thrilled Havelock House is our first project to receive BREEAM Outstanding certification.

Innovation, collaboration and determination are at the heart of everything we do and this recognition is thoroughly deserved."

Michael Heron, Gilbert-Ash Environmental, Social and Governance Lead, added: "Over the years, Gilbert-Ash has garnered a plethora of BREEAM Excellent and Very Good ratings but this is a new level for us.

"To achieve this BREEAM Outstanding recognition, we had to implement at least 10 minimum standards including an air quality plan, a building user guide, seasonal commissioning and the responsible sourcing of construction products.

"It would not have been possible to achieve this accreditation without early engagement by OMI Architects with the Green Guide. Implementing BREEAM Outstanding will ensure resource efficiency and lower maintenance and energy costs over the structure’s lifespan."