The practice, which has worked on several projects for The Crown Estate since participating In the AJs Office for the Future competition In 2016, aimed to transform its existing commercial property through the creation of flexible and healthy office spaces to support greater collaboration between occupants.This thinking was applied to 12 Little Portland Street, a Grade II-listed office building dating from the 1920s, close to Oxford Circus and Broadcasting House.Threefold based its overall approach to the project on four principles: minimising waste through auditing, preserving and re-use; restoring heritage; future-proofing fabric; and creating workspaces that promote wellbeing.AdvertisementGiven the desire to move away from the model of large, single occupiers in the post-pandemic working environment, the remodelled building now provides smaller, more flexible and fully accessible spaces to attract a diverse occupancy mix and support hybrid working.The buildings fabric and services have been significantly upgraded to improve energy performance and address the circular economy, according to the practice, with extensive use of natural and reclaimed materials. Threefolds interventions aimed to celebrate the grandeur of the existing building, including restoring the faade. Internally, the generous proportions of each space have been maximised, window reveals have been enhanced and period features refurbished and echoed by new design elements, while planting and colour add visual interest.A new BMS provides fully upgraded mechanical and electrical services throughout the building, while heating and cooling are served via a high-efficiency recovery condenser.Existing raised access floors were removed and reused in other projects while existing primary and secondary glazing was fully reused on site.The roof now features a new terrace for outdoor events plus extensive all year-round foliage in line with the Wild West End greening strategy to encourage biodiversity and improve air quality. Bee blocks and bird and bat boxes have also been incorporated into the external walls to support urban wildlife.AdvertisementArchitects viewThe 12 Little Portland Street project presented a fantastic opportunity to work with The Crown Estate to revitalise a heritage building and, in doing so; create a series of modern workspaces that promote health, happiness and wellbeing.This project celebrates heritage, promotes decarbonisation, enhances biodiversity and demonstrates how through sensitive and innovative design, existing buildings can be adapted to have bright and flexible futures.Jack Hosea, founding director, Threefold ArchitectsProject dataStart on site November 2022CompletionNovember 2024Gross internal floor area 2,484m2Form of contractDesign and BuildConstruction cost 6.1 millionConstruction cost per m2 2,451Architect Threefold ArchitectsExecutive architect Gravity DesignClient The Crown EstateStructural engineer Heyne Tillet SteelM&E consultant Watkins PayneQS QuantemAcoustic consultant Hann Tucker AssociatesProject manager Dendy ByrneCDM co-ordinator TFT consultantsApproved building inspector Assent BCMain contractor Artemis interior ServicesCAD software used VectorworksEnvironmental performance dataPercentage of floor area with daylight factor >2% Not availablePercentage of floor area with daylight factor >5% Not availableOn-site energy generation NilAnnual mains water consumption 5.28 m3/occupantAirtightness at 50Pa Not availableHeating and hot water load 28.86 kWh/m2/yrOverall area-weighted U-value Not availableDesign life 15 years (services only)Embodied carbon 199.35 kgCO2eq/m2Whole-life carbon 585.06 kgCO2eq/m2Annual CO2 emissions 23.9 kgCO2eq/m2