Header image

CIBSE AWARDS | UCL 22 GORDON STREET Core principles The CIBSE award-winning retrofit of 22 Gordon Street has saved University College London 110,000 in annual bills. Andy Pearson looks at how BuroHappold Engineering used thermal mass in the original structure to minimise energy use and how researchers helped identify comfort issues W hen engineer BuroHappold Engineering and architect Hawkins\Brown were first involved in the refurbishment of the former Wates House, home of the Bartlett School of Architecture at University College London (UCL), their brief was to improve the thermal performance of the buildings 1970s single-glazed, brick faade. The original buildings faade thermal performance was so poor that the cramped interior of the seven-storey building was too hot in summer, too cold in winter and expensive to run. It was soon apparent, however, that the expense and effort required to improve the performance of the faade would enhance occupants thermal comfort, but it would do nothing to resolve the issue of the buildings cramped interior. As an alternative, Hawkins\Brown proposed a deep retrofit, which in addition to replacing the poor-performing faade would extend the floor plates and reconfigure the interior, to help address the outdated learning environment while delivering better long-term value. The proposal was to: retain the buildings reinforced concrete structure; reconfigure its layout, including the addition of a new centrepiece staircase; extend the existing floor plates outwards; build a new, full-height extension on a small area of infill land adjacent to the building; and re-clad the entire building. The additions doubled the space for teaching and research, in addition to helping tackle the buildings poor energy performance. The deep retrofit also meant stripping out the buildings ageing mechanical, electrical and plumbing (MEP) systems, and replacing them with new, more energy efficient systems that would enable the building to achieve Breeam Excellent. At the same time, these systems would help maintain a comfortable environment for increased numbers of students. The schools plan was to expand; it was apparent that faade replacement alone would be expensive and the school would gain nothing in terms of increased floorspace without the new additions, says Kenichi Hamada, an associate at BuroHappold, the projects MEP engineers. In contrast to its sleek newly clad brick-and glass-exterior, the architect wanted the interior of the 22m refurbishment to provide a robust canvas for the creativity within which, in engineering speak, meant it wanted the rawness of the original concrete structure to remain on view for all to see. We estimate that retaining the original concrete frame not only saved money and build-time, but it also saved 400 tonnes of CO2, says Hamada. The exposed thermal mass of the concrete structure and soffits provide additional thermal inertia to help guard against large daily temperature swings. The architects vision for a robust canvas also included the building services, which it wanted to remain exposed to complement the unadorned concrete structure and utilitarian timber-joinery aesthetic it had planned for the interior. For BuroHappold, this meant working closely with the architect, client, PROJECT TEAM Acoustics, building services engineering, fire engineering, lighting design: BuroHappold Engineering Architect: Hawkins\Brown students and teaching staff to develop a solution to coordinate with the buildings exposed structure. The building is evolving all the time, so not having a ceiling will give it additional flexibility, Hamada explains. BuroHappolds solution was a mixedmode ventilation scheme based on active multi-service chilled beams that would provide heating or cooling as required. In addition to a heating/cooling coil, the multi-service chilled beams simplified the solution, incorporating presence and smoke detectors, a speaker, and low-energy LED lighting. 32 April 2020 www.cibsejournal.com CIBSE Apr20 pp32-35 22 Gordon Street.indd 32 20/03/2020 16:45