NABERS UK | DYNAMIC MODELLING MODEL NABERS Key to attaining a Nabers operational rating for a commercial building is the creation of a dynamic energy simulation model that closely predicts actual operational performance. Alex Smith looks at how Hoare Lea modelled Timber Square to achieve the UKs first design target rating T he widespread disclosure of operational energy in UK buildings has taken a big step forward this year, with large commercial developers awarded Nabers UK ratings. Landsec was the first in the country to achieve a design target rating for its proposed Timber Square office development in Southwark, which received a five-star rating in February, while Grosvenors 87,500ft2 Toronto Square building in Leeds has achieved the first Nabers UK rating for an existing office building. It was given 4.5 stars after 12 months of data was analysed by licensed assessor EP&T Global and independently certified by BRE. Nabers measures and verifies the actual energy use of commercial buildings, and awards offices a star rating of between one and six. The scheme was imported from Australia, where it has been used for more than 20 years, and where a recent report found that buildings benefited from an average 42% reduction in base building energy intensity after the 14th Nabers rating. The two rating systems for new and existing buildings are called 20 August 2022 www.cibsejournal.com Nabers Design for Performance (DfP) and Nabers Energy respectively. Nabers recognises buildings at the design stage by awarding a target rating after an independent design review (IDR), which assesses a detailed dynamic energy-simulation model of the building (see panel, right). The DfP process commits owners to design, build and commission a new development, or major refurbishment, to achieve a specific Nabers UK energy rating (See panel, Design for Performace process). Landsecs Timber Square is an ambitious 335,000ft2 development comprising two office buildings plus ancillary retail/leisure uses. The scheme consists of the 15-storey new Ink Building and the 10-storey Print Building, which is a refurbishment and extension of an existing building. Hoare Lea was involved from project inception and provided building services engineering and a range of other disciplines, including sustainability, acoustics and fire. There was a clear brief from Landsec that Timber Square would use modern methods of construction and circular economy principles