Designing energy efficient offices

The rising tide of concern about climate change is difficult to ignore, whether it is investors divesting from fossil fuel assets, the UK government's commitment to zero carbon, or the sustained effort of organisations such as Extinction Rebellion.

A swathe of commitments by built environment leaders and professional bodies acknowledges the important role that buildings play in mitigating and preparing for climate change. Better Buildings Partnership (BBP) launched its own climate commitment in September with 23 member signatories covering more than £300bn of assets under management.

This commitment acknowledged the scientific imperative to provide net zero carbon buildings by 2050, and to support this effort signatories will be publishing their net zero carbon pathways in 2020. But as the commitments and headlines ebb and flow, it is critical to put into place the mechanisms that will transform the efficiency of our new and existing buildings.

Introduced in 1998, NABERS helped to cultivate Australia's culture of designing for performance. The voluntary operational rating scheme benchmarked the energy used by a landlord to service an office building, referred to as a base building rating, and used a simple star scale with six being the best and one the lowest.

As a result of its success and voluntary take-up by the real-estate market, the Australian government introduced the Building Energy Efficiency Disclosure Act in 2010. This legislation made it a legal requirement for all commercial office buildings with a net lettable area of more than 2,000m² to obtain and disclose a valid NABERS Energy base building or whole building rating at the point of sale or lease.

In 2017, the threshold was lowered to 1,000m². Now covering 86% of the office sector by floor area, it has transformed the energy performance of such buildings. Since the introduction of the 2010 Act, the average energy intensity of all base building-rated offices has improved by 36%, with the average star rating increasing from 3.3 to 4.4.

Although initially focusing on existing buildings, NABERS has also changed the design approach to new office buildings and major refurbishments through the development of an energy commitment agreement. Established in 2002, this provides a framework for property owners and developers that commits their design teams and contractors to design and construct a new or refurbished office building that achieves a targeted base building rating.

Put simply, Australia has learnt to build or refurbish office buildings of a much better standard than those in the UK, thanks to the transparency of NABERS and the market benefits it brings. There are other schemes that focus on performance in use, such as the US Energy Star, but NABERS differentiates itself on the grounds that the base building rating enables clear accountability for energy use in a building, addressing the perennial challenge of split incentives and landlord and occupier responsibilities.

An initial feasibility study was followed by an 18-month pilot programme, to test which factors were key to the success of the rating and agreement framework in actual UK developments. The aim was to provide a sound evidence base that would inform how a scheme could be effectively implemented.

DfP has also attracted interest from an advocacy and policy perspective, with BPP's research supporting many recent recommendations on UK commercial buildings' efficiency and the development of green finance services. This critical work should give the government evidence to apply DfP in other sectors, where supportive policies will be vital.

Related competencies include: Sustainability