Box 9.32 The green building agenda

The green building agenda being embraced and promoted by many agencies is refocusing attention on responsible building and development, and directing resources to general upgrading of the built environment. This was thought to have benefits for heritage conservation, but instead the green building agenda is placing significant pressure on heritage buildings. The threats can be grouped into two categories—the impact of sustainability legislation, and the characteristics of heritage buildings themselves.

The Commonwealth Scientific and Industrial Research Organisation (CSIRO) has determined that the energy embodied in existing buildings in Australia is equivalent to 10 years of the total energy consumption of the entire nation.⁹⁹ However, sustainability legislation measures only the operational efficiencies of buildings, with the aim of achieving immediate greenhouse gas savings by increasing efficiencies in heating, cooling and ventilation, saving water and minimising waste. Rating tools generally do not provide any recognition of the sustainability benefits of conserving existing buildings, and do not acknowledge the embodied energy inherent in these structures. They also do not consider the contribution that the inherent quality of materials makes to the lifecycle of a structure, nor the cultural value of the building to the community.

Wasted embodied energy is a growing issue, and a lifecycle assessment approach is appropriate. Better recognition could be paid to the potential for improvement of the environmental performance of existing buildings.¹⁰⁰

The risk is that, rather than being conserved and refurbished, historic buildings will be demolished because they do not meet the contemporary green standards sought by industry and consumers. This risk will continue while the Green Star rating categories do not award points for heritage and do not adequately recognise the value in retaining existing materials. Points are awarded for replacing existing fabric with recycled material, even if the removed fabric is trucked off to landfill. Few, if any, points may be earned for retaining existing fabric; none for ensuring the 'integrity' of the original is maintained. Yet if the full lifecycle is considered, 'upgrading and maintaining an existing building to a 4.5 Green Star rating is 2.5 times more efficient than demolishing to build an equivalent 5 Green Star building measured at year 30 in the building cycle.'¹⁰¹ However, 'a refurbished building will not have new concrete poured and therefore cannot achieve the credit for use of recycled content in structural concrete.'¹⁰²

The requirement for commercial building disclosure now ensures that the National Australian Built Environment Rating System (NABERS) energy ratings are available for large commercial buildings (soon to be extended to residential buildings). As the NABERS rating tool only rates energy efficiency, there is a great danger that heritage buildings will become even less desirable to owners and tenants who seek higher energy ratings. This pressure is already well demonstrated by government policies that require government business to be done from buildings with high NABERS ratings (e.g. the John Gorton Building that houses the Canberra offices of the Department of Sustainability, Environment, Water, Population and Communities).

The physical characteristics of a heritage building may also pose difficulties for achieving high energy ratings. Higher star ratings under the current rating tools require significant investment in innovative technologies, and significant additional plant area for capturing water, recycling greywater and installing cogeneration or trigeneration plans. Heritage buildings often have smaller floorplates, sit on smaller sites and may be constrained by the inability to excavate for additional plant area, or to add this to the roof area. These characteristics affect the ability of heritage structures to compete in the current rating system.

Several organisations are working to redress the imbalance of the current rating tools in a number of different spheres. Organisations include the Green Building Council of Australia, which is developing a rating tool for existing buildings; the Australian Tax Office, which is proposing a green investment tax incentive for retrofitting; and RMIT University and Heritage Victoria, which are researching the embodied energy of various heritage building typologies. The CSIRO is developing the Australian Life Cycle Inventory materials database for eventual incorporation into the Nationwide House Energy Rating Scheme, and organisations such as the Property Council of Australia run seminars on retrofitting existing buildings.¹⁰¹

Box 9.33 Innovative approach – being mindful of operational needs and heritage values

The Lake Margaret Power Station on the west coast of Tasmania is one of the state's earliest hydro power stations. In 2006, the upper station was decommissioned and a proposal was lodged to demolish the unusual 2.2-kilometre woodstave pipeline that fed water to the station. The 70-year-old King Billy pipeline had reached the end of its effective life, and demolition was the only pragmatic option. However, the high heritage value of the site was a major consideration for future options. A collaborative approach between Hydro Tasmania, the Tasmanian Heritage Council, local government and community representatives ensured the preservation of the heritage values of the area. Hydro Tasmania's engineers found an economical solution to reconstruct the pipeline using ash cedar. The project blended modern and traditional construction techniques and incorporated elements of the original works dating from 1914. Three sections of the original King Billy pine woodstave pipeline have been preserved onsite and a further three were donated to museums. The power station recommenced operations in October 2009.