Energy renovation of historic buildings in New Zealand: Towards a holistic method for reducing environmental impact

As nations develop CO2 reduction targets, the energy renovation of historic and heritage buildings has been seen as an opportunity to reduce energy and Greenhouse Gas (GHG) emissions while preserving these buildings' historic values and character. Climate Change concerns are emphasising the built heritage environmental issues, resulting in both environmental and social benefits. Internationally, many countries have adopted energy retrofit policies, and there has been an increasing number of projects and published material on the energy renovation of historic buildings. However, New Zealand (NZ), unlike Europe and USA, has no country-specific policies or guidelines for historic retrofit considering social, cultural, environmental and economic aspects.

This research explores whether NZ would benefit from adopting similar guidelines from a policy and practice perspective. It discusses the environmental, economic and social benefits of such guidelines, and the country-specific requirements for adopting energy renovation guidelines for historic buildings. This research initially applies the existing European renovation process onto three hypothetical energy retrofits of heritage buildings in Wellington, NZ. These case studies, coupled with experts’ interviews, investigate the benefits and limits on the application of a specific procedure, multiple criteria assessments, some recommended methods and risk analysis for the renovation process. It also reveals possible trade-offs among different assessment criteria (e.g. energy, cost, thermal comfort, carbon footprint and heritage impact), and desirable modifications in the whole process of adapting it to the NZ national context.

This research concludes that adopting tailored retrofit guidelines can contribute to the national goal of reducing GHG emissions by 2050 and, at the same time, protect historic buildings from demolition. The interviews support energy retrofit guidelines for historic buildings as good practice and reveal experts’ recommendations, the perceived benefits and barriers to adopting country-specific renovation guidance. It concludes with the proposal of preliminary guidelines for energy retrofitting houses in NZ.