9 May 2013 — Sustainability and Heritage guidance sheets have been released by the Victorian Government to help owners of heritage homes improve energy efficiency and save money.

The guidance sheets cover contemporary houses, 1970s houses, postwar houses, bungalows, interwar, Edwardian and Victorian houses. They identify heritage features and the costs and savings associated with interventions such as ceiling insulation, underfloor insulation, thermal curtains and draught sealing.

Planning Minister Matthew Guy said the guidance sheets showed that relatively simple interventions could result in significant cost savings, an increase in the home’s star energy rating and a reduction in environmental impacts.

For example, if energy efficiency measures were implemented in a typical Victorian terrace, it could result in savings of up to $520 per year and a reduction in heating and cooling needs by 57 per cent.

The guidelines were developed from a study undertaken by RMIT University for the Heritage Council of Victoria, the Building Commission, the Office of the Victorian Government Architect, the Department of Planning and Community Development and the Department of Sustainability and Environment.

RMIT College of Design and Social Context research and innovation director Ralph Horne said the study started in 2009 after discussions with the Building Commission and Heritage Victoria around retrofitting and potential damage to heritage values.

Mr Horne said it was decided to take a few archetypes and create a software model using NATHERS ratings calculating heating and cooling – and model the results of various modifications to upgrade energy performance of the homes.

The study showed, “not surprisingly”, that retrofitting could be very worthwhile in terms of cost and payback, he said.

“We were looking at improvements that would maintain the heritage value and if buildings of different eras were more expensive to renovate,” Mr Horne said.

One of the simplest improvements was bulk insulation in the roof space which offered a range of payback from three to eight years. Gaps and cracks were also significant in providing energy savings while being relatively easy to fix.

Mr Horne said while the study had taken some time, with a suite of buildings involved, it had offered up a much better understanding of heritage homes.

The study, which also covered the life cycle energy of the houses, also found that the energy used to heat and cool the house was far greater than the energy embodied in the materials and it made sense to focus attention on upgrades when seeking to reduce life cycle energy use.

It also showed that if a house could be retained and improved, the primary energy associated with the construction and materials of a new, replacement house could be avoided.

However Mr Horne said while home renovations were a ubiquitous phenomenon, and increasingly people were looking for energy efficient renovations, at the same time renovations were often about creating bigger spaces, which had consumption implications.

“We need to know how to tap into renovating practices, and information (as in the guidance sheets) is part of the picture,” he said.

“This study is just an entrée – now the whole conversation has to be had on what we are doing with buildings.”

“I would like to see studies like this contributing to a conversation involving the broader community.”

Ralph Horne

The Sustainability and Heritage guidance sheets can be accessed at www.dpcd.vic.gov.au/heritage/projects-and-programs/heritage-places-and-sustainability

An Edwardian house case study

Outcome:

  • Heating and cooling needs reduced by up to 57 per cent.
  • Potential cost saving of up to $2900 per annum for $13,000 investment
  • 5 gigajoule per square metre of primary energy is embodied in the building itself
  • 94 GJ per square metre of primary energy is used for heating and cooling over the building’s lifecycle

This case study is one of a series which examines the use of energy for heating and cooling in typical existing and heritage homes. It also identifies upgrades to the building fabric which can be incorporated to reduce energy use. The study takes a life cycle approach which includes heating and cooling as well as energy used to create the fabric of the buildings. For more information on the methodology of analysis that formed these case studies, refer to the Guidance Sheet Introduction in this series.

Period: 1901–1918

This example, representative of many Edwardian style dwellings, has weatherboard walls, metal roof and a floor area of 220 square metres.

Edwardian period dwellings often include elaborate plaster ornaments and stained glass front windows, featuring geometric and curvilinear shapes and sometimes native plants or birds. Many feature red brick walls with flush joints with cream painted render to base and gable ends.

Life Cycle Energy Use

Over the life cycle of any building, primary energy, largely derived from fossil fuels, is used to manufacture materials, construct the building, heat and cool the building, maintain the building, and to dispose of the building at the end of its life. Using life cycle assessment it was determined that the house will use 100 gigajoule per square metre of primary energy over its life, of which 94 GJ is associated with heating and cooling, 5 GJ with materials and construction and 1 GJ with the other life cycle stages mentioned above (over a 100 year lifetime). Results exclude all appliances other than heating and cooling appliances.

Reducing Life Cycle Energy Use

The life cycle energy study tells us that the primary energy used to heat and cool the building is far greater than the energy used in other life cycle stages and should be the focus of attention when seeking to reduce energy use. It also tells us that 5 GJ per square metre of primary energy is associated with the manufacture of materials and the construction of the building itself. If the house is retained, the primary energy associated with the construction and materials of a new, replacement house can be avoided (a contemporary 5 star house analysed in the study required 4 GJ per square metre of primary energy for construction and materials manufacture).

To help place these figures into context, 100 kilograms of brown coal contains approximately 1 gigajoule of primary energy.

Interventions to Reduce Heating and Cooling Energy Use

The study also identified building fabric related interventions to reduce heating and cooling energy use. To determine how these interventions might perform, each was modelled independently and compared to a theoretical baseline comprising the same house with no insulation. Although based entirely on modelled results (no actual interventions were undertaken), the results show that significant energy efficiency improvements could be achieved. In addition, the primary energy associated with the materials and installation of the interventions was small relative to the house as a whole.

Additional Energy Savings

The study undertaken focussed primarily on the fabric of heritage buildings and how this relates to heating and cooling energy use. Although it did not consider the upgrade of heaters, coolers and other appliances to improve efficiencies, these items also represent good opportunities for energy savings. Good sources of additional information relating to home energy efficiency are www.yourhome.gov.au, www.livinggreener.gov.au and www.resourcesmart.vic.gov.au