Journal article

Energy and GHG reductions considering embodied impacts of retrofitting existing dwelling stock in Greater Melbourne

01 Jan 2018

Energy retrofits of buildings usually ignore the amount of embodied energy and greenhouse gas (GHG) emissions needed to reduce the operating energy and related emissions. Focusing on the Greater Melbourne Area (GMA), the fastest growing capital city in Australia, this paper analyses the embodied impacts of different dwelling stock retrofit programs using a combination of a top-down and a bottom-up approach. We look at dwelling stocks that have been built before 2005 (i.e., before a minimum 5-star rating in energy performance was introduced in Australia) because these are expected to consume, without any retrofit or upgrade, about 34.9 TWh of energy or emit 8.57 × 106 t-CO2eq GHG for heating and cooling every year. Retrofit options to improve their energy star rating range from relatively cheap and easy options (e.g., draught sealing) to relatively expensive options (e.g. double glazing of windows). If all these buildings' energy efficiency is improved to the level of a 6-energy rated dwelling across the metropolitan region, we can save about 25.5 TWh per year in heating and cooling energy (or 6.25 × 106 t-CO2eq GHG each year). 
Net energy and GHG emission reductions are analysed when upgrading the existing dwellings across the Greater Melbourne.
Input-Output analysis was employed for the embodied impacts assessment of building retrofit options.
Existing dwelling upgrade to 6-star energy efficiency level saves 25.5TWh/year in the Greater Melbourne Area.
The 6-star dwelling upgrade consumes a total of 4.7TWh of embodied energy.
Environmental and economic payback times are analysed for different levels of upgrade (to 3, 4, 5 and 6-star) in GMA.

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