Carbon Footprint Reduction through Residential Building Stock Retrofit: A Metro Melbourne Suburb Case Study

Seongwon Seo,Greg Foliente

doi:10.3390/en14206550

Abstract

Since existing residential buildings are a significant global contributor to energy consumption and greenhouse gas (GHG) emissions, any serious effort to reduce the actual energy and carbon emissions of the building sector should explicitly address the carbon mitigation challenges and opportunities in the building stock. This research investigates environmentally and economically sustainable retrofit methods to reduce the carbon footprint of existing residential buildings in the City of Greater Dandenong as a case study in Metropolitan Melbourne, Australia. By categorizing energy use into various building age brackets and dwelling types that align with changes in energy regulations, we identified various retrofit prototypes to achieve a targeted 6.5-star and 8-star energy efficiency rating (out of a maximum 10-star rating system). The corresponding operational energy savings through different retrofit options are examined while also considering the quantity of materials required for each option, along with their embodied energy and GHG emissions, thus allowing a more comprehensive lifecycle carbon analysis and exploration of their financial and environmental payback times. Results show that when buildings are upgraded with a combination of insulation and double-glazed windows, the environmental benefits rise faster than the financial benefits over a dwelling’s lifecycle. The size or percentage of a particular dwelling type within the building stock and the remaining lifecycle period are found to be the most important factors influencing the payback periods. Retrofitting the older single detached dwellings shows the greatest potential for lifecycle energy and carbon savings in the case suburb. These findings provide households, industry and governments some guidance on how to contribute most effectively to reduce the carbon footprint of the residential building sector.

Highlights

Since 38% of the world’s greenhouse gas (GHG) emissions come from buildings [1], government and industry groups around the world have been spending considerable efforts to reduce their carbon footprint
We adopt a bottom-up modelling approach to allow for a more granular investigation of retrofit options for different dwelling types in a building stock. This approach is highly dependent on the availability and accuracy of data, it is used in preference over a top-down approach that predominantly focuses on broader econometric impacts [76]. Both the operational and embodied energy and GHG emissions are considered for a lifecycle investigation of the targeted residential buildings in the City of Greater Dandenong
The right bar shows the annual cooling and heating energy reduced through the retrofit and the sum of embodied energy used for the retrofit (A1–A3, A4 and B5)

Summary

Introduction

Since 38% of the world’s greenhouse gas (GHG) emissions come from buildings [1], government and industry groups around the world have been spending considerable efforts to reduce their carbon footprint. The United Kingdom government has announced for all new houses a ‘zero carbon ready’ by 2025 goal [3]. This is a plan to apply the most energy efficient measures for new houses, reducing their carbon footprint by about 80% by 2025. Summit in San Francisco, CA, USA, currently has 98 businesses and organizations and 28 municipalities that have committed to reduce carbon emissions from buildings related to their business or municipality by 2030. Calculating the operating portfolio emissions of these signatory organizations can save about 3.4 million t of carbon dioxide equivalent,

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Results

Conclusion