What is the optimal robust environmental and cost-effective solution for building renovation? Not the usual one

Alina Galimshina,Maliki Moustapha,Alexander Hollberg,Pierryves Padey,Sébastien Lasvaux,Bruno Sudret,Guillaume Habert

doi:10.1016/j.enbuild.2021.111329

Abstract

Buildings are responsible for a large share of CO2 emissions in the world. Building renovation is crucial to decrease the environmental impact and meet the United Nations climate action goals. However, due to buildings’ long service lives, there are many uncertainties that might cause a deviation in the results of a predicted retrofit outcome. In this paper, we determine climate-friendly and cost-effective renovation scenarios for two typical buildings with low and high energy performance in Switzerland using a methodology of robust optmization. First, we create an integrated model for life cycle assessment (LCA) and life cycle cost analysis (LCCA). Second, we define possible renovation measures and possible levels of renovation. Third, we identify and describe the uncertain parameters related to the production, replacement and dismantling of building elements as well as the operational energy use in LCCA and LCA. Afterwards, we carry out a robust multi-objective optimization to identify optimal renovation solutions. The results show that the replacement of the heating system in the building retrofit process is crucial to decrease the environmental impact. They also show that for a building with already good energy performance, the investments are not paid off by the operational savings. The optimal solution for the building with low energy performance includes the building envelope renovation in combination with the heating system replacement. For both buildings, the optimal robust cost-effective and climate-friendly solution is different from the deep renovation practice promoted to decrease the energy consumption of a building.

Highlights

The building sector has more than doubled its greenhouse gas emissions (GHG) since 1978 resulting in 25% of global emissions [1,2]
We identify the uncertain parameters critical for the analyses of life cycle cost analysis (LCCA) and life cycle assessment (LCA) and possible renovation solutions and perform multi-objective robust optimization for two residential buildings with different construction period and architectural period located in Switzerland
It can be clearly noticed that optimal solutions with existing gas boiler have the highest overall GHG emissions in most of the cases

Summary

Introduction

The building sector has more than doubled its greenhouse gas emissions (GHG) since 1978 resulting in 25% of global emissions [1,2]. Due to a long life of a building, many sources of uncertainties can be identified in the analyses Such uncertainties include the ones related to the time when the analysis is performed, such as the embodied emissions, investment cost, energy price, and those related to the future – climate change, prospective electricity and energy mixes, replacement time of the materials, and occupancy behaviour. Many techniques currently exist and several studies using different methodologies have been performed for uncertainty quantification in LCCA [9,10] or LCA [11,12]

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Methods

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Discussion

Conclusion