Energy and carbon balance of materials used in a building envelope renovation

Abstract

Construction and demolition waste (CDW) are a priority waste stream in EU’s polices, accounting for about 30% of all waste generated. At the same time, according to the EU energy-efficiency directive, existing buildings subject to significant renovation need to be upgraded in their thermal building envelope in order to meet higher energy performance standard. This involves additional building materials and hence increases the CDW generation. This study investigates the energy and CO2 emission balance of building envelope renovation when using different building materials, taking into account the production and end-of-life stages. The study is based on a Swedish case-study building assumed to be upgraded to the passive house standard. Benefits from waste recovering are considered, including construction and demolition wastes. The results show that the selection of building materials can significantly affect the primary energy and CO2 emission balances. Depending on the material alternative the end-of-life primary energy use and net CO2 emission can be reduced by 5%-21% and 2%-24%, respectively, compared to the initial primary energy use and net CO2 emission. Therefore, a careful material choice at the design stage, as well as an efficient waste management, can contribute to reduce primary energy use and CO2 emission associated with energy renovation of existing buildings.