Material-versus energy-related impacts: Analysing environmental trade-offs in building retrofit scenarios in the Netherlands

The construction sector is responsible for a substantial share of adverse environmental impacts from materials usage, waste generation, energy use and greenhouse gas emissions. At the same time, the construction sector is a major creator of economic and societal value. Retrofitting existing residential buildings can contribute to the achievement of policy goals in building energy efficiency and reduction of energy use. Effects of retrofit activity pertain to both operational energy impacts and material-based impacts. To select effective retrofit strategies, both types of impact need to be taken into consideration, and trade-off effects examined. This study compares environmental impacts of different retrofit scenarios for three residential building archetypes in the Netherlands. Collectively, these archetypes represent 80% of the current Dutch residential building stock. A total of twenty scenarios are defined and analysed using process-based Life Cycle Assessment. Each scenario represents a unique combination of building archetype, construction period, insulation measures, and installations-based refurbishments. The results of the analysis show that under current Dutch energy mix conditions, energy-related impacts are more significant than material-based impacts. The analysis also shows that retrofit measures targeting replacement of installations must tackle both heating and electricity-generation in order to be effective. Improving insulation contributes to a significant reduction of environmental impacts in all retrofit scenarios, and can be considered a relatively low-cost, “no regret” element of any retrofit strategy. Sensitivity analyses show that the balance between operational energy impacts and materials-related impacts shifts if and when the energy mix transitions to a more sustainable composition. This finding highlights the complex dynamic facing decision-makers, researchers and practitioners: retrofit strategies that appear effective today may become less advantageous as framework conditions shift. Retrofitting leads to shifts in environmental impacts between impact categories. These shifts need to be factored into policy and decision making to avoid the risk of beneficial environmental impacts in terms of residential buildings leading to adverse impacts in other policy domains.