Towards Zero Carbon: A Comprehensive Evaluation of Conventional Renovation Strategies for Terraced Houses, Using Life Cycle Analysis (LCA) and Life Cycle Costing (LCC) to Enhance Decision-Making Support – accompanied by the design of a tool

Abstract

To reduce global warming the emission of greenhouse gases (GHG) must be net zero in 2050, Paris agreement. In the Netherlands the building sector is responsible for 38% of total GHG emissions, 27% being operational carbon (related to energy use) and 11% embodied carbon (related to the use of materials). A large portion of the GHG emissions in this sector originates from existing residential buildings and is for the majority related to energy for heating.

Renovating existing buildings is a key step in reducing operational carbon emissions related to heating. Due to the environmental advantages of renovation, it acts as the first step to reduce carbon emissions. The general strategy to reduce carbon emissions, first focuses on the operational carbon by transitioning from non-renewable depletable energy sources to renewable, sustainable energy sources, also known as the energy transition, starting with replacing natural gas for heating and cooking. In the Netherlands the target is to reduce 49% of GHG emissions compared to 1990 by 2030, and 95% by 2050. In practical terms this requires a renovation of 1.5 million residential buildings by 2030 and 5.5 million residential buildings by 2050.

As operational carbon decreases, reducing the embodied carbon becomes more important. Unlike operational carbon which is only present during the in-use stage of a building, the embodied carbon is present in all stages of a building’s life cycle. Clear standards on the assessment of carbon emissions over the full life cycle of a building are missing. Due to this current strategies are not selected to reduce carbon emissions on the complete spectrum of carbon emissions. The risk is that the overall carbon reduction of the building stock is less than expected.

Renovation changes the life cycle of a building and thus its long term performance. Renovations with high energy saving often can’t be performed in a single step due to high investment costs. Therefore renovation is often executed in multiple steps. Understanding the effects of different use-phase scenarios can help reduce carbon emissions on the long term.

Furthermore, assessing the performance of all generated renovation solutions, at an early design stage, can be time consuming and requires a high level of information. This limits the number of renovation options explored and indirectly influences the effectiveness of a renovation.

The aim of this thesis is to investigate how assessment of renovation strategies can be simplified to support decision making in renovation. The thesis investigates different renovation strategies and scenarios for the in use stage of a terraced house, to improve decision/making in renovation, by looking at the level of renovation, renovation measures, renovation execution and decision making criteria. The data gathered is used to create a tool, supporting decision-making for renovation strategies. Data is obtained using various tools, and by performing among others a simplified Life cycle analysis (LCA) and life cycle costs (LCC) assessment. The performance of the renovation strategies are evaluated based on energy performance, environmental performance and costs.