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StreamLAB - Streamlined environmental and cost life¬cycle assessment of building retrofits: a decision¬ supporting tool


Title: StreamLAB - Streamlined environmental and cost life¬cycle assessment of building retrofits: a decision¬ supporting tool


Coordinators at INESCC: Carlos Henggeler

Dates start/end: 09-2018 / 08-2019


Retrofitting of existing buildings can promote a significant reduction in the environmental load and operating costs of the European building stock. In Portugal, there are two million households needing renovation (34% of the Portuguese building stock). Most of those buildings are among the largest contributors to the poor energy performance of the building sector. Given their long life-span, it is essential that designers and developers are encouraged to identify effective and eco¬-efficient strategies that reduce the overall life¬cycle (LC) burden of buildings. LC approaches have been extensively applied to analyze building environmental impacts and costs. However, conventional LC approaches are very time consuming and resource ¬intensive to implement, preventing a more widespread use. Additionally, they are usually performed in late design stages when significant reduction in total LC impacts is costly to achieve. Streamlined LC approaches have been used as a technique to support early stage decisions of a product or system when less detail is known promoting greater potential in reducing environmental impacts and costs. However, early design decisions imply that less data are available. Existing methods for filling data gaps often ignore the effects of the uncertainty inherent in estimating data.

The StreamLAB project proposes a novel decision¬ supporting tool to assess the environmental impacts and costs of building retrofits in Portugal by integrating a streamlined LC environmental and cost assessment with a data envelopment analysis (DEA) model. The streamlined LC approach is used to derive eco¬efficiency ratios, and DEA is utilized to rank alternatives without a need to subjectively weigh the different environmental and cost LC metrics. The streamlined LC approach for building retrofits accommodates varying amounts (and quality) of information on retrofit design and provides estimates and associated uncertainty for environmental and economic performance. The method comprises the application of structured under¬ specification, probabilistic triage, and guided sequential specification. DEA compares alternatives without a priori consideration of any functional form between inputs and outputs or a priori subjective intervention concerning the weights of indicators. This novel decision ¬supporting tool aims to provide a scientific basis for informed decisions (recommendations for designers, stakeholders or policy makers). It also demonstrates the benefits of a LC perspective and helps to transfer research results and insights into current building design practice.

The main objectives of the project are:

  1. Develop an integrated (environmental and cost) streamlined LC approach to support early ¬stage decisions in building retrofits; 
  2. Apply the streamlined approach to assess the environmental and cost performance of various building retrofits in Portugal for three types of single ¬family houses (detached, semi¬detached and row) combined with three types of wall systems (single ¬pane stone, and single¬ and double¬ pane brick walls) representing buildings from distinct time periods (historic buildings built before 1919, buildings from 1919 to 1960, and from 1960 to 2000). These assessments will include a sensitivity analysis to three climate regions and two alternative residential occupancy patterns;
  3. Identify key drivers of environmental and cost impacts of building retrofits in South European climates and provide recommendations;
  4. Develop a tool integrating a streamlined LC approach and DEA for eco¬efficiency analysis and identify the most eco¬-efficient retrofit strategies;
  5. Implement the tool as a spreadsheet-¬based software prototype, which may later be developed into a commercial product. This project will advance methodological frameworks by developing a novel streamlined LC approach integrated with DEA to support the decision ¬making process of building retrofits. It will also provide insights and recommendations for current building retrofit design practice. The project will be also relevant for the international scientific community, as the framework developed here could be further adapted to other products/systems.

In order to carry out the StreamLAB project, we gathered a multidisciplinary team composed of researchers with complementary expertise and solid track records from three Portuguese Research Units (CIE¬ADAI, INESCC and CeBER¬-UC) which will collaborate with a team from MIT. The research team has large and diversified experience in LC modeling and assessment of various systems, including buildings (CIE¬ADAI), as well as a strong background and experience in uncertainty analysis, statistically¬-based models, optimization and DEA (INESCC and CeBER¬-UC). The MIT team collaborating in this project has relevant experience in creating decision¬ supporting tools to assess environmental impacts and costs of buildings.