the life cycle performance of sustainable renovation concepts

Scheuer & Keoleian (2002) distinguish three flows of a product system that areinventoried by a LCA:- Upstream flows (extraction, production, transportation, construction)- Use flows- Downstream flows (deconstruction, disposal)Subsequently, global and regional impacts arecalculated based on energy consumption,waste generation and a select series of otherimpact categories. LCA makes it possible toweigh the impact of different systems andmaterials against each other. LCA promotesclarity of information and allows for greatercomparability of products. Figure 21 describesthe general format for a LCA, according to ISO14040 conventions (Reijnders & van Roekel,1999)FIGURE 21-ISO 14040 FORMATSAOUTERSaouter (2008) states the following definition for a life cycle assessment:“Life Cycle Assessment is a method developed to evaluate the mass balance of inputsand outputs of systems and to organize and convert those inputs and outputs intoenvironmental themes or categories relative to resource use, human health andecological areas.”In his article about life cycle assessment, Saouter states that life cycle assessment is atool used to evaluate the potential environmental impact of a product, process or activitythroughout its entire life cycle by quantifying the use of resources („inputs‟ such asenergy, raw materials, water) and environmental emissions („output‟ to air, water andsoil) associated with the system that is being evaluated.According to Saouter, a life cycle assessment is used to answer specific questions suchas:- How do two different manufacturing processes for the same product compare interms of resource use and emissions?- What is the benefit of changing technology?- What are the relative contributions of the different stages in the life cycle of thisproduct to total emissions?- What is the environmental footprint of my product, service, and company?In other words, life cycle assessment seeks to increase eco-efficiency. LCA takes intoaccount every phase in the life cycle of a product. Therefore, apparent improvementsthat only shift the problem around are recognized and can be avoided.AZAPAGIC & CLIFTAzapagic & Clift (1999) define LCA as follows:“LCA is a quantitative environmental performance tool essentially based around massand energy balances but applied to a complete economic system rather than a singleprocess.”According to Azapagic & Clift (1999) LCA can have two main objectives when applied toprocess analyses.1. Quantify and evaluate the environmental performance of a process from „cradle-tograve‟and thereby help decision-makers to choose between alternatives.2. Helping identify options for improving the environmental performance of a system.40