2.5 Use of a baseline scenario

Deviations in the final results of product and building LCAs may arise from the use of different sets of parameter values, depending on the goal and scope and according to the study type definitions (see previous section). This can be an issue when comparing the outcomes of research projects. As a result, the methodological approach for the guidance document includes the use of a baseline scenario. A common set of parameter values for all European research projects is highly useful for supporting and providing consistency in comparisons.

The EeBGuide suggests some parameters some as a baseline scenario (see Table 1). The use of these parameters is suggested, but is not mandatory for all LCA studies conducted either within E2B EI projects or externally (LCA tool development, certification schemes). Even within E2B EI projects, such a reduced list of parameters does not guarantee comparable results among different project results. Differences may occur from, for example, different choices of LCA data, or from different modelling approaches for the energy consumption assessment, as the EeBGuide cannot recommend the choice of, say, only one LCA database or one dynamic thermal simulation software package to be used in E2B EI research projects. The provisions and guidance included in the guide help overcome this issue, but they cannot ensure total comparability of all LCA studies performed in the various E2B EI projects. In addition, the baseline scenario is goal and scope dependent, and a set of parameter values cannot be proposed for all situations (e.g. stand-alone LCAs, comparative assertions).

 

Table 1: Selected standard set of parameter values for the baseline scenario

Parameter

Standard parameter value

Reference study period

50 years

LCA data for electricity consumption

European (annual) average datasets or national (annual) average data if more relevant for the study

Future technological developments (Modules B, C and D)

No future technological developments are assessed; currently used technology is the basis for the assessment

Average transportation distance in Europe for Module A4

300 km

Carbon storage

Carbon sequestration is not considered explicitly

End-of-life scenarios (Modules C and D)

Use contemporary percentages for each building material (do not use a probabilistic scenario)

 

If comparable results are sought between different E2B EI research projects, practitioners should select a standard set of parameter values for their studies that is as uniform as possible. This includes the parameters listed above (adaptations are possible, if relevant), and the definition of the system boundaries for the building elements, operational energy and water use.

Note: the parameter choices given in Table 1 are neither ‘correct’ nor scientifically proven to be the best values, but rather represent a set of definitions to form a common basis for different studies. Therefore, in general, no scientific proof is given for these values. If available, reference to a third-party source is provided. If not, the values or decisions for these parameters have been defined by this guidance’s authors.

Additional in-depth work is needed to determine a comprehensive set of parameter values for the baseline scenario for product or building LCA studies with specific goals and scopes. The EeBGuide partners believe that this is the only way to move towards comparable results among different LCA studies. To that end, contributions from projects such as SBA Common Metrics, Superbuildings and OpenHouse can be very helpful.


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