A-06 Construction installation process impacts for screening LCA

Aspect

A-06 Construction installation process impacts for screening LCA

Description
Construction site impacts are driven mainly by the groundworks (fuel consumption), the transport of products, water and energy consumption (e.g. electricity), and the capital goods (such as crane, bungalow etc.), but also by the transport of construction workers. Under specific goal and scope, it might be interesting for a construction company or a building designer to assess the impacts of Module A5 by means of a default approach, without looking in detail at the different aspects, such as land preparation, water, energy and capital goods.

Related study objective

stand-alone LCA comparative assertion

Related study phase

goal and scope definition inventory analysis (LCI) impact assessment (LCIA) interpretation reporting

Relevant for

new buildings existing buildings building products screening LCA simplified LCA complete LCA
Provisions The assessment of construction site impacts may be taken into account in screening LCA by means of a default approach using global default values for Module A5. The intended use of this methodology is to get an overview of the share of impact of Module A5 when considering the full building LCA. If the results are sensitive to Module A5, the practitioner should refer to a more detailed assessment.
Rules from:
EN 15978:
7.4.3 Boundaries of the construction process stage

8.5 Scenarios for the construction process stage (Modules A4–A5)
Guidance
During the design of a building, it may be difficult to assess the information for land preparation, water and energy consumption, owing to the lack of data. However, information on the quantities of building products are information available upstream of a building project from the construction companies. One possibility is then to assess the construction site impacts from the building product impacts, for which the level of detail is comparatively higher. Such a rough estimation may be sufficient for some screening LCA studies of buildings. It is not necessary to define default values at the level of each impact source for Module A5, which considerably reduces the level of complexity in the first step of a building LCA study.The link between this information needs default values to be provided based on statistical studies for each building type or construction system. Figure 14 represents a theoretical example, for one environmental indicator and for one building type and construction system, of the share of impact between the building products and the four aspects of the construction site taken as examples in this guidance (energy, water, transport of workers, and capital goods).

Breakdown of impacts for a given indicator for one building type

Figure 16: Breakdown of impacts for a given indicator for one building type

The calculation steps required to derive the example results in Figure 14 might be as follows:

1) Calculate the impacts related to the building products (Iproduct).

2) Determine a ratio (default value) Ri, expressed as a percentage, for each aspect i of the construction site (energy, water, transport of freight, and capital goods). These default values can be derived from statistical studies of meter readings of representative construction sites, as well as for the building product impacts.

It is then possible to assess the impact of aspect i of the construction site by means of the global impact of the building products and the ratio (default value): Ii = Iproducts × Ri.

Such a methodology may be followed by the LCA practitioner, and adapted according to the goal and scope of the study.

To obtain representative ratios (default values), the LCA practitioner or LCA tool developer would need to work closely with or contact the construction companies to make such default values available.


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