2.3. “Cradle to Gate” Life Cycle Inventory (LCI) Considerations

Thermal insulation tiles for flat roofs are manufactured in an industrial plant situated about 150 km from Lisbon (the capital of Portugal). The study of this material began with some visits to the producer in order to allow the authors to understand the manufacturing process (A3) of the thermal insulation tiles studied and to prepare a questionnaire (LCI) to be filled with the main data related to it. The LCI questionnaire was interactively and iteratively prepared and sent to the manufacturer to register the production data necessary for the LCI modelling. The intermediate phases of the manufacturing process of thermal insulation tiles are identified in Figure 3. The LCI model is based on average production data from 2013. The background data for modelling the production process was based in data from Ecoinvent database (v3.2), available through the software tool used in this LCA study (e.g., data for the extraction/production of raw and packaging materials, electricity, and transportation of raw materials). As mentioned, all data used in the inventory phase was based on the answers that the producer provided in the questionnaire. The LCA tool chosen to model the production process was SimaPro (v8.4 of this software - PRé Sustainability, Amersfoort, Netherlands [17]).

The authors decided to subdivide the environmental impacts and potential benefits quantified in the A3 stage in order to make it easier to understand which was responsible for each environmental impact and taking into consideration the recommendations of European standards [11]. Thus, three independent information modules within the A3 stage were considered in this assessment, which set out the manufacturing process in more detail:

A3.1—including manufacturing and transport to the factory of the packaging material that leaves the factory gate with the product;

A3.2—including the gate to gate manufacturing of the product being studied and all internal transports;

A3.3—including the production and disposal of raw materials or admixtures’ packaging and of the wrapping material of the packaging products.

The production of packaging for raw materials or admixtures (and also of the material for wrapping the packaging products) was included in the A3.3 module rather than the A3.2 (or A3.1) modules because the producer did not provide values in the LCI for each of the flows but, instead, provided them within the global packaging waste streams.

In order to assess the quality of the site-specific data achieved, a method developed by Ferrão was used [13]. This method (reproduced in a simplified way in Table 4) includes the most relevant indicators to evaluate the quality of data collected and the measure to be attributed to each parameter (1 to 5). The method was applied to measure the quality of the information used in this LCA study, and the conclusions are presented in the last row of Table 4 (with the corresponding measure indicated between brackets).

Estimation of the quality of the information used in the Life Cycle Assessment (LCA) study and in the Life Cycle Inventory (LCI) of the thermal insulation tiles studied (adapted from [13,7]).

As mentioned before, the LCI data used in this study was collected from a Portuguese production plant, so it is therefore based on site-specific data. From Table 4, it is possible to conclude that the quality of the information of this study (with an average value of 2.0 in a 1 to 5 scale, where 1 = the best quality) can be considered good and adequate for the global purpose of this research work.

To sum up, the LCI was developed based on Portuguese site-specific data (for the manufacture site processes), and background processes were modelled based in modules from validated international databases (such as Ecoinvent and ELCD) during the modelling of the system process.