Environmental Product Declaration of Ready-Mix Products. a Practical Application
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ISBN: 978-84-697-1815-5 Environmental product declaration of ready-mix products. A practical application Abstract: this paper presents the calculation of Environmental Product Declaration, EPD, of functional units consisting in concrete waffle and flat slabs, from the environmental profile of its constituents: cement, concrete and steel, by applying the Product Category Rules that are being developed by the European Technical Committee CEN TC 104 Concrete. The implementation of module B( use), C (end of life), and D where carbonation, use of resources and thermal mass are involved, is presented. Some conclusions on the reliability of the information provided in cradle to grave DAPs at both, product and building level, are also provided. Key words: Environmental Product Declaration, concrete, functional unit, Product Category Rule. Arturo Alarcón Barrio, IECA; Pilar López Torres, PROMSA; Alejandro Josa García Tornell, UPC; Juan Eugenio Cañadas Bouzas, ANEFHOP. Introduction. The Environmental Declaration of Products has the explicit purpose of assessing and comparing product reliably from an environmental point of view and from a Life Cycle Analysis approach. This information can de considered as an input regarding the purchase decision-making, whether public or private. To this purpose, many evaluation schemes have proliferated internationally. Only in relation to the carbon footprint, 62 different initiatives in this field have been identified by the European Commission. Initiatives that do not evaluate the same parameters, use different criteria and weight the indicators in different ways. The solution proposed by the EC seems to be the Product Environmental Footprint, PEF (1). This scheme, designed to calculate, report and compare the environmental footprint of any product, evaluates 14 environmental impact categories. However, construction products have their own assessment methodology, based on the EN 15.804 (2) European Standard, since 2012. The reasons why these products have a particular method are well known and can be summarized in the fact that comparison only makes sense if we know exactly the function in which they were designed for. Its environmental performance becomes full meaning in the context of the building in which they are going to be installed. EN 15.804 evaluates seven impact categories plus 17 auxiliary indicators. On the other hand, the Construction Products Regulation, CPR, (3) lays down conditions for the placing or making available on the market of construction products by establishing harmonized rules on how to express the performance of construction products in relation to their essential characteristics and on the use of CE marking. This means that the free choice of a construction product for a given function or technical requirement, takes into account the Declaration of Performance (DoP) and the existence of the CE marking on it. 8291 ISBN: 978-84-697-1815-5 In addition, CPR establishes a new Basic Work Requirement of sustainable use of the resources, BWR7: which will be included in the DoP of construction products. CPR itself establishes that the tools to do so are the Environmental Product Declarations. If the DoP must include, in a near future, information on the BWR7, this environmental information will be taken into account at the time of the purchase decision. It is, therefore, extremely important to identify the comparability criteria of the environmental information provided in the DoP when is required and when environmental impacts are included. This article presents EPDs of functional units of structural concrete and aims to highlight the difficulties mentioned regarding the comparability and interpretation of results of EPDs. Finally, proposes, at the light of the results, specific proposals to clarify, under which conditions, environmental information can be transmitted and used in a meaningful efficient and reliable way, particularly in the case of functional concrete elements. Foreword. According EN 15.804, EPD communicates verifiable, accurate, not misleading environmental information for the products and their applications, thereby supporting scientifically based, fair decision-making and stimulating the potential for market-driven continuous environmental improvement. EPDs of declared (4) and functional units are very different conceptually. It is not possible to compare declared units because the precise function of the product or scenarios for its life cycle stages at the building level are not stated or are unknown. Examples of declared units are usually basic construction materials as 1 ton of cement or 1m3 of concrete. In this article EPDs of functional units are calculated. For a complete definition of these units, the quantified, relevant functional use or performance characteristics of the construction product when integrated into a building, shall be provided. In these cases, the FU supplies the basis for the addition of material flows and environmental impacts for any stage of life cycle. This means that information of the components of a construction system can be added in a bottom-top approach. Comparability of EPDs. From our point of view, a EPD of a functional unit in a cradle to gate approach is highly reliable. In this case, the uncertainty is minimal because it is no necessary to establish hypothesis out of the production process itself. Extrapolation of EPDs to the construction and use phases can only be done in a generic way, and with limitations that need to be highlighted. For example, a concrete flat slab serving as slab in a building, is a functional unit whose environmental loads can be fully known in a cradle to gate approach. At building level the prominence moves to the building´s functional equivalent, like intended use of the building, location, orientation, compactness, insulation systems etc. Only when generic scenarios defined at product level are particularized at building level in a certain and specific project, all the information necessary to perform the evaluation cradle to grave, becomes fully reliable. This is absolutely clear in cases where the functional unit considered has implications on the 9292 ISBN: 978-84-697-1815-5 operational energy consumption in the building, for example, due to the high thermal inertia of concrete walls and slabs, or due to the type of insulation of the building. In the following sections, the scenarios and assumptions for concrete functional units according Product Category Rule developed by the CEN Technical Committee 104 Concrete will be analyzed. Concrete product category rules. The latest available version of PCR that are being developed by CEN TC 104 Concrete has been used in the calculations. These specific RCPs will be published as a European Standard and will constitute the harmonized way in which DAPs of concrete products shall be declared in the future. The scope of the Standard includes how the parameters of EN 15.804 can be particularized for concrete and, therefore, driven by the concrete RCP and not by the Standard. These parameters are: boundary limits, modeling and evaluation of specific characteristics of the constituents of concrete, allocation rules in the production chain, rules for the definition of the Inventory and calculation of ACV itself etc. Modularity approach. Modular scheme of EN 15.804 is the basis to develop scenarios for any construction product. The most remarkable feature of the concrete PCR is, from our point of view, the end of waste criteria, the consideration of Module D and the influence of operational energy consumption at, either, product and building level. Regarding the end of waste condition, figure 1 summarizes the different possibilities considered. These alternatives involve module C, with three subcategories directly linked to four possible destinations of concrete as a waste: reuse in recovered concrete elements, land restoration, substitution of primary material, use as aggregate in fresh concrete. The figure shows when the end of waste boundary is reached and the relations between module C and D in each case. 10293 ISBN: 978-84-697-1815-5 Figure 1. Typical processes at the end-of-life of concrete and concrete product and their attribution to the life cycle modules C1-C4 and D. Module D can include the environmental benefits of concrete recycling (cells 3, 4, 5, 7 and 8). The benefits from the substitution of primary materials shall be included in this module. In our case disposal of concrete debris at a landfill site has been selected as reference scenario, therefore no benefits from substitution of primary materials have been accounted to module D. On the other hand, carbonation of concrete is a benefit that shall be allocated in the stage in which the process takes place. Carbonation is a natural process by which concrete absorbs carbon dioxide from the atmosphere. Atmospheric carbon dioxide reacts with particular cementitious compounds in concrete to form solid products that are either precipitated on the surface or within the matrix. In terms of EN 15804, carbonation may be considered as a negative emission, and as a consequence it should be allotted to the range of life cycle stages in the same way as other emissions. Carbonation of concrete can occur during the use stage (B1) and during the end of life stage (C3 or C4). In this article both contributions have been calculated. Concrete PCR includes a chapter of guidance requirements and guidance on calculation of carbonation impacts. The carbonation front progresses from the surface into the concrete