When creating an EPD, the environmental performance of the product/service shall be described from a life cycle-based perspective. Collecting LCA data to be included in the declaration is a core activity in the process of creating an EPD with the following for basic prerequisites:

• to comply with international accepted principles for life cycle assessment, LCA, according to the ISO standards 14040 and 14044,
• to follow the general purpose of EPDs, the collection of data, methods and assumptions used as advocated in the ISO standard 14025 and described in the General Programme Instructions and 
• to be in line with the product-category rules, PCRs, for the product category of interest. 

Issues to consider in case of lack of specific LCA data

In some cases specific LCA data do not exist. Lacking such information will for some time lead to difficulties for companies and organisations when it comes to acquiring specific data covering the entire life cycle of a product or service.

Lacking specific LCA data is often a reality in the supply chain "from cradle-to-gate". Therefore, as a special rule within the international EPD®system, companies and organisations are allowed to use a defined proportion of generic data and assigns data sources for selected generic data describing material flows connected to a number of input materials. When applying data for such materials these sources shall be used. If these data sources do not supply the necessary data, other generic data may be used and documented. The environmental impact associated to other generic data must not exceed 10% of the overall environmental impact from the product system.

Rules for similar products and services

The international EPD®system covers both individual as well as groups of products and services, provided that they are fairly similar with regard to environmental performance and that they show small or negligible variations within the limits of accuracy inherent in the LCA method. Therefore, the International EPD® System allows for groups of products and services, which have a similar extent of variation to be at maximum +-5% of the information, to included in the same declaration. This is especially important for companies or organisations featuring sets of products and services with only small modifications since it makes the EPD work more cost-effective.

It is also possible to include several products in the same EPD in case they could be regarded as modification of a given product concept and provided a large extent of similarities with regard inherent materials and substances.