In the last 20 years energy efficiency has become an increasingly important aspect of the planning and evaluation of buildings, as well as a subject of legislation within the EU. As a result, the operational energy consumption of new and refurbished buildings has decreased considerably during this time. Figure 1 shows the ratio between the operational energy (for regulated uses such heating, ventilation, cooling and lighting according to the EPBD) during the use phase, and the embodied energy due to the fabrication of the building products as well as their end of life (EoL). The use phase for the older buildings dominates all other life cycle stages. Today, new buildings may consume less than 15 kWh final energy for heating per m² per year if they complying with the Passivhaus standard. The new types of ‘energy surplus’ or ‘positive energy’ building may even be net producers of energy. Therefore the ratio between operational impacts (the use phase) and the embodied impacts (e.g. for production and EoL) is now more or less balanced (Figure 1).
Figure 1: Ratio of use phase to production/EoL for a 10–20 year old building compared with a newly built Passivhaus
These changes emphasize that as well as optimizing the use phase of a building it is also important to consider the embodied impacts of the materials used in its construction. As a result, the Energy-Efficient Buildings Initiative now needs to consider a life cycle perspective ‘from cradle to grave’, with energy consumption being only one environmental aspect within a multicriteria framework that includes, for example, waste generation and climate change.
Life cycle assessment (LCA) is the method used to address the environmental impacts of products and buildings. It models a product’s technical life cycle, documenting energy and material flows entering or leaving the product system, and assessing the associated environmental burdens.
LCA has been defined as a generally applicable method in [ISO 14040] and [ISO 14044]. Extensive documentation on LCA is given in the ILCD Handbook [ILCD 2011a, 2011b, 2010c]. More specific definitions on how to use LCA in the construction industry are given in [EN 15804] and [EN 15978]. This document provides guidance on how to conduct LCA studies of construction products and buildings, and how to apply the available standards and other rules.
- 1.1 Energy-efficient buildings in Europe.
- 1.2 Basic information about this guidance document
- 1.2.1 Goal of this guidance.
- 1.2.2 Scope of this guidance.
- 1.2.3 Primary audience for EeBGuide.
- 1.2.4 Secondary audience for EeBGuide.
- 1.3 Life cycle analysis in the construction sector
- 1.3.1 Previous European projects on LCA of buildings
- 1.3.2 European standardization works on LCA of buildings
- 1.3.3 LCA studies within research projects of the Energy-Efficient Building European Initiative (E2B EI)
- 1.4 EeBGuide within the European context