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21 December 2012

Katrin Lenz: Optimising buildings’ environmental footprint over lifecycle

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Performing life cycle assessment of energy efficient buildings can prevent shifting the environmental burden in different stages of the building’s lifespan

Katrin Lenz, an expert from the Department Life Cycle Engineering at the Fraunhofer Institute for Building Physics (IBP), Germany, shares her view with on optimising energy-efficient buildings environmental impacts

What has changed in building techniques in the past 10 years?
There are various trends resulting from discussions on energy-efficiency like design towards more compact building layouts and application of new materials for the building envelope with an improved thermal insulation. So-called passive building concepts target at climate adapted designs and optimal adjustment of the building layout according to specific weather conditions. What is more, high-end technology solutions for renewable energy production, storage and distribution are being developed, demonstrated and assessed in various European research projects as “active components” to support energy-efficiency.

Buildings in the city of the future will have to fulfil various functions. They will become more interactive with the user, offering greater control. Buildings will also have to serve as active participants in large-scale district level energy grids. The energetic building performance could help quantify the effect of such changes during the operation of the building. 

In this context, life cycle assessment (LCA) helps in assessing the environmental impact of energy-intensive processes for such innovative building material production, or for their recovery at the end of the life of the building. Materials used in these energy-efficient buildings are expected to have an increased impact compared to those used in conventional buildings.

For modern buildings life cycle analysis (LCA) has become a buzzword. What is it all about?
LCA provides information about the environmental performance of any product. For buildings, there is an internationally standardised LCA method that has been in use for more than 15 years now. In recent years, LCA has become an increasingly important tool for sustainable building certification. Its advantage is that it offers the possibility for an environmental benchmarking. It can also be used for declaring and communicating building product related environmental impact to designers and architects.

Since the Energy Performance Buildings Directive has imposed stringent climate protection goals, we have been observing a drive towards energy efficient buildings. Not only have we observed a shift in terms of costs but also in terms of environmental impact, away from the operating phase. LCA can provide decision support particularly to justify the use of high-end technology and the associated financial investment, should it make sense from an environmental point of view.

How is LCA connected with the increasing energy efficiency of buildings?
Energy efficiency measures focus on the operation phase of the building. With LCA, it is possible to look at the environmental impact during the entire life cycle of a building from as early as the planning stage. This means looking at aspects like building materials or expensive heating, ventilation and air-conditioning technologies. This provides a global view beyond mere energy efficiency during the use of a building to optimise its environmental performance over its entire life cycle.

Why is it important to take a global view over the entire life cycle of a building?
The problem is that focusing on a single parameter like primary energy consumption of a building might result in a “shift-of-burden” of environmental impacts to another phase in its lifespan. For example we might consider an insulation to save energy during the operation phase. But making and disposing of the insulation material might be harmful for the environment and therefore have a higher environmental impact. Both effects need to be assessed to obtain the net effect for the environment. Similarly, we want to avoid a shift of burden between different life cycle phases by opposing environmental impacts of the production phase, the maintenance and end-of-life phases to the impact during the use of the building. Optimisation on several environmental aspects is therefore only possible with a global view. provides its content to all media free of charge. We would appreciate if you could acknowledge as the source of the content.