How big is the carbon footprint of a building? How much grey energy is hidden in its four walls? If you want meaningful and honest answers, you need the right tools. The life cycle assessment (LCA) offers effective and tried-and-tested ways to ascertain the impact different construction techniques, energy concepts, building parts and materials have on the environment at every stage of the life cycle. The DGNB System was the first certification system in the world, that has taken the long-term environmental impacts of buildings into account.
What does the life cycle assessment (LCA) actually tell us? Buildings create emissions and require resources at every stage of their lifetime. This can be during raw material sourcing, processing, when materials are used, during transportation and even during disposal. To assess life cycle impacts, key environmental indicators are used, summarising required materials, all areas in which resources and energy are consumed and harmful substances – at every single stage. This means pulling together all factors from ‘cradle to grave’. The LCA covers four stages:
The LCA method
1. How much wood is used, how many insulation materials, and in what quantities, plus how much aluminium, concrete and linoleum is needed for a building? The first stage of the LCA involves capturing all quantities of planned or used materials in a building. Will individual materials be replaced before a building falls into disuse? Even renovations form part of the life cycle assessment.
2. How much energy will a building require? The next step is to examine energy ratings and the calculated energy requirements of a building during use (or as planned). This is in order to capture energy consumption and sources of energy. Another important factor for the LCA is grey energy. This is any energy that is required to produce, transport, store, sell and dispose of materials.
3. Once material volumes and energy flows have been determined, they’re merged with producers’ own environmental product declarations (EPDs) or data held in a German construction database called ÖKOBAUDAT. This is a free online database run by the Federal Ministry of the Interior, Building and Community (BMI) to offer access to uniform lists of data. Offering EPDs is not necessarily a given for manufacturers, so the fact that many firms now do issue EPDs shows how much progress has been made in this area over the past decade and how natural this has become when it comes to highlighting sustainability.
4. The final task is to work out the total scores for all selected LCA indicators. The DGNB currently recommends using seven indicators, all of which have a key impact on environmental factors. These include climate change (global warming potential; GWP), summertime smog (photochemical ozone creation potential; POCP), forest dieback (acidification potential; AP), the excess use of nutrients (eutrophication potential; EP) and consumption of fossil fuels and renewable energy (primary energy; PE). The numbers provide a binding statement, for example, on the size of a building’s carbon footprint.
LCAs are extremely useful for optimising buildings and decision-making
An LCA really becomes useful if you’re still in a position to change the carcass of a building, facades or individual building materials – without significant resource investment. The DGNB looks on a development positively if the LCA is carried out during the early stages of a project. Acknowledgment is also given to LCAs being used as a planning aid. Carrying out regular LCAs or working out and sharing results are also rewarded. Drafting a clear set of LCA results makes it easier to weigh up options during the planning process and decide in favour of options that make sense in environmental terms.
A good LCA is also useful when it comes to working out alternative solutions. Of course we appreciate that there are now a number of ‘green’ auditing products on the market, and this certainly doesn’t make it easier for anyone to make decisions when it comes to really making a building environmentally friendly. But one thing we consider particularly important when it comes to assessments is that different options or alternatives are costed up and that the period covered by energy evaluations extends beyond required energy saving ordinances. Overall, this serves to confirm that conducting an LCA is always worth every effort. Ultimately, an LCA opens everyone’s eyes to the many different ways to make building more efficient and enhance construction quality.