Energy Efficiency

Life Cycle Assessment in a nutshell

Magdalini Psarra
Magdalini Psarra
November 14, 2019

Everything you need to know about Life Cycle Assessment and how it can help lower the environmental impacts of a building

The Quad, a residential building

Addressing climate change requires us to become more aware of and more concerned about the impact of our actions and choices both as individuals and as a society. In the pursuit of re-evaluating our impact, methodologies such as Life Cycle Assessment (LCA) have grown in popularity in the recent years as they help us make informed decisions. But what is LCA exactly?

Simply put, LCA answers the question “What is the environmental impact of this object?” LCA provides a framework within which to assess the environmental impacts of a product or a service from a “cradle to grave” perspective. This means LCA considers every aspect­—from the extraction of raw materials until the product’s final disposal—considering factors such as which raw materials are used, how much water is consumed, how the material is transported and what the transportation distance is.

Why do we need to focus on the building sector and how can LCA help with that?

With buildings’ share of the total energy demand reaching 40% and their generated CO2 emissions contributing to 36% of the total emissions in the EU, there is no question that buildings play a critical role in the energy transition and the fight against climate change1. For us to make a difference, we need to get a deeper understanding of where the impacts come from and how different choices can help us reduce them.

LCA is a tool that can help us understand the environmental impacts of buildings so, in turn, we can design more sustainable and energy efficient buildings in the future.  By using LCA on buildings, we can learn how a building will affect the environment throughout its existence – from the extraction of its raw materials to its final demolition and disposal.

What does a building’s life cycle look like?

The typical life cycle for a building includes the stages described on the image below. These are according to EN 15978:2011 ”Sustainability of construction works. Assessment of environmental performance of buildings. Calculation method”.

  1. Product Stage – The product stage includes all the processes related to the impacts that building materials have until the factory gate. This refers to the impacts from the extraction of raw materials and their transport to the factory, and the impacts from the manufacturing of the final construction product.
  2. Construction process stage – The construction process stage includes impacts from the factory gate of the different construction products to the practical completion of the construction work;
  3. Use Stage – The use stage refers to impacts from the operation of the building – the impacts of the use, refurbishment, repair, maintenance of construction products and services and most importantly, the energy and water consumed during the building’s lifetime.
  4. End of life stage - This includes the impacts from the demolition of the building, the transport of the waste to the final destination of their disposal, their processing in the waste facility and their final disposal;
  5. Benefits and loads beyond the system boundary - This segment communicates all the potential impacts and benefits from the reuse, recycling and recovery of materials at the end of their life time. This segment does not belong to the lifecycle of the building but consists of information that it is important to know.
LCA model with stages in brand colours

What are the typical categories of impacts in an LCA?

Now that you know the stages of a building’s life cycle, you are ready to look at the environmental impacts of each stage. When we talk about environmental impact, we don’t just mean carbon footprint. When it comes to LCA, environmental impacts cover several indicators—and carbon footprint is just one of them.

The results of an LCA often include more than 9 different categories of environmental impacts that can give you a holistic view of the effect that the building can have to its surroundings. From climate change, to the use of resources, to the depletion of the ozone hole, a building can have a variety of different effects to the environment.

The image below provides an overview of the main categories environmental impact and their meaning.

Environmental impact factors for life cycle assessment models

Credit Trafikstyrelsen

How do I perform a Life Cycle Assessment of my building?

The recipe to conducting an LCA of a building includes mainly the following components:

  1. Information about the building: This may include the Bill of Materials for all the building parts, their service life, the building area, the energy consumption etc.
  2. Tools & Data: This includes calculation tools for an LCA assessment. These tools also offer generic information about the environmental impacts of building materials, but if you want to be more specific you can also look into Environmental Product Declarations from specific product manufacturers
  3. LCA assumptions: These include preliminary assumptions based on the stages and impact categories selected as well as general assumptions about the future stages of the life cycle, e.g. disposal routes and types of transport etc.

When performing an LCA it is important that you follow the standards that govern how LCA should be implemented in general and in buildings. For standards that cover how LCA should be implemented in general, you should refer to ISO 14000:2008 and ISO 14040:2008. For LCA in buildings and construction products, you should refer to EN 15978:2011 and EN 15804:2012.

How can we lower the environmental impacts of a building?

The results from the life cycle analysis of your building can give you an understanding of where the environmental impacts come from, the contribution of the different construction materials to the final results and the impacts that are attributed to the building’s operation.

Currently, a high fraction of environmental impacts comes from the use stage, which means that the primary way to improve the environmental profile of our buildings is to focus on their operation. So if we want to significantly lower the environmental impacts of a building, we need to ensure that it has low energy consumption levels. In other words, energy efficiency plays a crucial role in reducing the building’s environmental impact.

Having long lasting and durable materials also plays a significant role in the final environmental impact results. Lifetime has an indirect but important role to play when you are performing an LCA. Just imagine this: material A has double the impacts of material B but does not need to be replaced during the building’s lifetime. On the other hand, material B has half the impacts but you need to replace it at least 3 times during the lifetime of the building. Which one would you choose? The answer here is easy. Material A is the obvious choice: it is the material that has a bigger impact and does not have to be replaced in its lifetime – in other words, more bang for your buck.

When it comes to buildings, for us to make the right choices for the environment, we need to look at things from a broader perspective. How are buildings made? How are they operated? What happens to them when they’re demolished? Conducting an LCA helps us do just that.

We hope that reading this article has equipped you with some knowledge on what LCA is all about, how to interpret it and how it can be used to lower the impact of your building. LCA is something that we conduct to assess our own operations and something that we believe provides a holistic view on the environmental impact of the things and processes around us – helping us make the right decision

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