Life Cycle Assessment (LCA) is a methodology for categorising and analysing the environmental impacts of products and services. Most environmental statements about products talk about carbon (specifically carbon dioxide), and that is certainly one of the most important impact categories when thinking about climate change, but there are also many other factors which can be calculated using this method.
The rules for calculating an LCA are governed by International and Regional Standards and should be performed by a suitably qualified LCA practitioner. There are also specific software packages with built-in databases such as Ecoinvent which contains the background environmental information for materials, processes and fuels, and are updated regularly as the data and technology changes over time.
The Standard documents outline where and how to make assumptions and calculations in order to break down a complex system, like manufacturing steel frames for a building, into smaller steps and stages. The software then allows you to put all the pieces together and pull in the correct environmental impacts for the materials, transportation and fuels, etc. The results are generally a very large table of numbers which again need an expert to read and interpret!
LCA Stages, Scenarios, and Modules
LCA is called “Life Cycle” Assessment because it takes into account the materials that are needed to make a product, where these materials come from, how they are transported, what happens in the factory, where the finished product is sent and how, where it is installed or used, and what happens to it when it has reached its end of life. Each of these steps may have multiple possible scenarios, some of all of which need to be included in the calculations.
Module A relates to how a product was made and where it goes once finished. Module B takes into account what happens to the product when it is in use. If for example it is a plasterboard panel which lasts approximately 20-25 years, but the building stays in place for 60-100+ years, then that material will be repaired or replaced at some point. If energy and water are required during use, then this is also counted. Module C relates to the disposal of the product at the end of its life. Module D is purely for information and does not count towards the final result, but it gives value to the potential recyclability and reuse of a product after the fact.
Not all modules are mandatory, and some are purely scenarios of what may happen in the future.
Impact categories and Characterisation
As mentioned earlier, and LCA is not just about Carbon, but a whole range of environmental impacts. Each of the categories are calculated in different units and are related to specific aspects of the environment, energy use, resource use, and waste. Below is a list of the main impact categories, the detail of each one will be discussed in a later post.
- Global Warming Potential (GWP)
- Ozone Depletion Potential (ODP)
- Acidification Potential for Soil and Water (AP)
- Eutrophication Potential (EP)
- Photochemical Ozone Creation Potential (POCP)
- Abiotic Depletion Potential – Elements (ADPE)
- Abiotic Depletion Potential – Fossil Fuels (ADPF)
- Use of renewable primary energy resource, as energy source (PERE)
- Use of renewable primary energy resource, as raw materials (PERM)
- Total use of renewable primary energy resources (PERT)
- Use of non-renewable primary energy resource, as energy source (PENRE)
- Use of non-renewable primary energy resource, as raw materials (PENRM)
- Total use of non-renewable primary energy resources (PENRT)
- Use of secondary material (SM)
- Use of renewable secondary fuels (RSF)
- Use of non-renewable secondary fuels (NRSF)
- Net use of fresh water (FW)
- Hazardous waste (HWD)
- Non-hazardous waste (NHWD)
- Radioactive waste (total) (TRWD)
- Radioactive waste (high level waste) (RWDHL)
- Components for reuse (CRU)
- Materials for recycling (MFR)
- Materials for energy recovery (MER)
- Export energy (EE)
Each of the categories is stated in a particular unit, and by using a reference substance like Carbon dioxide or megajoules (MJ) of energy. All the contributors to each of the categories are converted into the equivalent substance by using conversion or characterisation factors. For example, methane also contributes to Climate change (here stated as Global Warming Potential) but is more damaging to the environment than Carbon dioxide on its own. Methane is in fact currently assessed to be 25x worse than Carbon dioxide, therefore 1 kg of Methane = 25 kg of Carbon dioxide. By doing this for all the categories you can summarise the information in a way that is easier to read later.
Environmental Product Declarations
Once the LCA is complete and you have your table of results, there are several Certification or Verification Schemes around the world that will review the results and issue certificates for specific material or product types. In particular there are many schemes for construction materials and the building industry. This is because the world that we live in is entirely confined to buildings where we live, work, and socialise (that is, when there isn’t a global pandemic happening to make everybody’s lives much more difficult). Therefore, the construction industry is the most aware of the damage done to the environment as a result of its operation.
The certificate is accompanied with the results table and is called the Environmental Product Declaration or EPD. It looks very similar to the nutritional breakdown on your food packaging – just with a lot more numbers! Owning a Verified EPD is often an excellent tool to market your products, and (with some restrictions) compare your products with others of the same type.
Can you compare EPD?
The only problem with comparing EPD is that not all schemes and LCA practitioners make the same assumptions or include and exclude parts of the process using the same cut-off rules. At the same time, some assessments are made for a metric tonne (1000 kg) of material, others for a square metre in area, a cubic metre volume, “one piece” of the product… and all other possible unit types.
This means that there isn’t a completely exact or correct way to do an LCA! Much of it is up to interpretation and will have a margin of error. But ultimately, it’s currently the best available method to show how a product is made and how much damage (or not!) is being done to the environment because of it.