A Life Cycle Assessment (LCA) can be a powerful tool in the fight against climate change. But what is it exactly?

Life Cycle Assessments are used for evaluating the environmental impacts associated with different stages of a product's life cycle. Depending on the stages taken into account, LCAs are also known as “cradle to grave” or “cradle to cradle” analysis, LCAs can take into account every step of the way, from raw material extraction (cradle) to the final disposal of the materials (grave) and even beyond including recycling or reuse (cradle)​​. In other words, an LCA analysis isn’t just a snapshot of a product, process, or service’s emissions at one point in time. Rather, it takes into account the cumulative environmental impacts of all the individual stages and the lifetime of a product.

This methodology is important because it provides a clear picture of the corresponding carbon impact a certain product has on the environment. Without this assessment, consumers would struggle to make conscious decisions, and manufacturers would not be able to improve the overall environmental profile of their products​.

For the built environment there are recognized guidelines to conduct LCAs, either at the European level or on a country-by-country basis. Specifically, norms like EN 15804 (construction products) and EN 15978 (whole buildings) outline the requirements and guidelines to perform an LCA. These standards define exactly which environmental impact indicators should be present in these assessments. Therefore, they allow a more comprehensive understanding of the impact a product or a building has into multiple areas such as human health, environment, resource use, and more.

There are four macro-stages to an LCA calculation:

- Stage A, which covers Product Phase and Construction Phase

- Stage B, which covers Use and Maintenance

- Stage C, which covers the End-of-Life Phase

- Stage D, which covers what happens beyond the End-of-Life-Phase

Each stage is subsequently divisible in sub-stages, covering specific aspects of the product’s life-cycle. For example, stage A can be divided in:

A1: Raw material extraction and processing, processing of secondary material input (e.g., recycling processes).

A2: Transport to the manufacturer.

A3: Manufacturing.

A4: Transport to the building site.

A5: Installation into the building​​.

The sum of all the stages A,B, C, and D determines the final carbon footprint of the product.

However, not all LCA stages contribute equally to the end result.

In this article, we are going to focus mainly on the first three stages of the LCA: A1 - A3 also known as “cradle-to-gate”. These stages are crucial in the quest to decarbonise the built environment for three reasons: 

01 they are the major contributors to the final embodied carbon figures 

02 they are based on reliable data which is immediately available for designers

03 they give a chance to alternative, low-impact materials to be used more in construction

The majority of embodied carbon emissions of a building come from the Product Phase with estimates attributing it between 65% and 85% of the total footprint.

While stages B1-B7 and the End-of-Life Phase’s contributions are far from negligible (11% to 30%), the bulk of the carbon emissions comes from raw material extraction and manufacturing. To make sense of how this could be, it is sufficient to think of materials such as cement or steel. They are the most used materials in the industry but they are also among the most polluting and have an immense impact on the environment. Cement alone contributes as much as 8% to global CO2 emissions and for every tonne of steel produced, around 2 tonnes of CO2 are released in the atmosphere during its production phase. All these contributions to the carbon footprint are accounted for in the A1-A3 stages of the LCA. Given all of this, it is evident how the “cradle-to-gate” calculations are extremely important to gauge the impact of a certain material both individually and in relation to the whole project.

The second reason why A1 to A3 stages are so important for the built environment is that unlike later stages in the LCA process, the A1 to A3 stages are often grounded in "real" data. What “real” means is that these data are generally derived from actual measurements taken in controlled environments by the material manufacturers, making it a solid foundation for assessing the emissions associated with individual building materials. In other words, the advantage of A1-A3 stage LCAs is that they are based on measurements rather than estimates which can be sensibly different from the real-world figures.

Even remaining in stage A, the numbers pertaining to the construction phase (stages A4 and A5) can have significant discrepancies between predicted embodied carbon numbers and actual measurements. This can happen due to a variety of reasons but mainly because of the uncertainties and mishaps faced by on-site contractors. A blocked road, malfunctioning vehicle, a delay or any other contingency can cause the carbon emissions associated with A4 and A5 stages of a product to go up substantially from what was initially predicted. Stage B, C, and D are also challenging to estimate beforehand, especially for whole buildings. It happens due to the relatively large time intervals between when calculations are performed and when the building (or product) is in operation and then deconstructed and eventually disposed of or recycled.

The immediate availability and reliability of A1-A3 stages data has also other crucial effects on the decarbonisation efforts of the built environment. Given that the first three stages of an LCA are where most of the embodied carbon comes from, being able to compare and evaluate data early on in the design phase of a building is crucial to make the right choices. For example regarding the materials to employ. Buildings are complex and cumbersome projects, and adapting their requirements mid-operations in order to lower their environmental impact becomes more and more expensive and impractical as time goes by. For this reason, the sooner an LCA is performed the faster adjustments can be made, the cheaper it will be to do so, the more impact it will have on reducing the overall emissions of the project. Ideally, already during the project phase architects and designers should be able to assess with reasonable certainty a ballpark figure for the carbon emissions of their project. This requires the data regarding A1-A3 LCAs of the selected construction materials to be readily available, for example through their Environmental Product Declarations (EPDs). Only then can architects choose the best materials to minimise the building’s carbon footprint.

In other words, given their huge contribution to the overall carbon emissions, A1-A3 stages hold the greatest capacity to influence the overall design and impact of a building project out of all the LCA stages.

And this brings us to the final reason why A1-A3 stages are so critical for the built environment.

If we are to attain the objective set by the Paris Agreement of remaining within the 1.5°C threshold, it is essential that a solid wave of change hits the industry. High-carbon materials such as cement and steel should be promptly ousted by other, lower-impact ones. Bio-based materials are a great option for many construction applications and are also far less polluting, with some materials such as hemp or straw even registering nominal negative carbon figures. Due to such properties as acting as carbon-sinks and needing greatly less energy to be produced and harvested compared to cement or steel, bio-based materials have a “score advantage” in A1 to A3 stages. A more widespread adoption of these methodologies would mean a greater chance for bio-based materials to become mainstream products. The higher initial costs, now one of the major deterrents for their worldwide use, would also diminish with the higher demand, leading to an overall net benefit both for the environment and for local manufacturers.

It's important to note, however, that while LCAs are an important tool, they aren’t widespread yet. Life Cycle Assessments are only mandatory for products that want to obtain an EPD as per EN 15804. Other than that, LCAs are generally not mandatory at a European level neither for individual materials, nor for whole buildings. The European Union has yet to indicate clear goals — emissions-wise — for new buildings and products. It is left to individual countries to define and enforce their own limits, resulting in a scattered and inconsistent architectural panorama throughout Europe. This lack of uniformity leads to LCAs being utilised in greatly differing capacities depending on the country. Certain countries have taken independent action and enforce stricter regulations.

Denmark, with the BR23 regulation, has set clear limits on the carbon footprints of new buildings larger than 1,000 m2 and has introduced obligatory whole building LCAs calculations to be performed even for smaller buildings. France, The Netherlands, and Sweden have passed similar regulations to address the carbon problem of the built environment, but there is still no European conformity on the theme. We have explored the different regulations throughout Europe in one of our previous article that you can find here.

Data availability has also been up to this point a big problem for the mass inclusion of the data from A1-A3 stages in architectural decision-making. With EPDs being often dispersed between a myriad of different sources, it is challenging for architects to gather accurate material data.

However, the future of the built environment can still change for the better. With the recent push for Nearly Zero-Energy Buildings (NZEB) and the EPBD, however, the European Union is showing encouraging signals of a renewed effort to drastically reduce the built environment’s carbon footprint.

On the availability of data, our platform aims at solving precisely this problem. We provide an extensive material library, complete with Environmental Product Declarations, and an easy, visual way to track upfront carbon, water usage and energy mix. For every project, the dashboard provides complete A1-A3 calculations based on the materials selected, making it as convenient as possible to try out new solutions on the fly and evaluate their impact in minutes. By doing this, we hope to encourage our community of impact-driven architects to significantly influence current and future construction material choices. 

In summary, the A1 to A3 stages, although only part of the full spectrum of a product's life cycle, hold significant potential to reduce carbon emissions from the built environment. They provide a quantifiable and actionable measure of our architectural decisions right when it matters the most: during the project phase. For this reason they are indispensable in our push towards a more environmentally conscious built environment. A1-A3 stages measure actual emissions that are being released to the atmosphere today. Therefore, minimising them means taking concrete action to reduce not only future carbon emissions, but most importantly current ones.

The climate crisis we are facing today demands ambitious action. We need to leverage all the tools we have in the most comprehensive, consistent, and progressive way possible.