Life Cycle Assessment (LCA) in construction: a practical step-by-step guide

Life Cycle Assessment (LCA) is the methodology that allows the environmental impact of a building or piece of infrastructure to be quantified across its entire service life, from raw material extraction to end of life. In construction it has become the basis for designing sustainably, comparing materials with objective data and meeting the requirements of certifications and European regulation.

In this guide you will see what LCA applied to buildings is, which standards regulate it (ISO 14040, ISO 14044 and the EN 15804 / EN 15978 series), what its phases and scopes are, and how to put it into practice in a real project.

What is LCA and what is its scope in construction?

Life Cycle Assessment (LCA) is a standardised methodology that evaluates the environmental impacts of a product or system by considering all the stages of its cycle. Applied to construction, it covers the manufacture of products, transport, installation on site, use and maintenance, and the demolition or end of life of the building.

This comprehensive perspective is necessary because of the sector's weight: according to the European Commission, buildings are responsible for around 40% of energy consumption and 36% of greenhouse gas emissions in the European Union. Assessing only the operational phase (the energy consumed during use) leaves out a very significant part of the impact, especially the embodied carbon in materials.

That is why LCA helps technical teams to prioritise improvements in materials, construction solutions and maintenance strategies that generate measurable reductions, not just estimated ones.

What are the phases of LCA in a construction project?

LCA follows a methodology structured in four phases, defined by the ISO 14040 standard. Knowing them is key to planning the study, ensuring data quality and turning the results into design decisions:

1. Goal and scope definition: the purpose of the study is set, along with the functional unit (for example, 1 m² of façade over 50 years) and the system boundaries (cradle-to-gate, cradle-to-grave or cradle-to-cradle).
2. Inventory analysis (LCI): the inputs (energy, materials, transport) and outputs (emissions, waste, effluents) of each phase are gathered. This is the life cycle inventory, the quantitative basis of the study.
3. Impact assessment (LCIA): the inventory data is translated into environmental indicators such as global warming potential (kg CO₂ eq), resource depletion or acidification. This is the life cycle impact assessment.
4. Interpretation of results: critical points are identified, alternatives are compared and concrete improvements are proposed, for example replacing a high-impact material or redesigning an element to extend its service life.

What types of scope are used in construction?

The scope defines which stages of the cycle are included and, therefore, how complete the result is. The EN 15804 series organises these stages into modules (A1-A3 product, A4-A5 transport and construction, B1-B7 use, C1-C4 end of life and D benefits beyond the system boundary):

• Cradle-to-gate: from raw material extraction to the product leaving the factory (modules A1-A3). Used to compare materials or components.
• Cradle-to-grave: incorporates transport, use, maintenance and end of life. This is the appropriate approach for assessing complete buildings.
• Cradle-to-cradle: adds the reuse or recycling of materials (module D), aligning with the principles of the circular economy.

A cradle-to-gate analysis is useful for procurement decisions, but only a cradle-to-grave or cradle-to-cradle study reflects the real impact of the building's full cycle.

Which indicators are analysed in a building's LCA?

The most relevant impact categories in construction include:

• Climate change (kg CO₂ eq): emissions associated with the use of energy and materials.
• Resource depletion: consumption of raw materials and fossil fuels.
• Eutrophication and acidification: pollution of soil and water.
• Water and primary energy consumption: key efficiency indicators.
• Waste generation and recyclability: linked to the circular economy and to construction and demolition waste.

How is LCA applied to a real project?

Applying LCA to a project means translating the methodology into concrete data, modelling scenarios and comparing design or material alternatives by their impact. The process can follow these steps:

1. Model the building with BIM, so that volumes and materials are extracted directly for the inventory.
2. Select construction alternatives and compare them by their impacts over the expected service life.
3. Calculate the impacts of transport and installation on site, including machinery consumption.
4. Analyse use and maintenance, considering energy consumption and the replacement of elements.
5. Evaluate end of life, incorporating demolition, waste management and recycling potential.
6. Interpret the results and apply improvements in the project phases that still allow it.

Which standards regulate LCA in construction?

LCA is governed by a set of international standards that ensure the consistency and comparability of studies:

• ISO 14040 and ISO 14044 (adopted in Spain as UNE-EN ISO) define the general principles and methodological requirements of LCA.
• EN 15804 sets the product category rules for producing consistent and comparable Environmental Product Declarations (EPDs) for construction products.
• EN 15978 specifies the method for assessing the environmental performance of the complete building from the EPD data.

Citing the standards applied in each study is essential to ensure its validity and allow comparisons between projects.

What role do Environmental Product Declarations (EPDs) play?

Environmental Product Declarations (EPDs) are third-party verified documents that communicate the environmental performance of a material in line with EN 15804 and ISO 14025. For two EPDs to be genuinely comparable, they must follow the same Product Category Rules (PCR). In construction they are the main source of reliable data to feed the LCA inventory of a building.

What benefits does LCA offer in the construction sector?

Implementing LCA not only improves the environmental performance of projects, it also brings competitive advantages:

• Reduction of impacts: it pinpoints precisely which materials or processes generate the largest footprint and allows action to be taken on them.
• Compliance and certifications: schemes such as LEED, BREEAM or VERDE value or require LCA to demonstrate the building's environmental performance.
• Competitiveness: companies that master LCA offer projects with verifiable data.
• Transparency: the results provide evidence against greenwashing practices.
• Circular economy: the cradle-to-cradle approach encourages the reuse and recycling of materials.

What are the main challenges in applying LCA?

The most common challenges when applying LCA in construction are:

• A lack of reliable data on materials and construction processes.
• The difficulty of modelling maintenance and end-of-life scenarios.
• Limited integration of LCA in the early design phases, when there is the most scope for decisions.
• Inconsistent interpretations when uniform standards are not applied.

To overcome them it is advisable to use specialised software with verified databases (EPDs) and to promote collaboration between architects, engineers and consultants from the earliest stages.

How to integrate LCA into a construction or development company's strategy

LCA should be taken on as a strategic tool, not as a formality. To do so it is advisable to:

1. Train the technical team in the methodology and its benefits.
2. Include LCA in the specifications for design and tendering.
3. Define quantifiable targets, such as reducing the carbon footprint per square metre.
4. Evaluate alternatives of materials and systems according to their impact.
5. Implement the improvements during the project.
6. Monitor results and produce verifiable reports.

How does LCA relate to the carbon footprint and the circular economy?

LCA and the carbon footprint are closely linked. The carbon footprint focuses on greenhouse gas emissions, while LCA covers a broader analysis that includes resource consumption, pollution and end of life. Integrating a circular economy approach means designing buildings that can be dismantled, reused or recycled, closing the material loop.

How does LCA vary by project type?

The LCA approach must be adapted to the nature of each project:

• New construction: requires modelling large volumes of materials and assuming a standard service life (for example, 50 years).
• Renovation: focuses on the environmental benefits of preserving existing structures versus building anew.
• Infrastructure: prioritises high-impact materials, such as steel or concrete, and considers a longer service life.
• Modular or industrial works: allow transport, assembly and future component reuse to be evaluated.

Frequently asked questions about LCA in construction

How much does it cost to carry out an LCA of a building?

It depends on the scope and complexity. A cradle-to-gate study of a component is considerably cheaper than a complete building LCA, which requires modelling all the phases and usually involves several thousand euros. It is advisable to request a quote based on the defined functional unit and system boundaries.

How long does an LCA take?

It varies depending on data availability and the complexity of the model. The longest phase is usually compiling the inventory, especially if supplier data is needed.

Does an LCA guarantee that the building is sustainable?

Not on its own. LCA quantifies impacts, but sustainability depends on how those results are acted upon during design and execution.

Can two buildings be compared through LCA?

Yes, as long as they use the same functional unit (for example, 1 m² of usable area over 50 years) and the same system boundaries and reference standards.

What role do EPDs play?

Environmental Product Declarations provide verified material data in line with EN 15804, which is fundamental for producing a reliable and comparable building LCA.

Conclusion

LCA is much more than a technical tool: it is the basis of sustainable construction. Applying it makes it possible to reduce impacts, comply with European regulation and stand out in an increasingly demanding market. If you want to go deeper, we recommend our articles on LCA methods and tools, the carbon footprint of construction materials and the new Construction Products Regulation of 2026. To measure and manage the carbon footprint of your projects with auditable data, you can rely on Manglai's product footprint solution.