Life cycle assessment is an evolutionary step forward in the pursuit of achieving truly sustainable buildings.

LCA Sustainable balance

Undoubtedly buildings consume less and less energy when it comes to their operation period. However, along the way to achieve the reduced energy demand, increased environmental impacts are generated at the earliest stage of the building life cycle. Taking into consideration the impacts associated with the manufacturing, transport, installation and deconstruction of the materials that constitute the building provides us the full picture of the total environmental load of the construction.

1. What is a life cycle assessment (LCA)?

Life cycle assessment (or life cycle analysis) is a methodology used to estimate the environmental impact of a product, process or a system throughout its whole life cycle. The products´ life cycle is divided into different phases of which the earliest one is the extraction of raw materials, following the manufacturing, transportation, final use and disposal. Life cycle analysis generates results for different life stages, including various environmental impacts then adding them all and offering a final result per unit of a product.

2. Main goals of the life cycle assessment

  • Quantification – to know the value of the total environmental load per product unit, in order to be able to compare products and take informed decisions.
  • Improvement - the careful analysis allows to evaluate the environmental performance at each stage of life and allows determining which actions would be the most beneficial in order to achieve an improvement.
  • Informative purpose – providing objective information to decision makers in industry, governments, local authorities, consumers etc., allows to influence the change and promotes the policy-making based on scientific data.
  • Encourage environmental competition – making the data about environmental impacts available to everybody (Environmental Declaration Product). LCA makes it easy to compare the products and since sustainability is becoming an important factor for many consumers, in order stay competitive companies have to embrace a new environmentally friendly approach and aim at reducing the negative impacts.

3. The origins of the life cycle analysis

The development of the LCA methodology has its roots in the realization of the fact that our planet is not infinite and has its limitations when it comes to providing us with resources, taking in the anthropogenic waste and being able to regenerate in a yearly cycle.

At the beginning of the 60s, due to the decreasing availability of energy and natural resources, the scientific and economic sector were interested in finding the way to quantify the energy and thus be able to know the future demand. In 1972 two famous studies has been published “The limits to Growth”  (Meadows et al) and “Blueprint for survival” (Goldsmith et al). The publications were focused on estimating how the increase of population will affect the demand for raw materials and energy. It was just shortly before the first oil crisis (1973) when it has been concluded that on a finite planet, the dynamics of exponential growth (population and product per capita) is not sustainable. 

On the other hand, in 1969, in order to learn about the future economic impact of its packaging (glass and aluminum), Coca-Cola Company has commissioned a group of researchers a study of their environmental impact. The objective was to analyze and to find out which of the beverage containers has the lowest emissions and is least dependent on the natural resources supply. The newly developed calculation methodology, to quantify the inputs and outputs, has served to establish the American life cycle analysis inventory, at the time known as Resources and Environmental Profile Analysis (REPA), developed by the Midwest Research Institute (MRI). In Europe, it was called an Ecobalance. During the oil crisis period (around 1970-1975) roughly 15 REPA´s were conducted, which has permitted to establish the protocol and standards of the methodology.

Between 1975-1980 with the fading oil crisis also the interest into carrying out more studies has faded away as well. Nevertheless, the life cycle inventory analysis continued to exist and over the course of time the methodology has slowly been improved. In Europe the LCA practice was also being developed as the European Commission has established an Environmental Directorate (DG X1), which have issued the Liquid Food Container Directive in 1985, which ordered the companies to monitor the stream of raw materials consumed and the generated solid waste.

When in 1988 the increasing amount of solid waste has become a worldwide recognized issue, the LCA has presented itself as a valid tool for analyzing the environmental loads. Along the way a need to progress and step out beyond just the inventory has given the necessary push to evolve the methodology to the next level.

Since then more and more institutions and companies started to show the interest into developing of a solid database and methodologies. In the early 90´s the first conference of the Society of Environmental Toxicology and Chemistry is held, to open the debate on the REPA methodology and adapt it to the present (SETAC 1991; SETAC 1993; SETAC 1997).

In 1992 for the first time a complete methodology has been published by Franklin Associates. Following that a Society for the Promotion of LCA (SPOLD) has been founded, forming an association of 20 large European companies focused of promoting the development and application of the life cycle analysis.

In 1997, the ISO standard 14040 has been published. At this point the LCA studies are being carried out everywhere around the world. In 2002, the World Summit on Sustainable Development was held in Johannesburg and life cycle assessment was recognized as an important tool in promoting the change in production and consumption patterns. Since then the method has been continuously improved and also the database has exponentially expanded over the time.

4. How to perform a life cycle assessment?

Life cycle analysis is developed in 4 stages:

1. Definition of a scope and objective
2. Inventory
3. Environmental impact assessment
4. Interpretation of the results

Stage 1. Definition of a scope and objective – in this phase it is being determined how big part of a products´ life cycle will be taken into consideration in the assessment, and what is the goal of the analysis, for example the chosen scope can be from cradle to gate (just the manufacturing phase) or from cradle to grave (full life cycle, including manufacturing, transportation, installation, final use and disposal).

Stage 2. Inventory – this step includes a collection of the data concerning the materials and energy flow within the considered system. This includes all the environmentally important inputs and outputs, which are:
  • Inputs: includes use of the resources such as raw materials, water, air, land, energy
  • Outputs: gas emissions, waterborne waste, soil pollutants, solid waste and by-products

The information used for the analysis is provided by international databases such as Ecoinvent, GaBi databases, Agri-footprint, ELCD, EU&DK Input Output database, Swiss Input Out database, USLCI, and others. To give some examples of the software that facilitates performing LCA the available options include One Click LCA, Sima Pro, Open LCA and others.

Once the data has been collected the preferred methodology to be applied is chosen. This depends on the scope and purpose of the study.

Step 3. Environmental impact assessment – using the collected data an evaluation of negative impacts and the quantity of harmful substances is being summed up. The importance of every impact category and life cycle phase is being assessed in order to identify the most and least contributing elements. In general, this process involves the association of inventory data with specific environmental impacts and distribution of the impacts between the life stages.
GLOBAL WARMING POTENTIAL Global warming potential (GWP) – it is a measure that relates the intensity of greenhouse effect produced by the gas in comparison to CO2. To put it simple, some of the greenhouse gasses has stronger potential to warm the planet. For instance, 1 kg of methane has the same effect as 21 kg of CO2, thus its global warming potential equals 21 kg CO2e (e stands for equivalent). Kg. Eq CO2
Ozone depletion potential (ODP) – it is a decrease in the amount of ozone found in the earth's stratosphere due to the release of gas such as halogenated carbon dioxide, solvents, propellants and foaming agents. The impact is measured relating the intensity of the ozone loss in comparison to CFC-11 as the reference substance. Kg. Eq. CFC-11 
ACIDIFICATION Acidification (AP) - it is the alteration of the chemical composition and loss of the neutral pH of soil and water. This is due to precipitation of acid rain caused by the emission of polluting gases into the atmosphere. The impact is measured relating the intensity of the acidification in comparison to SO2 as the reference substance.  Kg. Eq. SO2
EUTROPHICATION Eutrophication (EP) - it is an excessive growth of plants and algae due to the increased availability of one or more growth limiting factors necessary for photosynthesis, such as sunlight, CO2, nutrients and fertilizers. It affects the supply of drinking water, irrigation, and etc. The impact is measured relating the intensity the process in comparison to eutrophication caused by PO4 as the reference substance. Kg. Eq. de PO4


Formation of tropospheric ozone (POPC) – tropospheric ozone is a greenhouse gas and a harmful pollutant that causes urban smog and reduces plants ability to do the photosynthesis. The impact is measured relating the intensity of the process in comparison to the effect caused by Ethene as the reference substance.  Kg. Eq. Ethene

Step 4. Interpretation of the results – in this stage an analysis and critical review of the data is being performed with the aim to outline the conclusions. The obtained results can be also compared and confronted with other similar studies and from the comparison a possibility of improvement can be detected. For instance, we can compare two identical building, with the same transmittance (therefore same energy consumption) but with different kind of material applied as an insulation. Determining which of them has lower environmental impact indicators would point out the preferred material.

5. ¿Which normatives define and regulate the life cycle assessment process?

The international standard that regulates the methodology and indicates the scopes and steps to be followed is the international standard ISO 14040 (Environmental management - Life cycle assessment - Principles and framework). It covers two types of studies the life cycle analysis (LCA) and the life cycle inventory (LCI).

This regulation is included in the standards of sustainable development goals, a program being carried out by the European Union in order to address the most worrisome issues associated with the climate change and depletion of the resources.

Other normative standards that regulate the methodology of the assessment for buildings and the quality of data are: EN 15978 (Sustainability of construction works. Assessment of environmental performance of buildings. Calculation method), EN 15804 (Sustainability of construction works - Environmental product declarations - Core rules for the product category of construction products).

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