Buildings impact the environment in many ways. Examining the Life Cycle Assessment of building materials is an important part of reducing these impacts.
Typically, a cradle-to-grave LCA involves the manufacturing and transport of construction materials, the construction process itself, and the building occupancy and maintenance phases. It also includes energy and water use as well as the production of emissions, such as photochemical smog.
EPDs
Buildings are responsible for 40% of energy consumption and 36% of greenhouse gas emissions. In order to reduce these numbers, builders must understand the environmental impact of each material they use in construction projects. EPDs can provide transparency on the environmental impacts of these materials by allowing builders to compare data for a range of different products in an easy-to-use, standardised format.
However, it’s important to note that not all EPDs are created equal. The EPDs available are based on different Product Category Rules (PCR), which differ in their calculation requirements and methodologies. This means that EPDs based on different PCRs cannot be directly compared with one another.
When selecting an EPD, look for the following things:
Comparison with Similar Products
A good EPD will provide information on how a particular building product compares with similar products in the market. This allows builders to make more informed purchasing decisions. End-of-Life Scenario
EPDs should include information on the product’s end-of-life, including recycling options and disposal methods. EPDs should also include the main assumptions used in the LCA to evaluate the environmental impact of the product.
Finally, the EPD should include contact information for the organisation that developed the EPD, as this will allow builders to openly communicate with the company about any questions or concerns they may have. This will help build trust in the EPD and encourage collaboration with other manufacturers to reduce their environmental footprints.
Databases
Buildings are complex systems that consist of many different materials. Each material has a different impact on the environment throughout its lifetime, from raw material extraction through construction, operation and demolition. A cradle-to-grave life cycle assessment of a building considers all the resources consumed and emissions generated during each phase of a building’s lifetime. These include the extraction of raw materials, the manufacturing and transporting of construction materials, a building’s embodied energy, and its operational emissions.
To conduct a full LCA of a building, it is necessary to use a comprehensive database of material information and process data. Many databases are available, including the Ecochain Mobius database and the PEF datasets, which are compatible with a range of LCA software tools. However, the quality of these databases varies widely.
Some databases are dedicated to specific materials, and offer Environmental Product Declarations (EPDs). These are useful for selecting high-performing materials that will have the lowest overall impact in a building. Other databases are generic, and aggregate data from multiple sources. These may not be as helpful for evaluating the performance of individual materials and are less reliable in terms of overall environmental impact.
Using a combination of both EPD and generic database data can improve the accuracy of an LCA. This can help ensure that the most important processes are considered and that any gaps in the data are adequately addressed. This will also help to avoid over-spending on data collection efforts, since only the most relevant data will be collected and used.
Data gaps
Production, construction and operation of buildings lead to the use of natural resources and cause undesirable effects on the global and local environment. These impacts are influenced by the type and quantity of building materials used. Therefore, it is necessary to provide environmentally relevant product information. This is achieved by preparing life cycle assessments. The results of these assessments are now increasingly being included in funding programs, sustainability assessment systems and legal requirements.
A key challenge in completing a life cycle assessment of a building material is dealing with data gaps. These are usually resolved in different ways by different LCA tools. Some choose to ignore them, others use best estimates or leave them blank, and others collect additional data to fill in known data gaps.
The most common impact category is global warming potential (GWP 100) – the total amount of greenhouse gas emissions that are released throughout the building’s life cycle. Other impact categories include ozone depletion potential, acidification potential and eutrophication potential. The ozone depletion potential is the result of releasing ozone-depleting substances, and the acidification potential is caused by aqueous contaminants like sulfur dioxide, nitrogen oxides and ammonia. The eutrophication potential describes the effect of acidic pollutants on soil and water.
An additional criterion is the impact on biodiversity, measured as the extinction potential of specific species. This criterion is also assessed at different levels of analysis – unit process, company, sector and country. The paper uses a multilevel consequential life cycle assessment (CLCA) approach to demonstrate how such an evaluation can be used to address the above-mentioned data gaps.
Implementation
Building materials contribute to significant amounts of environmental impacts, especially embodied energy and air pollution. This makes it important to assess and use these materials wisely. An LCA can identify hotspots and help reduce overall impact through optimized material selection and design alternatives. The results can also be used to inform procurement and to guide innovation in the construction industry.
To assess the environmental impact of a building, the first step is to create a bill of materials for all components. This includes the type and quantity of each material, its life cycle, and how much is needed to construct a given functional unit (e.g., a square meter of floor space). This information is then used to calculate the total amount of environmental impacts generated by the building. This is referred to as whole-building LCA, or WbLCA.
The next step is to evaluate the end-of-life treatment of each material in a building. This includes land-filling, recycling, and incineration. The final step is to calculate the total mass balance of all the building materials in the building, including the embodied carbon and other impacts associated with each material.
To perform an LCA, the most common method is to use a standard software application called Gabi. This software allows users to search for construction materials and their EPDs using specific keywords, such as “LCA”, “ePD”, and “material.” A more comprehensive LCA method is to follow the cradle-to-grave approach. This method considers the entire building’s life, from product manufacturing to transportation to the construction site, a long phase of building occupancy and maintenance, and finally, demolition.