Architects are increasingly interested in reducing the environmental impact of the buildings they design. Life Cycle Assessment (LCA) helps answer questions that arise during the design and construction of a green building since it provides scientific justification. ASTM E2921-22: Standard Practice For Minimum Criteria For Comparing Whole Building Life Cycle Assessments For Use With Building Codes, Standards, And Rating Systems provides a practice supporting the use of whole building LCA in building codes, standards, and building rating systems.
Life Cycle Assessments and Buildings
The construction industry is responsible for 39% of global greenhouse gas emissions and other adverse environmental impacts such as pollution and waste. Consequently, mastering and understanding the numbers related to its processes is extremely important. Assessing the impact of a product or a material is complex: it includes the exhaustive collection of data about its inputs (e.g., the raw materials, energy, and water used) and outputs (e.g., emissions, pollution, waste, energy use, global warming potential, habitat destruction, and resources depletion) associated with each stage of the life cycle. LCA provides real numbers for a comprehensive and unified comparison between materials and products. It allows for the quantification of the embodied carbon and other environmental impacts and thus the identification of where performance can be improved.
Whole Building Life Cycle Assessment (wbLCA) is similar to a product LCA, but the product is the building. It analyses the totality of products present in a building, useful information for decision-making related to the design, construction, operation, maintenance, and eventual demolition in the building. More specifically, a wbLCA analyzes the building structure, elements of the envelopes and interiors, excluding mechanical, electrical and plumbing (MEP) systems and other services, equipment and furniture, and other site activities.
What Is ASTM E2921?
ASTM E2921-22 provides criteria to be applied when Life Cycle Assessment (LCA) is undertaken at the whole building level to compare a final whole building design to a reference building design. The comparative assessments of final whole building designs relative to reference building designs take account of the relevant building features, life cycle stages, and related activities in similar fashion for both the reference and final building designs of the same building.
This standard only addresses environmental impacts and aspects of sustainability. It deals specifically with material selection for initial construction, including associated maintenance and replacement cycles over an assumed service life, taking operating energy use into account if required or explicitly allowed under the applicable code, standard, or rating system. ASTM E2921-22 provides criteria that building design teams should use to compare the environmental impacts associated with a reference building design and a final building design, including additions to existing buildings where applicable.
The standard does not address the social and economic impacts and aspects of sustainability. It also does not deal with basic LCA methodology, calculation methods or related matters that are covered in cited international standards.
Benefits of Life Cycle Assessment in Construction
In construction, LCA entails a holistic analysis of the environmental impact of the products used in the building throughout their entire life cycle: phases of raw material supply, production, transportation, use, and disposal. This method informs property developers on the cost of natural resources for buildings as well as their carbon emissions. Here are some of the benefits of using LCA in a construction project:
- Save Costs: LCA helps project developers compare various products and materials to pick the most cost-effective option, dramatically cutting costs in both the short and long term.
- Reduce Environmental Impact: LCA results help select the products that reduce a structures ecological footprint. Also, if a building project takes place in an environmentally vulnerable zone, LCA helps developers tackle concerns like habitat destruction or resource depletion.
- Smoother Project Management: LCA provides a nuanced scheme to assist all the team members; it provides a scientific system for architects to make the best decisions about their buildings and tackle many challenges that arise during, before, and after construction—to achieve an LCA-based certification or make environmental claims about buildings.