General agreement exists that we have to slow the growth of carbon emissions and then shrink them. As researchers seek ways to reduce human-generated carbon emissions at a cost that society will accept, buildings consistently emerge as the best opportunity. Yet it often feels like we have to choose between financial constraints and using more energy-efficient measures in our buildings. Wouldn’t it be great if we could integrate both?
A group of researchers has led just such a pioneering project to calculate the environmental impact of residential buildings. The novelty of this initiative is an open-source computing tool which can calculate the CO2 emissions in each phase of a building project. In the near future, a building’s carbon footprint will be obtained digitally, starting with its conception and through to every stage of the construction process.
“The first step in managing and reducing the CO2 emissions associated with building construction is to calculate them, to know the importance of this environmental aspect, and apply measures to improve the situation,” explains the University of Seville instructor and head of the project, Jaime Solís. “To better understand the environmental impact and work on it, it is important to measure the CO2 emissions from the design and conception of the building and, according to its measurements, know the different possibilities for reducing its carbon footprint and make it a more sustainable, low-carbon building.”
Existing tools for environmental certification of buildings have failed in their ability to reach the general public and to create social awareness. They tend to require not only specialized knowledge regarding construction and energy source but also environmental knowledge of the elements of a carbon footprint. A carbon footprint consists of determining the emissions of greenhouse gases produced to directly and indirectly support human activities.
In recent decades, building regulations at the national and international level have reflected two areas of concern. The first has been scrutiny of the environmental impact caused by the construction sector. The second has been a reduction of the carbon footprint generated by the manufacture of construction materials, which has been identified as the cause of more than 40% of the total impact of the construction phase in the life cycle of a building.
Most recent studies that attempt to estimate the environmental impact of buildings have been subject to reviews that focus on life-cycle assessment (LCA), life-cycle energy analysis, life-cycle carbon footprint, or a combination of these.
Regardless of methodology, the following conclusions are generally drawn:
- The manufacturing and construction phase of a building’s life cycle, which is usually concentrated into a short period of time (1–2 years), causes the most intensive environmental impact. This is mainly due to the consumption of concrete and steel for the structure, both of which represent a high percentage of the emissions produced during this phase. This impact is reduced the longer the building’s service life is considered. However, the decisions made during this phase greatly influence the results of the other life-cycle phases of the building.
- The use and maintenance phase is generally responsible for 80–90% of the CO2 emissions generated during a building’s life cycle, almost 60% of which is caused by the energy demand for heating and air-conditioning. An operational phase of more than 50 years duration reduces emissions, and this should be a primary goal.
- Reductions in energy consumption during the use and maintenance phase should be achieved through decisions made during the design phase, which implies the use of materials with a higher embodied energy. This means that, in nearly-zero-energy buildings, the emissions during the construction phase represent a higher percentage of the total emissions of the entire life cycle. Therefore, once the operational energy has been reduced, attention should be focused on the development of new insulation materials that require less energy to manufacture.
Goals to Determine a Building’s Carbon Footprint
Reducing a building’s carbon footprint is difficult due to the economic, technical, practical, and cultural barriers that prevent professionals from selecting materials with low carbon emissions. Solis and the team from ARDITEC Higher Technical School of Building Engineering at the University of Seville studied the methodology for the calculation of CO2 emissions of a building’s construction processes. These included time constraints during the design phase, the high cost of new products and additional professional training, the difficulties for small industries competing against established industries, a lack of full-scale demonstration projects, and negative perceptions among practitioners and clients.
The main aims of their research project included:
- Studying the methodology for the calculation of CO2 emissions of the construction process and throughout the life cycle of materials at European level;
- Establishing a common European curriculum in this area, thus increasing awareness of climate change and providing information on the emissions generated by each element;
- Developing an Open Educational Resource (OER) to spread knowledge on CO2 emissions in construction processes; and,
- Launching an online tool accessible to all building agents (students, professionals, etc.) at European level. Specialized knowledge on the environmental impact of building processes is not necessary for its use.
The research results show that construction materials have more influence (90–95%) than that of machinery (5–10%) in the evaluation of the carbon fiber. “We have tried to work towards the concept of sustainable construction, taking into account, also, concepts related to the recycling and reuse of materials, and putting this tool at the disposal of all the agents involved in the construction sector, such as students, professionals and the users of the house themselves,” adds Solis.
The tool that Solis and his team developed evaluates CO2 emissions generated by construction processes in ways different than previous attempts. This online tool doesn’t demand specialized knowledge regarding environmental impact assessment from the users such as students, professionals, or administrators. That may lead to a higher acceptance of the basic concepts of sustainability in the building sector. The online platform where the tool is hosted also allows those who are interested to expand their knowledge in the building sustainability field.
One of the applications of the online tool is that it allows for buildings of similar characteristics to be compared from an economic and environmental point of view — in essence, knowing which of them is more sustainable and better respects the environment.
The researchers point out that it is vital to be aware of the CO2 emissions that are generated in the first phases of a project, so that early preventative actions can be taken by means of the choice of different materials, mean of transport, construction methods, use during the life of the building, deconstruction systems, and reuse that contribute to reducing a building’s emissions.