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May 6, 2024

By : consist2 / 0 Comments

Reducing Carbon Emissions In Construction
“I think that in future people will look back on 2018 as the year when climate reality hit. This is the moment when people start to realise that global warming is not a problem for future generations, but for us now.”

-Prof. Hans Joachim Schellnhuber, award-winning climatologist
As the above quote suggests, the last couple of years have seen an undeniable, unprecedented growth in the awareness regarding climate change, and the carbon emissions endangering our planet. As this awareness spreads, governments, NGOs, corporates and citizens alike are coming together in new and unprecedented ways to speak out for climate action.

This week itself, the UN Climate Action Summit took place, where a number of new ideas and plans were introduced, especially by the private sector. There was an increased urgency to the demand for world leaders to step up and tackle climate change, and the voice of the youth demanding climate change was unmistakably heard. In short, if there was ever a time in the history of the world where mankind seemed to have a shot at a sustainable future…that time is now.

Every sector in the world has woken up to the reality of climate change. With the construction sector contributing around 39% of the total carbon emissions in the world, it is inevitable that green building will come to take the lion’s share of contributing to the cause of sustainability.

Did you know that 28% of these emissions from construction come from the operational “in-use” phase- heating, lighting and cooling them- while 11% are attributed to embodied carbon emissions? Embodied carbon is that which is released during the process of construction and material manufacturing.

While the focus of the construction industry, and indeed the world at large, has rightly been on the operational or ‘in-use’ carbon, tackling embodied carbon is also a necessity if we are to fully decarbonize by 2050 and keep global warming to below 1.5 degrees. Hence, on the occasion of the World Green Building Week, we decided to address the process of Green Building, with a focus on reducing carbon emissions in construction.

Carbon Emission throughout Building Life Cycle

The construction life cycle consists of 5 major stages:

1. Planning and Design
2. Material and Construction
3. Operation
4. Maintenance and Renovation
5. Deconstruction and Waste Disposal

Each of these stages has a number of processes and materials that will play a part in emitting CO2.

Planning and Design:

The planning and design phase is of paramount importance for carbon dioxide reduction. The decisions we make during this stage directly affect operational efficiency. A good design is that which increases the potential for emission reductions over the building life cycle, as well as eliminates the need for expensive carbon dioxide reduction measures during the later stages.

Materials and Construction:

A number of processes result in the emission of greenhouse gases, such as the extraction and processing of raw materials, production and transportation of construction materials, materials delivered to site and disposal of construction waste to landfill. As the energy and materials used during this phase are mostly non-renewable, the carbon reduction we achieve in this phase can be very substantial.

Operation:

Several studies focusing on energy consumption and associated emissions during the operational phase have postulated it accounting for 70-80% of the environmental impact throughout the building life cycle. Energy consumption during the operational phase is 28%, nearly 3/4th of the total emission contributed by the construction industry. We can attribute the amount of energy consumed during this phase to the extensive use of electrical appliances, including heating, cooling, and lighting systems over the entire lifespan of building operation.

Maintenance and Renovation:

As the building approaches the later period in its lifespan, the wear and tear results in two options: to renovate the building or demolish and reconstruct it.
Renovation and maintenance activities involve replacing low-performing systems with newer ones. This process, of removing low-performing systems and disposing of them results in significant carbon emissions.

Deconstruction and Waste Disposal:

The construction industry consumes 40% of raw materials worldwide. This means that we need to dispose of roughly the same amount of materials when we deconstruct a building. Hence, carbon emission during the deconstruction and waste disposal stage is also quite substantial.

Environmental impacts during the demolition phase include demolition activities and the transportation of any waste building materials to the landfill site or reusable materials to a recycling site. A large amount of scrap building materials produced at the disposal stage of the building life cycle highlights the need for the reuse or recycling of materials to reduce carbon dioxide emissions in the building industry.

Reducing Carbon Emissions in Construction

As we have seen above, reducing carbon emissions is absolutely essential. There are two types of solutions that we can implement for this purpose:

Design Solutions

These are the solutions that we can implement during the design and planning phase. They look for ways to reduce carbon emissions through the fundamental design of the building itself. Here are some examples of Design Solutions to reduce Carbon Emissions:
  • Maximize structural efficiency
These are the solutions that we can implement during the design and planning phase. They look for ways to reduce carbon emissions through the fundamental design of the building itself. Here are some examples of Design Solutions to reduce Carbon Emissions:
  • Establishing a carbon emission footprint
The practical process involved in designing the solutions to reduce carbon needs to be an integrated process. This involves careful calculation and assessment of carbon emissions, recognizing which parts of the building are ‘embodied carbon hotspots’ and then figuring out the solutions to minimize said carbon. Architects, structural engineers, MEP engineers, and quantity surveyors all need to be involved in the process.

Construction Solutions

These are the solutions that we can implement during the construction phase of the building. They deal more with the selection of materials and processes that reduce carbon emissions.

“Cement, the vital component of concrete, is the chief factor for carbon emissions in terms of materials,” says Mr. Mahir Desai, Structural Engineer associated with Consistent. “Replacing a major part of the cement-content is, therefore, the way towards lowering carbon.”

Some of the Construction Solutions for reducing carbon are:
  • Low carbon concrete mixes
The preeminence and weight of concrete make it the biggest source of embodied carbon, despite the fact that the emission per ton is not relatively very high. The obvious answer is that we design lower-carbon concrete mixes by replacing the cement quantity using fly ash, slag, calcined clays, or even lower- strength concrete where feasible. Despite varying access to such materials in different countries and regions, with increasing options, there’s always a better one that can reduce the carbon footprint.
  • Reusing materials
Salvaged materials- brick, metals, broken concrete, wood- usually have a much lower embodied carbon footprint than newly manufactured materials, since the carbon to manufacture them has already been expended. We can use the salvaged materials to replace up to 50% of the aggregates, which form a major part of the concrete. This results in a further reduction of embodied carbon.

In addition to such measures, reclaimed wood is also a good option. With reclaimed wood, the energy consumed in cutting the tree down, transporting, and processing it is saved. Also, the extra tree that we never cut down still continues to sequester carbon.
  • Lower carbon alternatives
A wood structure instead of steel and concrete, or wood siding instead of vinyl can reduce embodied carbon. It’s impossible to avoid carbon-intensive products entirely, such as metals, plastics, and aluminium. However, Environmental Product Declarations can be reviewed and utilized to look for lower-carbon alternatives.

Operational Solutions

Operational solutions to reduce carbon emissions are the solutions that we implement at the operational stage of constructing a building. The majority of operational carbon emissions come from heating, cooling, ventilation, and lighting of the building. Hence, reducing this consumption of energy is a major factor in reducing the carbon footprint. For this, there are several solutions that we can implement, such as:

1. Energy-efficient light and water fixtures
2. Proximity and occupancy sensors
3. Intelligent control of HVAC and power systems
4. Usage of onsite/offsite renewable energy solutions
5. Use of recycled water

Role of Consultants in Reducing Carbon Emissions

Consultants play an important role in the reduction of carbon emissions, by providing a number of specialized services, such as:

1. Conceptual Analysis and Evaluation of various options to reduce carbon emissions    Detailed Engineering
2. Regular and Proper Monitoring during execution to achieve design parameters
3. Energy Modeling Services

“Consultants play a key role in both the design and construction stages of the building,” says Mr. Sagar Kulkarni, MD of Consistent Engineering Consultants. “Taking an integrated approach towards building design, we can make great progress towards an emission-free future.”

Endnotes

The industry must unite to develop an effective strategy to reduce carbon dioxide emissions.”

-Sir Rod Eddington, entrepreneur, Chairperson of Infrastructure Australia  
Reducing Carbon Emissions in construction, significantly enough to achieve global goals, is a responsibility we shouldn’t take lightly. We must generate more and more awareness regarding carbon reduction, to facilitate progress at all stakeholder levels, from the developer to the end-user. On the occasion of the World Green Building Week, we must reaffirm our commitment to reducing carbon emissions.

As Mr. Sagar Kulkarni says, “In an era besieged with the crises of military conflicts, trade wars, and economic impacts, it is important not to lose sight of achieving sustainable development goals. Our most important aim must be to create a sustainable future. Occasions like the Green Building Week are a great way to remind ourselves of that.”

So, how are you celebrating World Green Building Week? What are your ideas on reducing carbon emissions in construction? Let us know in the comments below.
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