The term carbon footprint refers to how much greenhouse gases (GHGs) are being released into the environment when using or manufacturing a product or performing an activity. Many gases can cause damage to the earth’s environment, such as carbon dioxide, methane, nitrous oxide, hydrofluorocarbons, perfluorocarbons, and sulphur hexafluoride. They affect the environment by keeping heat within the earth’s atmosphere. This can lead to warmer temperatures, changing climates, and destruction of wildlife habitat. Construction activities consume a lot of materials, create a lot of debris, and require a lot of energy. These types of activities can increase greenhouse gas emissions. We’re going to look at how these activities create these gases, how to calculate your carbon footprint, and finally how to reduce or offset these emissions.
What affects the carbon footprint of a project?
There are three main construction activities that contribute to the carbon footprint of a project. They are the use of fossil fuels, using electricity, and sending refuse to the landfill.
Use of fossil fuels – Equipment and vehicles that use traditional gasoline or diesel fuel are contributing to GHG emissions. According to the University of Michigan Center for Sustainable Systems burning coal creates 2.2 pounds of CO2, petroleum creates 2.0 pounds, and natural gas releases 0.86 pounds. These fuels are often used by bulldozers, excavators, generators, dump trucks, pick-up trucks, and semi-trucks that transport materials to a project. The use of fossil fuels contributes about three-quarters of GHG emissions caused by humans.
Electricity use – Electricity use goes hand in hand with burning fossil fuels. Most of the electricity in the United States comes from coal-burning plants, which burn fossil fuels to make electricity. According to the Center for Sustainable Systems, each kilowatt-hour of electricity generated in the US creates 0.998 pounds of CO2 at the power plant. Almost all the tools and equipment that are used on a construction site are run by electricity.
Sending refuse to landfill – When construction debris is sent to a landfill, instead of being recycled, it wastes the energy that went into producing and transporting the material to the site in the first place. Construction projects create a lot of debris, whether from demolition activities, packaging material, or scrap material. Recycling allows the material to have a second life, and it usually doesn’t require as much energy to create a product from recycled material as it does from raw material.
How to calculate carbon footprint
Different gases create different levels of damage to the environment. The unit of measure for this damage is CO2e, or carbon dioxide equivalent. Each type of gas is assigned a global warming potential (GWP), and this is multiplied by the amount of the gas that is released to come up with the CO2e. This calculation converts any quantity and type of greenhouse gas into the amount of CO2 that would have the same global warming impact.
The Greenhouse Gas Protocol is the most widely used way to report carbon footprint. It was created in 2001 by the World Resources Institute and the World Business Council for Sustainable Development and has been used by businesses and organizations worldwide. Another popular method is ISO 14064, as it builds on many of the concepts in the GHG Protocol.
The first step in calculating carbon footprint is to define the boundary of the project that you are going to measure. Having a clear operational boundary will help you get consistent data over time. The GHG Protocol includes three groups of emissions that you may want to measure.
- Scope 1 – Emissions that result from activities under your direct control. This could include on-site fuel combustion, process emissions, or company vehicles.
- Scope 2 – Emissions from electricity, heat, or steam you purchase and use. By using this energy, you are indirectly responsible for the emissions.
- Scope 3 – Emissions from sources outside your direct control, including purchased materials, employee commuting and travel, waste disposal, and water consumption.
Once you’ve decided on the activities you want to measure, gather data regarding fuel, electricity, and material use. You can use meter readings or utility bills to get electricity or natural gas usage. You may be able to look at fuel cards and bills to gain information on the amount of fuel being used in vehicles. If that isn’t available, you can estimate based on the mileage on the vehicles and assumptions about fuel efficiency.
Next, plug the usage information into a carbon footprint calculator. The calculator will use your data combined with standard emissions factors to come up with an overall score, expressed as tons of CO2e. Just as an example, the average US household creates 48 tons of CO2e each year.
How to reduce the carbon footprint of your construction project
The major contributors to a project’s carbon footprint are its fuel use, electricity use, and the amount of debris that goes into the landfill. Any steps you can take to reduce these factors is going to lower the carbon footprint of a project. More specific measures would include:
Reducing the amount of transportation that is needed to get materials to the site. This could include using green fuels, sizing trucks to handle loads more efficiently, and taking steps to improve the fuel efficiency of all vehicles and equipment on the site.
Use construction materials made from recycled content. These materials usually require less energy during production, and you are saving them from going to the landfill. Supporting recycled material products also ensures that there will be a market for recycled materials.
Recycle as much construction waste as possible. The less material that goes to the landfill, the better it is for the environment. Sorting recyclable materials can cost extra time and money, so be sure to include this in your project budget.
Add green building design features that improve energy efficiency, such as additional insulation, efficient HVAC equipment, LED lighting, and daylighting. Also include the infrastructure to monitor energy use and report on where energy is being used the most. This is beneficial for spotting trends and changing user’s behavior to help save more energy.
Modular construction is another construction method that allows for a lower carbon foot. See here, to learn more.
Ways to offset greenhouse gas release
If you can’t control the emissions from the project to the degree that you would like, there are ways that you can offset them through investments.
You can purchase carbon offsets, which provide investment funds for carbon-offsetting projects. There are many companies that offer these offsets. Be sure to research them thoroughly so you know where your money is going and that it is being used specifically to combat greenhouse gases.
Many utilities allow their customers to select where their electricity comes from, including renewable power. You can make the choice with your utility or install a solar power panel or windmill on your property. Installation of a power source will require more of an investment, but you also get to reap the benefits for years to come.
If you don’t want to fund someone else’s offset project, you can always invest in your own. These projects include tree plantings, providing clean drinking water, wind farms, geothermal power plants, and solar projects. You can invest on your own property or use property in another location.
Reduce, Reuse, Recycle
The best ways to reduce the carbon footprint of a construction project is to reduce the amount of fuels that are being consumed, lower the rate of electricity use, and defer as much debris away from the landfill as possible. If you want your project to not have a detrimental effect on the environment, then you can also invest in carbon offset projects, either your own or others’. These efforts will help ensure that your project enhances the earth’s environment as much as it does the built environment.
