Coming to Terms with Sustainability Terms: Net Zero vs Carbon Neutral vs Carbon Negative vs Carbon Positive – what do they mean exactly? 

Sustainability Terms

When it comes to sustainability terms and climate change, there are numerous ‘buzzwords’ and phrases used to describe organisations or buildings that are very energy efficient and use renewable energy sources to reduce or eliminate emissions. The most popular sustainability term is of course ‘Net Zero Emissions’ which has been widely popularised since the Paris Agreement in 2015 where many governments have formalised their commitment to achieve net zero emissions by 2050.

There are, however, many other terms used that are related to net zero but mean something else entirely different. This has led to much confusion to those not familiar with all the nuanced variations and concepts. In this article, we have compiled definitions and meanings of some of the most commonly used sustainability terms.

20 Sustainability Terms You Probably Didn’t Know The Meaning Of

(click on the links to jump to each section)

Key term Equivalent/Related Term 
Greenhouse Gases  
CO2 CO2-e
Net Zero / Net Zero Emissions  Carbon Neutral, Climate Neutral 
Energy Efficiency  Energy Efficiency Upgrades, Retrofits
Net Zero Carbon Emissions  Carbon Emissions, Net Zero Carbon 
Carbon Footprint  
Carbon Offsetting Carbon Credits
Low carbon  Energy Efficiency / A highly energy efficient building or portfolio
Zero Carbon  Carbon Zero, Net Zero Carbon 
Net Zero Energy Building  Net Zero Carbon Building (NZCB), Zero Energy Building (ZEB), Net Zero Building (NZB)
Zero Energy Building/Campus/Portfolio Net Zero Energy Building, Green Building
Net Zero GHG Emissions   –
Carbon Neutral  Net Zero Emissions 
Carbon Negative  Climate Positive 
Carbon Positive   –
Emissions Reduction Energy Conservation/Energy Conservation Measures
Electrification Degasification
Circular Economy
Built Environment


Each of the above terms describe a stage along the sustainability journey. The answer to the question – ‘out of all the sustainability concepts described below, which one should I focus my efforts on?’ – varies depending on where you are now and what your priorities are in the short, medium and long term.

What are Greenhouse Gases?

Greenhouse gases are gases present in the Earth’s atmosphere that trap heat and contribute to global warming. They include carbon dioxide, methane, nitrous oxide and other gases that are primarily produced by burning fossil fuels. These gases allow sunlight to pass through the atmosphere, but trap heat that is radiated back from the Earth’s surface, leading to warming of the planet and climate change.

From an organisation’s perspective, greenhouse gases are a significant contributor to their carbon footprint and are considered when setting emissions reduction goals. Reducing the emissions of these gases is essential for organisations to meet their sustainability targets and contribute to the global effort of mitigating climate change.

What is CO₂?

CO₂ stands for carbon dioxide, it’s a colorless, odorless gas that is present in the Earth’s atmosphere. It is made up of one carbon atom and two oxygen atoms, and is naturally present in the air in small amounts. CO₂ is a greenhouse gas, which means that it traps heat in the Earth’s atmosphere and contributes to global warming. It’s also one of the most important greenhouse gases that is produced by human activities, such as burning fossil fuels and deforestation.

What is CO₂-e?

CO₂-e stands for “carbon dioxide equivalent” and it’s a way of expressing the total amount of greenhouse gases produced by an activity or organisation in terms of the amount of CO₂ that would produce the same warming effect. It takes into account the warming effect of all greenhouse gases, not just CO₂, and allows for easier comparison of emissions across different organisations and activities.

What does Net Zero Emissions mean?

Net zero emissionsrefers to achieving an overall balance between greenhouse gas emissions produced and greenhouse gas emissions taken out of the atmosphere. Think of it like a set of scales: producing greenhouse gas emissions tips the scales, and we want to get those scales back into balance with no new greenhouse gas being added to the atmosphere in any given year. Eventually, we will probably need to tip them the other way to repair past harm.

Net zero describes the point in time where humans stop adding to the burden of climate-heating gases in the atmosphere.

The concept of net-zero emissions is akin to “climate neutrality.”

What is Energy Efficiency?

Energy Efficiency refers to the use of technology and design to reduce the amount of energy required to perform a task or function, resulting in cost savings and reduced greenhouse gas emissions for an organisation. It can be achieved through various measures such as using energy-efficient appliances, implementing building design strategies that reduce energy consumption, and using renewable energy sources.

It is considered as an important aspect of achieving sustainability, as it not only helps to lower the energy costs but also reduce the carbon footprint and the dependence on fossil fuels.

What are Carbon Emissions

Carbon emissions refer to the release of carbon dioxide and other carbon-containing compounds into the atmosphere. These emissions can come from various sources such as burning fossil fuels, deforestation, and industrial processes. These emissions contribute to climate change by trapping heat in the atmosphere and causing global warming.

What is Carbon Footprint?

A carbon footprint is the total amount of greenhouse gases produced by an activity or organization. It includes direct emissions from the organization’s own operations and indirect emissions from the activities of its suppliers and end-users. Measuring and understanding an organization’s carbon footprint is crucial for identifying areas for improvement and setting emissions reduction targets in line with global efforts to combat climate change. Reducing a carbon footprint can be achieved through a variety of measures such as energy efficiency, renewable energy, sustainable transportation, and green building practices.

What is Carbon Offseting?

Carbon offsetting is a way for individuals and organisations to reduce their greenhouse gas emissions by supporting projects that remove or reduce an equivalent amount of carbon dioxide from the atmosphere. These projects can include renewable energy, energy efficiency, reforestation, and more. The goal of carbon offsetting is to neutralise the impact of emissions by balancing them with an equivalent amount of carbon reduction or removal. It is often used as a way to achieve carbon neutral status.

What does Low Carbon mean?

Low carbon means an organisation/building is highly energy efficient and partially powered from on-site and/or off-site renewable energy sources.

Low carbon is often used to describe an economy, organisation or building whose power needs are derived not primarily from carbon-intensive sources such as fossil fuels but from ‘cleaner’ or less carbon-intensive energy sources, such as wind, solar and hydroelectric power. Other forms of clean energy include, for example, wave power and geothermal which are technically feasible but less common than wind or solar. Biofuels can play a role, but they may be viewed as fuel substitutes rather than a clean technology.

What does Net Zero Carbon mean?

On the other hand, an organisation/building that is highly energy efficient and fully powered from renewable energy sources, may be considered a ‘net zero carbon organisation/building’.

What does Zero Carbon mean?

Zero carbon – also known as Carbon Zero – means that zero carbon emissions are being produced from a product/service e.g. zero-carbon electricity could be provided by a 100% renewable energy supplier. This term describes an activity where no carbon was produced in the first place.

What does Net Zero Energy Building mean?

A Net zero-energy building (NZEB), a building with zero net energy consumption, meaning the total amount of energy used by the building on an annual basis is equal to the amount of renewable energy created on the site. Net Zero Energy Building is often interchangeable with Net Zero Carbon Building,  Zero Energy Building (ZEB) and Net Zero Building (NZB).

What does Zero Energy Campus / Portfolio / Community, mean?

An energy-efficient campus /portfolio/community where, on a source energy basis, the actual annual delivered energy is less than or equal to the on-site renewable exported energy.

Net Zero Carbon Emissions v Net Zero GHG emissions

Net Zero GHG emissions can be confused with net-zero carbon emissions, but when accurately used, net zero GHG emissions means all greenhouse gas emissions decline to zero, as opposed to just carbon dioxide. This is the same concept as net zero carbon emissions but conveys a net zero emissions target for CO2 and all non-CO2 gases.

Carbon Neutral / Carbon Neutrality

Carbon Neutral is a term used to describe the state of an entity (such as a company, service, product or event), where the carbon emissions caused by them have been balanced out by funding an equivalent amount of carbon savings elsewhere in the world. This is often achieved through funding climate-beneficial projects to make up for the greenhouse gases they emit. Such outside projects used as mitigation for greenhouse gas emissions are commonly called “offsets,” since they’re used to offset the emissions of the person or company who buys them.

Carbon Neutral vs Net Zero Emissions

As previously mentioned, Carbon Neutrality is akin to Net Zero Emissions. While carbon neutrality is considered a synonym for net zero carbon emissions, one key difference, however, is carbon neutrality can be achieved at the domestic level with offsets from other jurisdictions, while net zero emissions does not have the same connotation (though theoretically could be met via offsets).

What does Carbon Negative mean?

The reduction of an entity’s carbon footprint to less than neutral, so that the entity has a net effect of removing carbon dioxide from the atmosphere rather than adding it. This means removing CO₂ from the atmosphere, or sequestering more CO₂ than is emitted. This might include a bioenergy process with carbon capture and storage. Becoming carbon negative requires a company, sector or country to remove more CO2 from the atmosphere than it emits – see also Carbon Positive.

What does Climate Positive mean?

Carbon Negative and Climate Positive are interchangeable terms: Climate positive means that an activity goes beyond achieving net zero carbon emissions to actually create an environmental benefit by removing additional carbon dioxide from the atmosphere.

The benefit of climate positive initiatives is the spillover benefits they create for other people, companies, or localities that may not have the means or initiative to reduce their own carbon footprints. Ideally, carbon neutrality will become the eventual standard across the board, climate positive initiatives can, in the meantime, help pick up some of the slack.

What does Carbon Positive mean?

A ‘carbon positive’ building takes this a step further, producing more energy than it needs and feeding that energy back into the grid.
Carbon positive moves beyond carbon zero by making additional ‘positive’ or ‘net export’ contributions by producing more energy on site than the building requires and feeding it back to the grid. Carbon positive projects can make significant contributions by helping to address the carbon intensity and damaging impacts of past building practices and lifestyles, and by offsetting situations where carbon zero buildings are not possible.

Carbon positive is mainly a marketing term, and understandably confusing because it is sometimes how organisations describe ‘carbon negative’ and ‘climate positive’. Carbon Negative sounds bad even though it’s the most altruistic of all sustainability concepts and terms.

What is Emissions Reduction?

Emissions reduction refers to the deliberate actions taken by organisations or governments to decrease the amount of greenhouse gas emissions that are released into the atmosphere. This can be achieved through a variety of measures such as increasing energy efficiency, implementing renewable energy sources, adopting sustainable transportation and land use practices, and more.

Emissions reduction is a critical step in addressing climate change and promoting sustainability, as it helps to reduce the amount of greenhouse gases that contribute to global warming. Organisations can benefit from implementing emissions reduction strategies as it can lead to cost savings, improved energy security, and improved reputation among stakeholders. Also Read – Emissions Reduction vs Energy Conservation.

What are Energy Conservation Measures?

Energy Conservation Measures (ECMs) refer to the actions, strategies or technologies that organisations or individuals can take to reduce their energy consumption and costs. This can include activities such as turning off lights and appliances when not in use, using energy-efficient equipment, insulating buildings, and implementing smart building systems. By reducing the amount of energy used, ECMs can help organisations save money on energy costs and decrease their carbon footprint. Additionally, implementing ECMs can also lead to improved environmental performance and energy security, and it could also lead to increased efficiency and productivity.

Emissions Reduction vs ECMs

One important aspect to note is that while emissions reduction and energy conservation measures both aim to decrease the amount of energy consumed and reduce greenhouse gas emissions, they approach it from different angles. Emissions reduction focuses on reducing the amount of emissions released into the atmosphere, while energy conservation measures focus on reducing the amount of energy consumed in the first place. Both are important for achieving sustainability goals, and often work together to achieve a significant reduction in emissions and energy consumption.

What does Electrification mean?

Electrification refers to the process of using electricity as the primary energy source to power various systems and operations, instead of fossil fuels. It aims to reduce greenhouse gas emissions, improve energy efficiency and promote the use of renewable energy sources. Electrification is an important strategy for organisations and other places to achieve energy security, reduce dependence on fossil fuels, combat air pollution and climate change.

For organisations, common forms of electrification include electric vehicles, electric heating and cooling systems, and electric public transportation. They can also include the electrification of their manufacturing processes, data centers, and other operations.

For other places such as aquatic centers, electrification can include using electric pumps and filters for water treatment and circulation, electric heating systems for pools and spa, and electric vehicles for transportation and maintenance.

Overall, electrification can help in creating new economic opportunities by allowing for more distributed, cleaner and reliable energy systems. Also read- Degasification.

What does Degasification* mean?

Degasification refers to the process of replacing gas-powered systems with electricity-powered systems in order to achieve certain goals such as reducing emissions, increasing energy efficiency, or improving the safety and security of energy supplies. This can include replacing natural gas in buildings with electric heating and cooling systems, or replacing gasoline and diesel vehicles with electric or hydrogen fuel cell vehicles. The goal of degasification is to reduce dependence on fossil fuels, decrease greenhouse gas emissions, and increase the use of renewable energy sources. Additionally, it can help to improve energy security by reducing dependence on imported fossil fuels and increasing the use of domestic energy resources. Also read – Electrification.

*Please Note: Degasification in this context refers to gas substitution and not the scientific process of degasification.

What is Circular Economy?

The circular economy is an economic system in which resources are used, reused, and recycled in a closed loop to minimise waste and pollution, and to promote sustainable economic growth. The goal is to keep resources in use for as long as possible by designing out waste and pollution and recovering valuable materials and energy at the end of each service life.

In a circular economy, waste and pollution are designed out of the system, and products and materials are kept in use for as long as possible. This can be achieved through design and innovation, as well as through new business models and collaborations.

From an organisation’s perspective, implementing circular economy practices can help to reduce costs, increase resource efficiency, and decrease environmental impacts. It can also help organisations to become more innovative and competitive by developing new products, services, and business models.

What is Built Environment?

The built environment refers to the man-made structures and spaces that make up our cities and towns, including buildings, infrastructure and public spaces. From a sustainability perspective, the built environment plays a crucial role in reducing carbon emissions, conserving energy and natural resources, and promoting healthy and livable communities. It encompasses a wide range of initiatives such as green building design, energy efficiency, sustainable transportation, and smart city planning to create a more sustainable future. Strategies to improve the built environment can lead to a reduction of greenhouse gas emissions, energy savings, and improved air and water quality, which ultimately leads to a more sustainable and livable environment for all.

Which sustainability term/concept and target should you focus on?

Each of the above terms describe a stage along the sustainability journey. The answer to the question – ‘out of all the sustainability concepts described above, which one should I focus my efforts on?’ – varies depending on where you are now and what your priorities are in the short, medium and long term.

The short-term target may be to achieve ‘Low Carbon’ at first; and then the medium-term target may be to achieve Net Zero Energy or even Carbon Neutral Status – and then a longer-term strategy may be to work towards achieving Net Zero Emissions or Carbon Positive.

Governments have placed a significant emphasis on achieving Net Zero Emissions by 2050 – which is about achieving a balance of naturally occurring greenhouse gases vs GHG caused by human and industrial activity. But we can’t stop there – there needs to be movement ‘beyond net zero’ which ultimately means achieving carbon positive or climate positive outcomes across the board.

Whatever your sustainability target is based on – low carbon, net zero energy or net zero emissions – you can rely on 3E Group’s expertise and end-to-end solutions


If you’d like to discuss your organisation’s energy and sustainability needs and see how the Energy Efficiency & Sustainability Experts at 3E Group can assist you – click here to book a Net Zero Strategy Consultation today!

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