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What is Net Zero and Low Carbon? How do they differ?

Net zero and low carbon blog post cover

Within the development industry, there are so many classifications for sustainable building, which is great, but which one are you targeting, which should you be targeting, and which are you capable of targeting? Is the project going to be neutral-, low- or net-zero? What does this even mean?

What are we trying to do?

In the bigger picture, what are we addressing when trying to classify these buildings as low-, no- or neutral carbon? We’re essentially targeting energy use/emissions created from the manufacture, transport, construction and operation of buildings. Human activities such as transport, construction, manufacturing and the burning of fossil fuels create greenhouse gases which are day by day continuing to increase within our atmosphere. Greenhouse gases are mainly carbon dioxide (CO2), methane (CH4), nitrous oxide (N2O).

Net Zero
Image 1: Overview of US Greenhouse Gas Emissions, 2021 (Source: United States Environmental Protection Agency)

The building and construction industry consumes such a large portion of the worldwide emissions pie chart because you must consider the energy used to build the development, and then the year-on-year energy expenditure to run, heat, cool and maintain that development for its lifetime. Depending on your source, you’ll likely note around 40% of the world’s emissions are attributed to development, with 15% quoted for building the development (including material transport) and 25% for operating/running with electricity and heat production. Decisions made in the design stage of all buildings will have significant impacts on total energy usage and greenhouse gas production for many years to come. As buildings should be designed to last a minimum 100 years, that’s a huge swing in obtaining sustainable living practices.

net zero energy vs emissions
Image 2: Global share of buildings and construction final energy and emissions, 2018 (Source: International Energy Agency)

Note: the construction industry has been separated and further broken down in the light-dark blue portions

Now that we’ve discussed what we’re tackling, we can see which sustainability targets are helping us get there.

Some examples of low-energy target development include:

Net Zero Energy Building

The energy required for the building is created locally (on site), meaning no energy is being sourced from the grid. A zero-energy building likely needs to have the capability to produce more energy than it needs on site to allow for instances when conditions aren’t suitable for energy generation (e.g. low-wind for wind turbines or continued cloud cover for solar panels).

Net Zero Carbon Building

It may be likely that the site does not facilitate the means to create sufficient energy to power its own functions, and compensate for the times that it requires grid power. In this instance we can seek to apply Carbon Credits (or offset credits) to reduce the carbon impact by planting trees, or other carbon absorbing activity.

Buildings that balance out the emissions, potentially by utilising offsets (such as carbon credits or tree planting). Climate Active’s Climate Active Carbon Neutral Standard for Buildings outlines the following steps in obtaining carbon neutrality:

  1. Calculate emissions

  2. Reduce emissions

  3. Purchase offsets to compensate for remaining emissions

  4. Arrange validation (independent assessment)

  5. Publish a public carbon neutral claim

Net Zero

When ‘carbon’ is not specified in the title, we are looking beyond carbon dioxide and having a net zero impact on all greenhouse gases. The Paris Agreement is founded on Net Zero sustainable human inhabitation by 2050. Signed by nearly 200 countries, it is a monumental milestone in moving towards a more sustainable lifestyle. The following image depicts a roadmap to 2050:

roadmap to net-zero
Image 3: A roadmap to net zero by 2050 (Source: International Energy Agency)

As a sidenote, the IEA (International Energy Agency) is a great website with well displayed, easy to read/digest energy consumption information. See the link to the CO2 Emissions in 2022 report.

How should you start?

Whichever targets, self-imposed or legislative, for any project you undertake, the first step should always be to seek to reduce the emissions as much as possible before considering any form of renewable energy. This is so important because it:

  1. Reduces energy consumption from the grid when renewables aren’t efficient (cloudy days etc)

  2. Reduces the amount of renewable energy sources required to move towards the ‘zero’ targets

Continuing to design poor buildings and throwing a million solar panels on top is not the way forward. As discussed in previous blogs regarding sustainable architecture and passive house design, key items such as suitable orientation, window size/placement, cross-ventilation, ample insulation, and airtight building envelopes will drastically reduce energy consumption alone. The ability to then add renewable energy sources, such as solar panels, could mean that your project could then contribute to selling back to the grid and moving away from low energy into zero energy.

When it comes to our buildings, if we can make significant reductions in energy consumption, both during- and post-construction, we are taking greater strides towards sustainable life practices.

Which is best?

This one should be clear, but ‘no’ is better than ‘low’. Whilst low carbon is a great starting point, ‘net zero’ or ‘net zero carbon’ is a greater commitment. It is also measurable as it has a target; zero. Low could just mean ‘lower than yesterday’.

The further the measures can be challenged and adopted will increase the success rate of agreements such as the Paris Agreement. It is understood that two thirds of the buildings standing in 2050 likely haven’t been constructed yet. These new buildings will be held to increased energy efficiency standards (which should probably be harder to pass than they are).

What targets exist?

The following examples highlights some certifications that can be sought for low-, net-zero- and neutral- development:

Businesses and other sectors can seek carbon-neutral certification through similar organisations and websites.

What baby steps can you take?

If you cannot commit to full neutrality, revert to the underlying message from earlier in the piece. Aim to reduce your emissions as much as possible from the start.

On existing buildings, look at introducing films to poor window assemblies (confirm suitability with the original window supplier before placing films or other pieces), improve insulation where possible (e.g. ceilings) and consider adding external shading devices that keep the sun out in summer.

On renovations and new builds, undertake a detailed design assessment at the earliest stage possible. Orientation, room layouts and window locations can be no-cost decisions that severely reduce energy requirements. Consider exploring Passive House design methodologies. Speak to your architect, builder or consultant about ways to improve your efficiency. Please reach out to Shore Architects if you have any initial questions.

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