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What makes a building sustainable?

Sustainable buildings are efficient to run, built from environmentally-friendly materials, have low embodied carbon, and are built using efficient production processes.

The World Green Building Council [1] defines a green building as “a building that, in its design, construction or operation, reduces or eliminates negative impacts, and can create positive impacts, on our climate and natural environment. Green buildings preserve precious natural resources and improve our quality of life.”

In this article we provide an overview of 8 key areas that make a building sustainable:

  • Airtightness
  • Good insulation
  • Sustainable materials
  • Embodied carbon
  • Energy efficiency
  • Sustainable production process
  • Renewable energy
  • Designed for human health


Airtightness refers to the process of creating a highly efficient envelope around or within a building to avoid unintended heat loss. A key part in ensuring airtightness is in assessing all connection points in the structure – such as windows, doorways, roofing, and electrical outlets – to ensure that all junctions have a robust, continuous seal. A well-designed airtight building will also eliminate the risk of mould and damp caused by condensation through the correct use of vapour control membranes. Triple glazed window units also ensure minimal heat loss.

Good insulation

High levels of insulation – also referred to as super insulation – are incredibly important in maintaining a robust building envelope (also outlined above) for energy efficiency and low running costs. The insulation should sit snuggly within the building’s structure to ensure that there are no air gaps.

Sustainable materials

Using materials that have low or no environmental impact – or even materials that perform carbon sinking to remove carbon from the atmosphere – are important in the design and construction of green buildings. Sustainable materials are often renewable, recycled, and ethically sourced. Timber-framed buildings are usually very sustainable as the trees that provide the timber have locked up carbon from the atmosphere over the years that they have grown. That said, timber that is imported from the other side of the world will have a large carbon footprint due to the miles travelled for delivery.

Embodied carbon

Embodied carbon refers to the carbon that’s locked up in something, such as a building. In the case of construction, embodied carbon would account for the carbon produced in all the materials and processes that go into a particular building. It’s a cradle-to-grave approach of assessing the entire supply chain that leads to the final building’s carbon count. A building constructed with a lot of carbon-heavy materials like concrete or steel would have high embodied carbon, whereas a building with low embodied carbon would usually be constructed using sustainable or renewable materials that lock up carbon, as well as via efficient and environmentally-friendly production processes.

Energy efficiency

Buildings should operate as efficiently as possible, meaning that their energy requirements (such as for heating, lighting and ventilation) should be as low as possible in order to reduce energy consumption and running costs.

Sustainable construction process

The process of building can sometimes impact the environment, but there are also highly sustainable construction processes that minimise environmental impact. The construction environment, e.g. a live construction site or a factory environment, can be assessed in terms of sustainability by looking at factors such as its own energy supplies, wastage levels, and the carbon miles required for deliveries. Modular and offsite construction methods are usually very efficient and sustainable thanks to the controls possible within a factory environment.

Renewable energy

Even a highly efficient building will have energy requirements. For a truly green building, renewable energy supplies – such as solar panels or heat source pumps – can be incorporated into the building. Alternatively, opt for a renewable energy supplier that guarantees clean, green energy.

Designed for human health

Something that is sometimes overlooked in sustainable building design is the human aspect. How do people feel in the buildings that they live and work in? Buildings are designed for humans to spend their time but too often they don’t support good human health. Healthy buildings are spaces that are well ventilated (sometimes using mechanical ventilation systems), have plenty of natural light, and are built without harmful toxins.

In summary

What makes a building green and sustainable?

There are different design and build considerations that make a building green and sustainable. From the materials used in the build-up and the construction processes, to the long-term efficiency of the building to ensure that low energy consumption.

Green Unit designs and builds highly efficient modular buildings using sustainable materials within a factory that’s powered by 100% renewable energy. Green Unit’s buildings are designed with high levels of insulation, are airtight, and incorporate high-performance triple glazing and sustainable materials throughout. Learn more about Green Unit’s design principles.

[1] World Green Building Council – About Green Building

Page last updated: 02/08/2021


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