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49. Construction - Eco House - Carbon Reduction

Even more so than single-use plastic production and waste, our reduction of carbon should be our highest environmental priority for a lasting solution to climate change.

Household carbon emissions can be reduced:

  • During construction by considering the embodied carbon of materials; and
  • By using clean energy (usually solar, but occasionally wind on rural sites) to make the house carbon neutral or carbon positive.

Embodied Carbon

The embodied carbon of a material refers to the required carbon used in the manufacturing process of that material.

Estimates are that Portland cement (a key ingredient of concrete) is responsible for 5% of total global CO2 emissions. Replacing some cement with supplemental cementitious materials (SCMs), using higher quality aggregate, or reducing water content are all effective ways to help reduce the embodied energy.

Steel is also a major culprit, with a tonne of steel creating up to a tonne of greenhouse gas emissions. The best way to minimise this is to avoid the need for steel in the design process, but when unavoidable, to use recycled steel.

Carbon Neutral/Positive

Carbon neutral, also known as carbon-zero is when the carbon footprint of the house is non-existent. The clean energy created by the household is equal to the energy being used with no reliance on carbon-based mains electricity. On the carbon landscape, the carbon-neutral house is invisible.

Carbon positive is the ideal environmental situation where the house is using zero carbon, but it is contributing additional (positive) clean energy to the grid to be used by homes that are more reliant on carbon-based power. Carbon positivity is when the homeowner is not just negating their footprint but making a positive contribution to the environment.

If a household is carbon negative because it produces too little or no clean energy, it may still achieve carbon-neutrality by sourcing its mains electricity through a clean energy provider. However, this is the home owners responsibility and not part of the design stage.

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