Embodied carbon refers to the greenhouse gas (GHG) emissions associated with the entire lifecycle of building materials, from their extraction and manufacture to their transportation, installation, maintenance, and eventual disposal. It's crucial to distinguish embodied carbon from operational carbon, which represents the emissions generated from a building's energy consumption during its use (e.g., heating, lighting, ventilation).

In the context of UK house building, residential retrofit, home renovation, and extension sectors, understanding and reducing embodied carbon is becoming increasingly vital. As new homes become more energy-efficient and the grid decarbonises, the proportion of a building's total lifecycle emissions accounted for by embodied carbon will become significantly larger.

Practical Examples in the UK Residential Sector:

• Material Selection: Choosing locally sourced timber for a new extension, as opposed to imported steel or concrete, can significantly reduce embodied carbon. This is due to lower transportation emissions and timber's ability to sequester carbon during its growth. Similarly, opting for recycled content in materials, such as recycled aggregate in concrete or recycled plastic insulation, lowers the embodied carbon footprint.

• Construction Methods: Prefabricated timber frame systems, often used in new build and extension projects, can have lower embodied carbon than traditional masonry construction. This is because they can be manufactured off-site in controlled environments, leading to less waste and more efficient material use.

• Renovation and Retrofit: When renovating an existing home, retaining and reusing existing structural elements (e.g., brickwork, joists) rather than demolishing and rebuilding new structures drastically reduces embodied carbon. For example, insulating existing solid walls with internal or external insulation systems (e.g., mineral wool, wood fibre) has a lower embodied carbon footprint than demolishing and rebuilding the wall.

• Waste Management: Efficient on-site waste management, including segregation and recycling of construction and demolition waste, directly contributes to reducing embodied carbon by diverting materials from landfill and promoting their reuse or recycling.

Relevance to UK Building Regulations:

While there isn't a direct Building Regulation specifically targeting embodied carbon emissions, the push for more sustainable construction practices aligns with the overarching goals of the Building Regulations 2010 and their Approved Documents. For instance:

• Approved Document L (Conservation of Fuel and Power): While primarily focused on operational carbon, the drive for highly insulated, air-tight buildings indirectly encourages the selection of materials with good thermal properties, which can sometimes correlate with lower embodied carbon (e.g., natural insulations).

• Future Homes Standard (coming into effect in 2025): This will significantly reduce operational carbon emissions for new homes. As a result, the relative importance of embodied carbon will increase, putting greater pressure on the industry to address it. Although not a direct regulation, the government's long-term environmental targets and commitment to net-zero emissions by 2050 (enshrined in law) are driving the industry towards considering whole-life carbon.