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Why is embodied carbon a problem and is timber-framed housing the answer?

Embodied carbon in housing construction makes up a large proportion of emissions from the housing sector. Shifting to timber framed housing and eco-friendly materials has the potential to significantly reduce these emissions, potentially even having a net negative effect on CO2.

As many people are becoming aware, it’s crunch time for our climate. However, the housing sector still has a lot to do if we’re to meet our targets.

A recent report by the Committee on Climate Change (CCC) stated the UK’s housing emissions are ‘off-track’. Policies designed to reduce emissions have been withdrawn by current government – including the Zero Carbon Homes regulation and the Code for Sustainable Homes.

The decarbonisation of our built environment proves crucial if we are to keep warming to 2 degrees or below. Embodied carbon is an essential factor in those decarbonisation efforts; in some cases, becoming the dominant source of carbon impacts from buildings.

But this doesn’t mean reducing emissions from construction isn’t achievable.

What is embodied carbon?

Embodied energy is the amount of energy released in the extraction, refining, processing, transportation, fabrication, and disposal of a material or product – in this case a building or house.

It does not include the operational energy utilised once the building has been built. See diagram below:

Embodied Carbon

Embodied energy and carbon in buildings is quickly becoming a topic of rising importance in the housing sector as pressure mounts on individuals, governments, and contractors to improve the ecological credentials of housing construction.

Why is embodied carbon important?

Typically, it was assumed that the embodied energy from a building was small compared to the energy used in operating a building over its lifetime. However, this is not the case for the majority of standard constructions using traditional building methods.

In fact, embodied carbon emissions make up a large fraction of the emissions from the construction sector. These impacts are significant; in some cases amounting to 50% of the whole life-cycle emissions of a building, i.e. when operational carbon emissions are considered as well.

What quantity of UK housing emissions result from embodied carbon in buildings?

The average 3-bed semi-detached house built today, under current building regulations, produces unnecessary quantities of emissions from building materials, manufacturing processes and transportation.

For most buildings, the largest amount of emissions result from the production of materials that make up its foundation and structure; such as cement, concrete blocks and mortar. These materials are manufactured through a chemical process that produces a significant amount of CO2.

If we look at recent figures on the embodied emissions from building construction in the UK, we find that the average 3-bed semi built today produces around 10 tons of carbon during its construction. However, if we factor annual embodied emissions from domestic properties since 2001, the results show an average of 44 tons of CO2 equivalent per home (see here for an explanation of CO2 equivalent).

The graph below shows the total energy related (operational) and embodied CO2 emissions resulting from current building practices up to the year 2030. This is based on the assumption that the government target of 300,000 new homes each year is achieved.

It shows that taken together, both operational and embodied, the UK’s emissions from housing in 2030 will be slightly more than the annual territorial emissions of Mozambique. If current building practices continue, the emissions from the housing sector will be more than a country of 28 million people.

Embodied and operational emissions from the UK housing sector.

Such a situation is clearly unsustainable.

What can we do about embodied carbon in building construction?

This pathway, dictated by traditional building methods and stripped back building regulations, can be shifted. We at Sustainable Design Collective use alternative, natural, lightweight building materials which can work to mitigate the aforementioned emissions from standard construction methods.

The largest amount of emissions from construction arise from the materials that make up its foundations and structure. These are materials that can be substituted with eco-friendly and low emission alternatives.

The processes, behaviours, and resources that dominate our building sector, and are responsible for its significant embodied carbon emissions, can be avoided in a number of ways:

  1. Use of structural timber and natural building materials

  2. Lightweight constructions and foundations

  3. Low carbon concrete using fly ash or other alternatives

  4. Embodied carbon conscious architectural design

Furthermore, our use of timber and other plant-based materials in a building’s construction offer the double benefit of requiring less energy to produce as well as sequestering CO2 from the atmosphere. Looking at the graph below, comparing the emissions from a traditional concrete block construction and those of a timber framed and clad house, it is notable to see that a timber-framed house can have a negative effect on CO2 emissions; sequestering more than that which was embodied in its construction. In comparison, a traditional masonry build adds 12.25 tons of CO2 equivalent to the atmosphere.

Comparison of emissions from a traditional concrete block construction and a timber framed house.

Additionally, it is normally possible to reduce the embodied energy and carbon of a building or construction project by 10-20% without adding to the total building costs.

And so, not only can our timber frame kit homes be built on a tight budget in quick time and save you significant operational costs on energy in the long run; it also proves to embody significantly less carbon than the traditional masonry construction that dominates, so much so that it can actually sequester carbon and have a negative effect on emissions.

To find out how we can help you on your self-build journey to a highly sustainable and energy efficient building, get in touch with our team at enquiry.sdc@gmail.com.