Wood and carbon
[edit] Introduction
Net zero, carbon free, embodied carbon and offsetting carbon: each concept is a step in the right direction to tackle the climate emergency, but the terminology needs demystifying.
The article below explores each concept, how it is being implemented and what this means for the built environment.
[edit] Net zero
Since the UK government’s 2019 announcement to target net zero by 2050, the phrase has become the most well known term when it comes to reducing the impact of climate change.
Net zero is the balance between the emissions that are produced and the emissions that are removed from the atmosphere. Emissions are removed by offsetting carbon.
The net zero goal outlined below includes the ways to make it happen.
[edit] Carbon neutral = Offsetting carbon = Carbon free = Zero carbon
The journey to achieving net zero means knowing how to offset emissions. According to the Carbon Trust, carbon neutrality is achieved when the emissions produced are offset by carbon credits or natural carbon sinks.
Carbon credits are permits and work as part of a ‘cap and trade’ programme. Companies that pollute are given a limit, in credits, that they can pollute up to. Any unused credits can be sold to another company that is exceeding its limit. The aim is for companies that pollute to reduce their emissions and over time their limits for pollution are reduced.
Natural carbon sinks are ecosystems such as the ocean or forests. They absorb and store around half of the carbon dioxide (CO2) produced by human activity. However, these ecosystems are under threat due to increased emissions and deforestation.
Political awareness of the need to increase tree cover as a viable solution to reduce CO2 emissions has grown recently. This awareness also places responsibility on the timber industry and wider construction industry to ensure timber is sustainably sourced - particularly tropical timber.
To determine if a building or building product is carbon neutral, there is a standard to prove that it genuinely offsets carbon emissions and is not ‘greenwashing’. PAS 2060 can be used to prove carbon neutrality for buildings, product lines, manufacturing and more.
[edit] Carbon positive = Carbon negative
Confusingly, carbon positive and carbon negative initiatives both seek the same outcome: to remove more carbon from the world than they add. This is the next step after net zero.
[edit] Sequestered carbon = Carbon capture
To sequester carbon is to capture CO2 from the Earth’s atmosphere and store it. This can be done in a natural or manufactured way. Trees naturally absorb and capture CO2, acting as a natural store. Consequently, forests and woodland are considered to be the most efficient natural carbon sinks.
Carbon capture and storage (CCS) is a new technology to remove CO2 emissions from fossil fuel power stations and industrial processes that use or produce coal and gas. The CO2 can be captured in three different ways and in the UK, it is stored offshore.
Carbon can be captured or sequestered in buildings and building products made from wood.
[edit] Embodied carbon
Embodied carbon is defined by the UK Green Building Council as ‘the total greenhouse gas emissions generated to produce a built asset’. This means knowing how much CO2 is emitted from extraction, processing and manufacturing, transportation and assembly of every building product used. It extends to the lifecycle of each product so also considers end of life.
[edit] Operational carbon
Operational carbon is often measured alongside embodied carbon. It is the collective CO2 emissions produced in order for a building to run, from the energy and ventilation systems through to IT equipment.
[edit] Taking action
The UK built environment currently contributes around 40% of the country’s total carbon emissions. To reach the 2050 net zero goal, new homes need to be built to offset carbon.
Even with the most natural building materials, CO2 will be released before and during the construction process. By estimating embodied and operational carbon, designers can ensure this is offset through the materials, products and systems used.
[edit] Going beyond zero
The BaleHaus system uses prefabricated straw bale panels, ModCell and structural timber frame elements. This system works to Passivhaus principles and is made from locally available materials that are designed to be dismantled, re-used and recycled at the end of a typical 75+ year life.
It also has triple glazing, a biomass boiler and energy efficient electrical fittings and appliances. The careful design and specification of the BaleHaus reduces carbon emissions by almost 50% each year. It goes beyond zero carbon as it banks 22 tonnes of CO2, making it carbon positive (or negative) and a carbon capture.
[edit] From old to new
Older properties can be improved too. To reduce the built environment’s impact on the planet, the aim should be to reduce the number of new buildings, reuse as many buildings, materials and products as possible and recycle responsibly if there is no other option.
An example of this was the sensitive retrofit of a home on Walter’s Way, designed by architect Walter Segal. The timber-framed home had its windows replaced, the roof rebuilt and full insulation was installed including the roof. Solar PV panels were added alongside a new solar water heating system, passive ventilation and mechanical ventilation heat recovery, water-saving devices and low energy appliances and lighting.
Where possible, natural materials such as cellulose and wood fibre insulation were used. The result of the refurb was a reduction of 73% in carbon emissions.
[edit] Zero = Hero
The built environment has the tools and the knowledge to refurbish and create homes, offices, schools, hospitals and many other buildings that remove rather than contribute carbon emissions. It is a cultural and educational shift, but it is possible to make beautiful and practical buildings that have less of an impact on the planet.
[edit] Related articles on Designing Buildings
- A zero-carbon UK by 2050?
- Carbon footprint.
- Carbon negative.
- Carbon neutral.
- Deforestation.
- Low or zero carbon technologies.
- Nearly zero-energy building.
- Net zero carbon building.
- PAS 2060.
- Passivhaus.
- What we need for the journey to net-zero carbon emissions.
- Wood and custom build homes.
- Zero Bills Home.
- Zero carbon homes.
- Zero carbon non domestic buildings.
Featured articles and news
RTPI leader to become new CIOB Chief Executive Officer
Dr Victoria Hills MRTPI, FICE to take over after Caroline Gumble’s departure.
Social and affordable housing, a long term plan for delivery
The “Delivering a Decade of Renewal for Social and Affordable Housing” strategy sets out future path.
A change to adoptive architecture
Effects of global weather warming on architectural detailing, material choice and human interaction.
The proposed publicly owned and backed subsidiary of Homes England, to facilitate new homes.
How big is the problem and what can we do to mitigate the effects?
Overheating guidance and tools for building designers
A number of cool guides to help with the heat.
The UK's Modern Industrial Strategy: A 10 year plan
Previous consultation criticism, current key elements and general support with some persisting reservations.
Building Safety Regulator reforms
New roles, new staff and a new fast track service pave the way for a single construction regulator.
Architectural Technologist CPDs and Communications
CIAT CPD… and how you can do it!
Cooling centres and cool spaces
Managing extreme heat in cities by directing the public to places for heat stress relief and water sources.
Winter gardens: A brief history and warm variations
Extending the season with glass in different forms and terms.
Restoring Great Yarmouth's Winter Gardens
Transforming one of the least sustainable constructions imaginable.
Construction Skills Mission Board launch sector drive
Newly formed government and industry collaboration set strategy for recruiting an additional 100,000 construction workers a year.
New Architects Code comes into effect in September 2025
ARB Architects Code of Conduct and Practice available with ongoing consultation regarding guidance.
Welsh Skills Body (Medr) launches ambitious plan
The new skills body brings together funding and regulation of tertiary education and research for the devolved nation.
Paul Gandy FCIOB announced as next CIOB President
Former Tilbury Douglas CEO takes helm.
UK Infrastructure: A 10 Year Strategy. In brief with reactions
With the National Infrastructure and Service Transformation Authority (NISTA).