Ian Pritchett, co-founder and Growth & Innovation Director at Greencore Homes, has produced a module on natural and bio-based materials in sustainable construction for School of Specification. Here, he discusses the methodology behind carbon budgets and targets, and the importance of the ‘one planet living’ framework.
How do you categorise natural materials and what are their main advantages in terms of sustainable construction?
I have chosen to categorise natural materials as ones that are:
a. Local
b. Unprocessed or with minimal processing
c. Historically widely available
d. Secondary (or waste) products
e. Low-energy and low-carbon
They have many advantages – not least that vegetable or bio-based materials are ‘renewable, i.e. they can be grown and re-grown. Furthermore, natural materials absorb carbon during their growth and can sequester it into the building, and they are often multifunctional, i.e. they are good at more than one function.
Can you explain the methodology behind carbon budgets and targets?
At the Paris Climate Conference in 2015 (COP 21), most of the world governments agreed to legally binding targets to limit the rise in global temperature to less than two degrees (and preferably less than 1.5 degrees). In order to achieve this, the world has to limit its emissions of greenhouse gases. This is expressed in terms of budgets for carbon dioxide (or carbon dioxide equivalent). These budgets start at a global level and can be broken down country by country and local authority by local authority.
One Planet Living is the concept that everyone should live within their fair share of the planet’s resources. At the moment, Western Europe is consuming three times its fair share and North America is consuming five to six times its fair share”
How should we be building houses to minimise embodied carbon and carbon in use?
We take the following approach to building low-carbon houses:
a. Use bio-based materials to lock up (or sequester) carbon
b. Design using the Passivhaus thermal performance standard in order to minimise energy use
c. Use electric heating, hot water and cooking (no fossil fuels)
d. Use roof-mounted PVs to generate renewable electricity and batteries to store it
e. Employ post-occupancy evaluation to ensure houses are performing as designed
What is the ‘one planet living’ framework and why is it important?
One Planet Living is the concept that everyone should live within their fair share of the planet’s resources. At the moment, Western Europe is consuming three times its fair share and North America is consuming five to six times its fair share. The OPL framework allows us to design sustainable projects that focus on the following aspects:
a. Health and happiness
b. Equity and local economy
c. Culture and community
d. Land and nature
e. Sustainable water
f. Local and sustainable food g. Travel and transport
h. Materials and products
i. Zero waste
j. Zero carbon energy
Our goal is to create places and communities that can live sustainably in the future.
Are there any disadvantages associated with natural and bio-based materials?
Some people consider them old fashioned, or primitive, but they can create very sophisticated buildings. They are not always widely available. Some require higher levels of skill in design or construction. Some are less durable. Some can be more labour intensive.
Do these materials come with a cost premium? And if so, can anything be done to offset this? They can sometimes be more expensive. This can be offset/mitigated by self- sourcing/collecting and self-application/ installation i.e. being very hands on and doing it yourself.
Join Ian Pritchett to learn more about natural and bio-based in sustainable construction at:
www.schoolofspecification.co.uk/courses/bio-based-materials/
