Globally, there is a serious shortage of accessible and sustainable housing. It’s estimated that there are more than a billion people who are without homes and living in poverty. Moreover, this figure is expected to double by 2030. The world population is constantly increasing; to meet housing demands and reduce carbon emissions, we must evolve and develop new sustainable building methods.

In 2015, the United Nations developed an initial agenda for sustainable development. Named the 2030 agenda, the shared blueprint established 17 sustainable development goals (SDGs) with each goal being tailored to a global sustainability issue.

The SDGs act as an urgent call for action for all countries in a global partnership. Sustainable, accessible housing falls under SDG 11, which aims to make cities and human settlements inclusive, safe, resilient, and sustainable. This includes exploring new sustainable construction materials. .

A study published in the Open Access journal Buildings investigates the resource availability and implications of scaling up the use of straw in domestic home construction in the UK.

Sustainable housing in the UK

Construction in the UK accounts for 25% of national greenhouse gas emissions. The majority of this is caused by the production of materials such as concrete, steel, aluminium, and fired clay products.

The UK is currently facing a serious housing crisis; there are 8.5 million people who are unable to access appropriate housing. Moreover, the UK government has set a target to build 1.5 million new homes; however, it’s unlikely they’ll meet this target. This is due to a shortage of long-term affordable homes caused by a range of factors, including supply shortages . Supply shortages are caused by delays due to strict planning permission as well as a rise in material costs.

Discovering and utilising new building materials such as straw, which are lower in cost and readily available in the UK, could contribute to solving this crisis as well as reducing carbon emissions. Straw has high potential to replace common building materials in the UK. Low-rise buildings, which are most favourable for straw-based construction, constitute 87% of total new floor space added over a year in the UK,

“Straw is an incredibly common resource here in the UK. It’s used as livestock bedding and feed or ploughed back into fields to improve the soil. It’s also used for energy generation, horticulture, and even mushroom cultivation.

However, despite being a renewable, low-carbon and historically important building material, very little straw is currently used in construction. In the UK, less than 20 new homes a year are built using it as a material.” – Charlotte Taylor, Lead author of the study.

The researchers from the University of Bath and Aberystwyth University analysed the feasibility and advantages of using straw predominantly as the primary wall material of contemporary buildings.

Can straw be used in sustainable domestic housing construction?

The researchers investigated how straw is currently being used and analysed using multiple scenarios for how they could redirect its supply into construction. They used scenario and sensitivity analysis to estimate the quantities of straw currently produced and used in different applications in the UK. This involved a multi-step process:

• Developing an integrated modelling framework to evaluate the technical availability, allocation potential, and feasibility of straw as a construction material;
• Quantifying total straw production and existing end uses within the UK agricultural system;
• Constructing a scenario analysis to evaluate how much straw could be available for use in construction, including sensitivity analysis and consideration of competing uses of straw in agriculture and bioenergy;
• Assessing how straw supply and construction demand varies across the UK over time to assess straw supply and construction demand to identify regional opportunities and logistical constraints.

Their analysis was limited to the construction of low-rise residential typologies such as end terrace, mid terrace, detached, semi-detached, bungalow, converted flat, and low-rise flats. This is due to straw bales having limited compressive strength, which could struggle to support taller structures, affecting the structural integrity of the house.

Redirecting straw use to meet sustainable housing demand

The researchers identified that the UK produced 9.9 tonnes of straw per year. The straw is used for a range of applications, including use for animal feed, pet bedding, biofuel and agriculture. They identified that if straw production for these industries was redirected into the construction industry it could be used to build over 300,000 homes a year. This would meet the UK government’s target as well as helping to cut UK carbon emissions.

However, they also noted that removal of all straw from fields may negatively impact soil health. Instead, diverting 60% for construction could help to achieve more of a balance, helping to meeting housing targets while leaving sufficient straw in the fields. Further research is needed to understand the long-term impacts on soil health and agricultural productivity.

The authors conclude that utilising straw as a building material could form a significant part of the UK’s future zero-emissions resource pool under appropriate institutional and policy conditions. Furthermore, they note that future studies should move beyond resource quantification and focus on economic viability, ecological impacts, labour requirements, and governance arrangements associated with scaling straw-based construction.

If you would like to read more about sustainable building materials, you can read about them across MDPI’s Open Access journals, Buildings, Materials and Sustainability.