Material technology at crossroads

It is time to face the facts following COP27. The built environment continues to be one of the largest contributors to climate-damaging emissions, while exploiting non-renewable materials and energy sources, consuming areas of untouched green field, leaving behind plastic and demolition waste. Although political frameworks and policies are addressing carbon emissions, embodied carbon needs to be considered with urgency.

Embodied carbon will be regulated soon and the industry is only beginning to understand the complexity of material emissions. As these occur during sourcing, manufacturing, transportation and demolition, the whole lifecycle has to be assessed, as does our current throwaway culture. To date, buildings are mostly developed to last 40 to 60 years. The harmful cycle of demolition and rebuilding needs to be broken. With the climate protection goals of the Paris Agreement still in reach, the industry needs to show greater accountability, commitment and transparency.

As the world is rapidly approaching the 1.5 celsius warming limit, adverse weather events are increasingly noticeable. Climate adaptation needs to be looked at in addition to climate change.

Design strategies and material choices begin to reflect the new realities. Note the emergence of sponge cities, permeable surfaces, greening of existing stock, elevated buildings, glazing that endures flood waters and strong winds, regenerative materials that absorb clean water and the need to balance adjacent temperatures.

The construction industry will have to do better (by improving efficiency), differently (by improving consistency), with less material (by improving sufficiency). Carbon-calculating BIM-based software platforms such as EC3 and Oneclick LCA and increasingly sophisticated product data bases enable the selection of less harmful materials.

The most sustainable method of construction is to avoid or reduce any emission intensive materials. Some materials require zero or minimum energy input when sourced, transported, installed and dismantled. These materials include rammed earth (pictured), locally sourced stone or unglued wood.

Another way of reducing the carbon footprint is by embedding circularity principles and harvesting materials from buildings approaching the end of their lifecycles. This can be done by reusing materials in their original built-in form, colour, dimension and texture. Key examples of these are recycled bricks, stones, aggregates, sand, insulation and timber. We also need to consider modularity of construction, simple assembly and separability of components.

Traditional construction materials follow at distance. There is no magic wand yet. Research institutes and start-ups are developing possible solutions, but these solutions are too early stage to be considered commercially. Some have not left the lab, others have not yet obtained Environmental Product Declarations (EPD) or certifications. This top-level research needs to be acknowledged, challenged, specified and supported by architects and developers.

The following products and materials could be promising:

Mycelium: Root structure of fungi that returns to the cycle of growth and decay. Insulation as one possible application.

Cork: Tree bark as exterior cladding, flooring, interior material or insulation. Durable, strong, provides thermal and acoustic insulation, resistance to fire, water and rot. Renewable material, as oak trees replace its bark every nine years.

Fibr: Biomimetic and fibre composite materials developed by the Institute for Computational Design and Construction (ICD) and the Institute of Building Structures and Structural Design (ITKE). A departure from a pre-digital, material-intensive towards a digital construction method, locally made from just a few kilos of construction material.

Seratech: Award winning low-cost process that captures CO2 and produces a cement additive that can replace Portland cement in concrete by up to 40%. Developed by Imperial College London, Sam Draper, Barney Shanks.

Concretene: Graphene-enhanced concrete providing a viable CO2 reduction technology by Graphene Engineering Innovation Centre at the University of Manchester, Nationwide Engineering.

KBRIQ: A brick with a tenth of the carbon footprint of a traditional brick. Made from inert recycled input materials.

Degradable plastic: Wood-based degradable plastic with semi-structural strength. Unlike thermoplastic, the material can be broken down without causing harm to the environment, according to the KTH Royal Institute of Technology in Stockholm.

Wood fibre: Cement product which synergises calcined clay with lime filler. Futurecem is produced by Troltekt and can be used internally due to its acoustic properties and fire rating.

Rammed earth: Traditional rammed earth is made of a mix of clay-rich soil, water and a natural stabiliser. Especially in France, Britain and Germany, rammed earth buildings are enjoying a resurgence.

With the industry at crossroads, the life cycle of a building, processes of the industry and the social and environmental impact of every decision need to be scrutinised.

Solutions for sustainable materials and processes lie as much in past innovations as they do in future research. It takes courage, curiosity, knowledge and a moral obligation to those who are not among the perpetrators and suffer the most.