A route to Net Zero in the Construction Supply Chain: Alternative Materials and Designs

Part 1

The construction sector is massive — around 6% of European countries’ GDP on average — and it is hugely damaging to our environment. Construction paves our daily lives — urbanisation in Europe is expected to reach 84% by 2050. And paradoxically, construction will end up being one of the main drivers of our environmental devastation, handling no less than 36% of the waste generated by the EU in 2018, making the sector the largest waste generator. We should fix this and we can!

Consumers and governments are putting increasing pressure on construction companies to limit their Co2 emissions and waste. For instance, in March 2020, the EU published “A new Circular Economy Action Plan” in which a number of new circular economic development strategies were presented, such as the obligation to introduce recycled content for certain construction products. But the private sector also has a big role to play in financing the Net Zero construction economy. The construction sector remains one of the least digitised and investors have started to acknowledge the large untapped opportunity. According to McKinsey, “venture-capital investment growth in construction tech has far outpaced the overall venture-capital space”. As an analyst at Amplifier, an early stage fund focused on the supply chain, I decided to investigate the technologies and business models that could make the construction sector more sustainable. To unpack the problem, let’s start with where the waste comes from.

About 850 million tonnes of construction and demolition waste (C&DW) is generated every year in Europe. A few different construction processes produce waste as a byproduct.

• Materials Budgeting and Procurement: When a construction company procures materials for a new site, it often over orders materials rather than under orders given it is considered an easier problem to handle. Once construction is over, the excess materials become waste. Often, they are suitable for reuse. If companies cannot reuse the materials, they may try to sell or recycle them.
• Building Processes: Excess, damaged or scrap building materials often end up as waste after construction is over. Materials such as wood, glass, metal and concrete, may come from construction, restoration or remodeling projects. If the materials are relatively intact, the construction company may be able to reuse, sell or recycle them instead of sending them to the landfill.
• Demolition: Many construction projects involve demolishing an existing structure. In this case, the pile of rubble the project creates will require some form of disposal. Demolition projects generally produce many of the same waste materials as new construction projects — after all, the demolished structure was a new construction once. Many of the waste materials created through demolition are recyclable — even reusable if they remain in acceptable condition. Materials too degraded or contaminated to reuse or recycle will likely go to a landfill for disposal.

Now, what can be done? In Part 1, I will run you through the latest sustainable materials and design solutions that I have found.

Sustainable Building Materials

A key to make construction more sustainable lies in the use of sustainable materials. What makes a material sustainable?

• It is renewable
• It is produced with low or lower environmental impact
• It contains a high recycled content
• It can be used over a long lifetime

The construction industry mostly uses three types of materials: steel, concrete, and brick. (And wood, stone and glass, but those are not considered as damaging for the environment).

Steel

The steel industry is the third-largest contributor to air pollution and one of the largest contributors to emissions of carbon dioxide

The iron and steel industry is responsible for about 4% of CO2 emissions in Europe, and 8% worldwide according to McKinsey, due to the massive use of coal. “Steel can be produced via two main processes: either using an integrated blast furnace (BF)/basic oxygen furnace (BOF) or an electric arc furnace (EAF). While integrated players produce steel from iron ore and need coal as a reductant, EAF producers use steel scrap or direct reduced iron (DRI) as their main raw material. As the predominant production method in Europe is the conventional, coal-dependent BF/BOF process, the need to assess alternative breakthrough technologies to reduce carbon dioxide emissions is high.”

What is steel and what is it used for? Steel is a metal alloy of iron and carbon (often derived from coal-heavy processes), with other materials used in its composition to make it stronger and more fracture-resistant than iron. Stainless steels resist corrosion and oxidation because of the additional chromium in their make-up. Because it is so strong compared to its weight and size, engineers use it for the structural framework of tall modern buildings and large industrial facilities.

Some interesting innovations have been made around steel production processes:

• According to the European Parliament (2020), replacing coal with hydrogen generated with renewable energy from solar panels and wind turbines for instance, would make it possible to largely decarbonise the industry. The way in which hydrogen can replace coal is well understood in principle, and the first pilot plants currently being set up will make it possible to further refine the processes. Hybrit and H2 Greenstee are two startups working on replacing fossil fuels with green hydrogen in the steel production process.
• Producing iron, the primary component of steel production, by electrolysis rather than conventional smelting could also prevent the emission of a billion tonnes of carbon dioxide into the atmosphere every year. Boston Metal, a MIT company, is developing direct electrolysis from iron ore, a process similar to that currently used for aluminum. While electrolysis has great potential to reduce carbon emissions, there are obstacles to overcome: the scarcity of adequate materials and the huge volume of electricity involved. These barriers lead to high prices that cannot compete with traditional methods of iron production unless governments impose a strict carbon tax.
• Steel can also be replaced in some cases by bamboo, that comes across as a natural replacement of steel for reinforcing concrete, that is gentler on the planet without compromising on durability. Because bamboo grows so quickly, it can easily be regenerated while simultaneously absorbing CO2. It is still at a very experimental stage but The Swiss Federal Institute of Technology Zurich is developing a bamboo composite called BambooTECH, which they believe can replace steel with its strength, high versatility, and durability.

Concrete

Concrete is one of the most used commodities in the world, second only to water, and among the most polluting.

The industry accounts for about 2.6 billion tonnes of carbon dioxide each year, or about 6% of global emissions.

What is concrete and what is it used for? Concrete is a composite material made of fine and coarse aggregate bound together by a liquid binder such as cement that hardens or cures over time. Concrete is hugely versatile and can be used in many applications including basic foundations, superstructures, wastewater treatment facilities, water treatment facilities, parking structures, floor construction, and exterior surfaces.

In future, concrete could be improved in a few different ways.

• Self-healing concrete is mostly defined as the ability of concrete to repair its cracks autogenously or autonomously. It is also called self-repairing concrete. Cracks in concrete are a common phenomenon due to its relatively low tensile strength. Durability of concrete is impaired by these cracks since they provide an easy path for the transportation of liquids and gases that potentially contain harmful substances. Self-healing concrete is a new type of concrete. It imitates the automatic healing of body wounds by the secretion of some kind of material. To create self-healing concrete, some special materials such as fibers or capsules, which contain some adhesive liquids, are dispensed into the concrete mix. When cracks happen, the fibers or capsules will break and the liquid contained in them will then heal the crack at once. Basilik Concrete is a startup developing self-healing concrete based on an autonomous repair system that is made possible by limestone-producing micro-organisms (bacteria). When these bacteria come into contact with oxygen and moisture, they are able to convert certain nutrients to calcium carbonate (limestone), allowing concrete to heal itself.
• Moreover, software is being developed to optimise the production of concrete in order to limit waste and emissions. Alcemy,a berlin-based startup, is building a predictive quality control AI which will enable production of low-carbon green concrete at scale. Converge’s ConcreteDNA module is developing AI and cloud-based technologies powered by wireless sensors to make the construction process more efficient and sustainable, providing real-time strength data with predictions to help users design more efficient and eco-friendly concrete mixes.

Brick

“Brick kilns are recognised as one of the largest stationary sources of black carbon, which along with iron and steel production, contribute 20% of total black carbon emissions.” — CCAC

What are bricks and what are they used for? Bricks are used as part of masonry construction as individual units to build structures that are usually bound together by some kind of mortar. The strongest and most commonly used masonry unit now is a concrete block, which may be reinforced with steel.

Here are some interesting alternatives to bricks:

• Production process with low environmental impact: Materrup produces bricks that are formulated from raw clay using local resources. Its range of clay-based bricks is available in the form of ready-to-use concrete as well as prefabricated products for a variety of applications.
• Mushroom bricks are made of mycelium, the fast growing fibrous roots that make up the vast majority of fungal life forms. It is known to be durable, waterproof, non-toxic, fire-resistant and biodegradable. These mushroom bricks have the potential to be stronger than concrete.

Designed by architect David Benjamin, the Living Tower, built primarily built from corn husks and fungus.

Sustainable Design

Better design is key to facilitating recycling and helping to make buildings and construction products easier to repair or more durable, thus saving precious resources. Circular design weighs resource use against the needs and functionality of a building and considers deconstruction scenarios.

Softwares

Predicting a building’s performance early in the design process gives teams the greatest opportunities to optimize a project and understand which decisions will have a significant impact on carbon footprint.

One Click LCA, for example, provides an automated life cycle assessment software that helps calculate and reduce the environmental impacts of building and infrastructure projects, products and portfolio, by allowing the comparison of design options to optimise carbon, cost and circularity throughout the design process.

Modular buildings

Modular or “prefabricated” buildings consist of producing standardized components of a structure, called modules, in an off-site factory, and then assembling them on-site. A few advantages:

• It is cheaper as there are fewer contractors and the majority of work is done offsite
• The construction is 30% to 50% faster than traditional housing
• It is made to be energy efficient
• It uses eco-friendly materials
• They are easy to deconstruct and recycle

Modular housing is likely to experience strong growth in the construction sector over the next few years. Indeed, Fortune Business Insights forecasts the global market to grow from $75 billion in 2021 to $114 billion by 2028, at a CAGR of 6.1% during the period. This growth would be driven mainly by increased infrastructure investment in fast-growing economies, and by the evolution of government initiatives to promote green infrastructure. McKinsey’s 2019 report sees modular construction as a serious disruptor in the construction sector, noting that the field is receiving increasing attention from investors, such as Polcom, which was acquired by Griffin and PIMCO funds for over $200 million.

There are many fascinating startups developing innovative modular solutions. Two German companies that I found particularly interesting are Containwerk, which transforms used sea freight containers into living spaces using cutting-edge technology; and Cabin One, which offers an end-to-end modular housing solution, from finding the land to delivery and installation.

Cabin One’s “Cabin Black” Model

I have spent Part 1 presenting sustainable solutions and companies that are addressing the inputs of the construction supply chain. However, if we really want to make the construction sector more sustainable, we need to tackle its whole value chain. By this, I mean tackling the outputs with reuse, repurposing and circular economy solutions. Hold tight for Part 2!