Aircrete – a sustainable product

So what makes aircrete a sustainable building product?
Aircrete, or, more correctly, autoclaved aerated concrete, was conceived as a sustainable product nearly 100 years ago. While the understanding of what makes a “sustainable product” are evolving, H+H aircrete products make a compelling case.

Using waste materials

Pulverised Fuel Ash (PFA) accounts for up to 70% of the material used in the manufacture of H+H Aircrete in the UK. As a by-product of coal-fired power stations, most of this material would otherwise be sent for landfill; we have provided a way for this otherwise useless product to make a positive contribution.  

The creation of fresh PFA is reducing as we decommission our coal-fired power stations. However, a century of energy generation has produced huge stockpiles of PFA. 

At H+H we have modified our manufacturing processes to enable us to capitalise on this resource of stockpiled PFA and are confident in our ability to use these reserves for decades to come.

In addition, waste aircrete generated from the manufacturing process is recycled as an aggregate back into the process, allowing this product too, a new lease of life. 

Lightweight and thermally efficient

Aircrete is essentially concrete with air pockets. The characteristic lightweight structure, with air pockets captured within the blocks, is created through a chemical reaction during manufacturing. The catalyst for this process is aluminium and H+H uses recycled aluminium powder to achieve this reaction.

Embodied carbon

More recently the demand for sustainable building materials has focused on the carbon emissions associated with the manufacturing process.

Such a calculation needs to take into account every stage of the product’s lifecycle: from the sourcing of the constituent materials, through manufacture, transport, service life and then the eventual disposal or recycling.

This detailed Cradle to Grave Iifecycle analysis process will provide a figure for embodied carbon and the results are to be found in an Environmental Product Declaration (EPD).  For the UK aicrete industry, this information has been complied by the Aircrete Products Association.

This EPD considers every aspect of the lifecycle of an aircrete product and combines each phase to produce a single figure for the carbon dioxide equivalent (CO2e) emissions associated with its manufacture, use, and end of life disposal.

Making an objective judgement about which building material has the least environmental impact damaging is a very complex process. It is important not to be distracted by any single phase of the lifecycle. 

Materials that are very energy intensive in manufacturing may provide significant benefits in use (such as absorbing carbon dioxide as part of the aging process) or may have a negative impact during the disposal phase (such as releasing sequestered carbon).

A further complicating factor is the lifespan of the product. Embodied carbon is best evaluated over the useful life of the product. Is it better to use a product which uses little energy to manufacture but decays after 50 years, or one which uses more energy initially but supports a building lifespan of well over a century?

A century of inertia

At H+H we believe that the most sustainable buildings are those which last a very, very long time without needing significant maintenance along the way.

Once manufactured, aircrete won’t rot or burn, is resistant to sulfates and the effects of freeze/thaw cycles and cannot be attacked by pests such as termites or vermin. Should an aircrete building reach the end of is useful life the aircrete blocks can be crushed and used as an inert aggregate for a variety of construction processes.

Just as importantly, it is estimated that walls built of aircrete will last for over 100 years – certainly for generations.

Reducing the travel miles

Not surprisingly, H+H is also a supporter of local sourcing. Reducing the miles that any product needs to travel from its source to its end use should always be part of the environmental calculation. With factories in the North and South of England, we provide local supplies direct to site.

And we extend our environmental focus to our product packaging, with fully recyclable wrapping and a pallet recycling service operated, we aim to support a zero waste to landfill ambition for our customers.