Using low-carbon or carbon-neutral insulation materials can substantially improve the energy efficiency and sustainability of buildings.
With heating and cooling in buildings accounting for about 40 per cent of global energy consumption, thermal insulation is critical to minimise heat flow and energy use, allowing for a lowering of related emissions. Low-carbon building designs – using sustainable materials – and energy retrofits work together with renewable energy systems to optimise building energy performance, and insulation plays an integral part in minimising energy consumption.
A report by Passive Buildings Canada and Builders for Climate Action, which examined the total emissions of 503 homes in Canada, found that 73 per cent of all the homes’ carbon emissions came from just three material categories. These were concrete at 33 per cent (for foundation walls, slabs and footings); insulation at 26.1 per cent (for foundations, walls and roofs); and exterior cladding at 13.4 per cent.
Reducing the carbon emissions associated with the insulation used in buildings can therefore substantially mitigate the embodied carbon of the building as well as operational emissions. Common insulation materials include organic foams such as expanded polystyrene and polyurethane foams and inorganic fibrous materials such as glass and mineral wool.
Conventionally manufactured organic foams are producedfrom fossil fuels, resulting in a high embodied carbon contribution to the building they are used in, while the release of fibres from mineral wool has raised health concerns.
A key method to mitigating the environmental and wellbeing issues around insulating materials is to find substitutes which use secondary, renewable, or recycled sources that comply with sustainability and ecological requirements.
Build ecologically, insulate with wood fiber wool
Natural fibres such as straw, hemp, wool, or flax can be used for their insulating properties, as they are completely compostable and far less polluting than conventional insulation. Certain types of cane, being water repellent, can also be used in insulation, as well as in roof cladding and earth bricks.
Growing awareness around the environmental and potential health concerns of traditional insulation materials has prompted interest in and the development of organic composites, textile fibres, and cellulose fibres.
Some examples of materials used to create insulating fibres include sheep wool, linen and cellulose derived from paper. Other innovative materials which have properties such as low density and high insulating capacity are aerogels, which are very low weight due to many microscopic air-filled pores, and vacuum-insulated panels, which contain a microporous core that is evacuated, encapsulated, and sealed in a thin gas- tight envelope.
A European Union report on the global insulation market found it was dominated by fossil-fuel derived materials that offer the best performance in terms of unit cost, with plastic foams to see the highest growth over the remainder of this decade. The report noted that glass (at 36 per cent) and stone wool (at 22 per cent) represented 58 per cent of the European market, followed by expanded polystyrene (27 per cent), polyurethane (8 per cent), and extruded polystyrene (6 per cent).
It added: “However, these insulation materials could have negative environmental impacts in the building’s decommissioning or due to a high level of embodied energy in the production phase.
“Although the thermal properties and performance of the traditional building insulation materials have significantly improved over the years, new emerging insulation solutions with similar or higher performances based on biotic renewable or biopolymers are expected to be adopted to a larger extent in the future.
“There are various innovation opportunities for improving a building envelope through developing advanced materials for renovation [such as] super-insulating materials [and] phase change materials.
“These opportunities will be driven by increasing insulation thickness requirements, as well as consumer demand/preferences, manufacturer choice, prices, and resources – new government initiatives and regulation can also be a driver for innovation.”
