The UN World Urbanization Prospects estimate that between 2018 and 2050, the share of the global population living in urban areas will increase from 55% to 68% adding 2.5 billion to the world’s urban population. This rapid urbanization across the world is expected to lead to a corresponding increase of (urban) infrastructure which will be accompanied by a respective increase in material and resource use.
The building and construction sector is one of the most chemical-intensive sectors downstream of the chemicals industry with the largest end-market for chemicals and generating the highest chemical revenue. Some of the chemicals in building materials and building products may have harmful impacts on human health and the environment along their life cycle and pose barriers to increased circularity of materials.
Under the GEF funded project funded “Global best practices on emerging chemical policy issues of concern under SAICM, UNEP is developing an infohub on chemicals of concern in building products and materials.
This infohub provides resources for designers and architects, sustainability practitioners, procurers and other actors in the construction value chain seeking to reduce the risks and impacts of chemicals in building materials, and supporting a shift towards more sustainable products and materials. Additionally it aims to mainstream knowledge in this area for policymakers, the private construction sector and civil society organisations.
Information on chemicals in building materials may not be made available throughout the value chain, and may not be well understood by those specifying, installing or involved with end-of-life treatment of building materials. It is important that key actors in the value chain are able to make informed decisions on material selection – therefore the infohub contains links to a range of assessment tools to identify chemical hazards. Similarly, when considering substitution of a chemical within a building product, support is often needed to ensure that the approach to this is sound and that replacement substances can be assessed are safer.
Chemical management processes that avoid “regrettable substitutions” are needed; in some cases, a replacement chemical in a product is no safer that the original one; or it may be from the same chemical family with similar properties and toxicity, or no safety assessment at all is in place. Taking an approach of assessing chemicals as a group contributes to more impactful reductions in toxicity, rather than addressing chemicals individually.
Taking a value-chain approach
The value chain for building products and materials can be complex and lack transparency in chemical information provision. From raw material extraction to manufacture, design to installation, and through the occupancy and end-of-life phases. For the end-user, whilst it may be assumed that materials and products sold and installed are safe, this is not always the case and crucial chemical information may not be passed along the value chain, or even present in the first instance. Workers along the supply chain may also be exposed to hazardous substances.
Chemical ingredient information, including hazard assessments, should be accessible at all stages of the building value chain to ensure that actors at all stages are able to make the most informed decisions to benefit health and the environment. A variety of resources are available in the hub that support this approach.
Information is becoming more widely available through both existing and newer initiatives. For example, Health Product Declarations and products certified against chemical safety criteria are available through a number of existing databases, alongside platforms (such as the German GISBAU system) that provide chemical safety information for workers.
Blueprints for Material Passports are also being seen – this approach would enable chemical and other data to be full tracked for a product across the value chain. Such data would be invaluable at a building product’s end of life to inform how a material should best be dismantled or disposed of, or the re-use potential. However, at the current time data is rarely available for a material that was manufactured or installed several years prior.
Better chemical information provision should also lead to an increased evidence base for improved policy making. In turn, this can contribute to further market transformation, and support markets for lower impact, and innovative alternative materials.
Chemicals of concern and their impact on material circularity
Use of certain chemicals in building products can be a major barrier to the more circular, resource-efficient model that is needed for the sector. This is seen in a number of ways:
- Presence of a toxic substance, for example in building plastics, may mean that the material cannot be recycled at the end of life, or may contaminate other installed materials that could be recycled or re-used
- Use of adhesives, where there is an option for a mechanical connection, or an alternative that allows for better dismantling of building components, can inhibit the process of material segregation and repurposing
- A lack of chemical data increases the likelihood that materials will be disposed of in a manner that causes adverse health or environmental effects.
A combination of improved building design for circularity, that considers the full value chain, and better chemical choices and management are key to ensuring that the useful lifetime of materials is maximised, and that end-of-life processes to manage construction and demolition (C&D) waste are effective. Construction-as-usual approaches that prioritise demolition over deconstruction and recycling do not only result in the adverse effects of embodied carbon emissions from continually produce new materials, but also can result in release of persistent chemicals to the environment.
Chemicals of concern in building products and materials: an overview
The below infographic shows some chemical hazards from common building materials (this list is non-exhaustive).