Materials for improved health and wellbeing
Dr Clare Perkins and Emily Walport describe the factors that are driving the development of lower emission materials and reducing hazardous content in construction and design.
Over the past few years, the health and wellbeing agenda has developed rapidly, with wellbeing becoming increasingly important. Human wellbeing is a complex issue, covering a wide range of factors, from comfort and productivity through to nourishment and fitness. Developing an understanding of these factors within the built environment affects the materials used in design.
Traditionally, the impact of buildings on health is only considered once occupants become unwell, as in the case of sick building syndrome, where symptoms are shared by people spending time in certain buildings. However, from a materials perspective, the wellbeing of building occupants can be addressed more proactively by avoiding materials with hazardous substances. This leads to a more preventative approach, supporting and enhancing human health and wellbeing by starting with the right materials.
Buildings and health
People commonly spend up to 90% of their time indoors, where volatile organic compound (VOC) levels can be significantly worse than outdoors. Poor indoor air quality (IAQ) can severely impact an occupant’s health and wellbeing, causing drowsiness, headaches and skin irritation through to chronic respiratory problems. It can also negatively affect the productivity, commercial and operational performance of a building’s occupants. To further reduce exposure of building occupants and the environment to hazardous substances, a project design team may adopt a list of substances to be avoided on a project. Typical substances that are avoided and their alleged hazards include:
- Halogenated flame retardants (HFRs) – many are persistent, biaccumulative and toxic to the wider environment
- Phthalate plasticisers – reprotoxic
- Chlorinated plastics such as polyvinyl chloride (PVC) – also persistent, biaccumulative and toxic to the wider environment
- Certain heavy metals including cadmium, lead, mercury – toxic to humans enviroment
- Added formaldehyde – known carcinogen
- Volatile organic compounds (VOCs) – a mixture of volatile substances with various hazardous properties, some may be carcinogenic, mutagenic or reprotoxic, but most are classed as skin or respiratory irritants, respiratory or skin sensitisers.
These hazardous substances are added for many reasons, but broadly because of their useful technical properties, and consequently removing them is unlikely to be straightforward for a manufacturer. For example, HFRs are used to improve the reaction to fire of highly flammable polymer foam insulants. Some can be more easily replaced than others. In the case of HFRs, certain brominated compounds are less persistent, bioaccumulative and toxic than others. However, more of them must be added to have the same benefit as the widely used Hexabromocyclododecane (HBCD).
A materials blacklist approach can lead to unitended consequences, and an environmental preference approach to materials specification is preferable. For example, rather than ban PVC on a project, lower impact flooring should be considered, such as linoleum or rubber. This is not always possible and exceptions for demanding applications must be taken into account. The use of VOCs in liquid applied finishes, such as paints and coatings are very hard to avoid altogether. Even water-based paints under the Decorative Paints Directive can contain a certain level of VOCs. Manufacturers have done a great deal to reduce harm. In particular, the use of less hazardous plasticisers is increasing. Where it is possible to move away from PVC itself, alternative materials, such as timber, stone, other rubbers and linoleum have been used.
Other examples of where alternatives can be used include using copper, PEX or polypropylene to replace PVC in piping. Whilst most brass fittings and valves contain trace amounts of lead, eliminating lead from flux and solder will reduce it. Manufacturers have significantly reduced the amount of mercury used in fluorescent tube lights. Mercury is a known developmental toxicant, and is suspected of causing negative health effects. LEDs are more energy efficient and do not contain any mercury.
Lower hazard solvents are being developed and construction product manufacturers are seeking to reduce the solvent content of their products. This is particularly relevant for wet-based products such as adhesives, paints and sealants. LEDs are now far more energy efficient and do not contain mercury. Materials safety data sheets enable users to see what a product contains and to avoid those with higher hazard ingredients, such as those which are carcinogenic, mutagenic or toxic, or which are persistent, bioaccumulative and toxic. Awareness within the construction industry is putting pressure on producers to use lower hazard solvents, such as water and bio-based solvents, particularly esters, and to avoid higher hazard VOCS.
Some clients are committed to eliminating some of these hazardous substances from the building products they use. The redevelopment of the BBC Television Centre site in the London, UK is an example of a design, which included the development of a bespoke materials and indoor air quality (IAQ) strategy to improve the living enviroment for occupants. The problems with outdoor air quality in London are well documented, so the project team tried to mitigate the impact of air pollution as far as possible. The strategy was based on emission requirements for formaldehyde and total volatile organic compound (TVOC) using limits required in European legislation and for best practice third party certifications. Products specified by the architect, Allford Hall Monaghan Morris, were assessed for compliance with these materials strategies and alternative products were identified where necessary. Many low-emission alternative materials were sourced without any cost increase. The strategy requirements were written into the architect’s specifications. The work is ongoing to ensure the trade contractors select and install products accordingly.
Exposure to hazards
Two key aspects of materials that influence health and wellbeing are whether they emit hazardous substances and whether they contain anything that could be rubbed off in service or form a dust, for example plasticisers and stabilisers in plastics. While hazardous content in a building product may not affect users, their manufacture and disposal could cause hazards to workers and damage the environment. Emissions – the concentration of pollutant indoors depends on:
- outdoor pollution
- human activities
- emissions from building fabric and contents
- removal by ventilation
- absorption by surfaces
Control of emissions from construction products is achieved either by complying with national regulations or following voluntary schemes. The approach adopted in UK regulations is to ensure that ventilation levels are sufficient and consequently pollutant concentrations will be acceptable. In the UK Building Regulations (Approved Document F), the only guideline relevant to emissions from building products is that in performance-based ventilation design TVOC concentrations should be less than 300μg/m3. To Arup’s knowledge, this is not widely used as a design basis and has never been verified on completion.
A large proportion of harmful emissions encountered within a building can be attributed to construction materials and, therefore, by substituting lower emission products these sources can be reduced or removed. This can lead to significant improvements in the quality of indoor air. Studies have found that the median concentration of TVOCs in UK housing is 1100μg/m3. This is well above the limits set in building standards, such as BREEAM and LEED. These are emitted as gases from certain solids or liquids. The most common solvents found in construction by the Health and Safety Executive are:
- White spirit in paints, varnishes and cleaning products
- Xylene in paints, adhesives and pesticides
- 1-butanol in natural and synthetic resins, paints and lacquers.
The primary means of removing VOCs is through ventilation. However, source control can be applied to avoid materials that contain them. Some technologies also exist that can break down certain pollutants. The impact of material content on occupants is less clearly defined. Exposure to asbestos or lead in old paint is well understood, where, as the product ages, it emits particles that can be inhaled or picked up as dust from surfaces and ingested. Consequently, legislation now prevents the use of these in modern construction products. Other substances, such as semi-VOCs are used in plastics, resins, and synthetic fibres and can be emitted over time. Material content, perhaps, is more significant for the wider environment than for human health, where compounds may be persistent, bioaccumulative and toxic to wildlife. While the risks associated with such substances are controlled by legislation, they can be reduced by selecting products that do not contain them.
Other countries, however, have much more detailed requirements that relate to emissions from construction materials. These include Germany, France and Belgium with national regulations and Finland and Denmark with voluntary schemes. There is also a range of Ecolabels which address particular product groups and demonstrate low emissions and content requirements. Unfortunately, national schemes are barriers to trade as product manufacturers have to undertake different tests to demonstrate compliance in order to sell into different countries.
A system of classes of performance based on VOC emission for labelling of products is currently under discussion at European level. This will intended to be a way of reporting emission performance consistently and demonstrating compliance with material safety regulations.
The WELL Building Standard is driving the health and wellbeing agenda. It sets performance requirements for air, water, nourishment, light, fitness, comfort and mind. Some features are prerequisites for certification – others are enhancements leading to higher levels of certification. Improving occupant health and wellbeing is now a fundamental part of Building Standards such as BREEAM, LEED, WELL and HQM. All of these have credits relating to the reduction of harmful emissions and toxic substances emitted and found in construction products, among others.
On the BskyB Meeting Centre, a materials blacklist was proposed for this project late in the design. The Arup Materials team reviewed the materials already specified and highlighted the implications of using these.
Many materials were not affected, but others would have been prohibited. For some materials, substitutions would have impacted technical performance and/or increased project cost. This work provided the design team and the construction with a comprehensive picture of the implications of such a blacklist on the project and the extent of compliance possible.
The focus on health and wellbeing is driving the development of lower emission and hazardous content construction products. Materials producers are increasingly likely to receive requests for emissions and content testing of their products. Having the information available in the form needed would increase the likelihood of a product being selected. Research and practice is progressing from just considering what is contained and emitted from products to other aspects of materials, such as self-cleaning, acoustic and reflectance properties to support health and wellbeing.
Materials producers will play an important role in developing this agenda.
Further information on the Well Building Standard can be found at wellcertified.com
Emily Walport is a Graduate Engineer at Arup in the Advanced Technology and Research group. In addition to materials for health and wellness, she has worked on a wide variety of materials projects, from atmospheric corrosion studies through to research into innovative and developing material technologies.
Dr Clare Perkins is a Senior Scientist within Arup’s Materials Consulting team and has worked with clients around the world advising on the environmental impact of construction materials and sustainable design. In addition to health, wellbeing and materials, Clare specialises in fire protection, insulation, plastics, adhesives and coatings.