Algae, of which kelp and seaweed are two of the better known varieties, is a naturally occurring aquatic organism.

One of the world's fastest growing, it thrives when temperatures rise yet has a short lifespan, decaying quickly and forming dense algae foam on the water's surface that suffocates other life forms below.

Algae contains a bio-polymer called alginate that is used as a gum in bio-plastics.

Residual odour can be an issue as can colouring - dark brown or green are still the main options!

Algae converts CO2 and water into a usable material.

Can also be used in roofing tiles, packaging, ink, footwear.

Seaweed can be dried, ground up and heated to create a natural glue thanks to its Alginate, a natural polymer.

This binder can be mixed with paper waste for example to create sustainable furniture, amongst other things.

Found in: paints, countertops, carpets, upholstery, soaps (microbials). Health risk: Endocrine disruptors (EDCs) interfere with natural hormone production.

Antimicrobials are chemical agents added to products such as disinfectants to hinder the growth of microbes such as viruses, bacteria and mold. Human exposure through inhalation or the skin can cause health issues such as respiratory problems, while overuse can lead to bacterial resistance, causing excess growth of unhealthy bacteria on surfaces and in homes. Antibacterials are a sub-group of antimicrobials that also negatively impact indoor air quality and are to be avoided in the pursuit of a truly healthy indoor environment. Nota Bene: natural antioxidant materials are an exception to this rule, such as a cork yoga mat, for example.

Linked to lung cancer (a 'carcinogen') once inhaled or ingested, asbestos is found in construction and insulation materials, these are the main problem areas even today. It is heat-tolerant and provides heat insulation however the health risks far outweigh any such functional benefits. Watch out for it in old flooring tiles, textured paints, plasters and cement products. Removal by a specialist service provider only!

A natural building material or textile derived from plant or animal sources, including the sub-groups of bio-fabricated materials made from algae, mycelium and hemp. By providing healthy, sustainable alternatives to toxic or resource intensive materials, such bio-based materials provide an increasingly viable range of options for the low impact, sustainable buildings of the future.

An emerging field of sustainable design that aims to leverage distinct yet inter-connected fields such as bio-materials, biomimicry, the circular economy and sustainable materials in the design of new products for healthy buildings and wellbeing interiors.

A design strategy that mimics patterns, shapes, forms or processes found in nature to increase efficiency, solve complex problems and inform design decisions. The underlying concept is that nature has a lot of the answers if only we knew the right questions to ask. Examples include velcro, pro swimsuits and the shape of turbines.

Asbestos, mercury, lead, halogenated flame retardants (HFRs), per- and polyfluoroalkyl substances (PFAS), orthophthalates, Volatile Organic Compounds (VOCS)

antimicrobials; alkylphenols; asbestos compounds; bisphenol A (BPA); chlorinated polymers; chlorfluorocarbons (CFCs) and hydrofluorocarbons (HCFCs); monomeric, polymeric and organiphosphate halogenated flame retardants (HFRs); perfluorinated compounds (PFCs); phthalates; polychlorinated biphenyls (PCBs); short-chain and medium-chain chlorinated paraffins; toxic heavy metals; arsenic; cadmium; chromium; wood treatments containing creosote or pentachlorophenol

A historical turning point in our relationship to the built environment that took shape over the 17th and 18th Centuries, largely associated with the Frenchman Antoine Lavoisier. This steady revolution would unleash a barrage of chemicals into society and in particular our building materials that would in turn expose us to an ever greater number of potentially harmful substances in our indoor environments.

A design philosophy that focuses on closed loops, keeping materials and products at their highest value for as long as possible while encouraging recycling and reuse to avoid waste - i.e. minimizing all externalities that inevitably have a negative impact on the environment. This concept is part of the Circular Economy that promotes a transition to renewable energy and materials, the elimination of waste and pollution and a regeneration of nature.

Clay is a type of fine-grained earth - malleable when wet yet brittle when fired at high temperatures, it is one of our oldest building materials. 'Clay plaster' meanwhile is a finishing material for walls and surfaces that combines clay with natural minerals and pigments, in some cases with added hemp or rice for a textured finish. Why does this matter? It's a completely natural, non-toxic wall finish that contributes to creating a healthy indoor environment, be it an office, home or gym. 'Clay tiles' on the other hand are a decorative yet highly functional interior design solution formed from clay with an especially high iron content and porosity that has been fired in a kiln before being glazed or decorated. The aesthetic options are seemingly endless but again here, the key takeaway is just how healthy, natural and non-toxic a solution clay tiles are within the context of a healthy home or wellness interior design concept.

A cyclical system in which materials and/or resources are consumed and then recycled and reused, creating a sustainable 'closed loop' process in which practically no waste is generated. For example, using one specific type of recyclable material for each component in a piece of modular furniture so that the individual parts can each be easily recycled and 'kept in the loop' at their end of life.

Coffee industry waste is full of nitrogen for fertilizing plants but largely ends up in landfill.

If dried and treated, it can however be used as a filler in plastics and composites or as an exfoliant in skincare products.

A number of companies are now upcycling it into a bio-based sheet material to replace other composite boards such as MDF or OSB, even tiles, home decor pieces or veneers.

Cork is extracted from the bark of a type of a quercus tree, a sustainable harvesting process that can be repeated every nine years after an initial ~20 years of tree life.

Portugal is the largest manufacturer and producer of cork and the production process is highly regulated.

Most of these oak trees are Forest Stewardship Council (FSC) certified, and the bark stripping is done by hand, resulting in minimal environmental impacts.

To form most cork products, cork granules are collected, glued together with a binding agent, and sliced to their desired shape.

'Black' or 'expanded' cork meanwhile is from lower quality cork that is granulated, sifted and steamed at high temperatures and then moulded into shape using the naturally occurring resins.

A process where a material or product is recycled into a new material or product, often with a lower value and structural integrity. The goal of downcycling in real estate and interiors is to reduce materials waste sent to landfill and reuse available resources as far as possible. It may not be a perfect solution (see closed loop recycling) but it is still a viable option.

The total carbon footprint of a material during its entire lifespan, considering its extraction / production / growth, transportation, in-use phase and end-of-life disposal or re-purposing. Embodied carbon is typically measured in kg of CO2 per unit of the material in question. Taking this 360-degree approach of a material's lifespan provides comprehensive carbon data upon which to make an informed comparison with other materials, for example in the case of a building material to be deployed across multiple floors in a high-rise tower, that one decision would have a considerable impact on the project's environmental impact.

A late phase in the life cycle of any material or product that accounts for what happens at the end of its functional use. This ideally includes a process that diverts possible waste ending up in landfill - from which it will never escape - and can include processes such as recycling, composting, reuse or other disposal when applicable. Manufacturers, architects and designers need to collectively consider (take at least some responsibility for?) where such materials go when they no longer serve their purpose.

A chemical substance that has the ability to slow or inhibit the spread of fire, causing the product or material such as furniture upholstery to burn more slowly in case of contact with flames. Despite this purported benefit, fire retardants also contain toxicants that are known hormone disruptors, immune system and nervous system problems; they should therefore be excluded from a healthy indoor environment. Instead, for a healthy building interior we can leverage sprinkler systems, smoke detectors, strict no smoking policies and fabrics that are slow to burn.

A naturally occurring compound that is a harmful carcinogen (causes cancer) and often present in low-grade adhesives, insulation, fabrics, gas stoves, and pressed wood. This chemical has a strong odor and off-gasses at room temperature as a VOC. Long-term exposure poses a serious health risk. Consciously specifying formaldehyde-free insulation materials and adhesives should, in theory, be standard practice by now.

Forestry Stewardship Council certified wood indicates that the forest a timber was extracted from is sustainably managed. For the avoidance of doubt, many forests are unsustainably managed which in turn leads to deforestation, negative environmental impacts via a reduction in the total number oxygenating / CO2 reducing trees on the earth's surface. Think of Brazil's section of the Amazon rainforest for an urgent example of this issue. FSC certification takes into account these extraction strategies and is a globally recognized standard.

Granite is a naturally occurring rock that is mined and extracted in quarries for its durability, strength and weight-bearing characteristics. That extraction is admittedly an energy intensive process but once done, the material can be cut into slabs in a manufacturing facility before being polished, it will then quite literally last a lifetime. Often used in countertops, granite is an inherently heavy material meaning its transport emissions can be high, therefore local or regional sourcing is recommended where feasible. Using granite may mean avoiding a synthetic alternative that contains petrochemicals, and is an investment in long-term functionality matched by aesthetics.

A bio-based and nature-inspired Research & Development process focused on healthy, non-toxic new materials that facilitate, in a subsequent phase, the manufacturing and design of innovative circular economy products for forward-thinking developers, architects, interior designers and consumers. Green chemistry is the front line in developing eco-friendly, non-hazardous materials for use in society.

Chemicals that reduce and stop the spread of burning and fire. They contain toxins that can lead to hormone alterations, immunity and nervous system problems. In buildings and interiors they can be found in carpets, curtains, upholstery, mattresses and electrical devices.

Metallic elements that have a higher density than water and contain toxins - examples typically found in the indoor environment include arsenic, mercury and lead, which causes adverse health affects on building occupants.

Hemp is a variety of the Cannabis plant with the woody stalk used in innovative building materials such as Hempcrete, a combination of hemp, water and lime-based binder (min. 90% calcium content) that is suitable for walls, floor slabs or insulation.

Hempwood flooring tiles meanwhile combine hemp stalks with soy-based adhesive.

It is naturally fire-, mold- and pest-resistant, as well as having acoustic sound-absorbing and thermal insulation properties.

Lightweight yet strong and breathable, it comes from a rapidly renewable resource and requires no pesticides or fertilizers to grow.

Pure hemp can be used as an underlay flooring solution or wall insulation material. Hemp can help prevent deforestation if used in place of wood, it also grows much faster than oak, for example.

Lightweight yet strong and breathable, it comes from a rapidly renewable resource and requires no pesticides or fertilizers to grow.

Hemp can help prevent deforestation if used in place of wood, it also grows much faster than oak, for example.

Naturally occurring chemical compounds commonly used in water-resistant and stain-resistant products. HFCs can be inhaled, ingested or absorbed via skin contact, causing kidney and thyroid problems as well as potential pregnancy issues. As part of a healthy indoor environment strategy, a healthy materials plan would deliberately avoid all HFCs in carpets, furnishings, adhesives and sealants.

A product or material that contains relatively few allergy-producing substances. Examples of naturally hypoallergenic materials include silk, bamboo, and cotton, making all three especially useful for use in a child's bedroom for example.

Indoor air is affected by a range of factors such as off-gassing Volative Organic Compounds, dust and other particulate matter ( PM2.5 / PM10), Carbon Dioxide, Carbon Monoxide and, indirectly, humidity, and temperature. Wrap all of that up i the context of a building's ventilation, be that natural or mechnical, and if not properly monitored and maintained, poor indoor air quality can be a major factor in Sick Building Syndrome causing fatigue, drowsiness, headaches and scratchy eyes.

insulation materials; paints; adhesives; furniture and fabrics; composite wood products; flooring materials

Not some magical solution for removing waste from the earth's surface, as some might like to think but rather a giant garbage dump where society's waste is taken to be covered with dirt and earth. Note - this does not remove the waste from our natural ecosystem, merely hides it from view, leaving future generations with the problem of how to responsibly deal with the consequences. As green building consultants with an eye on sustainability, we look to use circular design and closed loop systems to keep building and interior materials out of landfill for as long as possible - ideally, indefinitely, but for this to happen at sufficient scale we will need the green chemistry sector to provide us with more innovations.

Lava rock is formed when volcanoes erupt and the lava comes in contact with cool air, causing the rock to solidify and harden. Once extracted, the rock is sawed and shaped into strips, slabs, or paving tiles depending on the desired end product. Once cut, the lava blocks are often then glazed and prepared for use. As one might expect, it's a thermally resistant and fire resistant material (!) with acoustic insulation properties. What's more, it is an almost infinite, naturally occurring resource. Keep a look out for it in wall tiles and design objects!

Lead is a hazardous chemical still found in sources such as batteries, old paint, insulation material, roofing tiles, pipes and flooring. Although lead paint was banned in the US in 1977, homes built before then may still be at risk. As it can both pollute soil and become airborne, if ingested or inhaled lead can accumulate in the blood and impair cognitive function, meaning it is especially problematic for vulnerable populations such as kids. Lead in wine glasses however is perfectly safe as it is stably trapped inside and does not release into the atmosphere.

Leather is, at least in one sense, a waste diversion strategy from the food industry.

The global meat industry uses the animal primarily for food consumption with the hides typically discarded and sent to landfill.

Ultimately, the issue may be less about whether humans are designed to eat animals or not (clearly, we were designed to have that option available to us) but whether the 'high quantity / low quality' operating model of the current Big Agriculture system is sustainable, desirable or even remotely good for the health of our planet (clearly, it is not).

Demand for meat consumption is therefore the main driver ('culprit') here, not the demand for leather upholstery as such. An important distinction when assessing leather's sustainability credentials.

Reduce global meat consumption, reduce the absurd quantities of grain and water needed to support all that livestock and, yes, reduce the amount of natural leather coming into circulation (the byproduct) replacing it with bio-based, or plant-based, sustainable materials.

First and foremost, it is the world's eating habits that need to change, in other words. There is plenty of protein to be had in less energy intensive foodstuffs.

Leather production sees hides being removed and tanned in a manufacturing process that converts the hide from effectively a decomposing animal byproduct into a material we call leather that can be used in furniture upholstery and at least given a practical purpose. Chemical-filled, synthetic fabrics containing petrochemicals and fossil fuels are the alternative in most cases - bad for our health and also bad for the planet's natural resources.

A 'vegetable tanning' process at least avoids the use of harmful heavy metals in the leather, for example via natural tannins such as tree bark or even from olives - this is the only viable route in the long-term, and it has to happen in tandem with a massive reduction in supply of the raw material from Big Agro.

A complex issue if ever there was one, with no obvious win-win solution, and yet one point is crystal clear: WE SHOULD ALL EAT LESS MEAT.

In many ways similar to the Embodied Carbon concept, albeit with a slightly wider scope to incorporate all environmental impacts of a product or material. The LCA process considers the environmental impact of extraction, manufacturing, processing, use and end-of-life phases. This is helpful for architects and designers as it provides essential background information when comparing products and/or materials prior to a procurement decision.

Marble is a naturally occurring stone formed when limestone is heated to extreme temperatures and put under pressure from the earth's crust. This process, known as 'crystallization', forms the marble we know. Impurities within the limestone such as clay or sand can form swirls and patterns, giving it those glorious aesthetic qualities. Extraction of marble is energy intensive, as is its transportation, however it is extremely durable and requires minimal upkeep once in place making it a long-term investment in a completely non-toxic, natural material that can, if so desired, introduce an additional layer of biophilic design. In Europe, marble hubs include northern Tuscany in Italy and Alicante in Spain.

A naturally occurring element that evaporates at room temperature into a toxic gas. If inhaled, it can cause problems to the nervous, immune and digestive systems -- with extreme health implications (even death), if not controlled. We find mercury in glass thermometers, light bulbs, some face creams and of course fish!

Wood products that have had their cellulose cells modified via a combination of heat treatment, vinegar, starches or linseed oil in order to permanently alter the properties of the timber, giving it tropical hardwood-like durability and enhanced performance. Often used for outdoor decking or saunas, for example. Not to be confused with composite woods that can off-gas formaldehyde.

Prone to instigating cataclysmic events every 10 million years or so. Nature is generally not to be messed with but we are 100% convinced she is already a fan of green and healthy buildings. Pay your respects at the altar of biophilia by using healthy materials in your buildings!

Mycelium, most simply explained as the root of a mushroom, is a natural organism that plays a key role in distributing water, nutrients and many argue 'information' or at least signals amongst plants underground.

As a bio-based MATERIAL however, it is 'grown' organically rather than chemically 'manufactured', making it especially sustainable.

It is typically combined with local agricultural waste and water in pre-made growing molds, where the mycelium takes shape over several days before being heated and dried to create a stable material that can be used to make acoustic panels, lampshades and more.

Key characteristics include being non-toxic, fire resistant, sound insulating and rapidly renewable. What's not to like?

Natural rubber originates from sap in a variety of different trees most commonly found in South America and Southeast Asia.

The latex sap is extracted and ammonia is added to stop the liquid from solidifying.

An acid is then added to extract the rubber from the liquid mixture, where the rubber is then pressed to remove excess water and hung to dry. The rubber is then processed, heated to high temperatures, purified and shaped. It may sound like a lot of work - and in a sense it is, with numerous opportunities for chemicals to find their way into the end product. Therein lies the problem.

Additionally, rubber harvesting can be land and labor intensive, creating jobs in poor communities on the one hand but coming with a concomitant risk of deforestation if not responsibly sourced.

We can only recommend natural rubber, not the synthetic varieties or even most recycled rubber as these contain toxic chemicals that are best avoided for health reasons, specifically indoor air quality.

Additionally, those same chemicals can ultimately leach into the soil when the product ends up in landfill at the end of its life, meaning it also negatively impacts the health of the planet.

A chemical group used in the production of plastic to make it more durable. They can cause health problems such as liver, lung, kidney, and reproductive system damage. Commonly found in vinyl flooring, wall coverings, floor coverings and food packaging.

Paper waste's cellulose residue can be repurposed into a sustainable construction board.

Paper waste can be used to form a variety of such materials, most commonly though a wood-like board or panel structure, with processes varying slightly depending on the desired end product.

At its end of life, having served its purpose, the paper waste material can be reused and repurposed again — going through another cycle and avoiding the creation of waste that ends up in landfill.

Naturally occurring substances that can be inhaled, ingested or absorbed through skin contact causing kidney and thyroid problems as well as potential pregnancy issues. Commonly found in stain resistant or water resistant carpeting and furniture.

Found in the chemical scents of some personal care products, as well as PVC pipes, plastic toys and vinyl flooring (one of the great evils of indoor environments), phthalates are hormone disruptors that can negatively impact male reproduction. Often mentioned in the same breath as Bisphenols, as in "Bisphenols & Phthalates".

A chemically resistant, highly durable and oh-so-versatile plastic resin that contains many toxic elements that can be harmful to humans, especially children. Commonly found in building elements such as window frames, pipes, roofing membranes and cable and wire insulation. Also known simply as 'vinyl'. Avoid it!

Rammed Earth is some combination of clay, sand, chalk, gravel and lime.

To create a rammed earth brick or block, the wet mixture is poured into a frame, where it is then left to dry and solidify into the desired shape.

To create rammed earth walls, a stabilizer is added before placing the mixture between framed to be compressed and dried into shape.

The key insight here is that considerable amounts of earth have to be excavated on building sites and often ends up in landfill rather than being converted into a building material directly onsite.

The finished material is durable, sound insulating, reduces waste and is low embodied carbon.

In some instances, it may be stabilized (reinforced) with the addition of up to 10% cement in the mix.

The portion of a product or material that has been recovered and diverted from a landfill. Most commonly, materials are diverted from the manufacturing process (known as pre-consumer recycled content), or after consumer use (known as post-consumer recycled content).

Although glass comes from natural sources - primarily sand, soda-ash, and limestone - it has an environmental impact due to the energy required for heating, melting, and transportation. It is still a fundamentally healthy and non-toxic material but, given this context, recycled and ‘end-consumer’ glass is more than worthy of our attention. The latter is glass that has been used, then collected, crushed and melted down to be placed into molds and cooled into its desired form. Think of the glass used in electronics equipment for example - a massive yet largely untapped resource. 'Foam glass' is a decorative yet highly functional, recycled building material known for its sound absorbing and insulation properties that is made from powdered glass and a chemical foaming agent that creates micro pockets of air in the new material, giving it a distinctive look and appealing in-use characteristics.

The production of plastic involves fossil fuels and chemicals, contributes greenhouse gases at various stages of its life cycle and represents a key driver of continued oil demand. Plastic has even been called 'the new coal' in terms of its impact on climate change.

Furthermore, plastic production facilities and the landfills much plastic ends up in at the end of its life are often located in low-income communities of colour.

Despite valiant ocean clean-up efforts, the great plastic garbage patch isn't going away any time soon nor is the issue of where all this material is meant to go once consumers have finished with it.

The problem, clearly, has to be tackled from both sides, replacing plastic production with sustainable, bio-based alternatives wherever possible to stop the relentless stream of new plastic coming into use, whilst also reusing, repurposing and recycling the vast reservoir of used plastic already in circulation to prevent it ending up in landfill or the oceans, on the other. That doesn't sound all that simple, let's be realistic.

End-consumer plastic such as yoghurt pots, chopping boards, window frames, gutters, and of course bottles can however be collected, sorted, and repurposed to form an increasingly wide array of solutions for buildings and interiors, from plastic panels, to facade elements, tiles and more, ideally using a single type of plastic.

When these upcycled products are made from one single type of plastic, rather than a blend of different plastics, they can be recycled back into the system again at their end of life - a concept known as Circular Design as it is a closed loop that does not spit out waste that ends up in landfill.

a list of worst in class chemicals and materials to be avoided in architecture and interiors - or ideally phased out of production completely. The term is closely associated with the Living Building Institute (LBC) whose definitive and highly rigorous Red List is now an industry reference point.

Manufacturers may try to stay ahead of legislation around toxic chemical content by replacing one harmful chemical covered by legislation with another equally as bad but not yet covered by the same legislation. The regulators are always playing catch-up in other words, so read your product ingredient labels carefully and keep a healthy dose of skepticism by your side at all times. See Precautionary Principle above.

Sea shells are a naturally occurring, durable, unique composite created by marine animals.

These shells are high in calcium carbonate, which is a key ingredient in many materials such as glass, steel, paper, and, most notably, concrete.

Excess seashell waste can be collected from the seafood industry or beaches to aid the formation of a variety of materials.

The shells are ground down, combined with a non-toxic binder, and often placed in molds to harden and create the desired end product.

If not repurposed for material use, shells would end up in the landfill, adding to the global waste problem.

Toxic chemicals that evaporate similarly to VOCs but are released at a slower rate; once released into the air however they too can pose serious health risks. Chemicals in this category include some types of phthalates, bisphenol A (BPA), and halogenated flame retardants (HFRs), which may be found in flooring, wall coverings, furniture, and electronics.

A chemical-based product added to fabrics to prevent stains; often contains carcinogens and can be harmful to human immune systems if inhaled. Healthy buildings avoid all stain-repellent materials, such as furniture fabrics in favour of natural alternatives.

Straw bale can be used in many contemporary building applications as it is a byproduct from grain production such as wheat, meaning there may be plenty of it around, however it is bulky to transport so proximity to the building site is a crucial factor to consider.

When the grains are harvested the stems can be collected and formed into bails instead of simply being discarded.

Hay bales can provide structure and insulation for a building, serve as infill between timber structures or some combination of the two.

Conditions need to be dry when working with straw to avoid the risk of moisture causing rot, equally a straw wall needs to be finished with a breathable material such as a clay and sand mix to allow it to exchange air with the outdoors.

At its end of life, the material is 100% biodegradable and can responsibly be left to decompose naturally.

Carbon compounds that can become gas at normal room temperature, aa process known as off-gassing and often recognizable as an odour. Commonly found in plastics, binders, composite woods, insulation, paints, coatings, adhesives, water resistance treatments and stain repellant treatments. Health risks include throat and eye irritation, headaches and nausea - symptoms of Sick Building Syndrome in other words.

Volcanic lava rock is formed when volcanoes erupt and the lava comes into contact with cool air, causing the rock to solidify and harden. Once extracted, the rock is sawed and shaped into strips, slabs, or paving tiles depending on the desired end product. As one might expect given its origins, it's a thermally resistant and fire resistant material (!) with additional acoustic insulation properties.

Found in: walls, wet areas, roofs. Health risk: Contains highly fluorinated polyurethane linked to asthma, throat/eye irritation, respiratory problems).

Wool is derived from the natural fibers that come from animal fleece, most commonly - but not exclusively - sheep.

After the animal has been sheared its fleece is then cleaned in hot water to strip the fat and dirt before being sorted, straightened and separated into fibers that are spun into yarn. The resulting wool can then be woven into any desired shape or function.

Common uses include building insulation (more common in Europe than the US) and flooring underlay thanks to the material's thermal and acoustic, sound-absorbing properties.