Materials overview
By choosing your building and home interior materials carefully, you can enhance durability, lower maintenance costs, and protect human health and the environment.
The materials used to build your home need to be strong and durable - but they also need to do more. The materials you use can affect your family’s health. Extraction and processing of materials can also harm waterways and ecosystems, and contribute to global warming.
The best materials for your building and home interior will be:
- non-toxic
- durable and strong enough to do the job required of them
- sourced sustainably
- reusable or recyclable.
Toxicity, emissions and air quality
Some materials used in home construction and home interiors contain chemicals that can be harmful to human health as well as the environment. For example:
Some materials contain volatile organic compounds (VOCs) - these are chemicals that become airborne (and therefore breathable) at room temperature. VOCs are present in some paints and finishes, carpets and textiles, engineered timbers such as MDF, glues, and many other materials used in our homes. VOCs have been linked to health problems, including asthma and skin conditions. Some chemicals that give off VOCs - for example, benzene, which is used in polyurethane - can be carcinogenic.
Timber treatments use toxic chemicals such as chrome and arsenic that may leach out when exposed to weather.
For many of the chemicals used in common building materials, there is little research about potential health impacts of constant exposure in the home.
Even if a material isn’t toxic within your home, toxic chemicals may be used during the manufacturing process. This can be hazardous for workers involved in the manufacturing process. It can also harm the environment.
Recycling, reuse and waste minimisation
An average three-bedroom home generates six tonnes of waste during its construction. You can save yourself landfill costs, and reduce harm to the environment, by:
choosing materials that can be reused or recycled at the end of their useful life, or choosing materials that are biodegradeable and can be disposed of safely
designing any new home or renovation to avoid unnecessary use of materials. Speak to your designer or builder about reducing waste when designing and ordering materials.
With some materials, even if there’s no recycling or reuse option available at the moment, those options may become available in future. Check with your supplier and with local council or landfill about what can be recycled or reused.
Sustainability
To say something is 'sustainable' essentially means that it meets present needs without compromising future needs. A building material is unsustainable if it is extracted and used in amounts that will cause it to run out in future. It is also unsustainable if its use causes environmental harm that will be difficult or impossible to repair.
How fast is the material being used?
Sustainability issues vary from one type of material to the next. Some materials used in building structures and interiors are renewable - for example, timber, wool, cotton and other raw materials used in textiles. Whether these materials are managed sustainably depends in part on how fast they’re being extracted.
Timber that is felled faster than it can regenerate is not sustainable. In many parts of the world, for example, tropical rainforests are being felled at an unsustainable rate.
Wider environmental impacts
A material is also unsustainable if its extraction or manufacture cause harm to people or the wider environment - for example:
- by polluting land, air or waterways
- by producing large amounts of waste
- by harming wildlife
- by being toxic or hazardous to processing workers, or
- by generating harmful emissions.
Durability and functionality
You won’t be doing the environment any favours if you choose products that wear out quickly or don’t do the job you need them to do. Products that aren’t durable or aren’t functional will have to be replaced, which means more raw materials will have to be extracted and more energy used. This costs you as well as the environment.
In some cases, decisions about building and interior materials will involve judgment calls between natural materials that may wear out more quickly and synthetic or modified materials that may last longer but also contain chemicals or produce emissions that can harm the environment and damage your health. In these cases, you’ll have to balance the benefits of a more durable material against the potential harm the material can do.
Sourcing
Some products have eco-labels or environmental certification schemes to show that they have been produced in a sustainable way and are not harmful to health. Look for labels and certification that are independent and have government backing - some eco-labels are little more than marketing schemes.
There are several independent timber certification schemes - see decking and outdoor furniture for more information about them. For other products, look for the independent, government-endorsed Environmental Choice New Zealand label.
Life-cycle analysis
'Life-cycle analysis' considers the total environmental impact of a material or product through every step of its life - from obtaining raw materials (for example, through mining or logging) all the way through manufacture, transporting it, using it in the home and disposal or recycling. A life-cycle analysis will also consider a wide range of environmental impacts including:
- depletion of resources
- chemical degradation
- energy and water use (including embodied energy)
- greenhouse emissions
- waste generation
- toxicity to people and the environment.
A life-cycle analysis can be applied to a whole house, to an individual element such as a wall, or to a service such as heating or lighting. It is considered the most comprehensive way of understanding a home’s full environmental impact.
Life-cycle analysis is a complex process. An international standard (ISO14040) has been agreed for life-cycle assessments defines what can be a complex process. New Zealand-based life-cycle analysis data is not yet widely available.
The life-cycle analysis approach is a way of thinking about the impact materials and design decisions can have when renovating or building, regardless of the size of your project. You can ask your designer to consider life-cycle analysis of materials as part of the design process.
Ecological footprinting
Ecological footprinting estimates the total environmental impact a person, population or country has on the environment. Ecological footprints are expressed in terms of the number of hectares of land it takes to sustain that person, population or country’s lifestyle. For example, research conducted for the Ministry for the Environment has estimated it takes 8.35 hectares of land to sustain an average New Zealander’s lifestyle (including food consumption, energy use and all other environmental impacts). The Ministry for the Environment website has more information about New Zealand’s ecological footprint, as well as a calculator allowing you to estimate your own ecological footprint.
Energy use
'Embodied energy' is the total amount of energy used over the life of a material - including the energy used to extract and process it, the energy used transporting to building sites, the energy used to build with it, and the energy used to dispose of it at the end of its useable life.
Calculating embodied energy is very difficult, and measurements of embodied energy will vary depending on who is doing the calculation and the assumptions used.
Furthermore, the amount of embodied energy in a material will change over time as manufacturing processes become more energy efficient and reuse/recycling becomes more common. A material’s embodied energy also varies depending on how far it has to be transported.
Balancing embodied energy and household energy use
Embodied energy is not the same as energy you need to run your home and carry out daily activities. A material that is high in embodied energy may be justified if it reduces overall energy consumption in your home, or is very durable. For example, concrete and insulation materials include substantial embodied energy but can significantly reduce the amount of energy a home uses for heating and cooling.
Reducing embodied energy use
You can generally reduce the amount of embodied energy you use by opting for building and interior materials that:
- last for a long time
- are made from recycled content
- can be recycled at the end of their useful life
- are made locally.
More information
From Smarter Homes
From ConsumerBuild
From other sites
Building regulations
The Department of Building and Housing website has information about weathertightness and building regulations.
Choosing materials
The NOW Home’s website has a page on choosing materials for construction.
Ecospecifier is an Australian website with guidelines about selection of healthy building products and materials.
The Environmental Choice New Zealand website has information about independent labeling of environmentally friendly materials such as carpets, paints and plasterboard.
The Building Biology and Ecology Institute’s website has publications on natural building materials.
The Waitakere City Council’s website has sustainable home guidelines, including a section on materials.
Life-cycle analysis
The Green Building Council of New Zealand website has information about life-cycle analysis of materials, as well as general information about sustainable building.
Toxicity
You can find out more information about toxicity of various materials commonly used in building and home interiors from the websites of the following organizations:
- National Occupational Safety and Health Advisory Committee
- Environmental Risk Management Authority
- Ministry of Health
- Occupational Safety and Health
- Ministry for the Environment
Embodied energy
The Institute of Professional Engineers New Zealand (IPENZ) website has a report The energy embodied in building materials (PDF, 53.6KB) including the embodied energy of a standard house shell.
Victoria University’s Centre for Building Performance and Research has information about embodied energy on its website (see ‘resources’).
Handling materials
The Occupational Safety and Health Service’s website has information about safe handling practices for treated timber and other materials.
Waste minimisation
The REBRI (Resource Efficiency in Building and Related Industries) and RONZ (recycling operators of NZ) websites have information on re-use and recycling options for building wastes.
The Waste Management Institute of NZ has information about waste exchanges.
Information about specific materials
The Good Wood Guide website is an online guide to environmentally friendly timber purchasing, with a listing of New Zealand timber suppliers.
The NZ Forest Owners’ Association’s website has details about sustainable forest management standards.
The Ministry of Agriculture and Forestry website has information on illegal logging.
The New Zealand Timber Preservation Council website has information about timber treatments, including quality assurance standards (WOODmark®) for processing plants.
The Rain Forest Alliance website has information about certification systems.
The Forest Stewardship Council website has information about FSC certification.
The Cement and Concrete Association website has extensive information to help with concrete choices.
The Plastics New Zealand website has information about plastic recycling and sustainability.
The National Association of Steel-Framed Housing website has contact details for further technical and training information for building with steel.
Technical information
You can buy copies of New Zealand Standards relating to building materials and construction systems from the Standards New Zealand website.
You can buy BRANZ technical bulletins relating to building materials and construction systems from the BRANZ website (click on the link to the online bookshop).
The New Zealand Institute of Chemistry website has technical information on the manufacture of a range of building materials.
