Materials
Introduction
Building
materials form a large part of the overall environmental burden
of buildings:
- Raw materials
extraction damages ecosystems, consumes energy and degrades water
quality.
- Manufacturing
produces waste and pollution, including toxic waste.
- Many materials,
once installed, release toxic gases, affecting occupant health.
- Material
cleaning and maintenance often causes health risks and toxic waste.
- Eventual
disposal wastes recoverable resources, consumes landfill space
and often degrades groundwater.
However,
not all materials are equal. “Green materials” used in
building are carefully selected for low consumption of scarce raw
materials; low pollution in their production, delivery, use and
disposal; long life; low maintenance; and their suitability for
salvage or recycling.
Salvaging
Buildings and Products
One
of the most effective means of reducing new materials use is remodeling
or adaptive reuse of all or parts of existing buildings. When feasible,
this is often a better environmental option than demolition and
recycling, and helps preserve the history of the neighborhood. However,
the energy consumption of existing buildings should be carefully
considered when assessing the environmental merits of a project.
Major renovations are the best time to incorporate envelope upgrades
such as improving insulation, installing high-performance windows
and sealing air leakage.
In
some projects, valuable materials salvaged from demolition can be
used in the new design, avoiding the waste and pollution of new
production. If there are no salvageable materials available from
the site, they can be purchased directly from building demolition
sales, from salvage contractors and used materials dealers.
Environmental
Issues of Materials Choices
The
importance of materials choices is increasingly recognized in green
building design and construction, as well as in all types of purchasing.
“Green purchasing” received national attention in 1998
through Executive Order 13101, “Greening the Government Through
Waste Prevention, Recycling, and Federal Acquisition”, one
of a series of presidential orders bringing environmentally-responsible
practices to government. The order mandates that greener materials
will be preferred in all federal purchasing, and defines how to
perform life-cycle assessments to determine materials’ environmental
impacts.
Life-cycle
assessment of construction materials and assemblies is complex and
time-consuming. Fortunately there are now several programs that
rate products for their environmental performance and award “environmental
labels” to those with merit. These certification programs can
be of great aid to concerned designers and specifiers.
A
complete life-cycle assessment of a material includes consideration
of:
- resource
extraction
- manufacturing
and transportation
- installation
- operation
and maintenance
- salvage,
recycling and disposal
Recycled-Content
Products
Many
new and established construction products made with reprocessed
waste materials are now available. Products with recycled content
are “industry ready”, generally of equal or better quality,
and usually require no special handling. Some products, such as
outdoor lumber made with waste plastics and composite panels made
with mineral waste and plastic, are uniquely suited to some applications,
and have new uses that are still being explored. It is important
to obtain information from manufacturers verifying that the recycled
content listed for a product is actually material that would otherwise
have been discarded. Materials containing post-consumer waste or
recovered materials have the greatest recycling merit. In-plant
recycling, though it increases the efficiency of manufacturing,
does not have the same environmental benefits since it does not
close the consumer/manufacturer waste loop.
Healthy
Products
Many
building products contain chemicals that evaporate or “offgas”
for several days or weeks after installation. If large quantities
of these products are used inside a building, or products with particularly
strong emissions are used, they pollute the indoor air. Other products
readily trap dust and odors and release them over time. Building
materials can also support growth of molds and bacteria, particularly
if they become damp, potentially causing allergic reactions, respiratory
problems and persistent odors -symptoms of "sick-building syndrome".
Recently,
several lawsuits with large damage awards have been won by building
occupants suffering from health problems linked to chemicals off
gassed
from building materials, setting legal precedents across North America.
This is prompting many insurance companies to examine their policies
and their clients’ design and construction methods. Following
a rigorous selection procedure for construction materials, aimed
at minimizing occupant chemical exposure, is an effective way to
reduce health risks – and exposure to liability by building
developers, designers, contractors and operators.
The
most common “unhealthy materials” associated with health
problems in buildings are pesticides, engineered wood products and
furniture containing formaldehyde glue, new carpets, plastic and
rubber flooring, new paint, mineral and glass fiber insulation,
and glues and caulking used for interior construction. Most other
sick building problems are related to moisture problems, faulty
heating and air-conditioning equipment and extraordinary pollution
sources.
Healthier
materials have minimal chemical emissions, dust release and cleaning
or maintenance procedures requiring toxic chemicals. They help to
make healthy buildings and are better for the environment and the
safety of those who make and install them.
Healthy
building practice extends well beyond the building design; it requires
building occupants to select and use safe maintenance chemicals,
restrict smoking and other pollution sources, and reduce waste.
Local
Economy
A
healthy community has a healthy local economy; building construction
can aid by using local products and services where they are available.
A locally based economy can be more sustainably managed than one
based on imported materials and exported goods and services. Local
materials, such as stone, tile, brick and timber, also give a building
a quality of "place", or belonging in the region.
As
well, local materials substantially reduce the energy and environmental
impacts of transporting materials long distances.
Product
Leases
One
recent trend in building product selection is to lease the use of
a product from the manufacturer instead of purchasing it, similar
to the way furniture and office equipment are leased. The lease
method has been recently applied to carpet, office partition systems,
air-conditioning equipment and lighting. The principle of the lease
is that many organizations do not want to own and maintain these
items, they only want the services provided by them. If users can
pay a monthly fee and eliminate their role in maintenance, they
can save on capital costs and concentrate on their own business.
An
environmental lease is one in which the supplier provides the product
and the installation, arranges for maintenance as required, and
removes and recycles the product when its service life has ended.
A lease that holds the manufacturer responsible for recycling provides
an incentive for them to make recyclable products and operate recycling
facilities.
