Page 136 - Materials Chemistry, Second Edition

132 6. Life cycle thinking for sustainable development in the building industry

6.3.2 Application of green building materials
The selection of materials for green buildings not only needs to consider the resource con-
sumption and environmental emissions in the process related to material production, but also
needs to consider the performance of materials in the specific building structure, both of
which are indispensable.
At present, a variety of green building materials have been developed globally, and these
have been widely used in the application process. Insulating glass is a new kind of green
building material invented in the United States. It not only has the characteristics of adequate
quality, low energy consumption, but also has the advantages of high intensity and high den-
sity. In practical green building applications, the use of insulating glass not only meets the
actual requirements of green building materials, but also plays a very good role in promoting
green city construction (Tang, 2016).
Domestic study found that, the annual average environmental impact on building win-
dows, recycled wood-plastic composite windows, and wood-plastic composite windows is
lower—about 23% lower than aluminum alloy windows. Using green materials to reduce
the heat transfer coefficient of building windows is an effective way to improve the environ-
mental protection performance of building windows in its whole life cycle (Liu and
Zhang, 2016).
The materials for door and window design in China have gradually emerged as new
energy-saving materials such as unplasticized polyvinyl chloride (UPVC) plastics and alumi-
num alloy heat-insulation; this not only improves the thermal insulation performance of
doors and windows, but also improves the sealing performance (Tang, 2014). For building
wall materials, with the same insulation performance, the total environmental impact of aer-
ated concrete blocks is the least, and that of solid clay bricks is the largest, which is more than
three times that of aerated concrete blocks (Liu and Zhang, 2016). Green wallboard can be
made by processing and compressing renewable raw materials. The use of green wallboard
not only reduces air pollution, but also reuses waste products, which greatly saves costs and
reduces pollution. Common green wallboard raw materials include straw, precast concrete,
etc. (Chen, 2018).
The life cycle evaluation method can scientifically and comprehensively evaluate the en-
vironmental impact of the whole life cycle of building materials, and determine which build-
ing materials can obtain the best environmental benefits under the premise of realizing the
same function. The environmental impact analysis of energy-saving building materials based
on the life cycle assessment method not only contributes to the development of new building
materials, but also provides a powerful method and data support for the selection of green
building materials.

6.4 Recycling of construction and demolition waste

Construction and demolition wastes (CDW) are the status of building materials after the
end life of buildings. CDW could be concrete, steel, wood products, asphalt shingles, and
bricks from building. Old buildings approaching the end of their lives are demolished, pro-
ducing millions of tons of concrete wastes, large quantities of construction products rejected