Page 132 - Materials Chemistry, Second Edition

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

assessment is a process of categorizing environmental impacts and characterization and
quantifying their potential environmental impacts based on inventory analysis. The resource
input, renew cycle, renew times, energy consumption, and material recycling rate per unit
area of each stage shall be displayed in detail to provide data support for subsequent envi-
ronmental impact assessment.
The environmental impact assessment of buildings mainly combines the recycling of
resources, and analyzes the input of raw resources, the amount of recycled resources, the
amount of waste materials and waste generated, and the final treatment volume at each stage.
There are usually three steps to evaluate the environmental impact burden of building ma-
terials: (1) classify buildings and building materials into types; (2) calculate the annual build-
ing material use; and (3) estimate environmental impacts associated with building materials
production (Huang et al., 2018a). Furthermore, resource life cycle reduction (LCR) and ma-
terial life cycle waste (LCW) evaluation are the final step of life cycle assessment for building
materials. The evaluation method is as follows: comparing the results of the building envi-
ronmental impact with the benchmark case, comprehensively analyzing the difference
between the evaluation case and the reference case in the materials input, waste generation
and other items, thereby calculating the corresponding reduction rate or increase rate (Yi and
De, 2005).
In our previous research (Huang et al., 2018a), we have tried to answer the following
research questions: (1) What kinds, how much, and in which building types have building
materials been used in recent years in China, and what are their development trends? (2) What
are the primary environmental impacts caused by producing these building materials?
(3) What is the spatial distribution of the key embodied environmental impacts? In addition
to the nationwide time series of 16years, we also explored the variation of material use and
associated environmental impact across different provinces of Mainland China. The research
method uses the three steps mentioned above: (1) classify buildings and building materials
into types; (2) calculate the annual building material use from 2000 to 2015; and (3) estimate
environmental impacts associated with building materials production.
Environmental impacts per kg of building material (Ek) are evaluated by applying the mid-
point parameters of the ReCiPe 2016 H method, which is a commonly used life cycle impact
assessment method with the most up to date environmental impact indicators and normal-
ization values (Huijbregts et al., 2016). Moreover, the ReCiPe method covers China with its
global scope impact mechanism.
In addition to the evaluation of environmental impact per kg of building material (Ek),
we also should analyze environmental impact considering the annual material use amount
(Ev). This is important because materials are used in different amounts for specific buildings,
and it is quite possible that materials with higher per-mass environmental burden are con-
sumed at lower rates and vice versa. Ev was calculated according to:

Ev t t
i
i,x ¼ MU Ek i,x
t
where Ev i,x is the total magnitude of environmental impact x formaterial i in year t from all
construction, summed for the eight building types j; Ek i,j,x is the per-kg environmental
t,k
impact x of material i in building type j; and MU i is the annual use of material i of year t
in province k.