Ecological Footprint of the Life Cycle of Buildings
7
3.1 Materials
The methodological map starts in the materials section, aimed at collecting all the
data and preliminary considerations necessary for a good approach to the BLC to be
applied in the model. For this purpose, the following subdivisions will be taken into
account.
(a) BLC stages and duration
In this section, the time limits of the system are defined by determining the moment
when the BLC begins and ends; that is, the scope is delimited in a longitudinal
direction. Likewise, the limits between the phases of the BLC will be marked, which
should establish a clear and strict separation, so that there is no duplication in the
quantification of the different impacts.
In this sense, the limits are clear in the case of new buildings, whose cycle begins
with the transformation of the land for construction and ends with the completion
of the demolition work. The starting point of the use and maintenance phase is
established after the completion of the construction work and the commissioning
of the building. This, being available to be occupied, use stage is the longest of its
life cycle, which is usually estimated between 40 and 100 years, and ends when the
building’s useful life.
Defining the moment when its useful life ends is not so simple. For example,
Adalberth [52] divides the BLC into three phases, subdivided in turn into the manufacture of the materials, their transport to the site, the construction of the building, the
occupation of the building with an intermediate period dedicated to the renovation,
to finish with the demolition and waste or recycling. This division by phases is quite
generalized, with slight variations from one study to another, and limits the use and
maintenance phase to energy consumption and renovation or remodelling work.
On the other hand, the CEN/TC 350 “Sustainability of construction works”, UNEEN 15804 [53], recommends the consideration of not three, but four stages in the
life cycle of buildings, separating construction from product manufacturing [26],
so that there would be a first phase of production, which includes: extraction of
raw materials, transport to factory and manufacturing; a second phase that defines
construction, transport and construction or installation processes on site; the third
phase that focuses on use including, maintenance, repair and replacement of products,
reforms, operational energy (heating, air conditioning, ventilation, hot water and
lighting) and operational water consumption; and the fourth and last phase aimed at
the end of life, deconstruction, transport, recycling or reuse, and disposal.
These models have in common that the life of the buildings ends with their demolition, but what would happen if instead of being demolished it was decided to rebuild?
In the event that the renovation route was chosen, the question arises as to whether
the post-rehabilitated building could be considered the same building to which its
useful life has been extended or, on the contrary, it would be a new building to which
its life cycle begins again.
In response to the questions raised, for the present work, it is assumed that the end
of life of the building occurs when it ceases to exist, i.e. after its demolition. From the
7
3.1 Materials
The methodological map starts in the materials section, aimed at collecting all the
data and preliminary considerations necessary for a good approach to the BLC to be
applied in the model. For this purpose, the following subdivisions will be taken into
account.
(a) BLC stages and duration
In this section, the time limits of the system are defined by determining the moment
when the BLC begins and ends; that is, the scope is delimited in a longitudinal
direction. Likewise, the limits between the phases of the BLC will be marked, which
should establish a clear and strict separation, so that there is no duplication in the
quantification of the different impacts.
In this sense, the limits are clear in the case of new buildings, whose cycle begins
with the transformation of the land for construction and ends with the completion
of the demolition work. The starting point of the use and maintenance phase is
established after the completion of the construction work and the commissioning
of the building. This, being available to be occupied, use stage is the longest of its
life cycle, which is usually estimated between 40 and 100 years, and ends when the
building’s useful life.
Defining the moment when its useful life ends is not so simple. For example,
Adalberth [52] divides the BLC into three phases, subdivided in turn into the manufacture of the materials, their transport to the site, the construction of the building, the
occupation of the building with an intermediate period dedicated to the renovation,
to finish with the demolition and waste or recycling. This division by phases is quite
generalized, with slight variations from one study to another, and limits the use and
maintenance phase to energy consumption and renovation or remodelling work.
On the other hand, the CEN/TC 350 “Sustainability of construction works”, UNEEN 15804 [53], recommends the consideration of not three, but four stages in the
life cycle of buildings, separating construction from product manufacturing [26],
so that there would be a first phase of production, which includes: extraction of
raw materials, transport to factory and manufacturing; a second phase that defines
construction, transport and construction or installation processes on site; the third
phase that focuses on use including, maintenance, repair and replacement of products,
reforms, operational energy (heating, air conditioning, ventilation, hot water and
lighting) and operational water consumption; and the fourth and last phase aimed at
the end of life, deconstruction, transport, recycling or reuse, and disposal.
These models have in common that the life of the buildings ends with their demolition, but what would happen if instead of being demolished it was decided to rebuild?
In the event that the renovation route was chosen, the question arises as to whether
the post-rehabilitated building could be considered the same building to which its
useful life has been extended or, on the contrary, it would be a new building to which
its life cycle begins again.
In response to the questions raised, for the present work, it is assumed that the end
of life of the building occurs when it ceases to exist, i.e. after its demolition. From the