CEST2009 – Chania, Crete, Greece
Ref no: 431/31-12-08
DEVELOPMENT OF A WEB BASED APPLICATION FOR THE OPTIMAL
DEMOLITION WASTE MANAGEMENT IN THE REGION OF CENTRAL
MACEDONIA
N. MOUSSIOPOULOS1, G. BANIAS1, D. AIDONIS2, D. ANASTASELOS1,
CH. ACHILLAS1, E. IAKOVOU2 AND A. PAPADOPOULOS1
1
Laboratory of Heat Transfer and Environmental Engineering, Department of Mechanical
Engineering, Aristotle University of Thessaloniki, Box 483, 54124 Thessaloniki, Greece
2
Laboratory of Quantitative Analysis, Logistics and Supply Chain Management,
Department of Mechanical Engineering, Aristotle University of Thessaloniki, 54124
Thessaloniki, Greece
e-mail: gbanias@aix.meng.auth.gr
EXTENDED ABSTRACT
Construction and demolition (C&D) wastes constitute nowadays the largest by quantity
fraction of solid wastes in Greece, as well as in other countries, especially in urban areas.
In addition, it is widely accepted that the particular waste stream contain dangerous
materials for the environment, such as insulating materials, plastic frames of doors and
windows etc. Uncontrolled dispose of C&D waste has as a consequence long-term
pollution costs, resource overuse and wasted energy. Notwithstanding the massive
volume of rejected building materials, as well as their relevant economic value and
burden to the natural environment, none integrated management policy for such materials
at the end of their useful life has been implemented yet in Greece.
Within the framework of the DEWAM project (Information System for Demolition Waste
Management) a web portal with information on C&D waste management is being
developed, together with the construction of a web-based Decision Support System
(DSS) application (“DeconRCM”), aiming to identify the optimal degree of buildings’
deconstruction or demolition, as well as maximum recovery of materials. Economical and
environmental criteria are taken simultaneously into account.
This paper addresses both technical and functional structure of the developed web portal
and the “DeconRCM” application. In brief, the paper outlines the main alternatives for the
optimal treatment of end-of-life building materials and presents the outcome of the
DEWAM project. In a nutshell, the web-based DSS application has the ability to provide
an accurate estimation of the generated quantities of twenty one different waste streams
produced construction industry processes of four building types (single family residential,
multi family residential, office and industrial), based on the typical construction practice in
Greece. With the use of mixed integer linear mathematical programming, the
“DeconRCM” application provides the user with the optimal management of each
generated C&D waste stream regarding both economic and environmental criteria. The
DSS tool’s capabilities are presented through a case study of a residential building in
Kalamaria.
Key words: Environmental information; indicators; sustainable development
1. INTRODUCTION
Construction industry is probably one of most significant fields on a global scale, with
respect to its economic, technological, and environmental impact. In the European Union
(EU-25), there are about 2.3 million construction companies, contributing 9.8% to the
overall GDP and employing around 12 million people, which account for 7.1% of the total
European workforce [1]. The rapid growth of the construction industry worldwide has
resulted to an enormous increase of the produced construction and demolition (C&D)
waste. C&D waste often contains bulky, heavy materials such as concrete, bricks,
gypsum, metals, glass, plastics, etc. In quantitative terms, the stream of C&D waste
constitutes a significant proportion of all wastes within the EU-25, since the total amount
generated is estimated to be roughly 180 million tones per year (excluding earth and
excavated road material) [1]. Despite the significance of this particular stream of waste, in
many countries there is a lack of accurate information on the field, as C&D waste is not
studied separately from the rest municipal solid waste (MSW) stream.
Up to recently, the most common practice in the field of C&D waste management was to
discard all waste materials and debris to landfills, frequently in the same landfills that
were used for the disposal of MSW. This practice cannot in any case be considered as a
proper management practice for end-of-life building materials. Even worse, there are
many cases reported where C&D waste ended up in uncontrolled open dumps, not taking
into account the severe burden imposed upon the environment. The environmental and
health impacts of such disposal and treatment methods for C&D waste include apart from
the aesthetic degradation, soil and water contamination, air pollution as a result of fires,
reduced property values, destruction of open spaces and landscape blight. In addition,
heaps of C&D waste may include asbestos waste, which poses a significant health risk,
especially in building sites which are transformed into playgrounds and residential
buildings.
The aforementioned practice has expanded to all the stages of building materials’
lifecycle; production, construction, use, but most significantly their end of life
management (e.g. demolition of buildings). Furthermore, this practice is closely related to
the popularity of the fact that the majority of existing buildings in modern cities have not
been designed in a way that building materials to be reused or recycled at the end of their
useful life. Notwithstanding the fact that the current situation in the field does not seem
very optimistic, the underlying dynamics appear to be changing. There are already many
countries that have recognised the problem and the highest importance of
environmentally sound C&D waste management. However, changes still occur in a rather
slow pace.
2. INFORMATION SYSTEM FOR DEMOLITION WASTE MANAGEMENT
Following the modern trends in the field of C&D waste management, a research team has
been formed in the framework of the research project “Information System for Demolition
Waste Management” (DEWAM project), which is funded by the General Secretariat for
Research and Technology of the Hellenic Ministry of Development. The DEWAM
project’s principle objective is to minimise the waste of building materials that are
discarded to landfills without any prior processing and to increase their recycling and
reuse rates. Through a web portal, the end-user will be capable to be informed as
regards; (a) information on building materials, (b) guidelines for the optimisation of the
demolition procedure and the separation of building materials, (c) recyclable and reusable
building materials, (d) 3rd party logistics companies for the transport and storage of C&D
waste, (e) demolition waste management costs.
Moreover, in the context of the DEWAM research project, a web-based Decision Support
System (DSS) application, namely DeconRCM, will be accessible to the end user through
the developed portal. The basic scope of the DeconRCM is to provide the end user with
an easy-to-use tool for the optimisation of the C&D waste management in the Region of
Central Macedonia, Greece. In the material to follow, DeconRCM’s functional
specifications are presented, together with a description of its technical aspects. The
application’s capabilities are presented through a real-world case study of a residential
building in Kalamaria.
3. DEVELOPMENT OF “DeconRCM” DECISION SUPPORT SYSTEM APPLICATION
DeconRCM addresses the needs of specific target groups such as, contractors,
engineers and public stakeholders. In brief, DeconRCM provides an accurate estimation
of the generated quantities of 21 different waste streams produced by two main
processes (renovation and demolition - R&D) of four building types (residential, office,
commercial and industrial), based on the typical construction practice in Greece.
Furthermore, DeconRCM provides the user with the optimal management of each
generated R&D waste stream regarding both economic and environmental criteria. This is
materialised with the utilisation of linear mathematical programming, while incorporating
in a Google map all end-of-life processing facilities (including landfills) for the different
waste streams located within the Region of Central Macedonia. More specifically,
DeconRCM is a plug-in application in the content of the DEWAM project’s web portal.
The latter is based on an open source Content Management System (CMS), namely eZ
publish.
DeconRCM is built with the use of a web mapping via Google Maps API (free web
mapping service application and technology provided by Google that powers many mapbased services, including the Google Maps website via Google Maps API). A database
with all the adequate information regarding the disposal sites of the Region of Central
Macedonia, Greece is embodied in the application. The database, which is based on
MySQL, can be accessed and edited only by the administrator of the portal. Feedback
forms, based on php 5.0 scripting language, are developed for gathering data as regards
the source site (demolished or renovated building). Additionally, an algorithmical model,
built with the use of excel spreadsheets, is constructed and embodied in the DSS tool for
the estimation of the generated quantities of R&D wastes from a building. The output of
quantity estimation model is stored in databases, also developed with MySQL. Finally,
optimisation of the integrated C&D waste management of end-of-life buildings is solved
with the use of a mixed-integer linear programming model (MILP). The interdependencies
of the aforementioned structural components are captured in the flow chart of Figure 1.
The full description of the tool’s technical and functional specifications are provided in [2].
[A]
Final processing
facilities
[G]
Decision variables
[E]
Constraints
Google Earth
[C]
Travel route
[F]
SIMPLEX
[H]
Results
[D]
Waste streams
Calculation model
[B]
Building
characteristics
Figure 1: DeconRCM flow chart
[I]
Visualization
4. OPTIMAL MANAGEMENT OF C&D WASTE FROM THE DEMOLITION OF A TWOSTOREY BUILDING IN KALAMARIA
4.1. Calculation of waste quantities
The first step of the DeconRCM is to provide the end user with the analytical calculation
of the quantity and type of building materials that are embodied in the specific building’s
shell, as well as their classification according to the European Waste Catalogue (EWC).
The tool has a user friendly interface, as it provides the end-user with possible answers to
a series of questions by means of pull down menus and in some cases by simply
inserting the appropriate numerical data.
The tool developed and incorporated into the DeconRCM application for the analytical
calculation and the quantification of materials embodied in existing buildings and
generated during their demolition or renovation [3] was validated on two different two–
storey residential buildings, one in Kalamaria (Figure 2a,b) and another in the city of
Kozani (Figure 3c,d). Table 1 presents volume and calculated mass of all 21 different
waste streams, as those were calculated with the use of the developed tool, together with
their comparison with the streams weighted on site. The interpretation of the results
presented in Table 1 show that concrete - and thus inert waste - in both cases is the
dominant by mass fraction of the resulting waste stream, since in the two cases under
study this particular stream accounts for 83.13% and 84.86% respectively. Necessary
input data are depicted in Figure 3.
(a)
(b)
(c)
(d)
Figure 2: Case studies before and after demolition: (a,b) Kalamaria - (c,d) Kozani
Table 1: Comparison between waste quantities calculated with the tool developed for
the DeconRCM application and actual waste quantities weighted on site
Kalamaria
EWC
Code
Waste stream
Volume
[m3]
Mass
[t]
Actual
mass
[t]
Kozani
Difference
[%]
Volume
[m3]
Mass
[t]
Actual
mass
[t]
Difference
[%]
17 01 01
Concrete
124.57
298.97
321.66
7.59
84.12
201.89
220.56
9.25
17 01 02
Bricks
26.52
31.83
34.75
9.16
17.04
20.44
22.17
8.43
17 01 02
Roofing tiles
0
0
0
0
0
0
0
0
17 01 03
Ceramic tiles
0.04
0.09
0.09
6.32
0.02
0.04
0.05
5.76
17 01 03
Marbles
3.60
10.08
10.85
7.63
2.04
5.71
6.16
7.78
17 02 01
Wood
3.82
2.29
2.48
8.03
1.61
0.96
1.05
8.65
17 02 02
Glass
0.30
0.75
0.79
6.12
0.17
0.42
0.45
7.73
17 02 03
Plastic
0
0
0
0
0
0
0
0
17 04 01
Copper, bronze, brass
0
0
0
0
0
0
0
0
17 04 02
Aluminium
0.59
1.59
1.73
8.67
0
0
0
0
17 04 03
Lead
0
0
0
0
0
0
0
0
17 04 04
Zinc
0
0
0
0
0
0
0
0
17 04 05
Iron and steel
2.27
13.18
14.46
9.71
0.82
8.67
9.39
8.39
17 04 11
Cables
-
0.03
0.04
25.67
-
0.02
0.02
18.43
17 06 01
Insulation materials
containing asbestos
0
0
0
0
0
0
0
0
17 06 02
Other insulation
materials consisting of
or containing
dangerous substances
0
0
0
0
0
0
0
0
17 06 04
Insulation materials
0
0
0
0
0
0
0
0
17 06 05*
Construction materials
containing asbestos
0
0
0
0
0
0
0
0
17 08 02
Gypsum-based
construction materials
0
0
0
0
0
0
0
0
17 01 07
Inert R&D waste
154.73
340.97
367.35
7.74
103.22
228.09
248.93
9.14
17 09 04
Mixed R&D waste
161.91
358.86
386.95
7.83
106.75
246.85
259.91
9.12
(a)
(b)
Figure 3: Input data for the two buildings under study: (a) Kalamaria and (b) Kozani
Moreover, the difference between the results of the calculated quantities in comparison to
the actual quantities weighted on site varies from 6.12% to 25.67% for the case study of
the building in Kalamaria and from 5.76% to 18.43% for the case study of the building in
Kozani. The maximum resulting difference is related to the calculated quantity of the
cables, a waste stream which is considered as the hardest to estimate with the use of the
model, since it varies significantly according to the specific building structure. The
accuracy of the derived results is satisfactory, as the overall difference between the
actual and the calculated quantities lies within the acceptable tolerance limits (7.83% and
9.12%).
4.2. Optimisation of the integrated C&D waste management of end-of-life buildings
In this subsection, the methodological framework of a mixed-integer linear programming
model (MILP) that addresses the optimisation of the integrated C&D waste management
of end-of-life buildings is briefly presented. Full description of the model is provided in [4].
Firstly, the employed indices/sets are provided:
m = 1,…, M:
t = 0,…,T:
q = 1,…, Q:
Materials produced by deconstruction or demolition activities.
Container contents (single or mixture of products); value t=0 stands for
demolition materials and j=1,...,T stand for deconstruction materials.
Final recipients of the deconstruction and demolition materials; value q=0
stands for landfill and q=1,…,Q stand for recycling centres.
Following, the objective function of the MILP model is presented:
M
T
VARDCmt 
Maximize:
m 1 t 0
T
Q
VARTC 
t 1 q 1
t
q
T
 FIXRC
t
t 0
T
Q
VARTC
t
q
t 0 q 0
where:
VARDCmt : Total variable costs of producing and separating the deconstruction and
demolition materials, resulting from the sum of continuous variables defining
the total quantity of the generated material m that is stored in container type t
multiplied by the appropriate variable deconstruction and separation costs.
FIXRCt : Total fixed costs of using and renting containers, resulting from the sum of
integer variable defining the number of containers type t used on-site
multiplied by the appropriate fixed costs of renting and using the containers.
VARTCqt : Total variable costs of transporting the containers used for storing materials
generated by deconstruction activities to final recipients, resulting from the
sum of integer variable defining the number of containers type t that end up to
final recipients q multiplied by the appropriate variable transportation costs.
VARTCqt : Total profit from selling/recycling the deconstruction and demolition materials,
resulting from the sum of continuous variables defining the total quantity of
products that is stored in container type t and end up to final recipient q
multiplied by the appropriate variable revenues.
The constraints of the problem are the following:
 The total produced quantity of a deconstruction and demolition material is separated
and stored in containers.




The deconstruction and demolition materials that are stored in a single container are
transported to a final recipient.
The total number of containers, which are used for storing a single deconstruction and
demolition material or mixture of products, is transported to only one final recipient.
The total quantity of deconstruction and demolition products, which is transported to
recycling centres, is at least equal with the total quantity of produced deconstruction
and demolition products multiplied by an environmental factor (desired recycling
ratio).
There are trivial non-negativity, integrality and binary constraints for the decision
variables.
4.3. End-of-life management of waste quantities from the demolition of a two-storey
building in Kalamaria
A brief and indicative case study is presented in this section for demonstrating the
applicability of the proposed model and for obtaining managerial insights for the optimal
solution of the problem under study. More specifically, for our case, we consider a twostorey building in Kalamaria of a total weight equal to 358 tones. The building examined
is to be pulled down, so that another building to be constructed in its place. The problem
for the decision-makers is firstly to find the optimal disassembly method to obtain
valuable reusable materials, and secondly to optimise the transportation, recycling and
disposal processes of the produced C&D materials.
A number of 5 possible container configurations are considered to be placed in each
deconstruction site, regarding their alternative content. More specifically, potential
containers could be used for storing and shipping separately the following different
contents/materials: (a) demolition waste, (b) wood, (c) aluminium, (d) metals, (e) inert
materials (e.g. concrete, bricks and glass). Each container would be either shipped and
disposed to a landfill or shipped to a recycler for recovery purposes (with potential
revenues). Apart from the option of disposing the C&D waste to a landfill, four different
recycling centres are considered. Each recycling centre can undertake the recovery
operations of one or more different materials.
The resulting MILP model consists of 40 continuous, 25 integers and 5 binary variables,
and 68 constraints excluding binary, integrality and non-negativity ones. The model is
solved on a Pentium 4 computer with 3.6 GHz CPU, and 1GB RAM, via the CPLEX®
v.9.1 solver and through the mathematical programming language AMPL®. The
computational time is negligible (with an average of three seconds) and the solution
performance of the proposed MILP model is obviously satisfactory; this is quite
expectable for single building realisations of the examined problem (MILP models of
small to medium scale).
Figure 4: Optimal C&D waste management for the building under study in Kalamaria
In Figure 4, the optimal C&D waste management for the building under study in
Kalamaria is presented. From the 5 aforementioned types of containers, 2 (containing
demolition waste and inert materials) end up in Disposal site A in Gefyra Thessalonikis,
another 2 (containing aluminium and metals) are sent to Disposal site B within the limits
of the city of Thessaloniki, while containers containing wood are deposited in Disposal
site C, situated in the eastern suburbs of Thessaloniki.
5. CONCLUSIONS
In this paper the technical and functional characteristics for the development of a webbased DSS application, namely DeconRCM are presented. The application aims to
identify the optimal degree of buildings’ deconstruction or demolition, as well as maximum
recovery of materials.
Moreover, a novel MILP integrated model for supporting the decision-making processes
from the point of optimally determining the appropriate building disassembly method till
the transportation of the deconstruction and demolition waste to recyclers and landfills for
recovery and waste minimization purposes is also presented. The proposed analytical
approach contributes towards a comprehensive and integrated construction and
demolition waste management strategy.
Future research directions could include the expansion of the provided model for different
types of building and/or construction sites. An additional future research direction could
include the expansion of the provided model by adding additional meaningful financial,
environmental, regulatory and technological constraints.
ACKNOWLEDGEMENT
DEWAM project is co-financed by E.U.-European Social Fund (75%) and the Greek
Ministry of Development-GSRT (25%).
REFERENCES
1. European Commission, Directorate – General Environment, 2000. Management of
Construction and Demolition Waste, Working Document No 1.
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management. PhD Thesis, Department of Mechanical Engineering, Aristotle University
Thessaloniki (in progress).
3. Anastaselos, D., 2009. Development of an integrated evaluation system for thermal insulation
solutions. PhD Thesis, Department of Mechanical Engineering, Aristotle University
Thessaloniki (in progress).
4. Aidonis, D., 2009. Applied operations research methodologies for the optimal design and
operation of reuse and recycling networks of construction and demolition materials. PhD
Thesis, Department of Mechanical Engineering, Aristotle University Thessaloniki (in progress).