The Role of Using Durable Building Materials and Components in Reducing the Environmental Load of Buildings
Tülay Esin 1 Nilay Coşgun 2 T 52
ABSTRACT
Natural resource and energy consumption resulting from construction activities, emissions, construction and demolition wastes cause a great load on environmental values. The ecological characteristics of building materials and copmponents determine the ecological characteristics of the buildings, and accordingly their environmental loads. Durability is an important ecological characteristic for the building materials and components. In this study, the effects of the durable building materials and cpmponents towards reducing the environmental effects/loads of buildings are emphasized. In the scope of the study, durability and the potential for re-use possibilities is explicated in the context of the reasons for renewal of building materials and components by means of conducting a survey related to modifications done to existing houses. As a result of this study; it was discovered that modifications were done frequently mainly due to ageing and deterioration reasens, followed by modifications done due to aesthetic concerns. Only 25% of the modifications were done due to the ageing and deterioration of the buildings. Therefore the building material and components that not yet completed their usage life turn into waste. However, after checking the durability of such materials and components and making the necessary maintenance and repair, the possibility of re-use is considered as being quite high.
KEYWORDS
Durability, Building material, Building component, Environmental load , Reuse.
1 Gebze Institute of Technology, Faculty of Architecture, Gebze-Kocaeli, Turkey 41400, Phone +90 262 6051606, Fax 262 6538495, [email protected]
2 Gebze Institute of Technology, Faculty of Architecture, Gebze-Kocaeli, Turkey 41400, Phone +90 262 6051610, Fax 262 6538495, [email protected]
1 INTRODUCTION
Throughout their life cycle, buildings have negative effects on the environment due to many reasons.
Natural resource and energy consumption resulting from construction activities, emissions, construction and demolition (C&D) wastes cause a great load on environmental values. The level of this load is related to the sustainable characteristics of the buildings.
Methods adopted towards the protection of natural resources and energy, and reducing waste, which all compose the base for sustainable development can also be implemented in the construction sector.
The ecological characteristics of building materials and copmponents determine the ecological characteristics of the buildings, and accordingly their environmental loads. Durability is an important ecological characteristic for the building materials and components.
The reusability of building materials and components significantly reduces the environmental load of the buildings in which they are used. In this way natural resources and energy can be protected and pollution can be reduced. Building materials and components that are excluded from the scope of reuse and recycle are released to the environment as waste. This leads to environmental pollution which is amongst one of the most important environmental problems today. However, while reuse and recycling of materials prevents the formation of waste and pollution, it also allows for gaining new resources and reducing the environmental load. Reusability is related to the durability and usage life of the building materials and components against several effects.
In this study it is aimed to discuss the effects of the durability of building materials and components on reducing the environmental load of buildings. In this scope, the effects of the durability of building materials/components on reducing production of C&D waste and pollution is emphasized. It is known that buildings cause an important intensity of C&D waste during their life cycle. It is seen that a large quantity of C&D waste evolves particularly when modifications are done during usage phase. For this reason, in line with the aim specified, C&D waste that evolves the usage of buildings was chosen as the subject of the study.
2 DURABILITY OF BUILDINGS
Durability is one of the most important characteristic which defines the building materials and components and is expected to be permanent during the usage life of the building. Durability of building materials and components directly affects the durability of the building they are used in. The durability of building materials and components is related to their internal structure and their physical, chemical and mechanical characteristics. Durability can be reduced according to the faults and/or deficits done during the production and/or construction processes of the building and building materials. The building materials and components can be damaged due to the reasons such as detailing defects during the design phase , application defects and defects due to workmanship during the construction of the building. Accordingly the usage life of building can be shortened. External environmental conditions such as climatic factors and atmospheric emissions affect the durability of building materials negatively as well.
The durability performance expected from the building is directly related with the use of appropriate material. The selection of materials should be made according to the factors which affect the building materials on the basis of their usage position. Besides, it is important to state that different materials that are used together can interact and cause a reduction in durability. Using material with appropriate characteristic and standard at the construction is strongly associated with the material knowledge of the designer. The prevention of defects due to workmanship which effect the durability of the building and building materials negatively is possible by esuring detailing of design and efficient auditing.
Providing sufficient attention to maintenance and repair during usage of the building is important in terms of the durability of building materials and the building’s expansion of existence. Building
materials also have a definite life time and it is possible to expand this period via maintenance of building components at intervals changing according to building materials. The structure would be designed for the longest life +50 years. Exterior surfaces change about every 20 years. Wiring, plumbing, and other surfaces tend to wear out or go obsolete every 7 to 15 years. Interior walls and other components of the floor plan tend to change every few years in some buildings [Milani 2001].
3 ENVIRONMENTAL LOAD OF BUILDINGS – CONSTRUCTION AND DEMOLITION WASTE
Building life cycle is closely related to environmental impact. Buildings create a great burden on the environment during their existence because they utilize energy and natural resources and as a result of this, generate emissions and wastes. According to the data from Worldwatch Institute [Ngowi 2001];
building activities consume up to 40% of stone, gravel and sand, 25% of natural wood, 16% of water and 40% of energy used worlwide. Approximately 78% of carbon emissions come from fossil fuels that are burnt to make cement, and 60% of the water that runs through pipelines is consumed in cities [Eduardo 2007]. This situation causes some pollution and increases the deterioration of the environmental values. Waste production is accepted as one of the most important environmental problems of the 21st century. C&D wastes are defined as priority wastes in many countries due to their large volumes, quantities and complexities. Construction & demolition waste generates from:
• Building related waste; Construction, Demolition, Renovation,
• Roadway related waste,
• Bridge related waste,
• Landclearing & inert debris waste.
EPA (U.S.Environmental Protection Agency) estimates that in America 136 million tons of construction waste was generated in 1996 [EPA 1998]. It is stated that in Hong Kong 65% of the waste area was covered with C&D waste in 1994-95 [Stokoe et al. 1999]. This value is 35% in Canada [Cedar 2007]. According to EPA of Australia, 21% of all waste generated in Sydney is C&D waste [Gutovic et al. 2005].
There is no clear data in terms of C&D waste amounts in Turkey. It is stated that the average urban solid waste generation is 1.04 kg per capita/day or ~380 kg per capita/year in Turkey [Çevre ve Orman Bakanlığı 2006]. This value includes both the domestic waste and the C&D waste. According to the data from ISTAC (İstanbul Çevre Koruma ve Atık Maddeleri Değerlendirme San.ve Tic.A.Ş.), approximately one kilogram solid waste including C&D waste is generated per capita/day in Istanbul [ISTAÇ 2006].
As construction waste’s have a larger volume than residential waste’s, wide waste areas are essential since they put pressure on the existent landfill areas. When these wastes are released to the forests, rivers, streams or empty areas in an uncontrolled manner, they cause for erosion, the contamination of ground and surface water resources and the deterioration of natural areas [Construction Recycling Directory 2003]. The characteristics of solid changes and habitats are destroyed. Destructive contaminators spread out to the atmosphere by means of uncontrolled burning of paint, isolation materials and flammable materials. When these wastes are released to the environment uncontrollably they need to be cleaned and this is very costly both environmentally and cost economically.
4 THE ROLE OF USING DURABLE OF BUILDING MATERIALS AND COMPONENTS IN REDUCING THE ENVIRONMENTAL LOAD
C&D waste which causes economical and environmental load can be reduced through a rationalist management. However, the best method is to initially prevent waste generation. In this respect the
designer hold great responsibility. It is necessary that right decisions are taken towards preventing or reducing waste generation at the very beginning of design.
The selection of appropriate building materials and components is very important decision. It is also important to consider the durability and characteristics of reuse in the selection of building materials and components during the design phase. Because, the durability of building materials and components against variable factors is an important ecological characteristic which ensures the protection of resources and prevents waste generation. Such materials make important contributions to the reduction of environmental load as a result of their performances stated as follows;
• Building materials and components which have a high level of durability don’t require much maintenance and repair during usage. This way, the reduction in the use of new materials ensures the protection of resources and pollution doesn’t occur because waste that could be generated during maintenance and repair is prevented.
• Materials which have a high level of durability have a long life. For this reason, they don’t need to be replaced for a long time and this detains the need for new raw materials and thus, the protection of the resource is ensured.
• Building materials and components that have a high level of durability can be reused after the building completes its life cycle or is changed before the building completes its life cycle. Thus, the need for new resources disappears or is delayed and therefore the protection of natural resources is ensured. As the materials are reused, there is no waste to throw away and therefore waste generation is prevented and pollution is reduced through reuse of them as new raw materials or sources.
• As such materials reduce the use of new resources and materials, the environmental effects (consumption of resources and water, emission etc.) that they have during their life cycle also disappears.
• Because they have long usage time, their total environmental effects gradually diminish since these effects are separated into long time periods.
5 SURVEY STUDY/ DETERMINATION OF DURABILITY AND REUSE POTENTIAL OF BUILDING MATERIALS AND COMPONENTS GENERATED AFTER MODIFICATIONS Waste generation appears during various phases of the building’s life cycle. It is observed that an important quantity of C&D waste is generated during various modifications done in the usage phase [Esin, Cosgun 2005]. EPA has reported that nearly 44% of the C&D waste results from the modifications activities in the buildings [EPA, 1998]. The long utilization time of the buildings effects in increasing this amount. In order to prevent waste generation it is important -in terms of environmental and economic aspects- to recover these C&D wastes generated in this process.
In the scope of this study, a survey conducted to determine the possible potential for re-using or re- cycling construction wastes generated by the modifications on the basis of their durability. Knowledge in regard to the reasons for modifications is important in terms of determining potential for the reuse of building materials and components. For this purpose, the modifications done in buildings, the reasons for modifications, which building materials and components are focused on during modification and how they are evaluated was researched.
A survey was conducted face to face with 90 building owners in Istanbul, the city chosen as a research area. According to the survey data results; Buildings varying from 60-200 m2 are 1-20 years old. 80%
of the survey participants are the building owners with middle income. 77% of the participants have done modifications in their buildings. 74% of them stated that they had modifications done (generally 5-6 years) after they moved into building.
It is seen that in the majority of the buildings various types of modifications have been done. The mostly preferred modification is the floor covering (61%). Followed by exterior door (43%), kitchen components (sink, counter, kitchen cupboard, etc.) (39%), window frames (36%), wall covering (33%), bath/WC components (bath-tub, wash-bowl, closet, bath cupboard) (31%), debris of wall demolish (23%), interior door (16%), ceiling covering (carton pierre, wainscot, etc.) (14%), heating system (13%), plumbing systems (11%) and electricity systems (10%) modifications [Figure 1].
It is found out that after the modifications, high percentage of building materials and components are thrown away. Accordingly, 58% of the material generated during the modification of floor covering is thrown away. 63% of exterior door, 59% of kitchen components, 60% of window frames, 70% of wall covering, 59% of bath/WC components, 82% of debris of wall demolish, 64% of interior door, 50% of plumbing systems, 55% of heating system materials are thrown away after modifications. 100% of the material generated during the replacement of ceiling covering and electricity systems are thrown away [Figure 1].
61% 43% 39% 36% 33% 31% 23% 16% 14% 13% 11% 10%
58% 63% 59% 60% 70% 59% 82% 64% 100% 55% 38% 100%
0%
10%
20%
30%
40%
50%
60%
70%
floor coverings exterior doors kitchen components window frames wall coverings bath/wc components debris of wall demolish interior doors ceiling coverings heating systems plumping systems electricity systems
modification rate thrown away rate
Figure 1. The rate of modifications done in buildings and the rate of materials thrown away after the modifications.
In regard to the modifications made, the participants of the survey ticked one or more reasons listed in the survey form as reasons for making modifications. Accordingly, modifications are done mainly due to ageing and deterioration (%25). Then it is followed by reasons of aesthetic (%19), amelioration in the material quality (%16), difficulty of usage (%10), insufficient space (%9), security (%8), amelioration in the workmanship quality (%6), demand of using fashionable material (%4) and respectively health reasons (%3). It is found out that the rate of modifications done due to the reasons excluding ageing and deterioration is much more (75%) [Figure 2].
75%
25%
0% 10% 20% 30% 40% 50% 60% 70% 80%
group of high reuse potential group of low reuse
potential
Figure 2- The rates of reuse potentials of modified building materials and components.
As a result of the cross-examination on how the building materials and components are utilized (thrown away, reused or not re-used) in the context of the alteration reasons are given in Figure 3.
According to this, it is obseved that a majority of the generated materials for each modification reason are thrown away. It is determined that 65% of the building materials and components which changed due to reasons excluding ageing and deterioration and can be defined as “the group which have include high reuse potential” are thrown away [Figure 3]. Building materials and components which fit into the reuse group (sold, given to the modifier, given to somebody in need, kept in warehouse) are generally exterior and interior doors, kitchen cupboards and sanitary fixtures. The group defined as
“stayed onsite” after modification are the wall, flooring and ceiling coverings that can not be removed.
group which have high reuse potential (totally 75%)
16% 12% 11% 7% 7% 5% 3% 2% 2%
4% 4% 2% 2% 2% 3% 2% 1% 1%
5% 3% 3% 1% 0% 0% 1% 1% 1%
0%
2%
4%
6%
8%
10%
12%
14%
16%
18%
ageing/deterioration aesthetic amelioration in the material quality difficulty of usage insufficient space security amelioration in the workmanship quality demand of using fashionable material health
thrown away reuse stayed onsite
Figure 3- Reuse potentials of building materials and
components in context of the reasons for modifications done in houses.
In the survey, a question was asked towards determining the environmental sensibilityof the participants which was related to “the issues in regard to giving importance to the selection of building
materials and components during modification”. Figure 4 shows the results given by the participants to this question. According to this, while making modifications to their houses; it is observed that the users generally give importance to the durability and aesthetic outlook in the selection of building materials and components. Als it is observed that they don’t give significance to the issue of using material that is non-harmful to the environment [Figure 4].
79%
54%
44% 44% 44%
17% 14%
0% 0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
durability of material aesthetic workmanship quality cost functionality non-harmful material for the human health demand of using fashionable material non-harmful material to the environment
Figure 4- Issues given significance in the selection of building material and component during the modification
6 DISCUSSION AND CONCLUSION
Modification activities are done generaly due to ageing and deterioration. The second reason for modifications is due to the concerns of esthetic outlook. It is observed that the rate of building materials and components that are generated after modifications and that are thrown away is quite high [Figures 1, 3]. While the modification reasons are mainly due to ageing and deterioration, the materials and components which are replaced with new ones can hardly be reused. Thus they turn into waste materials. Some materials generated during modifications done due to the other reasons are modified before they complete their life cycle. Therefore their reuse potential is relatively high. 75%
of the modifications are done due to reasons that exclude ageing and deterioration [Figures 2, 3].
Building materials and components that are modified due to reasons that exclude aging and deterioration can be reused (if they are durable) as they haven’t completed their usage life. In particular it is understood that the majority of exterior and interior doors, kitchen components, sanitary fixtures and heating systems (radiators) are thrown away [Figure 1]. However, it is possible that such materials and components can be reused after their durability is controlled and the necessary maintenance and repair is done. As can be seen in ‘Fig. 3’, the majority of materials generated during modifications is due to the reasons that exclude ageing/deterioration are thrown away (~65%) and a very low rate of reuse possibilities (~23%).
The situation of the users in not giving signficance to using and selecting building materials that are
“non-harmful to the environment” can be acknowledged as an indictor of the lack of environmental sensibility and awareness. However, the situation of the users’ in giving importance to the “durability”
characteristics in the selection of building materials is positive since it contributes to the reduction of environmental load [Figure 4].
In Turkey there are many modifications done due to aesthetic outlook concerns and thus building materials and components become waste before they complete their usage life. If these materials are durable they have the high potential for reuse. For this reason, by designing buildings according to the users’ demands and expectations in a more satisfactory way, the modifications done before materials
complete their usage life and their turning into waste can be prevented. In meeting the users’
expectation for long usage, the materials that have the characteristics of durability and reuse should be seleced. It is important to realize the necessary studies in order to inform and raise the awareness of the users.
The designers must have knowledge and awareness in regard to the selection and implementation of building materials that have the characteristic of durability. This is an important issue which should be stressed in training programs. The production of building materials and components which don’t have durability and don’t meet the standard should be prevented with the corporation of universities, industries and government. An efficient auditing system should be established by preparing laws and regulations on this issue. It is a fact that the environmental load of buildings will increase as building activities continues to rise. Giving importance to the durability in the selection of building materials and components for the sustainability of environmental values will contribute to the reduction of the environmental load of buildings.
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