Indicators as a Foundation of Eco-Labelling of Baked Clay Construction Products in the Republic of Serbia

Abstract

Construction products based on brick clay have been intensively used for the construction of buildings in the Republic of Serbia. The basic raw material for the manufacture of these products is brick clay, which is a natural mineral resource. However, the natural origin of clay provides no guarantees as to whether this group of construction products is eco-friendly. The production of baked clay construction products significantly affects the environment and cannot be neglected. The existing eco-labels used for this group of products are not uniform, in the world or in Serbia. The aim of this paper is to present a new approach to eco-labelling of construction products based on baked clay in the Republic of Serbia. Eco-labels can be given to products which meet certain authentic criteria. The criteria is based on an innovative set of 24 indicators which connect the production of construction products and the impact on the environment. Indicators were defined for the most commonly used construction products—facade brick, standard block and energy block. The research was conducted on leading producers of baked clay construction products in three regions—Northern Serbia, Western Serbia and South Pomoravlje. The obtained results indicate that one of the producers meets the criteria for innovative eco-labelling. The remaining two producers do not meet the requirements for the eco-label at the moment because there is not enough available data on the grounds of which certain indicators could be valued in a more complete manner. The data are unavailable to third parties because they are treated as a trade secret. Further research and an upgrade of the indicator set would create an opportunity to expand the number of baked clay construction products which could obtain the eco-label based on indicators.

1. Introduction

Baked clay construction products are widely used in the construction sector in the Republic of Serbia. Having as a starting point the attitude that the main raw material for obtaining this group of construction products is brick clay, a natural mineral resource, producers highlight their eco-friendliness while neglecting the impact of production on the environment.

The impact of the construction sector on the environment is strong. The construction industry is responsible for 40–45% of primary energy consumption in Europe. This is why it is necessary to find new materials with less impact on the environment and build sustainable buildings [1]. Estimates show that around 40% of natural resources are used in this sector, along with 70% of electricity and 12% of drinking water, while 40–65% of the generated construction waste is disposed of in landfills. The Greenhouse Gas (GHG) emission per work phase is 30%, and 18% is also generated during material usage and transportation [2]. According to recent research, construction materials may be responsible for 20–90% of the increase in global warming potential (GWP) indicators [3]. Construction materials affect the environment in different stages of the life cycle: during the stage of material production, during the stage of facility building, use and maintenance and during the stage of disposal or demolition [4].

Baked clay construction products must fulfil numerous criteria in order to gain the right to eco-labelling. If existing systems of eco-labelling these products in the world and the European Union (EU) are analyzed, a conclusion can be drawn that they are diverse and uneven, varying from one country to another. For its greater part, eco-labelling is based on protocols and methods of leading associations such as: Tiles & Bricks Europe (TBE), The Brick Development Association (BDA), The Brick Industry Association (BIA), The Clay Brick Association (CBA), Think Brick Australia and similar. The number of references which are related exclusively to eco-labelling of baked clay construction products is very limited, so the authors are innovators in the procedure of eco-labelling based on indicators.

Manufacturers are facing ever growing pressures to provide ecologically acceptable products, the governments are introducing a sequence of new ecological regulations in this area, while the environmental awareness of consumers is also on the rise [5].

An eco-label is focused on the reduction of negative impacts on the environment, the prolongation of product lifetime through its appropriate eco-design and simple repair and maintenance, together with reduction or elimination of certain dangerous substances included in the product composition. In this way, the implementation of a circular economy (CE) is also encouraged [6]. A CE must be integrated into the construction industry in order to ensure a reduction in the generation of waste and creation of a sustainable future. This is how the introduction of cleaner technologies and ecologically designed products are encouraged [7].

The credibility or plausibility of an eco-label has a significant impact on the production process. All kinds of eco-labels must be trustworthy and strong. Trustworthy eco-labels signal the superiority of the product in comparison to unlabelled products, while providing, at the same time, a warranty of sustainable management of the production cycle [8].

Eco-labelling in the construction industry takes into consideration economic, social and ecological implementation [9]. Sustainable development in the construction material industry is in line with the goals of the UN Agenda 21 on sustainable building, which is a holistic way of thinking about buildings that encourages harmony between the natural and built environment [10]. During the last two decades, several green building certificates have been created that take into account social, economic and ecological aspects of the sustainability of buildings [11].

According to previous research [8,12], companies that want to build sustainable buildings have a higher probability of using inputs (materials) which are certified as sustainably produced. In this way, producers and suppliers of construction material are motivated to obtain a trustworthy form of a certificate or eco-label.

Life cycle assessment (LCA) is a methodological tool used in the industry for assessing a product’s impact on the environment and improving work and production efficiency. The areas in which it is most commonly used are: waste management, construction industry, agriculture, transport and chemical sector. Some international LCA studies have been conducted in order to analyze the impact of buildings and construction materials on the environment. ISO 14040 and 14044 standards provide principles, framework, requirements and instructions for implementing LCA [3,13,14,15]. The main goals of LCA for construction materials are quantifying and assessing ecological performances of materials so that the decision makers can compare and select materials with the weakest impact on the environment. In addition, LCA gives the foundation for assessing potential improvements in material performances with the goal of reducing their total impact on the environment [16].

Tiles & Bricks Europe (TBE) is a collection of industry associations and companies from 30 European countries, including 26 EU member states. This association promotes the interests of manufacturers of clay construction products (bricks and tiles) in Europe. It provides to its members information exchange on technical development, sustainable building, climate change, resource efficiency and other emerging issues. TBE has its methodology for declaring environmental construction products of type III (Environmental Product Declaration-EPD), which is based on the LCA method and harmonized with applicable standards in this area [17].

The research conducted by Zaborova and Musorina (2022) shows that the EPD for construction materials is very well integrated with the latest schemes for assessing sustainability in the construction industry (LEED, BREEAM, DGNB, GREEN ZOOM). The focus is on estimating different aspects of the ecological sustainability of buildings based on several quantitative and qualitative criteria. Scientists have been directing their activities towards the reduction of construction materials’ carbon footprint while developing new, ecologically more acceptable and safer production processes. Small improvements in production processes have a great impact on the reduction of carbon footprint [18].

Emergy analysis (EMA), which was introduced by H.T. Odum, represents the basis of the model of baked clay brick eco-labelling used in China. It integrates a mass flow, energy flow, currency flow and information flow into a unique system for calculating impact on the environment, services and economy, expressed in emergy units. Unit emergy values (UEV) are used for calculating emergy states of buildings made of clay brick, while emergy indices are crucial for the development of the policy of easing the environmental burden [19].

In the Republic of Serbia, there is no uniform model for the eco-labelling of baked clay construction products. The only products included in the legislation (Rulebook on detailed conditions, criteria and procedure for obtaining the right to use the ecological mark, elements, appearance and method of using the ecological mark for products and services—Reference no. 14) are clay roof tiles [20]. Other products are mostly certified through a type III environmental construction product declaration (EPD) which is valid for a period of five years.

The goal of this research is to present an innovative way to obtain an eco-label for baked clay construction products in the Republic of Serbia. Eco-labels can be obtained by the products which meet certain authentic criteria. These criteria are based on an innovative set of 24 indicators which connect the manufacture of construction products with their impact on the environment. The authors are pioneers in this approach to eco-labelling so it is not possible to fully compare their research to the existing models of construction product eco-labelling.

2. Materials and Methods

The research conducted in this paper is directed towards creating a set of indicators which connect the manufacture of baked clay construction products with the environment. Based on the created indicators, the criteria which a product should meet in order to fulfill the requirements for eco-labelling are defined.

According to the EEA Glossary, an environmental indicator is defined as a ‘parameter or value derived from parameters which describe the state of the environment and its impact on human beings, ecosystems and materials, pressures on the environment, moving forces and reactions which govern that system. The indicator has gone through a process of selection and/or aggregation so that it would be capable of directing an action’ [21].

Environmental indicators are becoming more and more important for connecting the state of the environment with those who are interested in or responsible for this state. In order to formulate indicators, information that is available at different scales is necessary. Environmental indicators are typically quantitative expressions which measure some condition compared to an existing limit value. Decision makers use indicators for communicating with the public. It is for this reason precisely that it is important to define and quantify indicators in a scientifically justified way [22].

Ecological indicators inform scientists, policy creators and the public on ecological, social, human and economic consequences of constantly changing ecological conditions. Qualitative or quantitative measures can be used for indicators. It is important to distinguish between absolute (total amount) and relative (specific) quantitative measures [23].

There is no universal set of eco-indicators which could be applied to serve any purpose. They exist in order to support a decision-making process, not to replace it.

2.1. Creating a Set of Indicators That Connect the Manufacture of Baked Clay Construction Products and the Environment

The process of selection of environmental indicators is a complex one because indicators are numerous and diverse. They are systematized according to their significance, relevance, measurability, simplicity and economic justification. A combination of elements of the DPSIR (D-Driving Forces, P-Pressures, S-State, I-Impact, R-Response) approach, the 3BL (Triple Bottom Line) approach and the key performance indicators (KPI) approach according to the CBA (Clay Brick Association of Southern Africa) was used for creating a set of indicators that connect baked clay construction products, following the principles of sustainable production.

A general DPSIR approach puts indicators into five categories: D-Driving Forces, P-Pressures, S-State, I-Impact, R-Response. It is important to describe various causal relationships between indicators because it is difficult to unambiguously attribute changes in the eco-system to the pressures coming from humans. It is, in the first instance, necessary to identify and collect all possible data and information on the five elements of the DPSIR chain that describe the relationships between the causes and effects of ecological problems. In order to understand their dynamics, it is useful to focus on the relationships between DPSIR elements. Any element of the chain can be modified by responses: moving forces through structural interventions, pressures through technological and prescribed actions, conditions through collective actions and impacts through economic compensation for damage [24].

Swarnakar et al. [25] examined the 3BL approach combined with sustainable manufacture (SM) and they defined sustainability indicators that were classified into three groups—environmental indicators, social indicators and economic indicators.

A leading South African association of brick products manufacturers, CBA (2017), has classified key performance indicators (KPIs) into nine categories: energy, greenhouse gas emission, air pollution, water, waste, materials, biodiversity, social and economic sustainability and continual improvement [26].

The impact of emissions from brick kilns on human health has been the subject of studies by numerous authors [27,28,29,30,31].

For the purposes of the conducted research, the manufacture of baked clay construction products was observed systemically, as a process with its inputs and outputs having a direct or indirect relationship with the environment (Figure 1).

Research has been conducted on three typical baked clay products most commonly used for the construction of buildings—facade brick, standard block and energy block (Figure 2).

Taking into consideration basic principles of the DPSIR, 3BL and KPI approaches, a set of 24 indicators has been created. In order to simplify their interpretation, they have been classified into five categories which correspond to the DPSIR approach adjusted to the production of the analyzed products.

Indicators of driving factors ‘D’ directly refer to the impact of baked clay construction products on the environment. These indicators depend on the characteristics of the technical and technological process, the state of the market of construction products and environmental acceptability of products. The technical and technological characteristics of the production process directly affect both the quality of products and the environment. The use of state-of-the art equipment in all stages of the production process reduces negative impacts on the environment, the proper choice of furnaces for baking products being the most significant step. The increase in demand on the market of construction products and the rise of consumers’ interest in products labelled as ecologically acceptable must be satisfied.

Indicators of pressure ‘P’ primarily refer to the consumption of raw materials, water and primary energy. This group of indicators includes both emissions into air (dust, HF, HCl, SOx, NOx, CO) and emissions into water. The impacts on soil during clay extraction, emissions of noise and vibrations during the production process and the generation of waste are also indicators of pressure.

Indicators of state ‘S’ define the way in which the production of baked clay construction products affects air pollution, water pollution and soil pollution. The production of baked clay construction products leads to the reduction of available raw materials (clay as a non-renewable resource) and the reduction of non-renewable energy sources (which are used as fuel in furnaces).

Indicators of impact ‘I’ indicate how the production of baked clay construction products affect the change of soil purpose (whether agricultural land or forest area are jeopardized by the extraction of raw materials), what kind of influence the production of baked clay construction products has on global warming (emission of greenhouse gases) and whether it has a negative impact on human health.

Indicators of response ‘R’ primarily refer to the legal and institutional problem solving aimed to address issues created in the environment by the production of baked clay construction products. National legislation adjusts to the trends that apply in a given area of production both in the European Union and the world. The leading manufacturers in the Republic of Serbia, in addition to environmental impact assessment studies, develop their own protocols of environmental protection in accordance with regulations and standards, and strive to switch to ‘clean technologies’.

In

Table 1. List of indicators and their meanings.

Label	Indicator Name	Indicator Interpretation	Category DPSIR
I01	Technological characteristics of the production process based on baked clay	Significant for forming a relationship between the production and the environment because it can be used to identify the consumption of raw materials and energy sources.	D
I02	Technical characteristics of construction product—brick, block	Serves to estimate: object energy efficiency, sound isolation, compliance with EU guidelines and European product standards (CE).	D
I03	Clay consumption	Useful for assessing the remaining amount of the non-renewable natural resource—brick clay—and for long-term production capacity planning.	P
I04	Fresh water consumption	A measure of optimal exploitation of water in the production process. It can also indicate the problems related to water consumption.	P
I05	Energy consumption	Indicates the consumption of energy in the production process and the assessment of non-renewable energy sources consumption.	P
I06	Emissions of pollutants into the air	Used for tracking emissions released from the production line into air (checking whether the emissions fall within the range of emission limit values—ELV)	P
I07	Emissions of pollutants into water	Refers to measuring and examining the quality of wastewater (checking the range of emission limit values—ELV, impact on recipient, data collection for register keeping)	P
I08	Noise emissions	Refers to noise measurement in a closed space—an industrial facility, in accordance with corresponding legal regulations.	P
I09	Air pollution	Used for measuring the quality of air in the area surrounding the production facility and for forecasting the air pollution prevention measures.	S
I10	Water pollution	Used for quality rating of surface water in the recipient into which wastewater from the production facility is released and for forecasting the measures for surface water pollution prevention.	S
I11	Impact on soil	Used for assessing: the surface of the soil which changes its purpose, the surface of degraded soil, disposed waste and spilled oil derivatives in the surface mining.	I
I12	Process waste	Indicates the quantity of process waste and the quantity of waste materials used for secondary purposes.	P
I13	Dust from waste gas purification devices	Used for estimating the quantity of dust resulting from waste gas purification and the quality of the purification.	P
I14	Wastewater quality	Represents a measure of the pressure which the wastewater from the production process puts on the environment.	P
I15	Sludge from water treatment plants	Enables the estimate of the quantity of sludge made during the purification of wastewater in the process and the assessment of economic profitability of its use for other purposes after additional processing.	P
I16	Packaging waste	Used for the estimate of the quantity of packaging waste made during the packaging of finished products and the possibility of its recycling and reuse.	P
I17	Industrial consumption index in the municipality	Indicates the environmental problems in the municipality created by the manufacturing of baked clay construction products, the taking of appropriate monitoring measures and financial investments into gas purification plants, wastewater treatment plants and waste treatment.	D/P
I18	Greenhouse gases emission	Provides information on the trends concerning emissions from main anthropogenic sources of GHG in the industry of baked clay construction products.	P
I19	Basic emergy indicators in clay brick production	Indicates the assessment of the share of renewable/non-renewable resources and the assessment of clay brick production sustainability taking into consideration the environment, services and economic factors.	I
I20	Other emergy indicators in clay brick production	Serves for the assessment of emergy sustainability based on emergy degrees.	I
I21	Potential incidence of disease due to emissions from brick kilns	Measures the incidence of human diseases caused by emissions from brick kilns.	I
I22	Legislation	The need to define a legal framework in the industry of baked clay construction products so as to avoid negative impacts on the environment and to make the products environmentally acceptable.	R
I23	Production of electricity by solar power plants	Indicates the possibility of producing electricity for personal needs by solar power plants and the reduction of carbon footprint on a global level.	R/I
I24	Switch to BAT (best available technology)	Reflects a manufacturer’s willingness to switch to BAT.	R

, individual indicators have been selected and their interpretation and category to which they belong have been given.

2.2. Indicator Priority

The selected indicators are of descriptive character and in order for them to be evaluated, it was necessary to assign a value to them. Based on readily available professional and scientific references, the method of prioritization was used to prioritize indicators, according to the Stevanović Čarapina model [35], which is based on the assessment of the impact of baked clay construction products on the quality of the environment and human health. The method has been combined with an assessment of the sustainability priorities of the 3BL approach. For the evaluation of indicators, four evaluation groups were introduced (availability of data, quality of data, significance for the production of baked clay construction products and significance for the environment). Within each group, categories with the corresponding value were defined, which is shown in

Table 2. Evaluation of indicators (harmonized with the methodology presented in [35]).

Group	Description	Value
I	Data availability
	Not available	0
	Partially available	1
	Available	2
II	Data quality
	No data on methodology	0
	There are quality data or methodology for data collection	1
	There are both data and methodology for data collection	2
III	Significance for the production of baked clay construction products
	No significance	1
	Has some significance	2
	Useful	3
	Significantly useful	4
	Extremely useful	5
IV	Significance for the environment
	No significance	1
	Has some significance	2
	Useful	3
	Significantly useful	4
	Extremely useful	5

.

2.3. Evaluation of Indicators

According to the defined prioritization, an evaluation was performed for each of the 24 indicators defined in Table 1. The procedure has been presented in the table for each indicator. The table for individual evaluation of indicators contains the following elements: indicator code, indicator name, ordinal number, area of indicator analysis, theoretical/practical foundations for indicator defining, indicator description, possibility of application, method of determination, measurement unit, data source, interpretation, assessment class and value. The indicator value (ValueI0i) is obtained by summing the assigned values for each assessment class from Table 1 (classes I, II, III and IV). The values obtained in this way are the maximum values of the indicator, and for the practical assessment of individual manufacturers, the range in which they can move has been determined. It ranges from zero to a specified maximum value. The maximum values of each individual indicator are shown in Figure 3.

2.4. Criteria for Eco-Labelling

Criteria for acquiring the right of baked clay construction product manufacturers to an eco-label for their products (brick, block) are defined by comparing the values for individual total sum indicators (SUMIND_individual) of an individual manufacturer with the referent value SUMIND.

When evaluating individual indicators for individual manufacturers, the criteria for obtaining values from zero to the maximum reference value are set in relation to their estimated applicability:

• YES (100%), completely applicable indicator—maximum value of the referent indicator,
• Partially applicable indicator—an estimated value is 50% of the value of the referent indicator and
• NO (0%), the indicator cannot be applied—the indicator value is 0.

The referent value SUMIND is a total of the maximum values for each individual indicator and it amounts to 250 points, that is:

$$\mathrm{SUMIND}={{\displaystyle \sum }}_{\mathrm{i}=1}^{24}\mathrm{SUMINDindmax}.$$

(1)

Individual total sum values of indicators for an individual manufacturer are calculated as:

$${\mathrm{SUMIND}}_{\mathrm{individual}}={{\displaystyle \sum }}_{\mathrm{i}=1}^{24}\mathrm{ValueI}0\mathrm{i},$$

(2)

where ValueI0i is the value of an individual indicator I0i.

The procedure for acquiring the right to the eco-label can be defined in the following way:

• If the value of SUMIND_individual is more than 80% of the value of SUMIND, i.e., is more than 200 points, the manufacturer acquires the right to eco-label their products.
• If the value of SUMIND_individual is within the range of 70% to 80% of the value of SUMIND, i.e., if 175 < SUMIND_individual < 200 points, the manufacturer has a possibility to acquire the right to eco-label their products provided they make certain corrections to the production process.
• If the value of SUMIND_individual is lower than 70% of the value of SUMIND, i.e., is less than 175 points, the manufacturer cannot acquire the right to eco-label their products.

The assessment procedure can be represented by a modified algorithmic approach, Figure 4.

3. Results

The assessment of the applicability of such an approach to eco-labelling has been conducted on the leading manufacturers of baked clay construction products in three regions—Northern Serbia, Western Serbia and Southern Pomoravlje. These areas were selected for two reasons. The first reason was the fact that the manufacturing of baked clay construction products is the most intensive in these regions. The second reason was based on the fact that there is a certain number of scientific and professional papers in which clays from these regions have been analyzed [36,37,38,39,40], which was significant for the assessment of certain indicators. The research was conducted on the three most frequently used products—facade brick, standard block and energy block. The manufacturers only provided data on technical characteristics of products and their certification, which are available in manufacturers’ catalogues and on their websites. The data related to a technological process, and the measurement and control of parameters which have an impact on the environment, were not available to the public.

In Figure 5, Figure 6 and Figure 7, the results of the assessment of the analyzed manufacturers’ indicators by region are shown:

Data analysis for all three regions shows that in Northern Serbia there are 15 (62.5%) completely applicable indicators, 8 (33.33%) partially applicable indicators and 1 (4.17%) indicator that is not applicable. In Western Serbia, there are 15 (62.5%) completely, 4 (16.67%) partially and 5 (20.83%) not applicable indicators. In Southern Pomoravlje, there are 9 (37.5%) completely applicable, 7 (29.17%) partially applicable and 8 (33.33%) indicators that cannot be applied.

The indicators shown in Figure 5, Figure 6 and Figure 7 show certain clustering trends. In all three leading regional manufacturers, it can be noted that the maximum value was attributed to the indicators that refer to the technological characteristics of the production process and clay consumption (I01, I02 and I03), as well as I11-impact on soil, I12- process waste, I22- legislation and I24-transferring to BAT (Best Available Technology).

The indicator that refers to the index of industrial consumption in municipality (I17) is the only mutual partially applicable indicator for all three leading manufacturers. The only mutual indicator valued with zero in all three leading manufacturers is I15- sludge from water treatment plants, because there are no available data on its management (manufacturers point out that the amounts are negligible).

If defined criteria for eco-labelling is applied to the leading manufacturers in all three regions, it can be observed that:

• the leading manufacturer from Northern Serbia meets the criteria for an eco-label because SUMIND_individual = 203.5 which is higher than the referent 200 points,
• the leading manufacturer from Western Serbia has SUMIND_individual = 183 (it falls within the range 175 < SUMIND_individual < 200 points) and can meet the requirements for an eco-label provided it makes certain corrections, and that
• the leading manufacturer from Southern Pomoravlje has SUMIND_individual = 136, which is less than the lowest referent value, i.e., less than 175 points, so it does not meet the requirements for an eco-label without significant corrections.

For the manufacturers (Western Serbia and Southern Pomoravlje) that, after the process of verification, do not meet the criteria for acquiring an eco-label based on the indicator approach, it cannot be claimed that their products do not deserve it. The authors did not have enough necessary information for a more complete assessment of certain indicators, because the manufacturers did not want to provide this information, in accord with their company policies (a trade secret).

4. Discussion

In the Republic of Serbia, baked clay construction products are intensively used. The most commonly used products for the construction of objects are facade brick, standard block and energy block. For this reason, these products were the focus of the research presented here. In Serbia, there is no unique system of eco-labelling for these products. The leading national manufacturers mostly use an Environmental Protection Declaration (EPD) of type III with a validity period of five years for the eco-labelling of their products.

Literary sources which deal with the topic of the research from a scientific and professional standpoint are very rare and these are aggravating circumstances. The approach applied by the authors is innovative because it is based on introducing indicators that connect the manufacture of baked clay construction products and the impact this manufacture makes on the environment. A set of 24 indicators was created for this purpose. The indicators are descriptive so a method of prioritization was used in order to determine the indicators’ priorities so that they could be valued and used for assessment (the procedure is explained in Section 2.2 and Section 2.3). The sum of values for all 24 indicators was adopted as the referent value for a comparison with the aggregate value of indicators for the manufacturer whose products are analyzed. In order to create a set of indicators that connect baked clay construction products and their impact on the environment, elements of the DPSIR approach [24], 3BL approach [25] and key performance indicator approach (KPI) according to CBA [26] have been used, while respecting the principles of sustainable production. Then the criteria for eco-labelling were defined. According to the criteria, there are three possible outcomes: a manufacturer is given the right to eco-label their products; a manufacturer has a possibility to obtain the right to eco-labelling, provided certain corrections are introduced to the production process and a manufacturer cannot obtain the right to eco-label their products.

During the last two decades, several green building certificates have been created that take into account social, economic and ecological aspects of the sustainability of buildings [11], which served as one of the guidelines for this research. As opposed to eco-labelling applied by TBE, a leading association for the manufacturing of brick products in Europe [17], and based on LCA [3,13,14,15], in the research presented in this paper, the authors did not use LCA software packages; however, the products were monitored through all stages of their life cycle using the defined indicators. The innovative nature of eco-labelling based on indicators also originates from the use of certain emergy factors. An emergy approach was used in the model of eco-labelling clay brick in China [19]. This approach is very significant because it takes into consideration the relationship between renewable and non-renewable resources, which has a direct impact on the sustainability of a production process and the reduction of negative effects on the environment. The impacts of emissions from brick kilns on human health were a subject of research done by numerous authors [27,28,29,30,31] and cannot be neglected. However, in the research presented in this paper, these impacts are traced through indicator I21 (Table 1).

Since only clay roof tiles are covered by national legislation in the Republic of Serbia [20], the authors could not compare their approach to eco-labelling baked clay construction products to similar models.

5. Conclusions

Eco-labelling of baked clay construction products, based on criteria resulting from a set of 24 indicators that connect production and the environment, is an innovative procedure in the Republic of Serbia. The procedure is harmonized with the EU standards, existing models of eco-labelling in this area and national legislation. The principles of sustainable development and ‘green design’ have been followed.

After extensive research on the eco-labelling of baked clay construction products, the authors came to the conclusion that the existing eco-labels mostly come in the form of construction products’ declarations on environmental protection type III (EPD). The innovative approach is based on defining indicators that connect baked clay construction products’ manufacture and the environment. After forming a set of 24 indicators, the processes of prioritization and value attribution were applied to them; the maximum value an indicator could have was set for each indicator. The sum of maximum values of all indicators gives a referent sum which is the foundation for setting up criteria for acquiring an eco-label.

The verification of the procedure on a concrete manufacturer means that individual indicators are assessed and evaluated first, then their values are summed and the obtained sum is compared to the defined referent sum. There are three possible outcomes:

• the manufacturer meets the requirement for obtaining an eco-label,
• the manufacturer can gain the right to an eco-label provided they introduce certain corrections to their production process, and
• the manufacturer does not meet the requirements for an eco-label.

Although the research was conducted on the three most commonly used construction products based on baked clay—facade brick, standard block and energy block—the approach could be applied to other products from this group. This would require further upgrading and expanding the set of indicators in accordance with the characteristics of other products.

The biggest challenge in the practical part of the research was the lack of information related to the reduction of emissions resulting from the production process, air and water monitoring and the production process impact on human health. The research data were taken from scientific and professional papers, as well as from the catalogues on official websites of individual manufacturers. The manufacturers were not ready to provide information on production and activities related to environmental impacts because this information is considered to be a trade secret.

To sum up, the interest of leading manufacturers of baked clay construction products in the Republic of Serbia in eco-labelling of their products exists. In this way, they demonstrate socially responsible behavior. Eco-labels on their products give an opportunity for a better product placement on both the domestic and foreign market, especially for environmentally aware consumers.

Since the authors of the paper are the innovators who created a set of indicators for eco-labelling, a drawback of the research is the inability to rely on previous sources. There have been no authors who have conducted research on eco-labelling of construction products based on a set of indicators. The authors leave the possibility of further research with the purpose of upgrading and advancing the presented procedure of eco-labelling based on indicators.