Carbon Footprint Estimation Tool for Residential Buildings for Non-Specialized Users: OERCO2 Project

sustainability Article Carbon Footprint Estimation Tool for Residential Buildings for Non-Specialized Users: OERCO2 Project Jaime Solís-Guzmán1, Cristina Rivero-Camacho 1, Desirée Alba-Rodríguez 1ID and Alejandro Martínez-Rocamora 2,*ID 1ArDiTec Research Group, Department of Architectural Constructions II, Higher Technical School of Building Engineering, University of Seville, Av. Reina Mercedes, 4-a. 41012 Seville, Spain; [email protected] (J.S.-G.); [email protected] (C.R.-C.); [email protected] (D.A.-R.) 2GACS Research Group, Department of Construction Sciences, Faculty of Architecture, Construction and Design, University of Bío-Bío, Av. Collao, 1202 Concepción, Chile *Correspondence: [email protected]; Tel.: +56-413-111-716 Received: 29 March 2018; Accepted: 24 April 2018; Published: 27 April 2018   Abstract: Existing tools for environmental certification of buildings are failing in their ability to reach the general public and to create social awareness, since they require not only specialized knowledge regarding construction and energy sources, but also environmental knowledge. In this paper, an open-source online tool for the estimation of the carbon footprint of residential buildings by non-specialized users is presented as a product from the OERCO2 Erasmus + project. The internal calculations, data management and operation of this tool are extensively explained. The ten most common building typologies built in the last decade in Spain are analysed by using the OERCO2 tool, and the order of magnitude of the results is analysed by comparing them to the ranges determined by other authors. The OERCO2 tool proves itself to be reliable, with its results falling within the defined logical value ranges. Moreover, the major simplification of the interface allows non-specialized users to evaluate the sustainability of buildings. Further research is oriented towards its inclusion in other environmental certification tools and in Building Information Modeling (BIM) environments. Keywords: life-cycle assessment; carbon footprint; construction materials; non-specialized users; estimation tool; environmental impact assessment; social awareness; sustainability; residential buildings 1. Introduction In recent decades, regulations at national and international level have reflected both a growing concern about the environmental impact caused by the construction sector, and the consequent focus on the reduction of the carbon footprint generated by the manufacture of construction materials, which has been identified as the cause of more than 40% of the total impact of the construction phase in the life cycle of a building [ 1 , 2 ]. This goal is not always easy to achieve, since there are economic, technical, practical, and cultural barriers that prevent professionals from selecting materials with low carbon emissions. These include time constraints during the design phase, the high cost of new products and additional professional training, the difficulties for small industries competing against established industries, a lack of full-scale demonstration projects, and negative perceptions amongst practitioners and clients [ 2 , 3 ]. In order to promote the use of sustainable materials, various procedures have been proposed: for labelling control and environmental product declarations (EPD) [ 4 – 7 ], for the application of life-cycle assessment (LCA) methodologies in the building sector [ 8 – 10 ], and for the sustainable management of buildings [11,12]. Sustainability 2018,10, 1359; doi:10.3390/su10051359 www.mdpi.com/journal/sustainability Sustainability 2018,10, 1359 2 of 15 One of the most extended LCA methodologies available currently is the carbon footprint (CF), which consists of determining the emissions of greenhouse gases produced by a certain process [ 13 ]. The fact that it is strongly related to the main aims of the Kyoto Protocol, along with the ease with which it can be understood by the general non-specialized public [ 14 ] and its simple application in decision-making and environmental policy [ 15 ] are key to the success of this indicator. However, the application of LCA methodologies in the construction sector is complicated and results vary across studies. This is due to the fact that the existing standards have failed to establish an exact methodology, and researchers therefore use their own interpretations of these standards [16]. Most recent studies that attempt to estimate the environmental impact of buildings [ 17 ] have been subject to reviews that focus on LCA [ 18 ], life-cycle energy analysis [ 19 ], or life-cycle carbon footprint [ 20 ], or a combination of these [ 21 , 22 ]. Comparing the results from these studies is problematic due to the variety of assumptions and decisions that must be made in the assessment process (service life of the building and materials, maintenance operations, energy consumption of the building, building typology, calculation formulae, etc.). However, the following conclusions are generally drawn: - The manufacturing and construction phase of a building’s life cycle, which is usually concentrated into a short period of time (1–2 years), causes the most intensive environmental impact. This is mainly due to the consumption of concrete and steel for the structure, both of which represent a high percentage of the emissions produced during this phase [ 23 , 24 ]. This impact is reduced the longer the building’s service life is considered; however, the decisions made during this phase greatly influence the results of the other life-cycle phases of the building. - The use and maintenance phase is generally responsible for 80–90% of the CO 2 emissions generated during a building’s life cycle [ 25 ], almost 60% of which is caused by the energy demand for heating and air-conditioning [ 26 ]. An operational phase of more than 50 years duration reduces emissions and this should be a primary goal. - Reductions in energy consumption during the use and maintenance phase should be achieved through decisions made during the design phase, which implies the use of materials with a higher embodied energy. This means that, in nearly-zero-energy buildings, the emissions during the construction phase represent a higher percentage of the total emissions of the entire life cycle [ 27 ]. Therefore, once the operational energy has been reduced, attention should be focused on the development of new insulation materials that require less energy to manufacture [28]. The knowledge generated by the significant number of studies on environmental impact is reflected in the development of calculation tools, which are usually oriented towards the environmental certification of buildings. The development of tools that enable us to measure the sustainability of buildings has intensified in recent years in order to promote policies that demand minimum sustainable standards in buildings. Currently, there are a number of tools available in Spain that enable the carbon footprint of buildings to be calculated. Despite the more widespread use of translated versions from internationally known methodologies such as LEED and BREEAM, which also allow recognized sustainability certification to be obtained for buildings, in recent years national alternatives have been developed from research projects. LEED and BREEAM are managed nationally by the Spain Green Building Council [ 29 ] and BREEAM Spain [ 30 ], respectively, and they evaluate various criteria to obtain a final score. The criteria include for example, the CO 2 emissions generated by the manufacturing of the construction materials used and the energy consumed in the operational phase of the building. While both of these methodologies require the quantification of the CO 2 emissions by a certified professional in order to assign a score to the corresponding section, these quantifications are not numerically reflected in the final certificate, which is based only on the total score. At the national level, Green Building Council (GBC) Spain offers VERDE certification tools [ 31 ], which focus on design assistance (HADES), new buildings (VERDE NE), rehabilitation (VERDE RH), and urban development (VERDE DU). Sustainability 2018,10, 1359 3 of 15 These assign the highest score percentage (~25%) to greenhouse gas emissions, as a demonstration of the importance of preventing the environmental impacts of emissions. Additionally, ECOMETRO is a web-based open-source tool for the measurement of the environmental impact of a building [ 32 ], and is similar to an EPD, but is applied to entire buildings. On the other hand, energy certification tools, such as CE3, CE3X, CERMA [ 33 ], and the Unified Tool LIDER-CALENER [ 34 ], developed by Spanish associations and universities, and CYPETHERM [ 35 ], developed by CYPE Ingenieros, estimate CO 2 emissions caused by the energy demand during the operational phase of a building, without taking into account the emissions from the construction materials consumed. Several other specialized platforms also exist that allow for the detailed calculation of CO 2 emissions based on a project’s bill of quantities, such as: the BEDEC cost database [ 36 ], developed by the Institute of Construction Technology of Catalonia, whose environmental data comes from the Ecoinvent LCA database [ 37 ], well-known for being one of the most comprehensive databases at European level [ 38 ] and for its integration with the Simapro LCA software [ 39 ]; and the SOFIAS tool, currently in its test version [ 40 ], with data from the OpenDAP database. As an intermediate solution, E2CO2Cero, funded by the Basque Government, is a software package that enables the embodied energy and carbon footprint of a building to be calculated, according to the materials consumed and the construction processes used for that phase of the life cycle [ 41 ]. There are two available versions of this software, the complete version, which requires the introduction of the project’s bill of quantities by the user, and the simplified version, which estimates the environmental impact from basic information that the user provides about the building. These tools, however, fail to achieve what should be a key objective in the general strategy, that is, the ability to reach the general public to create social awareness. Most of these tools require not only specialized knowledge regarding construction and energy sources, but also environmental knowledge. As a consequence, non-specialized users are incapable of auto-evaluation in order to obtain even a general idea of how sustainable their own house or building is, and how they might improve its environmental behaviour. In this case, non-specialized users are defined as those that, even if they possess technical knowledge (architecture or construction students, professionals from the construction sector, etc.), have not been trained in the assessment of the environmental impacts generated by construction processes. In this paper, a carbon footprint estimation tool for residential buildings is presented that has been designed for non-specialized users, which constitutes part of the main objectives of the OERCO2 project, oriented towards the transference of knowledge to society regarding the assessment of CO 2 emissions through an open online platform. 2. Materials and Methods 2.1. OERCO2 Project The OERCO2 project (http://oerco2.eu/) is funded by the Erasmus + program in 2016 within the scope of Strategic Associations in the Higher Education sector (KA203). The University of Seville (Spain) leads the project, and the partners are: Technological Centre of the Marble (Murcia, Spain), CERTIMAC (Faenza, Italy), Green Building Council (Bucharest, Romania), CTCV (Coimbra, Portugal), and the University of Transylvania (Brasov, Romania). The main aims of the project include: • Studying the methodology for the calculation of CO 2 emissions of the construction process and throughout the life cycle of materials at European level. • Establishing a common European curriculum in this area, thus increasing awareness of climate change and providing information on the emissions generated by each element. • Developing an Open Educational Resource (OER) to spread knowledge on CO 2 emissions in construction processes. Sustainability 2018,10, 1359 4 of 15 • Launching an online tool accessible to all building agents (students, professionals, etc.) at European level. Specialized knowledge on the environmental impact of building processes is not necessary for its use. In order to achieve these goals, four milestones have been established in the project: developing a state-of-the-art review of the existing environmental regulations concerning every production sector involved in the construction process, and of the implementation level of those regulations in the countries participating in the OERCO2 project; studying the existing environmental product declarations (EPD) of construction products in these countries; studying the various calculation methodologies of CO 2 emissions for construction processes in the participant countries; and finally, developing the OERCO2 platform, where an application will be hosted that enables CO 2 emissions of construction processes to be estimated. 2.2. OERCO2 Tool The OERCO2 tool (accessible at http://co2tool.oerco2.eu/) is an online application that enables the carbon footprint produced in the construction of residential buildings to be estimated. It stems from several previous research studies developed by the authors [ 1 , 42 – 45 ] and includes the evaluation of CO 2 emissions for the construction process of 140 different residential building typologies. For the embodied energy assessment, the tool uses a cradle-to-site LCA analysis, that is, A1 to A5 life-cycle phases, which correspond to manufacturing (A1–A3) and construction (A4–A5). The environmental data included in the OERCO2 tool was obtained from the Ecoinvent database through Simapro. In order to obtain the CO 2 emissions embodied into construction materials, their Life-Cycle Inventory (LCI) is analysed by applying the IPCC 100a methodology, which is used by the Carbon Footprint indication since it isolates CO 2 and other GHG emissions from the LCI. The tool has been tested and evaluated by all partners from the project, and it is considered that it includes all the building typologies and characteristics commonly used in Spain, Portugal, Italy and Romania, which are essentially those of any European country. The methodology for the evaluation of the carbon footprint of the construction of residential buildings is based on the projects’ bill of quantities and a classification system for construction work which breaks down this information on materials, manpower and machinery needs. The budgets of 140 different projects are analysed and classified; their budgets are reorganized in a construction-work breakdown system (CBS) that facilitates comparison. This organization system has been successfully applied in previous research to estimate the generation of construction waste [ 46 ] and to evaluate the ecological footprint of buildings [1,43,45,47,48]. In particular, the present model employs the Andalusia Construction Information Classification System (ACICS) [ 49 ]. Its most extended use is for the estimation of costs in the construction sector and it is mandatory in public works in Andalusia (Spain). ACICS uses a hierarchical organization for work units, where the highest level is the construction site, followed by categories called chapters, each representing a construction process (e.g., earthworks, foundations, installations, etc.), which are subsequently divided into sub-chapters. The base of this structure is formed by basic costs (BC), corresponding to elementary resources (materials, machinery and manpower), which aggregate to form auxiliary costs (AC), usually mixes materials such as cement mortar, gypsum plaster, or manpower teams, and simple costs (SC), representing the various activities or work units (Table 1). These three kinds of costs are employed by the OERCO2 tool for its calculations. The data obtained from each project’s bill of quantities is structured according to the aforementioned ACICS [ 49 ], and is expressed in units per built surface (u/m 2 ). From the 140 projects evaluated, the mean quantities of each activity (Q i ) are obtained through a statistical process for each building typology. These mean quantities are then transformed into materials, manpower and machinery needs by combining ACICS with a resource quantification database. The quantities of the various resources involved can then be evaluated by applying the carbon footprint methodology in order to obtain the CO2emissions generated due to the whole construction process. Sustainability 2018,10, 1359 5 of 15 The OERCO2 tool is structured with an initial screen where the user specifies general information regarding the project to be analysed, such as the number of floors, type of structure, and built-up surface area (Table 2). The selection of this initial data enables a similar project to be assigned from which the associated Qiare gathered [1]. Table 1. Internal cost classification structure [50]. Class Levels Definitions L1. Construction site All the constructive elements that give up a construction site L2. Chapter Element sets with a common characteristic. e.g., 05. Structures. L3. Sub-chapter Chapter division into smaller sets with a common characteristic. e.g., 05H. Reinforced concrete. L4. Sections Sub-Chapter division into smaller sets with a common characteristic. e.g., 05HH. Concrete. L5. Groups Section division into smaller sets with a common characteristic. e.g., 05HHJ. Reinforced concrete beam. L6. Work units Group division into unitary elements. e.g., 05HHJ00001 m3 Concrete HA-25 in... Table 2. Options for project configuration in the OERCO2 software tool. Unit Concept Tool Options Available INIT. INF. Num. Floors N/A Num. floors 1/2/3/4/5/6+ N/A Num. undergr. floors 0/1/2/3/4 N/A Shops in ground floor No/Yes C.02 Earthworks m3Excavations Excavator/Backhoe/Not applicable m3Fillings Manual means/Mechanic means/Not applicable m3Earth transport Manual means/Mechanic means/Not applicable C.03 Foundations m3Footings Isolated/Slab/Strip/Piles (m) C. 04 Sewer System u Manholes In situ/Prefabricated m Sewage pipes PVC/Concrete/Fibre-cement/Polyethylene m Downpipes and roof sinks Zinc sheet/Steel sheet/Reinforced PVC/Polypropylene/Fibre-cement C. 05 Structure m2/m3Supports Brick wall/Reinforced concrete m2Floor slabs Waffle slab w/non-recoverable caissons/Waffle slab w/recoverable caissons/One-way slab w/ceramic vaults/One-way slab w/concrete vaults/Solid slab m2Formwork Wood/Metal Sustainability 2018,10, 1359 6 of 15 Table 2. Cont. C. 06 Masonry m2Façades 1ft brick wall w/chamber/1/2ft brick wall w/chamber/1ft w/o chamber/1/2ft w/o chamber/1ft w/chamber + plasterboard/1/2ft w/chamber + plasterboard/Lightweight concrete block wall m2Claddings Ceramic brick/Single layer mortar/Cement mortar/Plastic paint/Cement paint/Ventilated cladding (natural stone/ceramic/resin/cellulosecement/wooden sandwich panel + XPS/Cladding (artificial stone/limestone/marble/granite/wood) m2Partitions Double hollow brick 9 cm/24 cm/Triple hollow brick 15 cm/Plasterboard C. 07 Roof m2Flat Non-passable and ventilated/Non-passable and non-ventilated/Non-passable and inverted/Passable and ventilated/Passable and non-ventilated/ Passable and inverted/Does not apply m2Sloping Wavy fibre-cement sheet/Sandwich insulating panel/Aluminium sheet/Galvanized steel sheet/Polyester/Slate tiles/Ceramic tiles/Cement tiles/Does not apply C. 08 Installations u Air-Cond. System Compact/Parted system w/ducts/Heat pump/VRF Inverter/None u Terminal units Ceiling unit/Console/Apartment type/None m Ducts Glass fibre/Galvanized steel/None m Pipes Built-in galvanized steel/Superficial galvanized steel/None m2Radiators Classic steel/Injected aluminium/Iron/Steel sheet/None u Boilers Diesel/Solid fuel/Gas wall-mounted/Mix electric wall-mounted/None m Cold-water pipes Copper/Galvanized steel/Polyethylene/Polypropylene m Hot-water pipes Copper/Galvanized steel/Polypropylene u Sinks PVC/Polypropylene m Ventilation Concrete/Ceramic/Helical galvanized Steel u Heater Gas/Electric/Does not apply u Solar panels Applies/Does not apply m Pipe insulation Applies/Does not apply u Lift Applies/Does not apply C. 09 Insulation m2Thermal-acoustic Polystyrene/Polyurethane/Glass fibre/Rock wool/Perlite/Cork/Polyethylene/None Sustainability 2018,10, 1359 7 of 15 Table 2. Cont. C. 10 Finishes m2Continuous claddings Gypsum plaster/Cement mortar/Does not apply m2Floorings Ceramic/Stoneware/Continuous concrete/Hydraulic tile/Linoleum/Carpet/Cork/Soft-wood parquet/Floating solid soft-wood/Floating laminated soft-wood/Hard-wood parquet/Floating solid hard-wood/Floating laminated hard-wood/Limestone/Marble/Slate/Granite/ Terrazzo/Concrete slab m2Ceilings Continuous plaster w/rods/Continuous plaster w/metal fixings/Removable plaster panels/Continuous laminated gypsum/Removable laminated gypsum w/hidden support grid C. 11 Carpentry and Protection Elements m2Windows Pine-wood casement/Lacquered aluminium sliding/Lacquered aluminium casement w/thermal bridge break/PVC sliding m2Doors Wood/Melamine m2Blinds Anodized aluminium/PVC/Wood/None m2Protection grids Hot-rolled steel/None m Railings Steel/Aluminium/Wood/None C. 12 Glass and Synthetics m2Glazing Thermal-acoustic 6 + 12 + 6/6 + 12 + 6 low-emissive/8 + 14 + 5 + 5 low-emissive argon and solar control C. 13 Paintings m2Exterior Plastic paint/Cement paint/Does not apply m2Interior Plastic paint/Does not apply In the subsequent step, the user specifies data about the project regarding constructive solutions for each element (Table 2). This is then employed by the OERCO2 tool to select which of the available simple costs (SC) must be used for the calculations. As mentioned before, SC are made of BC and AC. In this tool, resources (BC) contain not only economic, but also environmental information (e.g., CO 2 emission factors). The environmental data included in the OERCO2 was obtained from the Ecoinvent database through Simapro, and chosen for covering all the commonly employed materials in building construction [ 38 ]. In order to obtain the CO 2 emissions embodied in construction materials, their Life-Cycle Inventory (LCI) is analysed by applying the IPCC 100a methodology, which is used by the Carbon Footprint indicator since it isolates CO2and other GHG emissions from the LCI. Following this logic, when a specific work unit is selected, then an SC is assigned with two different associated factors: an economic cost ( € /ref. unit) and an environmental cost (kgCO 2 eq/ref. unit), where the reference unit is that of the SC selected (Figure 1). The selection of the initial data for the project enables the Q i of that work unit to be gathered, thereby making it possible to obtain the total cost and carbon footprint (CF) for that activity through Equations (1) and (2): Ci=Qi·Pi·Bs(1) where C i is the total cost of activity i( € ), Q i represents the statistically estimated quantity for activity i in the selected project (ref. unit/m 2 ), P i is the unitary price of activity i( € /ref. unit), and B s is the total built-up surface of the selected project (m2); and Sustainability 2018,10, 1359 8 of 15 CFi=Qi·UCFi·Bs(2) where CF i is the total carbon footprint of activity i(kgCO 2 eq) and UCF i is the unitary carbon footprint of activity i(kgCO2eq/ref. unit). Sustainability 2018, 10, x FOR PEER REVIEW 7 of 14 m2 Interior Plastic paint/Does not apply In the subsequent step, the user specifies data about the project regarding constructive solutions for each element (Table 2). This is then employed by the OERCO2 tool to select which of the available simple costs (SC) must be used for the calculations. As mentioned before, SC are made of BC and AC. In this tool, resources (BC) contain not only economic, but also environmental information (e.g., CO2 emission factors). The environmental data included in the OERCO2 was obtained from the Ecoinvent database through Simapro, and chosen for covering all the commonly employed materials in building construction [38]. In order to obtain the CO2 emissions embodied in construction materials, their Life- Cycle Inventory (LCI) is analysed by applying the IPCC 100a methodology, which is used by the Carbon Footprint indicator since it isolates CO2 and other GHG emissions from the LCI. Following this logic, when a specific work unit is selected, then an SC is assigned with two different associated factors: an economic cost (€/ref. unit) and an environmental cost (kgCO2eq/ref. unit), where the reference unit is that of the SC selected (Figure 1). The selection of the initial data for the project enables the Qi of that work unit to be gathered, thereby making it possible to obtain the total cost and carbon footprint (CF) for that activity through Equations (1) and (2): Figure 1. Cost structure and quantification of economic and environmental impacts. 𝐶𝑖= 𝑄𝑖· 𝑃𝑖· 𝐵𝑠 (1) where Ci is the total cost of activity i (€), Qi represents the statistically estimated quantity for activity i in the selected project (ref. unit/m2), Pi is the unitary price of activity i (€/ref. unit), and Bs is the total built-up surface of the selected project (m2); and 𝐶𝐹𝑖= 𝑄𝑖· 𝑈𝐶𝐹𝑖· 𝐵𝑠 (1) Figure 1. Cost structure and quantification of economic and environmental impacts. The tool shows the final results for the total construction cost (expressed both in € and € /m 2 ), and total CF (in kgCO 2 eq and kgCO 2 eq/m 2 ), the latter also being broken down into materials and machinery (Figure 1). This in-depth analysis of the way the OERCO2 tool works internally demonstrates that users require no specialized knowledge of the environmental evaluation of construction projects, such as the calculation of the embodied energy or CO 2 emission factors associated with construction processes. Instead, users only need to know about the solutions implemented in the construction of the building. The OERCO2 tool has been verified by all the partners in the project in order to include variations among the different countries in construction processes and solutions. The main current limitation of the calculation methodology used by the OERCO2 tool is the use of a common LCA database for the assessment of each case, since this does not take into account the variability in the energy mix among the different countries involved, thus leading to the corresponding homogeneity regarding CO 2 emissions from construction materials. Another limitation is the restrictive variety of solutions for structures, finishes and installations. This issue will be handled in forthcoming updates of the OERCO2 tool, which will include timber structures and recycled materials, as suggested by the initial testers of the tool. The introduction of timber materials is considered crucial given its Sustainability 2018,10, 1359 9 of 15 capacity to lower the environmental impact of buildings compared to other materials such as steel or concrete. 3. Case Studies In order to determine the reliability of the OERCO2 tool, a selection of the ten most representative building typologies (from the 140 typologies available) for the construction of residential buildings in Spain over the last ten years was analysed [ 51 ] using the CF calculation methodology explained in the previous section. Table 3shows a summary of the most relevant features of the studied projects: dwelling type, built-up surface, above-ground and underground floors, and the constructive solutions adopted for the foundations, structure and roof. These parameters will be taken into account in the assessment of the results, since the remaining characteristics of the projects are identical for every case study selected. The sensitivity of the tool to the aforementioned parameters can therefore also be analysed. Table 3. Characterization of the case studies. Project Identifier Dwelling Type Built-Up Surface (m2) Floors Above Ground Underground Floors Footings Structure Roof ADetached house 2696.57 1 0 Strip Brick walls Sloping BTerraced house 3836.17 2 0 Isolated Reinforced concrete Sloping C Residential building 7672.32 2 1 Isolated Reinforced concrete Flat D Residential building 4440.34 3 1 Isolated Reinforced concrete Sloping E Residential building 4440.34 3 1 Isolated Reinforced concrete Flat F Residential building 6660.60 4 2 Slab Reinforced concrete Flat G Residential building 6661.78 5 1 Isolated Reinforced concrete Flat H Residential building 7772.08 5 2 Slab Reinforced concrete Sloping I Residential building 12,210.97 6+ 1 Isolated Reinforced concrete Flat J Residential building 13,320.00 6+ 2 Slab Reinforced concrete Sloping The common characteristics are: mechanical means employed for earth transport, metallic formwork systems, lightweight floor slabs with ceramic hollow blocks, 24 cm ceramic brick walls for the envelope with an air chamber, polystyrene insulation and stone claddings on the outside, interior divisions with 9 cm-thick ceramic brick walls, gypsum plaster for interior wall finishes, terrazzo flooring, and plaster ceilings. Regarding carpentry and protection elements, the windows were considered to have painted aluminium frames with thermal bridge breaks, thermal-acoustic glazing 6 + 12 + 6, and PVC blinds without protective steel grids, while the doors are wooden and there are steel railings. For the installations, an air-conditioning system with a heat pump and console terminal unit is assumed. Hot water is provided by a solar energy system supported by an electric heater. Water is supplied through copper pipes and disposed of through reinforced PVC sewer pipes. Lastly, in order