LCC Estimation Model: A Construction Material Perspective

buildings Article LCC Estimation Model: A Construction Material Perspective Vojtˇech Biolek * and Tomáš Hanák Faculty of Civil Engineering, Brno University of Technology, Veveˇrí331/95, 602 00 Brno, Czech Republic *Correspondence: [email protected].cz Received: 30 June 2019; Accepted: 6 August 2019; Published: 8 August 2019   Abstract: The growing pressure to ensure sustainable construction is also associated with stricter demands on the cost-effectiveness of construction and operation of buildings and reduction of their environmental impact. This paper presents a methodology for building life cycle cost estimation that enables investors to identify the optimum material solution for their buildings on the level of functional parts. The functionality of a comprehensive model that takes into account investor requirements and links them to a construction cost estimation database and a facility management database is verified through a case study of a “façade composition” functional part, with sublevel “external thermal insulation composite system (ETICS) with thin plaster”. The results show that there is no generally applicable optimum ETICS material solution, which is caused by differing investor requirements, as well as the unique circumstances of each building and its user. The solution presented in this paper aims to aid investor decision-making regarding the choice of the building materials while taking the Life Cycle Cost (LCC) into account. Keywords: building; construction material; life cycle costs; thermal insulation system 1. Introduction Sustainable efforts are generally discussed from an environmental as well as economic perspective. On the one hand, there is a need to seek environmentally friendly solutions with minimum energy consumption and waste generation; on the other hand, there is the investor’s intention to pursue cost-effective projects. Building projects especially are marked by the fact that they are complex, are carried out over a long period of time, and face a high level of uncertainty and several risks affecting the final project outcome [1]. The building project should thus be considered in terms of its entire life cycle. In this relation, the BLCC approach (Building Life Cycle Costs) plays an important role as it focuses on cost optimisation throughout the entire life cycle [ 2 ] of a building. Zabielski and Zabielska [ 3 ] formulate LCC as a sum of the cost of purchase (project execution costs), cost of ownership (maintenance) and the cost of disposal decreased by the residual value of the property. This kind of planning of the building life cycle is crucial for informed decision-making [ 4 ], since operational costs usually significantly exceed construction costs [ 5 ]. For instance, it is estimated that about 80% of the energy use relates to the operational stage of a building’s life cycle [6]. A fundamental issue is to determine the lifespan of the building/building elements. In this regard, there is a lack of consensus in the relevant literature. Some authors consider the lifespan of 50 years [ 7 – 9 ], others use the value of 60 [ 10 , 11 ] years, while others even compare different service lifespans (30, 50 and 100 years) [ 12 ]. Generally speaking, the lifespan should correspond to the expected period of use, which may depend on the building’s technical parameters (wood/concrete structure) or expected time of operation (from the investor’s point of view), while it is also necessary to consider the lifespan of individual building elements. For example, Robati [ 13 ] uses 25 years as the period for Buildings 2019,9, 182; doi:10.3390/buildings9080182 www.mdpi.com/journal/buildings Buildings 2019,9, 182 2 of 19 replacement of glazed windows, so it is obvious that this particular element will be replaced several times during the lifespan of the building as a whole. As a building’s lifespan ranges across decades, the prediction becomes progressively less accurate with increasing prediction time. This inaccuracy and uncertainty of costs within the operational stage is associated with several factors, e.g., predicted inflation rates (energy prices), availability of new technologies, changes in applicable legislation, inspection costs, insurance, and local tax or labour costs [ 14 , 15 ]. The accuracy of cost prediction depends on various aspects involving the level of information detail on the building [ 16 ] (materials, conditions under which certain activities can be carried out, e.g., the cleaning service [ 17 ]) and information about materials and related data on deterioration behaviour [18]. Within the building life cycle, a major part of the costs will be incurred at the later stages, i.e., especially in the operational stage. For future costs such as maintenance and repairs, appropriate discount rate should be applied [ 19 ]. The value of the discount rate is important [ 20 ], and the influence is more significant with lower discount rates [ 21 ], and vice versa. As a result, building investments should be evaluated in terms of the NPV (Net Present Value) indicator [9]. One of the most crucial investment decision-making issues consists of striking a balance between construction and operation costs [ 22 ]. This problem is complex, and it also involves the effect of energy prices (growing energy prices result in a more significant role played by operation energy costs in the early years of the lifespan) [ 10 ] and many other factors mentioned above. That is why many researchers apply various optimisation techniques, e.g., mixed integer linear programming [ 23 ], genetic algorithms [ 24 ], hybrid algorithms [ 25 ], and regression models [ 26 , 27 ]. Many researchers also apply LCC minimisation with regards to a specific natural hazard. For instance, this refers to buildings threatened by earthquakes and wind damage [ 7 ], flooding [ 28 ] or seismic risks [ 29 ]. In this regard, the LCC approach also differs in that it takes into consideration the vulnerability of buildings to a particular risk, the risk exposure in a given location, as well as refurbishment costs incurred on account of the damage. There are numerous studies providing methodologies for estimating loss caused by natural hazards (see e.g., [ 30 ] for flood risk); however, distributing these losses over the lifespan of the building is subject to uncertainty from the NPV perspective. Recently constructed buildings have considerably improved thermal characteristics compared to older buildings. Incidentally, older buildings are often renovated with the aim of reducing energy consumption. In this regard, it should be noted that reduced consumption of energy during the operational stage of the building life-cycle usually comes with increased use of materials and the related environmental costs that may counteract its financial benefits [ 31 ]. Therefore, sustainable material cycles, recycling options and disposal costs [ 32 , 33 ] should be considered during the preparation of building projects. In the area of public works, procurement is governed by applicable national legislation, which in the case of the European Union (EU) is based on Directive 2014/24/EU of the European Parliament and of the Council. According to the directive [ 34 ], “life-cycle costing shall to the extent relevant cover parts or all of the following costs over the life cycle of a product, service or works: (a) Costs, born by the contracting authority or other user (acquisition, use, maintenance and end life costs); (b) Costs imputed to environmental externalities linked to the product, service or works during its life cycle, provided their monetary value can be determined and verified”. Unfortunately, no relevant databases of information on the expected lifetime of products, the time and extent to which they require repairs and the costs of maintenance of given structures are not available. That is why the LCC approach is rarely used in procurement practice. Nevertheless, such data should be processed in future BIM (Building Information Modelling) systems. In the future, the BIM model should serve as a source of information informing the work of the individual participants of the construction process. An approach that includes information with the BIM model will benefit from the data repository of transfer formats, allowing quick editing of the information and updating of Buildings 2019,9, 182 3 of 19 the LCC value [ 35 ]. The integration of BIM and LCC serves to ensure better maintenance accessibility and enhanced collaboration between asset and maintenance management [36,37]. This paper therefore reflects the growing pressure to ensure sustainable construction, which is also associated with stricter demands on the cost-effectiveness of the construction and operation of buildings and reducing their environmental impact. The objective of the research is to propose a methodology enabling the selection of an optimum building material solution for the individual functional parts of a building in terms of life cycle costs. This case study involves the proposed and applied methodology for a selected functional part: “Façade—external thermal insulation composite system with thin plaster” in the context of the current state of the Czech construction sector. The article is structured as follows: Firstly, the current state of knowledge is presented, followed by materials and methods and a description of the proposed methodology, where the methodology is then applied to the selected functional part in variant solutions and discussed. The final chapters summarise the research findings and limitations and outline future research directions. 2. Materials and Methods A proposal for a methodology for LCC calculation with respect to construction materials requires several steps. With regard to LCC calculation standards, it is first necessary to define the required input data (see Section 2.1); specify the lifetime, the cycle and frequency of repairs, and the maintenance of the functional parts of buildings (Section 2.2); and then to propose a system for data exchange (Section 2.3). The LCC indicator is calculated based on the formula indicated in the European ISO 15686-5:2017 [ 38 ] standard, which is based on the discounting of future costs during the examined period. Discounting means adjusting future costs (costs of reconstruction, utilities, maintenance, etc.) with respect to their present value. LCC are calculated according to following formula: LCC = T X t=0 Ct (1+r)t(1) where: Ctdenotes all costs as equivalent cash flows in year t; ris the discount rate; tis the analysed year (t=0, 1, 2 . . . ,T); Tis the length of the life cycle in years. Other models, such as those published by Bromilow and Pawsey [ 39 ] or Sobanjo [ 40 ], are based on the principle of different discounting of regular and irregular costs. 2.1. Input Data Requirements for LCC Calculation For the purposes of LCC calculation, input data are required in three main areas. Specifically, this includes determination of the length of the examined period, the value of the discount rate, and the identification of the individual types of costs arising throughout the life cycle. The length of the examined period either corresponds to the expected lifetime of the building, or can be set as a specific period corresponding to the investor’s requirements. The expected lifetime of buildings in the Czech Republic is indicated in [ 41 ], where, e.g., a masonry building is expected to have a lifetime of 100 years. The discount rate used when modelling LCC is up to the individual investors, but it should correspond to the rate of return of other similar projects or requirements for specific types of public projects. A 5% rate is commonly used [ 9 , 42 ]. Costs arising throughout the life cycle of a building then constitute the acquisition costs, operational costs (maintenance, repairs, replacement) and disposal costs. For the purposes of the present research activity, the discount rate was set at 5%. Buildings 2019,9, 182 4 of 19 The most complex part of the calculation consists in defining and quantifying the costs incurred in the operational stage of the building’s life cycle. It is necessary to define the scope and frequency in which the individual parts of a building have to be maintained, repaired or replaced. Each structure has different requirements when it comes to maintenance and repair, including a different expected lifetime. As a general rule, however, one of the main factors that has an impact on the expected lifespan is the material used to build a given structure. Other factors include the quality of production, quality of construction work, and maintenance frequency. The calculation of LCC makes it desirable to divide the analysed building into functional parts (FP). It is then necessary to establish the relevant repair, maintenance and replacement cycles, and costs; this study uses the data provided in [ 43 ]. For instance, “Exterior plasters, insulation” have their FP lifetime set to 30–60 years, with a repair cycle of 30 years and the scope of repairs of 20%. 2.2. Establishing the Lifetime, Cycle and Frequency of Repairs and Maintenance of Functional Parts The process of establishing the aforementioned values is based on a survey of already built and operated buildings included in a facility management (FM) system. In this regard, it is vital that the FM system contain data on the individual costs of repairs, maintenance and replacement (R/M/R), including the time when the given intervention took place. Using the aforementioned recorded data, it is possible to calculate the average R/M/R costs and the average length of the cycle between individual R/M/R interventions, where the average costs are calculated using the following formula: Cycle_A =(DA1−DC)+Pn i=2(DAi−DAi−1) n(2) where Cycle_A is the average length of the cycle between two individual activities (A), provided separately for each R/M/R component; DC is the date of construction; DA1is the date of the 1st R/M/R activity; DAiis the date of the ith R/M/R activity; nis the number of R/M/R activities. The concept of collecting R/M/R information and its transformation into a database of lifespans, frequencies and costs of repairs and maintenance of functional parts is introduced in [ 44 ]. Calculating LCC requires effective communication between three systems: (1) The LCC calculation system; (2) the FM system; and (3) the building cost estimation system, which is necessary to establish unit prices and other information from the price database that influence LCC calculation over the entire life cycle of a building. Another system that can be incorporated is the system for creating BIM models. A BIM model is essentially a database of all of the information on the building, which can thus serve as a source of input data for LCC calculation (e.g., surface area, materials used, dimensions, characteristics, etc.); conversely, information obtained through the LCC calculation can be transferred back into the BIM model for future use. Each of the above systems usually operates with a different data structure and a different classification of individual building structures. Accordingly, it was necessary to find a suitable structural division of a building that would be compatible with all the component systems. The proposed connecting database is based on a division of a building into four functional units—load-bearing structures, roof structures, façade and surface treatment of interior spaces. The individual functional units are divided into functional parts (FP); a detailed division is provided in Table 1. Functional parts are further divided according to the implementation possibilities or other distinct features of the given structural part. This brings multiple benefits over the building’s life cycle, both in terms of managing its construction and cost management in the operational stage. This makes it possible to consider functional units as actual parts incorporated in a building that are supplied as a whole. Since there Buildings 2019,9, 182 5 of 19 is no clearly available database for use in LCC calculation and the facility management system, the proposed connecting database appears to be the default option for both systems. Table 1. Proposed connecting database with division to functional units and functional parts [45]. Functional unit LOAD-BEARING STRUCTURES ROOF STRUCTURES FAÇADE SURFACE TREATMENT OF INTERIOR SPACES Functional part foundations walls columns ceilings girders, (main) beams staircase load-bearing part of chimney wooden roof frame roof covering metal sheeting of roof elements other roof elements—roof windows, skylights, antennas etc. windows entrance door, gate façade composition exterior window sills other façade elements—covers, railing, blinds, etc. wall plastering facings ceiling plastering suspended ceilings floor 2.3. General Description of the System The entire process begins with the design of a building. If the design is made using a BIM tool, it is important for the maker of the BIM model to supply information to classify all building structures into functional units and functional parts. The BIM model’s level of detail is high (LOD 200 to LOD 300) in order to include the selected construction solution, materials and dimensions, general information on the building and the size of the individual structures. If the design is made using traditional tools (2D design), the designer must input all the necessary information into the LCC calculation system manually. The required information (parameters) are dependent on the type of functional part, but generally speaking, this means its material characteristics and size. Among other information, functional parts also require information generally related to the whole building—its height, location etc. Once a building is classified into distinctly defined functional parts, the system for LCC calculation will communicate with the building cost estimation system. Individual items of the price database carry an information on classification into functional parts, i.e., the items from which the information necessary for LCC calculation will be retrieved (e.g., unit prices, unit weight, rubble, time needed for (dis)assembly in standard hours). The next stage consists in obtaining information for the calculation of costs in the operational stage of the building, i.e., the costs of repairs, maintenance and replacement (R/M/R). R/M/R costs information is transferred from the price framework of the building cost estimation system. As described above, there is a challenge consisting of the availability of information on the scope and frequency of R/M/R. The information can be entered into the LCC system in two ways: • Information on the R/M/R scopes and frequencies of the individual functional parts is based on observation of already built buildings. The information is managed in the facility management system and can be transferred to the LCC calculation system via the connecting database (see Section 2.2). • Repairs are simulated by the designer (LCC system user) based on experience or assumptions regarding the orientation or use of the building. The lifetime and maintenance can potentially be indicated by the manufacturer of the materials or can be simulated by the user as in the case of repairs. This possibility of recording can be used by users who lack data from the facility management system. The final stage consists in entering the calculation conditions. The conditions are based on the LCC calculation formula itself—discount rate and the examined period. These parameters are dependent on the customs of the investor and the building’s character. Once all information necessary for the LCC calculation has been entered or transferred from the individual systems, the calculation itself takes place. The entire calculation can be divided into five stages: •calculation of acquisition costs; Buildings 2019,9, 182 6 of 19 •calculation of replacement costs; •calculation of maintenance costs; •calculation of repair costs; •calculation of disposal costs at the end of the building’s lifetime. The individual stages of the calculation, i.e., the structure of the calculation, differ for each functional part in terms of the manner of costing, e.g., the costing of a reinforced concrete wall differs from that of façade composition. The manner of costing is based on custom and the principles of building cost estimation. After the calculation has been completed, an important added value of the proposed system consists in finding the most suitable solution that meets the same or better characteristics as the original solution. These properties depend on the type of the functional part and its typical characteristics, e.g., thermal insulation properties, dimensions, strength, etc. The proposed system will then calculate LCC for all alternatives and order them on the basis of various characteristics: acquisition costs, LCC, LCC minus acquisition costs, and so on. The user thus obtains a basis that will enable them to make a design based on the best possible solution. If a BIM model is available, direct transfer of information from the LCC calculation system into the BIM model is possible. In particular, this refers to information on the acquisition price, frequency and cost of R/M/R, which benefits the planning of funding sources in the upcoming operational stage of the newly constructed building. This makes the BIM model multi-dimensional, since it contains information on costs, facility management and partially also information on time (time of assembly of the individual building structures). The whole process of data exchange among the individual systems is shown in Figure 1. The diagram also shows other possibilities for linking the individual systems—LCA and energy consumption—which, however, are not part of the proposed methodology. Similarly, the methodology does not address costs associated with the entire project, i.e., costs associated with project documentation and other costs borne by the investor or the contractor. The proposed methodology covers only the costs associated with the structures incorporated in the building. The methodology addresses the structure of information and its processing in the individual systems, but not its mutual systemic interconnection at the data transfer level. Buildings 2019, 9, x FOR PEER REVIEW 7 of 20 Figure 1. The process of exchanging information among the individual systems to ensure the best material solution of the building. 3. Applying the Model: Case Study of the “Façade Composition” Functional Part To demonstrate the functionality of the system, the chapter below presents a proposed solution for calculating LCC for the functional part designated “façade composition”. In the first stage of the process, the creator of the BIM model must define the structural, material and dimensional characteristics of the façade. The façade composition functional part can be divided into four sublevels depending on the construction solution: • external thermal insulation composite system (ETICS) with thin plaster; • external thermal insulation composite system (ETICS) with facing; • plaster only; • facing only. The “external thermal insulation composite system (ETICS) with thin plaster” sublevel of the “façade composition” functional part, was selected for the case study. Viable types of external thermal insulation composite systems (hereinafter ETICS) and thin plasters are selected from the price database [46], which essentially contains all material and dimensional possibilities and is key for determining the costs. A total of 11 ETICS types and 13 thin plaster types were selected; a list of these, together with further details, is presented in Tables 2 and 3. There are 143 potential combinations. The thickness of the material depends on the type of ETICS and thin plaster used. Table 2. The list of individual types of ETICS with their possible thickness values, thermal conductivity coefficient and indication of special properties (none = no special properties; SO = meant for the socle area; PO = fire resistant) [46–50]. Type of ETICS and Reference Products Thickness [mm] Thermal Conductivity Coefficient λ [W/(m·K)] Property EPS 70 façade board (Isover EPS 70F) 10; 20; 30; 40; 50; 60; 80; 100; 120; 140; 150; 160; 180; 200 0.039 none EPS 100 façade board (Isover EPS 100F) 30; 50; 60; 80; 100; 120; 140; 160; 180; 200 0.037 none Figure 1. The process of exchanging information among the individual systems to ensure the best material solution of the building. Buildings 2019,9, 182 7 of 19 3. Applying the Model: Case Study of the “Façade Composition” Functional Part To demonstrate the functionality of the system, the chapter below presents a proposed solution for calculating LCC for the functional part designated “façade composition”. In the first stage of the process, the creator of the BIM model must define the structural, material and dimensional characteristics of the façade. The façade composition functional part can be divided into four sublevels depending on the construction solution: •external thermal insulation composite system (ETICS) with thin plaster; •external thermal insulation composite system (ETICS) with facing; •plaster only; •facing only. The “external thermal insulation composite system (ETICS) with thin plaster” sublevel of the “façade composition” functional part, was selected for the case study. Viable types of external thermal insulation composite systems (hereinafter ETICS) and thin plasters are selected from the price database [ 46 ], which essentially contains all material and dimensional possibilities and is key for determining the costs. A total of 11 ETICS types and 13 thin plaster types were selected; a list of these, together with further details, is presented in Tables 2and 3. There are 143 potential combinations. The thickness of the material depends on the type of ETICS and thin plaster used. Table 2. The list of individual types of ETICS with their possible thickness values, thermal conductivity coefficient and indication of special properties (none =no special properties; SO =meant for the socle area; PO =fire resistant) [46–50]. Type of ETICS and Reference Products Thickness [mm] Thermal Conductivity Coefficient λ [W/(m·K)] Property EPS 70 façade board (Isover EPS 70F) 10; 20; 30; 40; 50; 60; 80; 100; 120; 140; 150; 160; 180; 200 0.039 none EPS 100 façade board (Isover EPS 100F) 30; 50; 60; 80; 100; 120; 140; 160; 180; 200 0.037 none EPS graphite façade board (Isover EPS GreyWall) 20; 30; 40; 50; 60; 80; 100; 120; 140; 160; 180; 200; 220; 240; 260; 280; 300 0.032 none polystyrene socle board, façade (Isover EPS SOKL 3000) 20; 30; 40; 50; 60; 80; 100; 120 0.035 SO polystyrene façade board for thermal insulation of bottom parts of buildings (Isover EPS PERIMETR) 40; 50; 60; 80; 100; 120; 140 0.034 SO board with longitudinal mineral fibre (Isover TF PROFI) 40; 50; 60; 70; 80; 100; 120; 140; 160; 180; 200; 220; 240; 260; 280; 300 0.036 PO board with perpendicular mineral fibre (Isover NF 333) 20; 30; 40; 50; 60; 70; 80; 100; 120; 140; 160; 180; 200; 220; 240; 260; 280; 300 0.041 PO foamglass board, no surface treatment (FOAMGLAS®W+F) 50; 60; 80; 100; 120; 140 0.038 PO XPS polystyrene board (BACHL XPS 300 G) 30; 40; 50; 60; 80; 100; 120 0.036 (up to 60 mm) 0.033 (over 60 mm) SO sandwich insulation board (polystyrene+wool) (Isover TWINNER) 100; 120; 140; 150; 160; 180; 200; 220; 240; 260; 280; 300 0.033 (up to 200 mm) 0.032 (over 200 mm) PO wood fibre board (STEICO Flex-wood fibre insulation) 40; 60; 80; 100; 120; 140; 160; 180; 200 0.036 none Buildings 2019,9, 182 8 of 19 Table 3. List of thin plasters with potential thickness [46]. Type of Thin Plaster Thickness [mm] mineral granular plaster 1.0; 1.5; 2.0 mineral grooved plaster 2.0 acrylic granular plaster 1.0; 1.5; 2.0 acrylic grooved plaster 2.0; 3.0 acrylic mosaic plaster 1.0; 2.0; 3.0 silicate granular plaster 1.0; 1.5; 2.0; 3.0 silicate grooved plaster 2.0 silicone granular plaster 1.0; 1.5; 2.0; 3.0 silicone grooved plaster 2.0; 3.0 silicone hydrophilic granular plaster 1.0; 1.5; 2.0; 3.0 silicone hydrophilic grooved plaster 2.0; 3.0 silicate-silicone granular plaster 1.0; 1.5; 2.0; 3.0 silicate-silicone grooved plaster 2.0 The above material and dimensional characteristics (Tables 2and 3) are key to the proper classification of the proposed solution and must be inputted to the BIM model by its creator. Figure 2 shows the list of input information necessary for performing the LCC calculation. Aside from the material and dimensional characteristics of the façade layers, it also includes information that must be entered for the purposes of identification of all costs associated with implementing the façade layers. For the LCC calculation itself, it is also necessary to input the investor’s requirements for LCC modelling—the discount rate and the length of the examined period based on the DCF model. Buildings 2019, 9, x FOR PEER REVIEW 9 of 20 Table 3. List of thin plasters with potential thickness [46]. Type of Thin Plaste r Thickness [mm] mineral granular plaster 1.0; 1.5; 2.0 mineral grooved plaster 2.0 acrylic granular plaster 1.0; 1.5; 2.0 acrylic grooved plaster 2.0; 3.0 acrylic mosaic plaster 1.0; 2.0; 3.0 silicate granular plaster 1.0; 1.5; 2.0; 3.0 silicate grooved plaster 2.0 silicone granular plaster 1.0; 1.5; 2.0; 3.0 silicone grooved plaster 2.0; 3.0 silicone hydrophilic granular plaster 1.0; 1.5; 2.0; 3.0 silicone hydrophilic grooved plaster 2.0; 3.0 silicate-silicone granular plaster 1.0; 1.5; 2.0; 3.0 silicate-silicone grooved plaster 2.0 The above material and dimensional characteristics (Tables 2 and 3) are key to the proper classification of the proposed solution and must be inputted to the BIM model by its creator. Figure 2 shows the list of input information necessary for performing the LCC calculation. Aside from the material and dimensional characteristics of the façade layers, it also includes information that must be entered for the purposes of identification of all costs associated with implementing the façade layers. For the LCC calculation itself, it is also necessary to input the investor’s requirements for LCC modelling—the discount rate and the length of the examined period based on the DCF model. Figure 2. Overview of input parameters for calculating LCC for the individual variants. For a specific demonstration of how the proposed system works, the chosen default material solution consists of ETICS EPS 70 façade board (120 mm thick) with mineral granular plaster (2 mm thick)—see Figure 2. The input parameters of the discount rate and the examined period are modelled in three variants: • Variants 1 and 3—The examined period corresponds to the entire lifetime of the building (100 years) and the discount rate is set to 5%; the variants differ in the R/M/R database (for more details see 3.6) [9,42,43]. • Variant 2—The examined period is set to 30 years, i.e., the minimum lifetime of “Exterior plaster, insulation” according to [43], while the discount rate remains identical to Variant 1, i.e., 5%. Area [m2] FD parameters – Façade – external thermal insulation composite system with thin plaster ETICS type: ETICS thickness [mm]: Use of thermally insulating plugs [yes/no]: Use of dispersion (organic) reinforced plaster compound [yes/no]: Type of thin plaster: Plaster thickness [mm]: ETICS characteristics: General parameters Building height [m]: Landfill distance [km]: Years in which no maintenance is to be performed prior ETICS replacement [years]: Building lifetime [years]: Parameters for calculating economic efficiency: Discount rate: Examined period [years]: 100 100.00 EPS 100 façade board 120 yes no mineral granular plaster 2 no special characteristics 10 30 2 5% 5% Variant 2Variant 1 and 3 100 30 Figure 2. Overview of input parameters for calculating LCC for the individual variants. For a specific demonstration of how the proposed system works, the chosen default material solution consists of ETICS EPS 70 façade board (120 mm thick) with mineral granular plaster (2 mm thick)—see Figure 2. The input parameters of the discount rate and the examined period are modelled in three variants: • Variants 1 and 3—The examined period corresponds to the entire lifetime of the building (100 years) and the discount rate is set to 5%; the variants differ in the R/M/R database (for more details see 3.6) [9,42,43]. Buildings 2019,9, 182 9 of 19 • Variant 2—The examined period is set to 30 years, i.e., the minimum lifetime of “Exterior plaster, insulation” according to [43], while the discount rate remains identical to Variant 1, i.e., 5%. 3.1. Calculation of Acquisition Costs The calculation of acquisition costs for implementation of the façade layers consists of the items of the price database [ 46 ]. The use of the individual items of the price database depends on the type of ETICS or thin plaster used, respectively. The external thermal insulation composite system is costed separately for assembly and supply of material. Assembly of ETICS is differentiated according to the system’s type and thickness: • assembly of polystyrene external thermal insulation boards—thickness under 40 mm, under 80 mm, under 120 mm, under 160 mm, under 200 mm, under 240 mm, over 240 mm; • assembly of external thermal insulation mineral wool with longitudinal fibre—thickness under 40 mm, under 80 mm, under 120 mm, under 160 mm, over 160 mm; • assembly of external thermal insulation mineral wool with perpendicular fibre—thickness under 40 mm, under 80 mm, under 120 mm, under 160 mm, under 200 mm, over 200 mm. The price of the “ETICS assembly” item also includes the costs of assembly and supply of levelling compounds and fiberglass mesh. Each assembly item includes information not only on the unit acquisition price, but also information on the mass, which is essential for material transport calculations, and on the time demands of the work in standard hours, which is a required figure for calculating the assembly time. The material corresponds to various types of ETICS indicated in Table 2. The thickness of the insulating material indicated by the manufacturer is distinguished. Each item of material also includes an information on the unit price and mass, where the thermal resistance is calculated according to the thermal conductivity coefficient and the insulating material thickness. Thermal resistance is important for finding variants from among the individual ETICS types with the same or improved characteristics. ETICS costing also includes potential extra costs. The use of these extra costs is conditional on entering information into the BIM model in the form of an associated parameter. The following extra costs are included: • for anchoring boards 22.5 m and higher above ground—determined according to the insulating material thickness; •for use of thermally insulating plugs—determined according to ETICS type; •for use of dispersion (organic) reinforced plaster. The supply and assembly of thin plaster are indicated as one item in the price database. The price of the item also includes the costs of priming the substrate. As in the case of the ETICS, each item of the thin plaster includes information on the acquisition price, mass, and assembly time in standard hours. The thermal resistance of thin plaster is negligible and is disregarded. Complete supply and assembly of the “external thermal insulation composite system with thin plaster” also carries some associated costs such as material transport, where the total mass of all the items used is added up. The items of material transport depend on the height, type and construction solution of the buildings, as well as on whether mechanisation is used fully, partially or not at all. The case study assumes full use of mechanisation in the construction process. Another cost involves the assembly, lease and removal of scaffolding and the possible use of safety nets. The price database distinguishes multiple types of scaffolding—light tubular scaffolding, heavy tubular scaffolding, light frame scaffolding, heavy frame scaffolding. Based on the calculation needs, the most commonly used type of scaffolding will be considered—light frame scaffolding with decking size of up to 1.2 m. The cost of scaffolding lease corresponds to the ETICS assembly time converted to working days. One of the user-entered parameters is the height of the building, which affects the use of items for extra costs associated with the assembly of ETICS, scaffolding and material transport. Buildings 2019,9, 182 16 of 19 repairs twice during the examined period. The originally designed solution would have to be repaired 5 times during the examined period. In the third variant, where the R/M/R was identical to Variant 2, the best solution was EPS graphite façade board (100 mm thick). Considering; however, that the best solution in Variant 2 (polystyrene socle façade board) where the examined period was shorter, has almost the same resulting LCC price, despite the fact that the best solution in Variant 3 (EPS graphite façade board) will have to be replaced 3 times during the examined period, which is one replacement more than in the case of the best solution in Variant 2. The highest lifespan—60 years—was set for ETICS featuring mineral wool and foamglass. While this system would only have to be replaced once during the building lifetime, it ranked near the bottom in the comparison of the total LCC. This was because of the higher maintenance frequency of mineral fibre boards. Foamglass is also affected by its very high acquisition price. It is clear from the overview of the results of the individual variants that the R/M/R database and the length of the examined period play a very important role. The examined period and the R/M/R database affect the results in such a way that it is impossible to determine which façade layer arrangement is generally the best, which is documented by the variable LCC efficiency of the individual construction-material solutions in the three modelled variant solutions. 5. Conclusions This paper presented a methodology for building LCC estimation that enables investors to identify the optimum material solution for their buildings on the level of individual functional parts. From a theoretical perspective, this paper contributes to the current body of knowledge with the proposed LCC system, which takes into consideration various data inputs and interconnects the construction cost estimation database, facility management database and investors’ requirements into a comprehensive solution. Regarding managerial implications, the proposed LCC estimation system demonstrates the absence of a generally applicable optimum material solution for ETICS. Different investor requirements as well as the unique circumstances of each building and its user are a fact that underlines the need to apply comprehensive approaches to finding the best solutions. Differences between individual buildings lead to the fact that the results achieved (e.g., in the context of LCC calculations) will always be unique and, therefore, no ETICS or thin plaster type should be favoured in advance. There are three important research limitations that should be mentioned. Firstly, the model’s division in terms of materials and structures depends on the available price database, where the proposed system presented in this paper is based on databases used in the Czech Republic. Building structures and materials not indicated in the relevant price database cannot be assigned with costs, which means no LCC value can be determined. Nevertheless, if the methodology is applied generally, it could be used—with adequate modifications—also in other regions and with different price databases. Secondly, the calculation is unique for each functional part, because it is based on its own cost estimation principles and the LCC calculation thus has to be modified for each individual functional part separately. Thirdly, this system is limited only to those life cycle costs that are related to the building’s structures and materials and omits future energy costs in the operational stage (heating, air conditioning, etc.). Several future research directions can be outlined. It should be possible to follow up on the proposed system and the information necessary for LCA calculation in order to be able to select the best material and structural solution based on its carbon footprint as well, i.e., certainly in combination of LCC and LCA. This step would dramatically increase the potential for using the proposed system in the context of adhering to the principles of sustainable construction. Another step could consist of incorporating utilities and energy consumption (e.g., heating, water and electricity) based on information obtained from already operated buildings and BIM model information. This would enable a more comprehensive evaluation of buildings in terms of their LCC. Finally, the information on the construction time (see Figure 5) has the potential for a broader use in creating construction time schedules or in identifying the optimum solution for a building that Buildings 2019,9, 182 17 of 19 takes into account the construction time as one of the evaluation criteria (which can be significant in commercial development projects). Author Contributions: Conceptualization, V.B. and T.H.; methodology, V.B. and T.H.; software, V.B.; calculation V.B. and T.H.; discussion V.B. and T.H.; resources, V.B. and T.H.; writing—original draft preparation, V.B. and T.H.; writing—review and editing, V.B. and T.H.; visualization, V.B.; supervision, T.H.; project administration, V.B.; funding acquisition, V.B. Funding: This research was funded by Brno University of Technology, project Management of Enterprise and Investment Projects in Construction, grant number FAST-J-19-6052 and the APC was funded by FAST-J-19-6052. 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