Ecological Footprint of the use and maintenance phase 2 of buildings: Maintenance tasks and final results

Depósito de investigación de la Universidad de Sevilla https://idus.us.es/ Esta es la versión aceptada del artículo publicado en: This is an accepted manuscript of a paper published in: Energy & Buildings (2017): 10/10/2024 DOI: http://dx.doi.org/10.1016/j.enbuild.2017.09.038 Copyright: © 2017 Elsevier B.V. All rights reserved. El acceso a la versión publicada del artículo puede requerir la suscripción de la revista. Access to the published version may require subscription. “This is an Accepted Manuscript of an article published by Elsevier in [Energy & Buildings] on [2017], available at: http://dx.doi.org/10.1016/j.enbuild.2017.09.038 ” 1 Ecological Footprint of the use and maintenance phase 1 of buildings: Maintenance tasks and final results 2 Martínez-Rocamora, Alejandro (1,*); Solís-Guzmán, Jaime (2); Marrero, Madelyn (2) 3 (1) Department of Construction Sciences, Faculty of Architecture, Construction and 4 Design, University of Bío-Bío. Av. Collao, 1202 – Concepción, Chile 5 (2) ArDiTec Research Group. Department of Architectural Constructions II, Higher 6 Technical School of Building Engineering, University of Seville. Av. Reina Mercedes, 4- 7 a. 41012 – Seville, Spain 8 (*) Corresponding author Alejandro Martínez Rocamora: Department of Construction 9 Sciences, Faculty of Architecture, Construction and Design, University of Bío-Bío. Av. 10 Collao, 1202 – Concepción, Chile; Tel.: +56 944262674; email: [email protected] 11 12 Abstract 13 According to numerous studies, approximately 90% of energy consumption in the life 14 cycle of buildings occurs during the use and maintenance phase. The main aim of this 15 study is to propose a method for the detailed calculation of costs and environmental 16 impact corresponding to this phase, thus providing useful data for Facility Managers. The 17 organization of the consumption of resources into three fundamental elements 18 (manpower, materials, and machinery) enables the cost to be broken down and the 19 Ecological Footprint [1] indicator (EF) to be applied. In previous advances of this 20 research, the development of the model was focused on the utility consumption and 21 cleaning tasks. On this occasion, the model is completed with the handling of 22 maintenance tasks and a detailed assessment of the results, in which the factors that 23 mark the cost and environmental impact are identified, as well as the specific moments 24 of this phase in which peaks occur. In order to compare the costs and impacts produced 25 2 each year, economic and environmental discount rates are used with respect to a 26 baseline year. The methodology is applied to the case of a college hall of residence that 27 houses up to 139 guests. The results show that cleaning tasks represent 6% of the 28 annual EF and 63% of the annual cost, and maintenance 14% and 17%, respectively, 29 thereby justifying the need for quantification. Finally, seven tasks are identified that 30 together generate half of the EF and cost of cleaning, and nine other actions that incur 31 more than a third of the annual cost and EF of maintenance. 32 Keywords 33 Ecological footprint, maintenance, buildings, service life, Facility Manager. 34 35 3 1. Introduction 36 Economic and environmental assessment through indicators becomes essential for 37 efficient management during the service life of buildings. The operation of the building in 38 the use and maintenance phase causes a considerable impact that should be 39 measurable and quantifiable through economic and environmental indicators. 40 In recent decades, many calculation models for the environmental impact of buildings 41 during their life cycle have been published. Most of these studies can be consulted in 42 several recent reviews [2–5], but only those studying the use and maintenance of 43 buildings or using the EF indicator are hereby highlighted. The high complexity of the set 44 of activities carried out during this phase of the life cycle of a building, along with the 45 general perception that maintenance and cleaning are not environmentally significant 46 with respect to the utility consumption, have resulted in the estimation of these values 47 being omitted in almost every study. 48 Some interesting features have been identified in previous calculation models for the 49 environmental impact of the use and maintenance of buildings, such as the inclusion of 50 an inflow of materials for the building maintenance during its use phase [6–10], the 51 distinction between small renovations (e.g. repainting, lamp replacement, and door 52 repairs) and the complete rehabilitation of the building, the assumption that small 53 maintenance tasks will probably remain unfulfilled when the building nears the end of its 54 service life, or the likely reduction of the embodied energy of materials over the years 55 [11]. 56 Although most studies confirm that energy consumption during the use and maintenance 57 phase is by far the largest contributor (90%) to the environmental impact of the entire life 58 cycle of the building [2,12,13], in certain cases it has been pointed out that, regarding 59 new low-energy buildings, the relative importance of the different phases is undergoing 60 change [14–16]. According to Huberman and Pearlmutter [17], the embodied energy can, 61 4 in these cases, represent up to 60% of the energy consumption during the life cycle of 62 the building. Therefore, with the evolution of buildings towards a lower operational 63 consumption, attention will be diverted in the near future towards the reduction of the 64 embodied energy of construction materials. 65 Regarding the models of application of the EF indicator to the building sector, there are 66 currently only a few examples. Bastianoni et al. [18] use the service life of materials to 67 obtain their annual embodied energy, with an extra 5% as an approximation to the energy 68 consumed by machinery for its implementation. Their model has a number of 69 shortcomings, failing to account for water consumption, waste generation, and 70 manpower, thus obtaining results that could easily be assimilated to the Carbon 71 Footprint. 72 Bin and Parker [19] study the variation in the EF of buildings produced by energy 73 retrofitting (thermal isolation, air containment, and use of renewable energy). Solís- 74 Guzmán et al. [20] develop a calculation model of the EF for the construction phase of 75 residential buildings, which introduces not only the consumption of water during the 76 construction work, but also the food and mobility of manpower. González-Vallejo et al. 77 [21,22] improve the previous model and apply it to approximately 100 buildings that 78 constitute a representative set of the residential sector in Spain. These are classified 79 according to typology and broken down into the different phases of the construction 80 process, thus obtaining results that can be extrapolated to estimate the EF of similar 81 buildings built in that country. 82 Teng and Wu [23] analyze the complete life cycle of an exhibition hall in Wuhan, China. 83 Regarding the operation phase, they include the consumption of energy and water over 84 the estimated service life of the building. In its eagerness to cover the whole life cycle, 85 this model makes mistakes, such as assigning the impact of water consumption to the 86 productive surface of inland and marine fishing areas. 87 5 Finally, other researchers have successfully applied the EF indicator to other life cycle 88 phases of the building, such as urbanization [24] and rehabilitation [25]. In order to obtain 89 a complete life cycle assessment of buildings, unification of criteria for calculations 90 among the various models must first be accomplished. 91 Given the number of processes to be managed during the use and maintenance phase, 92 it is necessary to have a professional Facility Manager (FM, hereinafter) to attend to the 93 technical, economic, environmental and administrative aspects of the building [26]. This 94 FM needs tools that ease the work and allow these factors to be optimized. Both the 95 process and the boundaries of facility management are defined in the series of seven 96 standards UNE-EN 15221:2012 [27], which serve as a reference frame for this 97 professional group. 98 The main aim of this study is to propose a method for the detailed calculation of costs 99 and environmental impact corresponding to the use and maintenance phase of buildings. 100 The EF indicator has been selected for the environmental impact assessment due to its 101 simplicity for the general public [28,29], as well as its capacity to support legislative and 102 regulatory actions [30,31]. 103 The breakdown of costs into materials, manpower and machinery as basic elements for 104 the quantification of the resources consumed also manages to provide transparency to 105 a business sector that, generally, due to lack of knowledge or lack of interest, has yet to 106 be analyzed in depth. The reality is that maintenance and cleaning of buildings constitute 107 a considerable expense, whose detail in budgets is not usually demanded to the same 108 degree as for construction work. However, knowledge of this data would be considered 109 of vital importance to any FM or manager of tertiary buildings. 110 This article presents the latest advances in the study initiated in Martínez-Rocamora et 111 al. [32], and focuses on maintenance and renewal tasks, and final results. Reading the 112 cited article is therefore recommended for a full understanding of the model. 113 6 The following section clarifies certain aspects regarding the system boundaries of this 114 study. Secondly, the singularities of maintenance and renovation of construction 115 elements are determined, and these justify the need to adapt the calculation model from 116 the construction phase. These peculiarities affect the calculation of costs as well as the 117 hypotheses and formulation in obtaining their impact in terms of EF. Finally, the results 118 corresponding to the use and maintenance phase of the case study presented in the 119 aforementioned article are shown and discussed. 120 121 2. System boundaries 122 The system must have longitudinal boundaries to define the start and end points of the 123 use and maintenance phase. After the completion of the construction phase, the building 124 is ready to be occupied, thus beginning the longest stage of its life cycle, which is usually 125 estimated to be between 40 and 100 years. However, defining the end of the service life 126 of a building is not so simple. For example, Adalberth [33] includes the occupation of the 127 building, with an intermediate period for renovation, in the use and maintenance phase, 128 ending with its demolition. This is a rather generalized approach, with slight variations 129 from one study to another. For example, Blengini [13] does not specify whether there is 130 any maintenance work on the building, thus limiting the study to energy, gas and water 131 consumption according to statistical data from Italy. 132 CEN/TC 350 "Sustainability of construction work" includes maintenance, repair and 133 replacement of products, operational energy (HVAC, domestic hot water, and lighting), 134 and operational water consumption in the use phase of the building. This phase ends 135 with the beginning of deconstruction. The standard UNE-EN 15978:2012 [34] 136 establishes, in the first place, that the use phase extends from the end of the construction 137 work until the building is about to be deconstructed/demolished. 138 7 In short, most authors state that the occupation stage of the building ends with its 139 demolition. However, when a building is no longer habitable, we are faced with the 140 decision of whether to demolish or rehabilitate, and it is more common to opt for 141 rehabilitation for both economic and environmental reasons [35]. In that case, would the 142 building, whose life has been extended as a result of the rehabilitation, be the same 143 building? Otherwise, would this be a new building beginning its life cycle? 144 In response to this question, the following assumption is made in the present study: the 145 service life of a building ends when it is no longer habitable. For the model here 146 proposed, a building in a poor condition that is subsequently rehabilitated undergoes 147 major changes, both in its constructive solutions through a possible energy rehabilitation 148 and in its installations, which are modernized with the consequent changes in its 149 consumption patterns. It could even happen that, with the rehabilitation, the building 150 changes the type of use it was originally intended for. Therefore the building that 151 undergoes a rehabilitation is considered as a new building that is beginning its service 152 life [36]. 153 In the following section, a number of peculiarities of maintenance tasks are identified 154 regarding the definition of their corresponding costs, which will allow those tasks to be 155 broken down into the three main components: manpower, materials, and machinery. A 156 number of modifications in the previous methodology [32] for the application of the EF 157 indicator to the use and maintenance phase of buildings are also defined. 158 159 3. Methodology 160 3.1. Singularities of maintenance costs 161 The concept of maintenance is divided, in this study, into four different activities: 162 predictive, preventative, and corrective maintenance, and the renovation of constructive 163 8 elements. The cost structure defined in previous advances of the study [37] is 164 implemented, which relies on the Andalusian Construction Costs Database (ACCD) [38]. 165 The development of costs for the maintenance tasks does not use Functional Costs (FC) 166 in the upper level as it does for the cleaning tasks [32]. Although, in cleaning tasks, the 167 building is divided into functional cells excluding each other, i.e. the different types of 168 rooms or spaces, maintenance is mainly performed on construction elements: doors, 169 windows, installations, floors, painted surfaces, etc. These elements are expressed in 170 the same way as in a construction project. 171 Therefore, the costs for maintenance tasks are developed in Complex Costs (CC) when 172 they include several Simple Costs (SC), or in SC when it comes to actions for which the 173 manpower, materials and machinery necessary to carry them out can be directly 174 quantified [39]. In general, CC will be used for repair or renovation tasks, since they 175 usually include demolition and re-construction tasks already existing in the ACCD, 176 sometimes with slight modifications. 177 In Fig. 1, the structure of a CC (upper level) is shown, for the renovation of gypsum 178 plaster on walls. The amount of plaster to be renewed is exactly the same as in the bill 179 of quantities of the construction phase. As these costs are included in the estimation 180 from the project phase, the quantity of this element will be directly transferred from the 181 execution of the plaster at the construction phase, thereby implying no extra effort for the 182 professionals to adapt to this model. This CC is composed of three SC: one of demolition 183 of the existing plaster, another for the application of the new plaster, and another for 184 painting the new plaster. 185 15 Although the Hd factor is cancelled, it has been left inside Eq. (7) since it clarifies the 319 reasoning followed for the calculation. 320 𝐸𝐹 𝑓𝑜 =𝐻𝑤 𝐻𝑑 ·𝑀𝑑𝑖𝑓·𝐻𝑑 𝐶𝑐 ·∑𝐸𝐹𝑖 𝐷𝑦 𝑖 (7) 321 where EFfo, represents partial EF of food consumption (gha/year); Hw, total number of 322 hours worked per year (h/year); Hd, hours worked per person each day (8 h/person/day); 323 Mdif, metabolic-rate difference depending on the job description (kcal/h) (Table 3) [61]; 324 Cc, total daily consumption of calories per person (kcal/day) [62]; EFi, footprint of food 325 consumption per person in EF category i (gha/person/year) (Table 2); Dy, days in a year 326 (365 days/year). 327 Table 2. Ecological Footprint of food in Spain 328 Category i Percentage EFi (gha/person/yr) Cropland 55.30 % 0.809 Grazing land 14.76 % 0.216 Fishing grounds 23.58 % 0.345 Carbon 6.36 % 0.093 TOTAL 100.00 % 1.463 329 The relationship between the metabolic-rate difference and the average caloric intake 330 per person translates into the percentage of EF of the daily diet attributable to the work 331 developed. A low metabolic rate is assumed for the activity that a person would have at 332 home. The metabolic-rate data shown in Table 3 is valid for 30-year-old men, weighing 333 70 kilograms, and of 1.75 metres in height [61]. For calculations of greater precision, 334 these values must be recalculated. 335 336 16 Table 3. Metabolic rate per type of activity [61] 337 Activity Metabolic rate (kcal/h) Average (kcal/h) Sedentary work 85.4 – 108.7 97.1 Administrative work 108.7 – 155.3 132.0 Mason 170.8 – 248.5 209.7 Carpenter 170.8 – 271.8 221.3 Glazier 139.8 – 194.1 166.9 Painter 155.3 – 201.9 178.6 Blacksmith 139.8 – 310.6 225.2 Welder 116.5 – 194.1 155.3 Turner 116.5 – 194.1 155.3 Miller 124.2 – 217.4 170.8 Gardener 178.6 – 295.1 236.8 Machinery driver 132.0 – 170.8 151.4 Crane operator 100.9 – 225.2 163.1 Low metabolic rate 110.3 – 201.9 155.3 Moderate metabolic rate 203.4 – 310.6 256.2 High metabolic rate 312.2 – 403.8 357.2 338 The EF of MSW generation by manpower is obtained with a similar procedure to that of 339 MSW from materials. In 2013 each person in Spain generated 449 kilograms of MSW 340 [63]. Assuming that a person sleeps for 8 hours a day (not generating any waste), that 341 means 0.077 kg of MSW are generated each hour. The EF of MSW from manpower can 342 be determined using Eq. (8). 343 𝐸𝐹𝑀𝑆𝑊 = 𝐻𝑤· 𝐺𝑤· 𝐸𝑀𝑆𝑊 · (1 − 𝐴𝑜𝑐) 𝐴𝑓 ⁄· 𝐸𝑄𝐹 𝑐𝑎 (8) 344 17 where EFMSW represents partial EF of MSW from manpower (gha/yr); Hw, hours of work 345 per year (h/yr); Gw, hourly MSW generation (0.000077 t/h) [63]; EMSW, emission factor of 346 MSW (0.244 tCO2/t) [56]. 347 348 4. Case study 349 The building under study was built in 1948 on the site of the Conqueror’s Square from 350 the Ibero-American exposition of 1929, in Seville, and currently holds the Hernando 351 Colón college hall of residence. For the purposes of this study, a service life of 100 years 352 is assumed from the construction date. It is a T-shaped 4-storey detached building which 353 can host up to 139 residents. Its 7,187 m2 of built-up surface are mainly dedicated to 354 students’ rooms and facilities (gym, library, playroom, dining hall, kitchen, offices, store 355 rooms and meeting halls. 356 Since maintenance and renovation tasks are under study, the building’s description here 357 provided focuses on coverings, finishes and installations. Floors are mostly covered with 358 terrazzo, with several areas covered with marble or ceramic tile. Walls have textured and 359 smooth paint, with a marble plinth in certain areas. Windows are single-glazed with 360 anodized aluminum frames, while doors are mostly of painted light wood. 361 Regarding the installations, there are two gas-oil boilers with 160,000 kcal/h of useful 362 power in the semi-underground floor, fed by a 7500-liter diesel C tank buried outside the 363 building, which are used for Domestic Hot Water (DHW) and radiators. On the rooftop 364 there are four heat pumps with 33 kW of cooling capacity and 40 kW of heating capacity, 365 feeding a fan coil system distributed through every room. There is also a propane tank 366 in the outside with a 1029-liter capacity used for the kitchen. 367 Table A1 of Appendix A represents the maintenance plan assumed for the building, 368 since periodicities of the main maintenance and renovation tasks [43] have been adapted 369 to the building’s real conditions as well as to suggestions from the professionals in charge 370 of FM. A summary table of this maintenance plan is shown in Table 4. 371 18 Table 4. Maintenance and renovation plan of the case study building [43] 372 Element Task Periodicity (years) Interior walls and doors Repainting 4 Façades 10 Wooden doors Renovation 30 Metal doors 75 Stone flooring 75 Ceramic flooring 50 Sewerage system pipes 30 Sanitary elements 35 Electricity 35 HVAC machines 30 373 In the following section, the results from the application of the methodology in Section 3 374 to this case study are shown. Since the previous article focused on cleaning tasks and 375 utility consumption, on this occasion results are shown for maintenance and renovation 376 tasks, as well as final results of the complete model. 377 378 5. Results 379 The implementation of the explained methodology allows the results to be analyzed in 380 detail. It is therefore possible to determine the tasks that incur a greater cost or 381 environmental impact during the service life of the building. In this way, the aspects to 382 which priority should be given to the reduction of their impact can be identified. In the 383 previous article [32], the analysis of results focused on cleaning tasks and utility 384 consumption. This time the results of maintenance tasks and the overall results of the 385 whole set of tasks contemplated in the model are analyzed. It is important to remember 386 that the results of the cleaning branch from the previous publication have been modified 387 through changes in the calculation of the EF of food consumption. In Table 5, a summary 388 of the results for maintenance tasks classified by impact source and category of 389 productive land is shown. 390 19 Table 5. Annual Ecological Footprint of the maintenance and renovation tasks 391 RESOURCE CONSUMPTION ANNUAL ECOLOGICAL FOOTPRINT OF MAINTENANCE (2015) IMPACT DRIVER CONCEPT CROPLAND GRAZING FISHING FOREST CARBON BUILT-UP TOTAL % (gha/yr) MATERIALS TOTAL 0.928 9.212 10.141 97.62% MANUFACTURE 0.928 6.576 7.504 72.24% TRANSPORT 0.323 0.323 3.11% Materials MSW 2.314 2.314 22.27% MANPOWER TOTAL 0.110 0.029 0.047 0.027 0.214 2.06% FOOD 0.110 0.029 0.047 0.013 0.199 1.92% Manpower MSW 0.014 0.014 0.14% MACHINERY TOTAL 0.001 0.001 0.000 0.031 0.034 0.32% TOTAL (gha/yr) 0.111 0.031 0.047 0.928 9.271 0.000 10.388 100% (%) 1.07% 0.30% 0.46% 8.94% 89.24% 0% 100% 392 The EF of the maintenance of the Hernando Colón Hall of Residence is calculated as 393 10.4 gha/yr expressed in terms of the EF of 2015, taking into consideration that this is 394 an arithmetic mean which does not reflect reality, since the impacts of maintenance, 395 unlike those of cleaning or utility consumption, widely differ every year. Maintenance and 396 renovation tasks take place with periodicities generally greater than one year, thereby 397 causing punctual impacts that produce peaks in a hypothetical timeline of the EF of the 398 building. The total impact during its service life due to these activities is approximately 399 877 gha, and the total cost is around 5.7 M€ when economic [64] and environmental 400 discount rates (BLUE map scenario) are applied [65]. 401 The manufacture of building materials accounts for most of the EF of maintenance tasks, 402 which translates into the clear predominance of the carbon footprint and forest land 403 components. Therefore, something similar to that which happens in the construction 404 phase [21] also occurs with maintenance tasks, which is to be expected given the 405 analogous nature of the two processes. Moreover, a high percentage of EF due to the 406 management of MSW is observed, mostly produced by the demolition of elements to be 407 renewed and the low recycling rate applied in maintenance tasks. 408 20 Regarding the comparison of these results with those of the cleaning tasks (Table 6), 409 although the total EF of maintenance doubles that of cleaning, the economic cost is 410 approximately 25% of that of the cleaning tasks. This is due to the great need for 411 manpower in cleaning tasks, whose cost is considerably higher than that of materials. 412 The annual EF of use, cleaning and maintenance is 95 gha, mostly composed of carbon 413 footprint, as is usual in the application of the EF indicator to the building sector. 414 Table 6. Annual Ecological Footprint of Use, Cleaning, and Maintenance 415 IMPACT DRIVER CROPLAND GRAZING LAND FISHING GROUNDS FOREST LAND CARBON FOOTPRINT BUILT-UP SURFACE TOTAL EF COST (gha/yr) (1000 €) USE 76.747 2.636 79.383 98.6 CLEANING 1.445 0.386 0.616 0.692 1.861 5.001 303.5 MAINTENANCE 0.111 0.031 0.047 0.928 9.271 10.388 74.8 TOTAL 1.556 0.417 0.664 1.620 87.879 2.636 94.772 476.9 416 If 139 residents are assumed to be hosted in the Hernando Colón Hall of Residence, 417 then the annual EF per person is 0.682 gha/pers/year, which is approximately 17% of 418 the EF per capita in Spain in 2013 [66]. Furthermore, taking into account the plot area of 419 10,500 square meters, the EF per area unit is 0.59 gha/m2 or 0.009 gha/m2/year. 420 Compared with the EF of similar projects in the rest of life cycle phases, the EF of this 421 phase is 20 times that of the urbanization phase (0.03 gha/m2) [24], 2.5 times that of the 422 construction phase (0.24 gha/m2) [22], and 10 times that of rehabilitation (0.06 gha/m2) 423 [25]. 424 It should be noted that, with respect to the cited works and that by González-Vallejo et 425 al. [60], the change in the calculation applied to food consumption produces a reduction 426 of approximately 86% in the corresponding partial EF, which means that, if 427 methodologies were unified, then the proportion would be even higher. This reduction 428 21 would be partially diminished by the increase of the carbon footprint component in 33% 429 due to the application of the new findings by Mancini et al. [53]. 430 If the aforementioned studies were unified, a clear dominance by the construction and 431 the use and maintenance phases would arise, representing 26% and 64% of the total life 432 cycle EF, respectively. Compared with the distribution in the study by Teng and Wu [23], 433 where these phases represented 64% and 36% of the life cycle EF, the results reflect 434 opposite findings. This difference in the distribution is due to the service life assumed for 435 the building under study in Teng and Wu (45 years), and the omission of maintenance 436 and cleaning tasks during the use and maintenance phase, as well as other 437 methodological differences between the studies involved in this comparison. 438 On extending the results to the full 100 years of the service life of the building (1948- 439 2047), with updated impacts and costs, utility consumption represents 80% of the EF of 440 this phase. Bearing in mind that the model is applied to a specific building, the results 441 obtained for cleaning and maintenance are higher than expected (6% and 14%, 442 respectively), thereby justifying the need to study these tasks in detail, as carried out in 443 this work. Cleaning tasks have a relatively considerable impact, especially in non- 444 residential buildings, since cleaning frequencies therein are higher than in the domestic 445 environment. 446 As for the economic cost, cleaning is the largest investment (21.6 M€), followed by utility 447 consumption (7 M€), and 5.7 M€ of maintenance and renovation. The type of building 448 studied exerts a high influence on these proportions, whose use profile requires great 449 investment in cleaning; something that seldom happens in other types of tertiary 450 buildings, such as offices or shopping centers. 451 Next, the distribution of EF and costs over the service life of the building are analyzed 452 (Fig. 2), whereby long-term scenarios for costs [64] and EF [65] are applied. It has been 453 decided to accumulate results in periods of five years for two main reasons: firstly, the 454 22 periodicities used for maintenance are mostly multiples of this value; secondly, it cannot 455 be assumed that all tasks whose periodicity coincides are executed within the same year, 456 and hence it is estimated that they are carried out within that five-year period. The latter 457 is based on the assumption that each maintenance task is small and independent from 458 the rest. 459 460 Fig. 2. Cumulative EF and costs applying long-term scenarios 461 When representing the results with applied discount rates, the graph is deformed 462 accordingly (Fig. 2), which is a problem when identifying in which periods cost and EF 463 peaks are actually produced. It is therefore necessary to calculate the cumulative cost 464 and EF without applying discount rates (Fig. 3), so that the fluctuation of impacts can be 465 more easily appreciated. 466 23 467 Fig. 3. Cumulative EF and costs for five-year periods 468 It is observed that peaks occur every 30 years in the EF, with an isolated peak at 75 469 years, at which point the high-resistance carpentries and stone floorings are renewed. A 470 higher proportion of forest land EF can be observed in years multiple of 30, 471 corresponding to the renovation of interior wooden doors. As for the economic cost, 472 peaks occur every 10 years, being these not due to any particular task, but to an 473 accumulation of many tasks. 474 If the EF and cost of each task are analyzed (Table 7), then it can be seen that in cleaning 475 there is a correspondence between the cost and the EF of the tasks that predominate in 476 the results, since these factors are marked by the necessity of manpower. Specifically, 477 there are seven tasks that account for approximately 52% of the EF and cost of cleaning, 478 mainly due to their high frequency and the number of rooms of that type present in the 479 building under study. These cleaning tasks correspond to those of greater frequency in 480 public bathrooms and shower rooms, bedrooms, corridors, and in the dining room. Based 481 on these calculations, solutions for the reduction of both factors can arise, such as 482 alternative building distributions, configurations of elements present in those rooms, or 483 other means to increase the efficiency of cleaning staff. 484 24 In maintenance, on the other hand, the high incidence of the embodied energy of 485 materials means that those tasks with a greater cost do not always correspond with those 486 of greater EF. Five actions represent 32% of the total cost of maintenance: repainting of 487 façades, renovation of mortar in façades, renovation of fan-coils and electronic locks in 488 bedrooms, and pruning of trees. 489 Table 7. Cleaning and maintenance tasks with the highest economic and 490 environmental impact 491 Cleaning task Cost (M€/yr) % EF (gha/yr) % Twin en-suite bedrooms 2.3 10.72% 38.19 10.64% Shared bathrooms 2.3 10.69% 38.06 10.61% Shower rooms 1.7 7.85% 27.98 7.80% Single bedrooms 1.4 6.54% 23.26 6.48% Corridors 1.4 6.47% 22.97 6.40% Dining room 1.2 5.53% 19.65 5.48% Hall 1.1 5.08% 18.04 5.03% Maintenance task Tree pruning 0.47 8.61% 3.78 0.48% Repainting of façades 0.46 8.54% 17.28 2.18% Electronic coded lock 0.32 5.90% 5.20 0.66% Renovation of fan-coils 0.26 4.72% 87.42 11.01% Renovation of mortar in façades 0.21 3.94% 27.52 3.47% Renovation of interior doors 0.15 2.72% 52.91 6.66% Renovation of car park asphalt 0.02 0.33% 52.47 6.61% Renovation of interior plaster 0.16 3.02% 27.93 3.52% Renovation of closet doors 0.07 1.28% 27.74 3.49% 492 There are six tasks that cause almost 35% of the EF of maintenance: renovation of fan- 493 coils in bedrooms, renovation of interior doors and those of built-in wardrobes, the 494 resurfacing of the car park, and the renovation of mortar in external facades and plaster 495 in interior walls. The great impact of the renovation of doors is due to the considerable 496 EF of forest land assigned to wooden materials. On the other hand, the high number of 497 fan-coils present in the building and the embodied energy of asphalt materials cause the 498 EF of their renovation to stand out. To alleviate such impacts, it would be advisable to 499 31 http://data.footprintnetwork.org/compareCountries.html?yr=2013&type=EFCpc&c 739 n=203 (accessed July 31, 2017). 740 741