"Cons" at the moment of introducing new eco-efficient technologies to build a detached house. Case Study: A house in Palomares del Rio (Seville)

Proceedings of the II International and IV National Congress on Sustainable Construction and Eco- Efficient Solutions 843 ‘CONS’ AT THE MOMENT OF INTRODUCING NEW ECO-EFFICIENT TECHNOLOGIES TO BUILD A DETACHED HOUSE. CASE STUDY: A HOUSE IN PALOMARES DEL RIO (SEVILLE) 1 *Moreno Rangel, David; 1 Fernández Expósito, Manuel; 1 Esquivias Fernández, Paula M. 1 Grupo TEP 130: “Arquitectura, Patrimonio y Sostenibilidad: Acústica, Iluminación, Óptica y Energía”. Instituto Universitario de Arquitectura y Ciencias de la Construcción (IUACC). Universidad de Sevilla. Avenida de la Reina Mercedes 2, 41012 Sevilla, España e-mail: *davidmo[email protected] ABSTRACT The need for construction and restoration of buildings within an ecological and sustainable manner is highlighted in this increasingly aware global world; so it is very easy to fail thinking on how simple it could be to execute certain eco-efficient constructive proposal in any project, no matter its size. Despite having previous experiences in construction of several prefabricated buildings (fire stations, offices, schools), and participating in some important research projects on studying new eco-efficient constructive proposals for dwellings, as the Patio 2.12 project for Solar Decathlon Europe 2012, that was the mistake our team failed into when we decided to incorporate a new more efficient constructive system in a private promoted detached house project. This works shows, by means of a real and built example, that kind of things that is not usually told in a congress or an article: all those problems found during the incorporation process which have to be controlled to improve the viability of any building project which pretends to apply new solutions. In this case, the problem was to move from a traditional detached house project based on a system of structural walls with 3cm of insulation, plastered and painted, floor slabs with beams and concrete slabs, balustrades and small windows, pitched roofs... (private promoter’s first idea) to a contemporary house project based on a Steel Frame system with 14cm of insulation, and multiple eco-efficient architectural strategies, with mezzanine floor, double height and large windows(final project) ... at the same price and lesser execution time. All those problems our team had to face and the different constructive proposals and professional decisions we reached out during the different phases of this project, from first stages to the end of the building process, to obtain at the same price a detached house executed in less time and with more material and environmental quality than a traditional one through the incorporation of eco-efficient proposals are shown in this paper by adding real budgets, time programs, comparative studies, sketches, drawings and photographs. In spite of the economical crisis, this house has risen 50% in value. Keywords: Eco-efficient proposals, Steel frame, Viability, Rise in value Chapter III – Energy Efficiency 844 1.-Introduction The world of the construction in particular and the society in general is, fortunately, increasingly aroused by the need to construct and rehabilitate following an ecological and sustainable speech [1]. Architecture is been complemented with adjectives that try to describe a course to the change (ecological, green, sustainable, eco-efficient, bioclimatic, environmental …) in spite of the fact that still we do not know the differences between the different meanings of those adjectives. The market is been filled with patents commercialized by huge companies, constructive or structural solutions, regarding hygrothermal conditioning, energy efficient alternatives, that assure to improve the quality of life minimizing their environmental impact [2]. Eco-efficient constructive solutions are necessary, this is well-known and few people will question this reality. Nevertheless we are not always conscious about the difficulty an architect has to face with at the moment of wanting to introduce one of these constructive alternatives in any architectural project. Facing this panorama it is easy to fall down in the mistake of thinking how easy it could be to execute certain eco-efficient solutions in any project [3] [4], for small that it could be, especially when the developer companies are anxious to obtain clients and to demonstrate their scientific progresses and that’s why they will provide architects any help they need. In spite of previous experience at the execution of different prefabricated buildings (fire stations, offices, schools, housings) and participation in some important research projects focused on finding new eco-efficient constructive solutions for dwellings (as the Patio 2.12 project for the Solar Decathlon Europe 2012 competition) this one was the mistake we did when we decided to apply a new more efficient construction system when a private promoter ask us to design and build an single-family house. 2.-Objectives The aim of this work will be to show by means of a real and executed case study, those aspects that is not usually told in an article or in a conference: all the disadvantages of these processes that need to be controlled to provide viability to any project trying to apply new eco-efficient solutions. Firstly this work will compare the traditional and habitual constructive systems with their eco-efficient alternatives highlighting the advantages, but noticing the disadvantages that arise during the whole building process (from the preliminary design up to the end of the execution of the building). 3.-Methodology The case study is a building project which architects are two of the authors of this work (Dr. David Moreno Rangel and Manuel Fernández Expósito). The tasks done and the difficulties found will be described in a sequential process for each stage of the architectural project. Provided that this case study has served as base for the elaboration of a Master Thesis of the student Enrique Ramos Torres titled ‘alternative constructive systems: prefabrication and industrialization’ supervised by Dr. David Moreno Rangel, some of his research results will be shown to support some considerations and conclusions of this communication. The main objective of this work is to bring to light currently in existence alternative constructive systems showing their characteristics and basic specifications: materials, constructive sections, assembly, execution times, economical aspects, technical difficulties among others aspects. Proceedings of the II International and IV National Congress on Sustainable Construction and Eco- Efficient Solutions 845 Although some exemplifications are made based on this project, this experience is acquired after the execution of diverse promotions of this typology, including the participation in the research project about eco-efficient and sustainable detached house for Solar Decathlon Europe: Patio 2.12. 4.-Case study A single-family house placed at the council area of Palomares del Río (Seville, Spain) is proposed as case study. It is developed in a unique floor. The living room has the double of the normal height and it has a small mezzanine. Its built area is of 135.74 m 2 and a useful total area of 117.23 m 2 (Table 1). Useful area 117,23 m 2 Ground floor 105,89 m 2 Bedroom 1 8,79 m 2 Bedroom 2 8,82 m 2 Bedroom 3 8,54 m 2 Bedroom 4 15,34 m 2 Bathroom 1 4,09 m 2 Bathroom 2 4,12 m 2 Corridor 6,13 m 2 Hall 5,84 m 2 Kitchen 8,80 m 2 Living-dining room 35,42 m 2 Mezzanine 11,34 m 2 Studio 11,34 m 2 Table 1 “Useful area of the case study” It has four bedrooms (two doubles and two singles), two bathrooms, a dressing room, a kitchen, a hall, a double-height living room, a studio and a dining room (fig. 1). Fig. 1 “Case study: ground floor, mezzanine and two perspective views”. Source: estudio Heliopausa Chapter III – Energy Efficiency 846 It is placed not centred at the top of its 1100 m 2 piece of ground, opening two big windows facing southeast towards the freer area of the plot where the property will create a garden and build a swimming pool (fig. 2). Fig. 2 “Case study: Final location at the plot and some photographs during the execution”. Source: estudio Heliopausa Proceedings of the II International and IV National Congress on Sustainable Construction and Eco- Efficient Solutions 847 This case study has also been taken by Enrique Ramos Torres as an example to develop his Master Thesis titled ‘alternative constructive systems: prefabrication and industrialization’ within the master course Sustainable City and Architecture, official title of the University of Seville. 5.-Initial studies There were several start point premises exposed by promoters that helped to convince them about the need to use industrialized and prefabricated constructive solutions [5] [6], introducing eco-efficient solutions that clearly improved their quality of life as well as the relationship between useful surface/built surface. - The house had to be built within 4 months - The improvement of the traditional habitability conditions resulted from an selfbuilt house At initial design stage, six different design were made (fig. 4) complemented with their corresponding study of surfaces and economic valuation compared with the traditional system and other alternative prefabricated systems (fig. 3). It has to be noticed in this moment that there were important economic differences between those offers received by construction companies specialized in traditional solutions and by those companies focused on any eco-efficient system, at this preliminary design stage, all of them made by real companies and under competitive specifications. In this stage Balloon frame (26% cheaper than a traditional one), Steel frame (similar offer), Steel box (5% more expensive than a traditional one) and prefabricated concrete elements (38% more expensive than a traditional) companies were analysed. After the first meeting with promoters another seven variations were decided to be done trying to adapt to the needs of them and to the constructive and technique requirements of the chosen prefabricated solution. Fig. 3 “Case study: estimated economic comparison”. Source: estudio Heliopausa Chapter III – Energy Efficiency 848 Fig. 4 “Case study: initial proposals”. Source: estudio Heliopausa The final solution was valued by 82 companies, 71 of them were national companies and 11 of them were foreign companies, specialized in 7 different prefabricated and industrialized solutions (fig. 5): projected concrete over expanded polystyrene (EPS), EPS panels shuttering, EPS blocks shuttering, prefabricated concrete panels, crossfibres laminated wood panels, Balloon frame and Steel frame. Proceedings of the II International and IV National Congress on Sustainable Construction and Eco- Efficient Solutions 849 Fig. 5 “Distribution of offers obtained by solution”. Source: Enrique Ramos Torres (Master Final Project) Most of these companies sent a budget structured by chapters without details about their components. At the second requirement they reduced the budget. The costs of those chapters are compared below (fig. 6) Fig. 6 “Comparison of the 1st and the 2nd economic offers received classified by constructive solutions”. Source: Enrique Ramos Torres (Master Final Project) A comparison between U-values obtained with every system as ‘default option’ suggested by the company and those theoretical values based on the Catalogue of Construction Elements of the Spanish Building Code was also made (fig. 7), as well as a comparison between average execution times for the end of the building guaranteed by the company (fig. 8) Chapter III – Energy Efficiency 850 Fig. 7 “Case study: theoretical U-values vs provided U-values”. Source: Enrique Ramos Torres (Master Final Project) Fig. 8 “Case study: Constructive solutions, average guaranteed execution time and costs by month”. Source: Enrique Ramos Torres (Master Final Project) Taking into consideration all of these aspects and the requirements of the promoters, Steel Frame structural system was chosen. A summary of the constructive characteristics of every adopted solution is shown below. 5.1-Structural system 5.1.1-Foundation According to the geotechnical study ordered to CEMOSA, a foundation was executed based on a reinforced concrete slab of 40 cm height (HA 25-B-30-IIa, normal control, B-400-S) placed at 1 m depth respect to ground surface. This slab was on a 10 cm of Proceedings of the II International and IV National Congress on Sustainable Construction and Eco- Efficient Solutions 851 poured concrete (HL-150/B/20). It has some embedded Jimten sinks as part of the sewage system. 5.1.2-Supporting structure The supporting structure is a Steel Frame structural system composed by 2 mm thick S250GDZ275 galvanized steel profiles, disposed at vertically (C-form, 175.5x50 mm) and horizontally (U-form, 200x75 mm) linked between them and with foundation by means of hexagonal head self-screw bolts of 6.3x25 mm. 5.2-Construction elements 5.2.1-Vertical external wall External thermal Isolation system composed by: starting screwed steel profile, treatment of the viroc panels supports with RHONA A-2000 devices to bridge the gap, tapping of rigid expanded polystyrene panels (according to UNE-EN 13499 with mortar RHONA T-700) and fixing cleats spread covering 6 unit/m 2 , reinforce devices at every corner by means of corner brackets; superficial panel protection based on two mortar layers reinforced with alkali-resistant fibre glass mesh RHONAMESH T- 150 of 145 gr/m 2 ; first coat layer done with REVIQUARZ; final coating made with white acrylic mortar REVIQUARZ. Interior finishing made with plaster board panels of 15 mm thickness anchored to omega-form steel profiles. The air gap of this structural system has been filled with 10 cm of rock wool of 100 kg/m 3 . 5.2.2-Roof The roof is composed by a non-woven double geotextile layer danofelty PY300 with short polyester fibres of 300 gr/m 2 . Waterproof layer of grey coloured plasticised polyvinyl chloride (PVC) Rhenofol CG 1,2reinforced with non-woven glass fibre synthetic felt with a durability of 40 years, exposed even at the DIT400/R-09 in accordance with CTE. Flat roof system is finished by means of porous filtrón slab and extruded polystyrene, DANALOSA brand of 50x50 cm and 75 mm thickness. Rainwater system is made by ‘pluvia de Geberit’ system connected to sewage system. 5.2.3-Openings PVC frame windows of different sizes and dimensions. Security glazing 4+4 with 6 mm of butyl, air gap of 10 mm, and 4+4 with 6 mm of butyl. Kimberling premiline PVC frame system with thermal break and neoprene air tightness joints. Slide, close and security features. 5.2.4-Partitions Made by means of plaster board partition 46/600 composed by two plaster board layers of 15 mm thickness each screwed at each side of a galvanized steel structure of horizontal and vertical profiles of 46 mm with a separation of 600 mm between axis. Between the two double plaster board layers the partition incorporate a rock wool panel of 40 mm thickness. 5.2.5-Building services Conventional building services are implemented. The house is completely equipped with plumbing, sewage, electricity, telecommunications, cooling and heating active systems (a fireplace included), solar collectors and hybrid ventilation services. It has to be highlighted the Geberit system installed at the roof to execute it without slope, as well as those Jimten sinks embedded in the reinforced concrete slab.