CETHS Post Occupancy Evaluation: Residents' Perception on Design, Plot, and Comfort, Manuais, Projetos, Pesquisas de Arquitetura

Baixe CETHS Post Occupancy Evaluation: Residents' Perception on Design, Plot, and Comfort e outras Manuais, Projetos, Pesquisas em PDF para Arquitetura, somente na Docsity! PLEA 2003 - The 20th Conference on Passive and Low Energy Architecture, Santiago – CHILE, 9 - 12 November 2003 Environmental Comfort Perception in the Alvorada Sustainable Low Cost House Alessandro Morello; Giane de C. Grigoletti Aline Barroso; Constance Manfredini; Miguel Aloysio Sattler Núcleo Orientado para a Inovação da Edificação. Programa de Pós-Graduação em Engenharia Civil. Universidade Federal do Rio Grande do Sul Av. Osvaldo Aranha, 99. Porto Alegre. RS. Brazil Tel.: (51) 3316 3900 / Fax: (51) 3316 4054 Email: sattler@vortex.ufrgs.br ABSTRACT: This paper describes part of a larger study, developed by Núcleo Orientado para a Inovação da Edificação (NORIE), that deals with the urban and architectural design, construction and post occupancy assessment of Centro de Tecnologias Habitacionais Sustentáveis (CETHS), started in 1999. The settlement is located in the city of Nova Hartz, in the metropolitan area of Porto Alegre, capital city of the Southernmost State of Brazil. The settlement, so far, has eight occupied one-floor single-family houses. CETHS was submitted to post occupancy evaluation on several features that were considered in the design stage, such as: local food growth, income generation, environmental comfort, building functionality, spaces appropriation, among others. These studies intended to verify the efficiency of sustainable strategies that were adopted in the design stage. The results of research will allow modifications of the original design for future implementations. The presented results were obtained through post occupancy evaluation of building environmental comfort (thermal, luminous and acoustical) and design aspects. The tools used in the survey were interviews and questionnaires carried out with the residents of six houses of the settlement. The aim was to verify the residents’ satisfaction. It is hoped with the obtained information, to better develop and improve the design of the house. Conference Topic: Design for low-income housing Keywords: low-income house, post occupancy evaluation, environmental sustainability 1. INTRODUCTION NORIE has been developing, since 1997, studies on low cost housing, that were designed in accordance with principles of environmental, social and economic sustainability. One of these studies is the urban and building design, construction and evaluation of the Centro Experimental de Tecnologias Habitacionais Sustentáveis (CETHS), which was started in 1999, in Nova Hartz [1, 2]. Nova Hartz is a small town in the metropolitan region of Porto Alegre, capital city of the southernmost State of Brazil. CETHS has, so far, eight one-floor single-family houses [3], already occupied by residents. The design of CETHS aimed at the implementation of an urban settlement based in sustainable principles and technologies applicable to low-income housing, including: local food growth, jobs and income generation, passive and low energy strategies, use of low environmental impact materials, among others. CETHS was recently submitted to a post occupancy evaluation on several issues that were considered in the design phase, such as: environmental comfort, building functionality and spaces appropriation by users. These studies intend to verify the efficiency of the sustainable strategies adopted in the design stage. The results of the research are expected to allow adapting the original design for future implementations. The research aims to verify the residents’ satisfaction with the previously referred implemented strategies, as well as to identify possible improvements that can be implemented with basis on the residents’ perception. Interviews and questionnaires were used in the assessment. These were applied on the residents of six houses of the settlement. The obtained information is expected to help in the implementation of future projects. 2. CHARACTERIZATION Nova Hartz is a small city with approximately 15,000 inhabitants. It has a territorial area of around 60 km2. CETHS is being implemented in an area of 2,3 ha located in the urban perimeter of the municipal district, about 2 km far from its city centre, in an area PLEA 2003 - The 20th Conference on Passive and Low Energy Architecture, Santiago – CHILE, 9 - 12 November 2003 still not totally urbanized. So far, eight houses were built and inhabited (users moved in on July 2002). Six of these houses have the characteristic of being oriented with their main façade to the North direction (Fig. 1 and 2). Figure 1: Location of the houses (in darker shade) in the settlement. Figure 2: General view of CETHS. The six houses described in this paper, have each a floor area of around 48 m², in a plot of about 200 m². Each house has four usable spaces: two bedrooms, a living room/kitchen and a bathroom (Fig. 3), whose materials cost was about US$ 3,000.00. The constructional system employed ceramic bricks masonry. The walls are rendered only where a higher value for thermal or humidity insulation is justifiable or radiation and/or light reflectance requires it (mainly external south and west walls). The foundations were made using the locally available sandstone, topped with fly ash cement concrete beams. The foundation beams are of concrete. The floor simply sits on the ground having a layer of cement mortar topping construction rubble mixed with clay. The roof has a structure in timber, covered with ceramic tiles, with an intermediary layer of recycled aluminium offset sheets, to minimize long wave radiation transmission. As far as possible, the timber structure was made up of recycled wood used in the formwork, being the wood from sustainable managed forests, with no toxic treatment. The same principles of minimum toxicity were also applied to windows, made from eucalyptus and treated with linseed oil, for controlling humidity, and natural substances, for the control of termites. Figure 3: Plan of the house. 3. RESULTS 3.1 Building Design In order to assess the perception of the residents on building design, the following topics were included in the interviews: Table I: Users' perception and satisfaction with the design of the house. 1: size of the house 2: satisfaction (house) 3: number of rooms 4: satisfaction (kitchen) 5: satisfaction (bathroom) 6: space for professional work 7: open areas 8: aesthetics assessment 9: aesthetic modifications 10: changes (made) 11: changes (desired) 12: largest room 13: smallest room 14: windows handling 15: easiness of cleaning 16: artificial lighting 17: easiness of access to switches and outlets 18: number of electrical switches and outlets Table I, below, presents the answers obtained from the interviews: PLEA 2003 - The 20th Conference on Passive and Low Energy Architecture, Santiago – CHILE, 9 - 12 November 2003 Two out five interviewees considered the living room/kitchen (LR/K) the coldest room in winter. Three interviewees did not indicate any room as being colder in the winter. It must be considered that four out of five interviewees already spent one winter living in the house. The presence of small gaps through the external windows and doors (due to construction flaws), leads to air infiltration and causes heat losses, in winter, even when the windows and doors are closed. At the same time, as in the region summer is harder to stand than winter, thermal comfort is also more difficult to achieve in summer. Thus, it is understandable that residents are more tolerant to winter conditions than in summer. In winter, the simple act of keeping the openings shut seems to supply the residents’ comfort needs. This perception could also be attributable to the north orientation of the windows. Only one of the interviewees declares to use an electric heater in winter. But, this fact can also be associated to the lack of economical conditions of most residents. As pointed out by the interviewees, it can be concluded that the house presents more unfavourable conditions in summer than in winter. Landscape in the settlement is quite bare (the plot, in general, has little vegetation to promote shade and to lower the temperature of the air). This fact also reduces the possibility of reception of fresh air from outside that would help lowering indoor temperatures. 3.4 Luminous Comfort The residents were considered as meeting luminous/visual comfort, when able to develop their daily tasks, requiring good visibility, with no complaints. The house was considered as offering (natural) visual comfort when the user did not need to turn on the electric lights for the development of these tasks, during the period of the day (just needing to open the louvers of the windows). For assessing luminous comfort, the following topics were considered in the interviews: 1. Need to turn on the lights, during the day (state the room), in summer (even with the window is open); 2. Need to turn on the lights, during the day, in winter; 3. Use of curtains or other shading devices to avoid excess light entering a room; 4. Clearest room in summer; 5. Clearest room in winter; 6. Darkest room in summer; 7. Darkest room in winter; 8. Place where the interviewee accomplishes tasks that require a higher illumination level; 9. Type of activity requiring higher illumination level; 10. Room where children use to accomplish their homework. Table IV, below, presents the results obtained with regard to visual comfort. Table IV: Perception of the interviewed users on visual comfort. HOUSE NR 1 2 3 4 5 6 1 no no no no no ** 2 no no no * BR2 ** 3 no no no no no LR/K 4 LR/KBR1 LR/K LR/K BR1 LR/K LR/K BR1 LR/K BR1 5 LR/KBR1 LR/K LR/K BR1 * LR/K LR/K BR1 6 BR2 BR2 BR2 BR2 BR2 BR2 7 BR2 BR2 BR2 * ** * 8 LR/K LR/K LR/K LR/K LR/K LR/K 9 Accounting,reading reading sewing shoe making sewing sewing * 10 no no BR1 BR2 BR2 LR/K ** the interviewee moved into the house six months before. As a consequence they did not know how to reply to the question; * * The interviewee did not answer the question. As it can be verified in table IV, the interviewees declared that it is not necessary to turn on the lights inside the rooms, during the day, in summer, when the windows are open. Just one of the residents didn't answer the subject. All users pointed out the living room/kitchen as the clearest room, both in winter and in summer. Four out of six residents also pointed out the bedroom at the façade, as one of the clearest rooms, in both seasons. On the other hand, the bedroom at the rear of the house was pointed out, by most of the residents, as being the darkest. However, just one of the interviewees declared necessary to turn on the lights, in this room, to improve visibility, even in winter. The users pointed out the following activities as being the ones demanding higher illumination levels: sewing, reading, writing and knitting. Everybody declared performing such tasks in the room/kitchen. However, It is not possible to conclude that these activities are developed in this room just because it is the clearest of the house. It should be observed that usually, it is in this room that they have the furniture for the accomplishment of the mentioned tasks (tables, sewing machines, etc.). Just one of the interviewees affirmed that he had to hang a curtain on the west-facing window (living room /kitchen) to avoid the direct incidence of the solar radiation. Coincidentally, that happened in the last house (house number 6), whose window is not shaded by the adjacent house (see implementation in Fig. 1). The place where the children developed their homework it considered of little significance, as it was chosen by other reasons than its brightness. In general, the aspects of visual comfort related to daylighting were achieved, according to the users' opinion. However, it must be stressed that in communities of low income, the extent of the inhabitants' demand regarding daylighting, can be below that recommended by the regulations and literature on the subject. PLEA 2003 - The 20th Conference on Passive and Low Energy Architecture, Santiago – CHILE, 9 - 12 November 2003 3.5 Acoustical Comfort Some potential noise sources oriented the formulation of questionnaires to evaluate the residents' acoustical comfort, both outdoors as indoors. The interviewees were questioned on issues like the noise produced by traffic in the nearby road, noise produced by neighbours and also on noise generated inside the houses and their interference in the daily activities. The following topics were included in the questionnaires to assess acoustical comfort: 1. Uncomfortable, due to traffic noise (nearby road); 2. Uncomfortable, due to the noise caused by the neighbourhood; 3. Uncomfortable, due to traffic noise on the local street (settlement street) during the night; 4. Uncomfortable, due to indoor noise. Table V shows the obtained results regarding the users' acoustical comfort. Table V: Users’ perception on acoustical comfort. HOUSE NR. 1 2 3 4 5 6 1 no no no no no no 2 no yes no yes no yes 3 yes yes no yes no yes 4 no no no no no yes All the interviewees affirmed that the noise from cars, coming from the nearby road does not cause any inconvenience. However, half interviewees' declared that they are disturbed by the neighbours' noise during the day (due to the music of sound appliances). Four out of six interviewees complained from the noise caused by the deliberate acceleration of vehicles, in the local street, in the night period. Five out of six residents declared that the noise produced in the living room/kitchen (music from radio or sound appliances, the television set or conversation), does not interfere in their residents' activities, when they are in their bedrooms with the doors closed. It can be concluded that the house presents reasonable conditions of acoustic insulation. There are few situations where noise interferes in the usual daily tasks of the interviewees. It was observed that the sixth interviewee was the one that presented more complaints regarding acoustical discomfort. That is also due to existing gaps between the door and window frames and the involving masonry. 4. CONCLUSIONS The obtained results, in relation to aspects of building design and plot, allow drawing the following modification proposals: -larger open areas (increasing size of the plot) to allow for the vegetation growth; -living room/kitchen in separate spaces (users considered the existing areas as being too small in the existing layout); -reduction of the area of the bathroom (considered too large by inhabitants, in relation to the total area of the house); -walls rendered and coloured or with impermeable painting, for easiness of cleaning (present in the design but not executed); -larger veranda to allow its use as a resting area for the whole family; -access to the higher windows to allow cleaning and manipulation; -increased ventilation in the bedrooms; -external shading elements in the east and west walls, such as pergolas with deciduous trees (present in the design, but not executed); -use of top ventilation inserts in the external and internal doors to allow permanent ventilation in the summer, even when they are shut; -roof ventilation for improving the thermal performance of the roof (present in design, but not executed); -rendering of the walls of BR2, pointed out as the darkest of the house, to increase illumination levels. In general, the inhabitants of the settlement houses are happy with them. The results obtained from the survey, pointed out the importance of the participation of future users in the design phase. The design of the houses was developed before its future users' definition, fact that did not allow the consideration of the users' needs in this phase. Most inhabitants pointed out that the majority of problems are due to the bad execution of the houses. This results in a diminished satisfaction of the users with the houses, not only in relation to thermal comfort, but also with the house quality, in general. However, the low standard of the houses previously occupied by the inhabitants (very low standard wood houses) seems to contribute towards a positive aesthetic perception, by users, in relation to their new dwelling, fact corroborated by the “finding it pretty " response in the interviews. Concluding, it is pointed out that some criticisms of the users in relation to the house probably would be reduced if they were built according to the original design and/or to best suit the users specific requirements. REFERENCES [1] SATTLER, M.A. Sustainable Housing for the Brazilian Poor. In: Proceedings of PLEA 96 – Building and Urban Renewal. Louvain-la-Neuve, Belgium, 1996. pp. 313-318. [2] SATTLER, M.A and SPERB, M.R. Experimental Centre for Sustainable Housing Technologies.. In: Proceedings of PLEA 2001 Conference – Renewable Energy for a Sustainable Development of the Built Environment. Florianópolis, Brazil, 2001. pp. 1107-1108. [3] SATTLER, M.A ; COSTA FILHO, A. and BONIN, L.C. A low cost sustainable house. In: Proceedings of PLEA 2000 Conference – Architecture, City, Environment. Cambridge, UK, 2000. pp. 187-191.