CONCERNS AND TRENDS IN BUILDING ENERGY EFFICIENT DWELLINGS IN ROMANIA. M. Brumaru and N. Cobârzan Technical University of Cluj-Napoca Romania

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1 Int. Journal for Housing Science, Vol.32, No.4 pp , 2008 Published in the United States CONCERNS AND TRENDS IN BUILDING ENERGY EFFICIENT DWELLINGS IN ROMANIA M. Brumaru and N. Cobârzan Technical University of Cluj-Napoca Romania ABSTRACT In Romania, in the 70es and 80es neighbourhoods with blocks of flats were intensively built, providing a large number of modest dwellings for those who moved from rural to urban localities to work in the new industrial branches. The high rhythm in building and concern for saving materials resulted in poor quality dwellings concerning the thermal comfort and energetic effectiveness, requiring today urgent thermal rehabilitation. The paper presents the constructive solutions for three types of residential buildings conceived following the rules of sustainable, environmental-friendly design. These buildings are analysed taking into consideration alternative thermal insulation details for each, also including the energetic impact of orientation, heating system and the climatic factors, in order to put into evidence the most reasonable solutions. The paper ends with conclusions related to the results obtained following the above analysis and with some recommendations concerning the appropriate solutions for building sustainable, energy efficient dwellings. Key words: Energy, thermal comfort, environmental-friendly design /04/ , 2008 Copyright 2008 IAHS

2 280 Brumaru and Cobârzan Introduction The demographic growth and the urban agglomeration as a consequence of the industrial development highly increased the dwelling demand (Fig.1), making the contractors to focus their attention first up on the number of the buildings erected and less on their quality. The short-term deadlines in delivering new buildings attracted a subsequent low-quality execution, most of buildings erected in the 70es and 80es being today seriously affected by poor thermal comfort, low energetic performance and degradations caused by humidity ,7 78,6 76,6 21,4 23,4 31,3 68,7 38,2 61,1 43,6 56,4 54,3 45,7 52,7 47, , Urban Figure 1 Migration of the population from rural to urban area in (Cluj- Napoca) Rural The residential sector is the second largest energy consumer after the industrial sector, having a final energy consumption of 7,197 toe (tonne of equivalent oil) in The total GHG emmissions gradually diminished, being with about 50% lower in 2002, compared to 1989, owing to the reduction of the industrial production, on the one hand and to the first nuclear-electric power station in function beginning with 1996, on the other hand. With the economic growth and improvement of the quality of life, it is assumed that the primary energy consumption as well as the CO2 emmisions will increase in an alarming way, making necessary the implementation of some measures for energy efficiency in the housing sector. The built environment is fundamental for the economic development and social wellbeing and it is unanimously accepted that without implementing the principles of sustainable development there is no other viable solution for preventing mankind from auto-destruction. The consequences for the construction sector deriving from this statement are multiple, one of the most important being their application beginning with the design stage.

3 Energy Efficient Dwellings 281 The Building Design Compared to other basic consumer goods, the building service life is much longer having a permanent impact up on the environment and the quality of life. Consequently, the building design activities are critical with a view of assuring the possibility of future rehabilitation/reconversion works for answering new exigencies, but avoiding demolition and the related problems of waste generation. Such targets were not taken into consideration in the last 4-5 decades and the result was dramatic: in order to provide appropriate internal comfort conditions also ensuring low energy consumption and CO2 emissions, about 97% of the Romanian building stock should undergo thermal rehabilitation, with an expected result of 60% reduction of final energy consumption. However, the gap between the advanced exigencies of the EU regulations related to the building energetic performance and the low level requirements of the Romanian regulations in the same area - much more permissive, - has been only theoretically bridged. Practically, most of the new buildings are still being designed and executed by ignoring the increasingly severe conditions imposed by the regulations in this period of transition. All these are generating a real need for radically improving both, the designers and beneficiaries attitude and practices against this serious problem. In order to put into evidence the benefits offered by a building conceived following the rules of sustainable design, three different types of buildings have been analyzed, each having the exterior walls considered in two constructive solutions, for which the results of the computational analysis are shown in Table.1. The constructive solutions for the external walls are: I - double layer wall: 30 cm thick, perforated brick masonry (Porotherm) and 10 cm polystyrene; II - simple layer wall: 38 cm thick, perforated brick masonry (Porotherm). Table 1 Thermo-technical characteristics of the building envelope component parts Crt. BUILDING External walls Floor A/V Q nec no. TYPE Constructive R [m -1 ] [kwh/m 2 wall R attic R basement.year solution [m 2 K/W] [m 2 K/W] [m 2 K/W] ] Detached I II Semidetached I II , Terrace I II

4 282 Brumaru and Cobârzan Most of the owners prefer the constructive solution II for the external walls, which is cheaper, but on long-term, by using the constructive solution I, the building energy performance increases, providing a reduction with 31.5% of the energy consumption for heating. In residential buildings the energy demand for heating is higher than that for cooling and air conditioning, consequently it is recommendable the building volume to be a minimum. The bigger the surface of the building envelope, the bigger the heat losses and so are the solar gains - an important aspect, directly linked to the reduction of non-renewable energy consumption and related CO2 emissions. It has also been confirmed that by increasing the A/V ratio, the rate of heat losses by ventilation also increases (see Table 2). Table 2 Heat losses depending on A/V ratio and/or building type Crt. no. TYPE OF BUILDING A/V [m -1 ] Heat losses by ventilation [kwh/m 2 ] Detached Semi-detached Terrace Besides the well known factors that influence the building design concerning energy effectiveness, like the geographic location with its characteristics (solar and regime of wind) and the building cardinal orientation, a special importance should be granted to the selection of the appropriate heating system and fuel used, that may bring substantial energy savings, also diminishing the CO2 emissions and their negative environmental impact. a. b.

5 Energy Efficient Dwellings 283 c. Figure 2 Detached building: a -energy demand for heating, b- energy cost; c - CO2 emissions The diagrams in Figures 2, 3 and 4 are illustrating the variation of three parameters: energy demand for heating, energy cost and CO2 emissions, for each of the building type subject to analysis. a. b. c. Figure 3 Semi-detached building: a -energy demand for heating, b- energy cost; c - CO2 emissions

6 284 Brumaru and Cobârzan a. b. c. Figure 4 Terrace house: a -energy demand for heating, b- energy cost; c - CO2 emissions Diminishing the energy demand for heating is not the only important issue to be focused on in the design stage. There is also the problem of reducing the wastes responsible for the pollution of soil and underground water, in the execution phase. One of the solutions recommended in this respect is to design - as much as possible - buildings with regular shape in plan, easier and cheaper to construct compared to those with elaborate contour. Another important aspect is to remove the possibilities of obstructing the solar radiation and day lighting, having a significant contribution to the overall energy saving process of buildings in service. Orientation and minimum distance among buildings should be carefully designed, in order not to exceed a reasonable density. Undeniably, a higher density brings over some advantages, like more effective public transports, improved safety, lower energy consumption (Table 3), but may also have social disadvantages and increased atmospheric pollution.

7 Energy Efficient Dwellings 285 Table 3 - Advantages of increased density (semi-detached and terrace houses compared to detached house) Crt. no. Type of building Investment in construction [%] Investment in land [%] Reduction of heat demand (Q nec ) [%] Total Economy [%] 1. Detached building 2. Semi-detached building 3. Terrace house A higher degree of land occupation results in increased rate of polluting gases emissions in the atmosphere and negative impact on the air capacity of selfpurification and on vegetation. At the same time, the environmental protection becomes a more complex process and difficult to achieve. The same parameter during the summer is with some degrees higher compared to the lower density areas, affecting the everyday life comfort conditions. The creation of green spaces may reduce this impact and by positioning the trees against the predominant wind direction the energy consumption may be reduced. In rural areas, the density of the built environment is much lower, the above negative effects are significantly reduced and keeping the ecological equilibrium of the air, water and soil is naturally achieved, as a general matter, therefore the measures concerning buildings energetic effectiveness are mostly imposed by social reasons: lowering the heating cost and improving the internal comfort conditions. Based on the above considerations, it appears as very important in the design stage of any type of dwelling or dwelling assembly to analyze carefully the surface allocated to each building, in order to exploit as much as possible the solar radiation, day lighting and natural ventilation opportunities. In order to offer the best design solution from social, economic and environmental point of view, the analysis of several constructive variants is always recommendable. Conclusion In Romania, a high number of dwellings have irregular shape in plan, high spread area, with high energy demand for heating and high exploitation costs. Environmentally friendly, economic design is a prerequisite for sustainable development at local, regional and national level, being technically superior, with higher service life, reduced exploitation and maintenance costs, lower environmental impact, also offering substantially improved comfort conditions to the inhabitants.

8 286 Brumaru and Cobârzan In order to implement the advanced concept of sustainable houses, a radical change in both, design principles and mentality of the owners/inhabitants are strongly necessary. Raising awareness by demo-projects and by any other effective procedure is an urgent and serious task for the professionals in housing domain, and the present paper is trying to accomplish a small part of it. References 1. Radu, L. Dumitrescu: Sustainable Development in Constructions under the Impact of Climate Changes and Rising Energy Cost, 2. Ministry of Environment and the National Institute for Environmental Protection-ICIM, Report on the National Inventory , Bucharest, 2004, a_romaniei_privind_schimbarile_climatice.pdf 3. Government Decision no concerning The Approval of the National Strategy in the Domain of Energy Effectiveness the National Census