The European Waste Framework Directive, as set forth by the European Union in 2008, introduced a waste hierarchy that prioritizes reuse of waste over recycling whenever technically feasible and financially possible. In the field of construction, life cycle analyses on different materials have shown that reuse of structures possesses a remarkable carbon saving potential. This is the main asset that reuse has over virgin and recycled materials, although many other opportunities have also been recognized. Nevertheless, reuse has not gained ground in Western industrialized societies such as Finland. The barriers hindering reuse have been documented in the literature and they include cost, quality, quantity, perception and trust, among others. In this study, a panel of experts working within construction and recycling industries, research and administration was surveyed about the reuse potential of prefabricated load-bearing components made of different materials in the Finnish context. In addition, the panellists were requested to identify the main barriers obstructing the reuse of the aforementioned components. The materials include concrete, steel and timber, which cover the majority of contemporary construction in Finland. The respondents evaluated that prefabricated steel has the highest reuse potential and concrete the lowest. The future potential of timber was seen as nearly equal to the potential of steel. In general, columns and beams were estimated to have better reuse potential than floor slabs and roof trusses. The potential of sandwich panels was evaluated to be the lowest. The survey answers point out a number of issues that need addressing in order to enable reuse of components in large scale and in industrial construction. These results may not only have implications for recycling but for the technologies used in new construction as well. Especially prefabricated concrete was seen to be burdened by not being designed for deconstruction. However, it is the lack of an established practice that seems to be the main barrier for reusing steel and concrete. Technological constraints and physical properties may nonetheless delimit the utilization of some components. As for timber, its nature as a biodegradable material seems to form the main handicap for reuse, restraining the demand. Remarkably, cost of reuse was not seen to be among the most significant barriers, unlike other studies suggest.
Ensuring that predicted (simulated) energy performance figures are realized once a building is in-use has been of growing concern since issues surrounding the ‘performance gap’ were realized in the mid 1990’s [1]. Increasing energy demand and a decrease in thermal comfort with an added pressure on fuel poor occupants has questioned why some dwellings are not delivering their design expectations. In accordance with the Energy Performance of Buildings Directive (Directive 2010/31/EC, EPBD) [2], each EU member state is required to evaluate at design stage the energy performance of buildings. Following these predictions, it is expected that the completed building is constructed to a performance level which ultimately reflects the design model. There is, however, significant evidence to show that buildings are not achieving these aspirational energy requirements which often translates into higher energy bills for the occupant(s). This paper has evaluated the difference in energy demand at the design stage and early-occupation stage of two similar dwellings constructed in Scotland for a large social landlord. The dwellings were constructed side-by-side, built using a similar timber frame system fabricated by the same manufacturing firm. One dwelling was constructed to Passive House (Passivhaus) standards, the other in accordance to conventional 2010 Scottish Building Regulations. Furthermore, this paper presents insitu thermal envelope evaluation results that were measured at post-construction and early occupation stage. The early findings from this research have shown that energy figures obtained through real-time hourly data of space and water heating for the Passive House and the more conventionally designed house during the first year of occupation were 37% and 35% higher in energy consumption, respectively, than the predicted figures. Field test results have provided evidence to suggest that this increased demand is, in-part, due to some deficiencies of the thermal envelope. Other factors that influence the operation of the dwelling, for example building services efficiency, control systems and occupant behavior have also contributed to widening the performance gap.
In the past few decades, small fibers are increasingly used in reinforcement of concrete as an enhancement or alternative to steel bars. The addition of plastic fibers in the concrete matrix improves performance, reduces material costs and provides better working conditions on site such as reduction in concrete mixing noise in residential areas. Fibers attenuate the formation of cracks in concrete and enhance the structural behavior with increased shear, ductility, flexural capacity as well as compressive strength. This paper examines the effects of incorporation of macro synthetic fibers on the properties of fresh concrete and structural behavior in hardened state. For this purpose, polypropylene fibers were added at a dosage of 0.25%, to 1% to the concrete mix. To assess the performance of polypropylene (PP) fiber reinforced concrete, the samples were compared with identical plain concrete members. From the experimental investigations, it was noted that the workability of concrete with a constant mix design] was adversely affected by the increase in fiber content. The slump tests with fresh concrete showed a slump of 50mm for plain concrete and decreased to zero slump for the same mix proportions with the addition of 1% of polypropylene fibers. The effects of fiber volume and type on hardened concrete were evaluated using standard strength tests. There was no significant effect on the compressive strength. However, at low fiber content of 0.5%, the results exhibited an increase in compressive strength. The flexural performance of small concrete beams showed improvement with the addition of low volume of plastic fibers. With the addition of fibers, there is a change in the pattern of failure, wherein even upon reaching the ultimate load the beams failed in a pseudo-ductile manner. This was attributed to the concrete crack bridging properties of the fibers. On the basis of the experiments and data analysis, the results have clearly showed enhancement in the structural and mechanical behavior of concrete reinforced with plastic fibers as compared to plain concrete. © 2015 IAHS.
Time is a very important factor in the architectural creation of structure, form, and utility of flats and buildings in human settlements. The impact of the age of inhabitants stimulates the needs and arrangement of these flats. The other question in this case is the relation between the flexibility of a building and its heritage. The aspect of the form in housing is also very interesting: flexibility, adaptation and external appearance (elevation) of these buildings. The method of the paper is based on case studies, in situ inquiry (city walk: photo documentation, interviews, materials analysis) and theoretical research (literature insight). In this paper the authors will present the state of actual knowledge in this field in Europe. The following case studies will be shown: the city of Zabrze, the Silesia region in the south of Poland (flats for the elderly)! as well as ‘Puls 5’ – an adapted multifunctional building in the revitalized post-industrial area of Untere Hard in Zurich, Switzerland, and ‘Park Hill’ – modernized buildings in the housing area in Sheffield, England (flexibility in the process of revitalization and modernization of the heritage, flexibility of elevations). The results will concentrate on functional, constructional and esthetical adaptation aspects and flexibility of buildings with flats as a sign of time evolution, considering the need to improve the life quality of people, the preservation of heritage, and finally, sustainable development.
The present paper refers to the development of a research about the housing problem in Sub-Saharan Africa region. The degradation of the urban environment, and consequent low quality of life, results from the lack of infrastructures and precarious housing due the absence of a planning and housing strategy model. This situation results mainly from inadequate housing strategies to territorial contexts, namely its environmental, social, economic and cultural features. The methodology points to the development of a new design process based on the understanding of the housing deficit and current housing strategies in Sub-Saharan Africa region in order to identify the main requirements related to social, economic, environmental and territorial aspects. Therefore, the research issue is: Is it possible to develop parameters that will perform a model, based on a global and integrated solution for housing? In future developments, the model will be applied through a case-study methodology and its evaluation and adequacy through two phases that considers the main stakeholders in housing processes: population, local entities, governments and specialists. Also, the research focuses in the creation of guidelines for low-cost housing programs and initiatives based on requirements and parameters recognized as fundamental for the housing solutions in developing countries.
