Towards an improved architectural quality of building integrated solar thermal systems (BIST)

Ecole Polytechnique Fédérale de Lausanne (EPFL), Laboratoire d’Energie Solaire et de Physique du Bâtiment, Bât. LE, Station 18, CH-1015 Lausanne, Switzerland
Solar Energy (Impact Factor: 3.47). 09/2007; 81(9). DOI: 10.1016/j.solener.2007.02.009
Source: OAI


Architectural integration is a major issue in the development and spreading of solar thermal technologies. Yet the architectural quality of most existing building integrated solar thermal systems (BIST) is quite poor, which often discourages potential new users. In this paper, the results of a large web survey on architectural quality, addressed to more than 170 European architects and other building professionals are presented and commented. Integration criteria and design guidelines established and confirmed through the analysis of these results are proposed. Subsequently, a novel methodology to design future solar thermal collectors systems suited to building integration is described, showing a new range of design possibilities. The methodology focuses on the essential teamwork between architects and engineers to ensure both energy efficiency and architectural integrability, while playing with the formal characteristics of the collectors (size, shape, colour, etc.). Finally a practical example of such a design process conducted within the European project SOLABS is given; the resulting collector is described, and integration simulations are presented.

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Available from: Maria Cristina Munari Probst, Mar 30, 2015
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    • "Specifically, the façade represents a fairly easy option for the installation of collectors as it provides a further potential envelope surface for solar thermal integration to supply hot water for domestic use, space heating and cooling. Although the amount of incident solar radiation on the vertical surface is about 30% lower than the amount hitting an optimal tilted surface, the implementation of these technologies into the façade avoids heat overproduction and collectors' overheating in summer-time, and allows to properly size the building energy system according to the actual heat demand (Munari Probst and Roecker, 2007). Moreover, when ST collectors are mounted in vertical, they are less sensitive to the weather conditions and dust, rain and snow will not damage them. "
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    ABSTRACT: In the perspective of the Net Zero Energy Buildings as specified in the EPBD 2010/31/EU, we propose the concept and design of a modular unglazed solar thermal (UST) fac¸ade component for facilitating the installation of active solar fac¸ades. The renovation of existing buildings offers an opportunity to improve the energy efficiency when using such a system and a novel design methodology tackled via a parametric approach is here proposed. We analysed a variety of building typologies as potential application targets of the UST collector, properly sizing the collector field for each typology to match the heat loads profile. We investigated the thermal behaviour of the novel thermal fac¸ade component and the energy potentiality in covering the heat demand using the TRNSYS software’s model of the UST collector field as a part of a combisystem. We concluded with the definition of rules of thumb for early design stage. The work here presented demonstrates that the low-cost, the versatile modularity and the easy installation make this active solar fac¸ade an innovative and promising technology for the building stock transformation, despite of the low quality of the produced energy due to the low outcome temperature of the unglazed collector
    Full-text · Article · Dec 2015
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    • "Kalogirou (2004) introduced the importance of solar energy as a survey of the various types of solar thermal collectors and applications. Probst and Roecker (2007) reported the results of a large web survey on architectural quality of building-integrated solar thermal systems (BIST). The various approaches in building integration of solar system and a number of successful examples were reported by Hestnes (1999). "
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    ABSTRACT: A new type of solar thermal collector which can be integrated with facades and roofs to provide pleasant shapes is introduced. The solar collector has an elliptic curved shape, and ellipse aspect ratio was varied to cover all geometric shapes. The mathematical equations were developed to calculate the beam and diffuse radiation absorbed on the elliptic curved collector. Theoretical analysis was done to determine the effects of the ellipse aspect ratio and the azimuth angle of the collector on the performance of the collector, and the results were compared with a conventional tilted flat plate collector for four typical clear-sky days (spring and fall equinoxes and summer and winter solstices). The total energy received throughout the year is also compared. The elliptic curved collector is able to absorb a sufficient amount of solar radiation to be competitive with a conventional flat plate collector. One of the advantages of this study is in the mathematical expression that enables the designers to simulate not only all possible configurations but also all possible orientations of the elliptic curved collectors covering all days.
    Full-text · Article · Apr 2015 · Solar Energy
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    • "The large majority of these systems were designed and optimized considering functionality and engineering aspects but, for large scale implementation at community level additional pre-requisites should be satisfied. A highly cited pole, answered by over 170 professionals outlined that the usual black or dark blue-shaded collectors, with rectangular shape are not welcome on visible places as facades, balconies, architectural objects, [2]. Thus, several research directions can be now identified, for developing: Multi-functional solar energy conversion systems, traditionally installed on the roofs and terraces, where there are less constraints of urban acceptance, as it is the combination of flat plate solar-thermal collectors for air and for water heating with PV/thermal (PV/T) modules and regular tiles, [3]; Novel solutions integrated in the buildings envelope, by actually " hiding " the convertors, as the massive solar-thermal collectors, using concrete, bricks or gravel as heat storage systems, [4], or colored mild steel sheets integrated in the facades, [5] [6]; another development recently reported is on novel solar-thermal collector, drain pipe integrated, thus practically invisible from the ground level, [7] [8]; Active transparent or translucent facades with integrated PV/T modules, [9] [10] or with transparent tube solar thermal collectors integrated in balconies or stairwells, [11] [12]; Active opaque facades, [13], containing flat plate solar thermal collectors (FSTC). "
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    ABSTRACT: Architectural acceptance of façade integrated solar-thermal arrays requires novel solutions for the flat plate solar thermal collectors, in terms of shape, size, colour and functionality. The paper presents a novel concept of solar-thermal arrays with variable geometry, based on non-rectangular collectors; different shapes and sizes are analysed and their adaptability in developing arrays with various geometries is discussed. Two “unit” shapes are proposed (equilateral triangle and isosceles trapeze), based on which various geometries can be developed; the size range of the collectors is discussed, along with the tubes’ design for the inner circulation of the water based working fluid. Several examples of façade and roof integrated arrays are presented, outlining the versatility of the proposed solution.
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