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Solar Energy 85 (2011) 757–768 www.elsevier.com/locate/solener
Quantifying the potential of automated dynamic solar shading in office buildings through integrated simulations of energy and daylight Martin Vraa Nielsen ⇑, Svend Svendsen, Lotte Bjerregaard Jensen Department of Civil Engineering, Technical University of Denmark, Brovej, Building 118, DK-2800 Kgs. Lyngby, Denmark Received 14 September 2010; received in revised form 12 January 2011; accepted 20 January 2011 Available online 15 February 2011 Communicated by: Associate Editor J.-L. Scartezzini
Abstract The fac ade design is and should be considered a central issue in the design of energy-efficient buildings. That is why dynamic fac ade components are increasingly used to adapt to both internal and external impacts, and to cope with a reduction in energy consumption and an increase in occupant comfort. To gain a complete picture of any fac ade’s performance and subsequently carry out a reasonable benchmarking of various fac ade alternatives, the total energy consumption and indoor environment need to be considered simultaneously. We quantified the potential of dynamic solar shading fac ade components by using integrated simulations that took energy demand, the indoor air quality, the amount of daylight available, and visual comfort into consideration. Three types of fac ades were investigated (without solar shading, with fixed solar shading, and with dynamic solar shading), and we simulated them with various window heights and orientations. Their performance was evaluated on the basis of the building’s total energy demand, its energy demand for heating, cooling and lighting, and also its daylight factors. Simulation results comparing the three fac ade alternatives show potential for significant energy reduction, but greater differences and conflicting tendencies were revealed when the energy needed for heating, cooling and artificial lighting were considered separately. Moreover, the use of dynamic solar shading dramatically improved the amount of daylight available compared to fixed solar shading, which emphasises the need for dynamic and integrated simulations early in the design process to facilitate informed design decisions about the fac ade. 2011 Elsevier Ltd. All rights reserved. Keywords: Dynamic solar shading; Integrated simulation; Energy demand; Indoor environment; Office buildings
1. Introduction The ever-increasing focus on the environment and climate transformation as a consequence of the emission of greenhouse gasses means that the building industry is facing a new reality (IPCC, 2008; Brundtland, 1987). Energy consumption doubled in the period 1971–2007, and the operation of buildings accounts for 40% of the overall energy consumption (International Energy Agency, 2009). The Energy Performance of Buildings Directive (EPBD,
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E-mail address: mavni@byg.dtu.dk (M.V. Nielsen).
0038-092X/$ - see front matter 2011 Elsevier Ltd. All rights reserved. doi:10.1016/j.solener.2011.01.010
174 | DESIGN WITH KNOWLEDGE | RESEARCH ARTICLES
2002) has become an important part of the new reality, and with the recent political acceptance of the new version that prescribes that all new buildings must be “nearly zeroenergy buildings” by 2020 (EPBD, 2010), energy efficiency at every level within the built environment has simply become a prerequisite. The overall reason for constructing buildings is to shield occupants from the outdoor environment and obtain a certain level of indoor comfort. Consequently, to a great extent, it is the level of occupant comfort that determines how much energy is used to operate the building. This puts the fac ade, as the actual separator between the indoor and outdoor climate, at the centre of the “energy reduction issue”. Choosing the optimal fac ade, however, is a complex