Energy and Buildings 45 (2012) 299–310 Contents lists available at SciVerse ScienceDirect Energy and Buildings j ourna l ho me p age: www.elsevier.com/locate/enbuild Experimental estimation of the solar properties of a switchable liquid shading system for glazed facades A. Carbonari a,∗ , R. Fioretti b , B. Naticchia a , P. Principi b a Department of Civil, Building Engineering and Architecture – “Building Construction” Research Team, Università Politecnica delle Marche, via Brecce Bianche, 60131 Ancona, Italy b Department of Industrial Engineering and Mathematical Sciences, Faculty of Engineering, Università Politecnica delle Marche, via Brecce Bianche, 60131 Ancona, Italy a r t i c l e i n f o Article history: Received 13 June 2011 Received in revised form 14 November 2011 Accepted 15 November 2011 Keywords: Dynamic solar shielding Liquid-shaded window Outdoor trials Solar factor Energy efficiency Test cells a b s t r a c t As solar gains often constitute a high fraction of the overall cooling and heating loads in buildings, dynam- ically and adaptively controlled fenestration may be an important strategy for energy efficient buildings. The higher the variability in climatic conditions over the seasons, the longer is the list of benefits deriving from the adoption of this type of technology. This paper reports the experimental evaluation performed on a dynamic shading system based on a liquid layer sliding within a dedicated glass stratification. The advantages connected with the adoption of the described technology derive from its easy adaptability to almost every fenestration, its reversible switching between high and low solar transmittance configurations in a short time and its capability to maintain transparency in both operating modes. The summer outdoor experimental campaign, reported in this paper, allowed the solar factor of the liquid-shaded stratification to be estimated and compared with a reference low-emission double stratification, where one of the panes was treated with a mag- netronic coating. The results showed not only that the shading provided by the dynamic liquid layer is more effective than its benchmark, but also that its dynamic capabilities have been preserved after a summer-long exposure to solar radiation. © 2011 Elsevier B.V. All rights reserved. 1. Introduction Currently numerous studies are being developed to limit the deterioration caused to the environment by human activities. A reduction in energy requirements is one of the solutions which needs to be urgently adopted, and evidence that buildings are responsible for a great percentage of the total energy consumed, allows us to infer that saving energy in this field would provide indisputable benefits. Furthermore, in industrialized countries, about half of the total carbon dioxide emissions comes from the building sector [1]. New energy efficient technologies for buildings should provide thermal comfort, and at the same time bear in mind other impor- tant goals such as visual comfort and internal air quality. Given the great extent to which transparent envelopes are used in con- temporary architecture, particularly in the service and commercial sectors, windows and glazed facades strongly influence the final energy balance. They affect energy consumption due to lighting, cooling and heating. ∗ Corresponding author. Tel.: +39 071 2204397; fax: +39 071 2204582. E-mail address: alessandro.carbonari@univpm.it (A. Carbonari). Considering that energy requirements generally vary over the four seasons, the influence of solar gains on the thermal behaviour of buildings also varies as a consequence: summer solar gains contribute to conditioning loads, which should be kept as low as possible, while winter solar gains positively add to the comfort provided by heating systems. Hence external envelopes should be able to switch their thermal and optical properties, provid- ing the best response possible for changing outdoor conditions, in order to obtain values which are as close as possible to internal comfort standards. In particular, the transparent part of external envelopes provides one of the biggest contributions to cooling loads in summer, and directly affects the power sizing of the conditioning equipment, which is decisive in order to avoid indoor overheating. Referring to the approach generally adopted by designers of highly efficient houses, the same solar gains, which must be shielded in summer, should be maximized in winter, as they bal- ance some of the heat losses and reduce the work of the heating system. Passive houses are generally able to completely balance winter heat losses through the adoption of very highly insulated envelopes by means of solar gains [2], which must be cancelled in summer. However this requires some switching devices to adapt the properties of the transparent surfaces according to the intensity of the external conditions. This paper reports a new technology, currently being developed, which integrates a switchable liquid shielding system in order to 0378-7788/$ – see front matter © 2011 Elsevier B.V. All rights reserved. doi:10.1016/j.enbuild.2011.11.022