Energy & Buildings 175 (2018) 208–218 Contents lists available at ScienceDirect Energy & Buildings journal homepage: www.elsevier.com/locate/enbuild Solar radiation entering through openings: Coupled assessment of luminous and thermal aspects Paula M. Esquivias ∗ , David Moreno , Jaime Navarro ARHESUS TEP 130 Research Group, Escuela Técnica Superior de Arquitectura, Universidad de Sevilla. Avda Reina Mercedes n°2, 41012, Sevilla, Spain a r t i c l e i n f o Article history: Received 18 January 2018 Revised 2 July 2018 Accepted 11 July 2018 Available online 19 July 2018 Keywords: Climate-based daylight modelling Building energy performance simulation Daylighting Solar heat gains Sunlighting a b s t r a c t Usually the effect of global solar radiation on buildings is evaluated by focusing on the visible part of its spectrum, namely daylight, or on the thermal equivalent of sunlight, solar heat gains through external windows. At present, due to the difficulty of integrating and comparing thermal and daylighting results, approaches considering the integrated effect of global solar radiation are scarce. As a consequence, both approaches separately provide strategies for sustainable buildings – strategies that can, in fact, be contra- dictory. In order to evaluate daylighting potential and its correlated solar heat gains, a common framework of calculation is established and a set of metrics are defined. These metrics are based on the Daylight Suf- ficiency criterion, the recommended illuminance ranges for visual tasks and the trigger irradiance value defined in the Blindswitch-A model. The results of applying this method to a simple model show the correlation between the luminous and the thermal performances that are simultaneously achieved on the workplane. This method, there- fore, allows both aspects of solar radiation entering through windows to be visualised on one graph, thus enabling an integral assessment, so necessary if strategies that consider both aspects at the same time need to be proposed. © 2018 Elsevier B.V. All rights reserved. 1. Introduction Daylighting has numerous positive effects on building’s occu- pants. It enhances visual performance, productivity, health and well-being, etc., and it is generally preferred over artificial light- ing, especially for office environments [1,2]. Furthermore, the ex- ploitation of daylight, commonly referred to as daylight utilisation or daylight harvesting, is recognised as an effective means of re- ducing the use of artificial lighting [3] as well as reducing internal lighting, and thus cooling loads [4]. It is well-known that for several reasons, especially for those of health and well-being, sunlighting is essential for any interior space, particularly during winter months. Solar heat gains can con- tribute positively to the reduction of heating energy consumption. Sunlight and solar heat gains are, however, not so desirable dur- ing warmer months – especially during summer – as they are in winter. A suitably daylit environment is one where the architectural de- sign provides both good daylighting and effective solar protection [5]. This means that the architectural design reduces excessive so- ∗ Corresponding author. E-mail address: pesquivias2@us.es (P.M. Esquivias). lar gains, glare and heating and cooling loads derived from exces- sive daylighting (i.e. including the solar component) [4]. This also implies a reduction in the need for occupants to operate blinds and/or shades and to turn on lighting and HVAC systems, which in turn will reduce the building’s energy consumption. Usually the effect of global solar radiation on buildings is eval- uated by focusing on the visible part of its spectrum, namely day- light, or on the thermal equivalent of sunlight, solar heat gains through external windows. At present, due to the difficulty of inte- grating and comparing thermal and daylighting results, approaches considering the integrated effect of global solar radiation are scarce [6,7]. As a consequence, both approaches separately provide strate- gies for sustainable buildings – strategies that can, in fact, be con- tradictory. The effective integration of daylighting and its thermal com- ponent, solar heat gains, requires daylight performance to be de- scribed in such a way that the description can be obtained and combined with the thermal performance. Based on the study of the nature of the climate-based daylight metrics and the solar heat gains, two main problems are highlighted. The first is that solar heat gains are expressed as hourly or sub- hourly, at a frequency of smaller periods than hours, time series for the whole space, usually visualised as a 2D curve or as a tempo- https://doi.org/10.1016/j.enbuild.2018.07.021 0378-7788/© 2018 Elsevier B.V. All rights reserved.