daylight availability

Hot arid areas are endowed with an abundance of clear skies. Thus, the solar energy available can significantly raise the temperature of interior spaces and also result in an uncomfortable visual environment. External perforated solar screens have been used to control solar penetration through windows. Such screens can also serve a social function, that of maintaining privacy. This paper focuses on a special case of girls’ schools in Saudi Arabia, where the privacy issue is critical due to socio-cultural and religious beliefs. Windows in girls’ schools facing public spaces are typically covered by dark opaque film to maintain privacy. This window treatment results in overreliance on artificial lighting, and in a corresponding increase in energy use. The performance of screens can be affected by many parameters, namely: perforation rate, depth ratio, shape, reflectivity of colour, aspect ratio of openings. This paper looks at how different Aspect ratios affect the performance of scre...

The role that lighting plays in buildings cannot be underestimated. Light is integrated into buildings because of its potential economic benefit and the effect on the occupants’ psychological and physiological wellbeing. This study concentrates on hostels along Kanu Nwankwo road, in Owerri north, Imo state, where poor architectural designs could affect the performance of students. Therefore, the primary aim of this study is to highlight the importance of light in all dimensions and comfort level of both daylight and artificial light, in satisfaction to the perception of the user’s and how to integrate proper lighting conditions in the hostels  Questionnaires and interviews, as well as empirical measuring of daylight levels in the spaces of selected hostels were used. Analysed data revealed that the level of illuminance in the hostels is considerably poor and this resulted in students using artificial lighting throughout the day. Nevertheless, the negative effect of this situation can be prevented from occurring in further developments in Owerri north by educating the public on the benefits of using natural lighting in buildings and by enforcing laws that will ensure that buildings have maximum openings that allow enough daylight into the interior spaces.  These  measures  will  help  reduce  utility  costs,  improve  the  well-being  of  building occupants and increase the performance of students.

This research presents an experiment where the relationship between view outside (VO), daylight availability (DA) and glare protection (GP) of nine shading fabrics were evaluated. This kind of shading device is placed on the market (Argentina) without a proper characterization of their lighting performance, leading to an inadequate application. Glare was evaluated through DGP model, by means of HDRI technique, calibrated through externally measured luminance and validating with vertical illuminance. Vision outside was evaluated through the View Clarity Index (VCI) and daylight availability was assessed through Useful Daylight llluminance (UDI) dynamic daylight metric. Finally, two roller blind selection procedure were proposed. The first one considering each parameter independently (GP, VO and DA) and the second criteria, weighing the scores through a ternary plot.

Glazed towers are predominant among commercial buildings built in recent decades. They advance the use of natural light, increase the visual contact with the outside and have a contemporary look. However, issues related to excessive daylight illuminances, glare and direct solar gains affect the visual and thermal comfort, and potentially increase the building energy demand. Passive design of protections is a key element to tackle these problems. A shading device consisting of a perforated screen is presented in this research with the aim of improving the Useful Daylight Illuminance (UDI), and reducing energy consumption and Daylight Glare Probability (DGP). The screen has been supposed to be used in an office space in Australia with windows on its north and west façades. Integrated daylight and thermal simulations have been carried out with the use of Rhinoceros/Grasshopper integrated specialist software. The geometry of the shading device has been optimized using Grasshopper integrated evolutionary optimization tool based on Genetic Algorithms. Size and distribution of the perforations in the solar screens have been chosen as optimization variables. Results, then, have been compared to a base case with no shadings and show significant improvements in UDI values, together with substantial reductions of energy consumptions and glare probability.

This paper analyses the influence of different perforated solar screens (PSS) in annual daylight conditions expressed using climate-based daylight metrics. The PSS design require parametric studies that are often complex and time consuming due to a large number of simulations. Hence, a new methodology is proposed to optimize PSS design by applying Design of Experiments using Orthogonal Arrays (DOA). A case study from the DOA perspective has been conducted, which involves an office space in Seville, Spain. The goal is to assess the effect of the following PSS design variables in daylighting performance: perforation percentage, matrix, shape and orientation. DOA results reveal that optimized PSS can increase daylit area by 33% and reduce over lit area by 35%, compared with reference models with no PSS. DOA method reduces the number of simulations from the 256 required to 16, so it could save time during the initial stages of building design.