Optimizing window size by integrating energy and lighting analyses considering occupants’ visual satisfaction

Abstract

PurposeThe purpose of this paper is to determine the approximate window-to-wall ratio (WWR), window width-to-height ratio (WHR) and sill level for a room in Rasht–Gilan province and to present an optimal window in each of the WWR ranges providing the minimum energy consumption by integrating artificial lighting and thermal analyses, whilst maintaining internal comfort conditions using dynamic evaluation.Design/methodology/approachThe process of modelling has four main steps: 1 – defining the building's features and requirements, 2 – validating input weather file data by on-site measurement, 3 – determining input parameters for the lighting and thermal analysis and 4 – clarifying variable parameters and fitness function for the optimization algorithm. Also, the survey study is performed in a daylit office room, in which 30 employees are employed to answer the questions in three different times of a day. In this process, the impact of daylight on their visual comfort is surveyed in 1,350 different illuminance levels which are manually recorded.FindingsThe range of useful daylight illuminance (UDI) values is determined as 200–1,000 lux. The optimum range of WWRs in the case study is 15%–25%. Also, due to the appropriate window height, electric lighting could be decreased by 40%.Originality/valueThermal and lighting performance in buildings is the relation of facade characteristics to environmental sustainability. Recent studies focussed on optimizing WWR and window characteristics considering thermal comfort and energy analyses. However, architects need freedom for designing façade and making decisions in their first sketches. Thus a guideline for optimum window conditions in each WWR is required. Also, considering occupants' behaviour in practical buildings, the visual comfort investigation is a gap in WWR optimization.

Smarter Window Selection for Smarter Energy Consumption: The Case of the United Arab Emirates

“…Montaser Koohsari and Heidari [13] studied the approximate WWR in addition to the width-to-height ratio (WHR) in Iran, and conducted artificial lighting and thermal analyses whilst maintaining the best interior living conditions. Their research showed that heating and lighting energy demand is more affected by the WWR than cooling energy demand in the studied location, and showed that the optimum WWR is in the range of 15% to 25%.…”

Review of Window Performance in A Hot and Humid Climate

“…The window-to-wall ratio was investigated in a total of 518 simulated window configurations (Marino et al, 2017), while the fenestration system (Mousa et al, 2017), window area luminance (Amirkhani et al, 2018), indoor-outdoor air movement comparison (Wahab et al, 2018), window configuration on energy performance (Altun & Kiliç, 2019), residential energy usage (Mori et al, 2020), and thermal investigation (Koohsari & Heidari, 2020) were studied in relation to various window opening types. These studies involved field measurements (Wahab et al, 2018), surveys (Mori et al, 2020), and computer simulations (Marino et al, 2017;Mousa et al, 2017;Amirkhani et al, 2018;Altun & Kiliç, 2019).…”

Fade Lighting Control Method for Visual Comfort and Energy Saving

“…Rapid changes in illuminance could cause the irises of occupants to contract or relax rapidly, resulting in visual discomfort and reduced work efficiency [13][14][15]. Various methods have been proposed to address the problems caused by drastic changes in lighting illuminance.…”