Enhancing visual comfort in staircases: A comprehensive analysis and design recommendations

Hassina Benkouda, Samira Louafi, Ammar Mebarki

Cite this article
Benkouda, H., Louafi, S., Mebarki, A. (2024) ‘Enhancing visual comfort in staircases: A comprehensive analysis and design recommendations’, Architecture Papers of the Faculty of Architecture and Design STU, 29(2), pp. 30-44. https://www.doi.org/10.2478/alfa-2024-0010

 

SUMMARY

People should be walking towards the inside of dwelling through an appropriate visual environment in transitional spaces. In these spaces, the occupants are able to experience the dynamic effects of the external climatic changes. The ability of users to adapt to changing dynamic conditions of the environment around them is very important. It is crucial to consider how the user will feel in the light conditions. Luminous conditions can change drastically as users transit from indoor to outdoor spaces or vice versa. A study by Mohamed et al. (2007) identified changes in lighting conditions in architectural transition spaces as one of the main factors in altering human eye adaptation, and identified this problem as a possible cause of “visual shock”. Therefore, in these transitional spaces, people might not have enough time to reach a stable state of visual adaptation to ensure the best response needed to perform a task. At the same time, the people could suffer some kind of visual discomfort. The proper understanding of visual adaptation parameters helps architects provide a suitable environment for inhabitants. Most studies were related to thermal comfort in transitional spaces. A few discussed the problem of visual comfort in transitional spaces, and examined eye adaptation and how users perform in these spaces.

This paper studies the effect of staircase design on the visual comfort of users and how they perform and adapt in this transitional space; it aims to specify design elements of the staircase in collective housing, to achieve a visual comfort in this transitional space. This research employs a two-pronged approach field measurements and a visual comfort survey conducted using a questionnaire; 144 questionnaires were collected, in four buildings with different staircases treatment in the city of Arris. Field measurements were conducted in winter 2021 and in summer 2021. The quality of day lighting was evaluated by measuring horizontal illuminance levels at the height of 1.5 m from the ground. 172 measurements were taken from the exterior of the buildings to the interior of the houses passing through each landing in the staircase. Illuminances were measured by Delta OHM LP 471 PHOTO. Illuminance and its distribution across the task area and its surroundings have a major impact on how quickly, safely and comfortably a person perceives and performs a visual task. Excessive variations of horizontal illuminance must be avoided; the diversity of illuminance expressed as the ratio of the maximum illuminance to the minimum illuminance.

The current method compares measured data to the CIBSE recommendations. Illuminance ratios were computed and then matched on a four-point scale ranging from “subtle” to “dramatic”, expressing the variations in illuminance ratios between various points of measurements. To determine how the residents felt and performed inside the staircases, a visual comfort questionnaire was designed. The questionnaire consisted of three sections: physiological symptoms, visual task performance and user preferences. The questionnaire responses were processed using Microsoft Excel, which produced graphs and charts to illustrate the survey results. The results show that at the entrance of Building 3, the solid overhang (with a depth of 2 m) permit “subtle” and “moderate” visual shock providing adequate transition leading to reasonable visual comfort and prepare the eye for the changes in the illuminance.  The absence of solid overhang at the entrances to buildings 2 and 4, means that there is no area that allows for the gradation of illuminance values, making the eye experience a sudden change between the outside and inside of the building, which makes entering and exiting the building visually uncomfortable. In addition to that, in part 3, question 4 of the questionnaire, when residents were asked what place caused them visual discomfort, most of those who answered: the entrance to the building, were from buildings 2 and 4.

In a staircase with the percentage of opening of 88% indicated “strong” and “dramatic” visual shock in many points and as this staircase is open, it is exposed to light conditions so it does not ensure the necessary transition which leads to advise against the open staircase. In the staircase treated with transoms of clear glass with the percentage of opening of 11%, these transoms direct the light to specific areas creating “strong” visual shock in many points of the stair landings which leads to advise against that. The staircases treated with vertical bays throughout the facade presenting a percentage of opening between 19% and 22%, these treatments allow the penetration of daylight in a diffused way which ensures a balanced distribution of daylight inside the staircases, indicating “subtle” in most points and “moderate” in some points provides adequate transition leading to reasonable visual comfort in the stair landings. In part 3, question 4 of the questionnaire, when residents were asked what place caused them visual discomfort, for those who answered: between level and another, low percentages (0%, 9%) were from buildings 2 and 4. The study suggests design elements that support the visual adaptation in the staircase: the existence of a solid overhang at the entrance; the façade treated with vertical bays, where the percentage of opening of the façade is between 19% and 22%, provide adequate transition leading to reasonable visual comfort and adaptation.

Keywords: design, transitional space, adaptation, illuminance, changes, occupants, staircase, performance, visual comfort