2019 - Daylight Symposium
"Window Size Effects on the Atmosphere of Daylit Spaces at High Latitudes" by Claudia Moscoso
Architect & Postdoctoral
Norwegian University of Science and Technology
Windows have been found to be responsible for 30 % of the heat loss of a building1. It is not surprising then, that the windows’ dimensions are deeply discussed in view of establishing new design regulations for sustainable architecture. Logically, the dimensions of the windows have a clear impact on the light levels of a space or the amount of view outdoors. Moreover, there is research evidence pointing the strong effect that different window dimensions have on the aesthetic perception of spaces2. Although large windows are generally preferred over smaller windows, other factors such as climate and sky type are also crucial when evaluating an environment. Yet, when designing windows in Norway, a country with special climatic and daylight characteristics, practicing architects and lighting planners usually consider a 2% daylight factor (D) as guideline to comply with the current regulations3.
Although a window can provide the minimum of 2 % D under overcast sky conditions, the same window under sunny sky conditions can produce dissatisfaction and visual discomfort. Furthermore, at high latitudes conditions, e.g. in Trondheim, Norway (location of the present study), the winter months present particularly low sun angles (i.e. around + 4°), which make the entrance of sunlight problematic in regards of visual comfort to the users, affecting also how a space is perceived. The Light and Colour Centre at NTNU, together with the LIPID Lab at EPFL performed an experiment designed to answer the question: How do different window size affect the atmosphere perception of a space? The experiment was carried out using virtual reality as a presentation mode. This study examines three different window sizes (the smallest fulfilling the minimum criteria of 2 % average D given by Norwegian building regulations) in two different spaces (small and large) and their effect on the atmosphere perception of daylit spaces. Additionally, three types of sky type (including clear sky with low sun angle as common conditions at high latitudes) were studied. Finally, the preference of window size was also studied under two types of context scenarios (social and work).
In total, 150 participants assessed eight atmosphere attributes (Pleasantness, Calmness, Interest, Excitement, Brightness, Complexity, Spaciousness and Amount of View). The paper will present statistical results discussing how these attributes are evaluated under different window size conditions by people residing at high latitudes. The study underscores the importance of the window size on the user evaluations of atmosphere perception. More specifically, it supports previous research underlining that window size dictated by a minimum 2 % D is usually not enough to provide a satisfactory atmosphere to the users. In times when new building standards regarding windows are being developed and deeply discussed in sustainable agendas, the user perspective is a crucial parameter, which cannot be disregarded. The findings presented in this paper can contribute in the discussion and in the development of new aspects for regulations and for architectural practice regarding window size in Nordic countries.
Claudia Moscoso is an architect and Postdoctoral fellow at the Norwegian University of Science and Technology (NTNU). She has wide professional experience in the development of architectural projects, being responsible of small- and large-scale projects in Peru and the US. Since 2010 she has been working in research, obtaining her PhD degree at NTNU, where she conducted research about the impact of daylight on the aesthetic perception of architecture using advanced visual equipment. She is now an active researcher of the Light and Colour Centre at NTNU. She focuses on daylighting studies and quantitative research using VR equipment.