# A Novel Approach for the Definition of an Integrated Visual Quality Index for Residential Buildings
## 1 Introduction  
Indoor human comfort is usually defined as the subjective satisfaction with the environment [1; 2] related to functional, physical, and psychological aspects [3]. It is influenced by a great number of stimuli at once creating a complex net of relationships between mind, environment, and perception. The task of understanding how a given stimulus contributes to improving or impairing the state of mind of a person is very challenging [4] and it may even not be worth doing [5]. In an attempt to clarify the relationship between the built environment and human satisfaction, several interesting approaches have been developed (environmental determinism, social constructivism, and user-centered theories [6]), expanding the research to fields like medicine and psychology. On the other hand, focusing on the features of the building that favor health and comfort of the occupants, it is possible to closely correlate human comfort to indoor environmental quality (IEQ) [7].  
IEQ is a general indicator of the quality of conditions inside a building and in the literature it has been interpreted in different ways. It is commonly defined by four basic factors: indoor climate, visual (or lighting) quality, indoor air quality, and acoustical quality [8]. It is certainly possible to account for more factors (like electromagnetic fields, vibration, greens, and water [9]) and some authors argue that it should be necessary to consider also parameters linked to personal, cultural, and interiordesign preferences (like view out, control, privacy, layout, and aesthetics [10]). In any case, the great majority of studies in this field accept structuring IEQ analysis using the four aforementioned aspects, which are evaluated as the most important and strictly related to human response to environment exposure. Many attempts to combine these factors and obtain an overall IEQ index have been made in past years [7; 11; 12; 13; 14; 15; 16; 17], but currently no consensus has been found on how to weigh the different factors.  
The study presented in this paper is part of a wider and upcoming research project on the definition of an integrated IEQ index for residential buildings. In particular, it is focused on visual quality (VQ) and presents an index with which to quantify it throughout a whole year. Five main aspects are considered: daylighting, electric illumination distribution, glare probability from daylight, glare probability from electric illumination, and color temperature. Additional parameters have been added for more personal evaluation like view out, shading device availability, and flexibility and control. Utilizing the method proposed by [PERSON] et al. [18], this new visual quality index (VQI) can synthetize the trend of different metrics and aims to become a tool for designers and constructors who want to quantify the visual quality of a residential building by comparing different design solutions. The index takes advantage of the potential of new building simulation software which allows the simulation of a large number of parameters with good accuracy, but it is also possible to use it for post-occupancy evaluation. Hopefully, this kind of study could contribute to providing better, more comfortable and, above all, healthier buildings.  
In particular, the research hereafter presented was developed in the context of the Comfort for Sustainable Buildings in the Alps (CASA) project, consisting of the design, construction, and monitoring of four residential buildings with the same shape and orientation but with different construction technology and installations. The aim of the project is to define a predictive IEQ index, to calibrate, and to verify it in different phases of the process: project (simulation), construction (environmental monitoring), and use (post-occupancy evaluation). Regarding the VQI, a simulation of a house of the CASA project was run using different applications to calibrate the index and to evaluate its performance in a real case study.