# A Novel Approach for the Definition of an Integrated Visual Quality Index for Residential Buildings
## 2 State of the Art  
In the last few decades several studies have been conducted on different building types with the aim of maximizing visual comfort. [PERSON] [19] defines a method for designing fixed shading devices, taking into consideration illuminance, luminance, and color, with the preference of daylight over electric light. [PERSON] et al. [20] propose an innovative lighting design for residential use that focuses on flexibility and seeks to reach visual comfort in terms of luminance balance of the vision field and visual task performance. [PERSON] [21], in his work about external shading devices in an office building in California, focuses the attention on avoiding glare. [PERSON] et al. [22] study luminous comfort as the result of the interaction between daylight and human behavior in residential buildings. [PERSON] et al. [23] try to define combined optimization criteria on window sizing procedures for balancing energy consumption and visual comfort, considering mainly glare and illuminance uniformity. In the literature there are some results that are commonly accepted, such as the positive effect of daylighting [24] or view out [25], but a shared definition of visual comfort has not yet been agreed upon [26]. Visual quality is defined as the characteristic of an environment that favors visual comfort. According to the IESNA lighting handbook [27] it is obtained through a design that balances human needs, architecture, and economic/environmental issues. Visual quality is one of the basic factors that influences the perception of the environment and the state of mind of the occupants [8]. This assertion may find supporting proof in an analysis of the studies conducted in the last decade on overall comfort that correlate objective parameters of the environment with user satisfaction acquired through questionnaires [7; 11; 12; 13; 14; 15; 16; 17]. All of these studies consider visual quality among the aspects that affect IEQ and the relative weight given to this aspect varies from 0.19 (school) [11] to 0.29 (commercial) [15]. According to these references it is possible to claim that visual quality has a non-negligible influence on overall perception of the environment in a proportion that depends on the use of the environment. For residential buildings the task of fixing a weight is even more controversial, because the choice of illuminance is task-related and depends also on external parameters like energy cost and personal preferences. According to a study by [PERSON] et al. [7] on 32 typical apartments in Hong Kong, for instance, visual quality has a weight of 0.21, significantly less than that for thermal and acoustic environments but much higher than that for indoor air quality. Monitoring visual quality is a challenging issue and it is often necessary to find a trade-off between accuracy and feasibility. The minimum parameter that is taken into account is illuminance, but [PERSON] et al. [15] highlight the necessity of a uniformity of temporal and spatial resolution of measurements in order to permit a correct comparison between different environments. Glare could also be considered but the measurement is absolutely non-trivial [28; 29] and it depends not only on the position but also on the orientation of the viewer. More detailed measurements comprehend daylight access and view out; an interesting approach is suggested by [PERSON] et al. [30]. An example of monitoring that tries to deepen the knowledge of the visual environment is given by [PERSON] and [PERSON] [9], who consider four parameters: average illuminance, average illuminance at the operated face, uniformity ratio of illuminance at the targeted face, and ratio of daylight. This is an interesting step towards a more exhaustive measurement of visual quality. Does current design practice tend towards visual quality? Regulations traditionally focus on electric lighting defining minimum levels of given metrics [31; 32].