The building sector in Europe represents 40% of the energy consumption and, of this amount, 26% is represented by office buildings that demand 44% of the energy only for lighting. Therefore, architects and engineers have a big responsibility to find design strategies and technologies that answer to this issue. In particular, a possible approach is the application of adaptive façades that respond to outdoor and indoor stimuli in order to fulfil requirements. In this research, a definition of adaptive façade will be given, and different typologies of adaptive facades will be investigated in order to understand what their future trends are. Moreover, particular attention will be given to smart windows and to daylight management strategies in order to provide a design solution that improves the visual comfort of an office space by solving glare, increasing the amount of daylight and therefore reducing the energy demand for electrical lighting. Furthermore, because of the strong correlation between visual comfort and thermal comfort - due to the fact that both of them depend on the solar radiation - the design will be further improved in order to achieve a façade that controls visible light and solar heat gain independently. This will enable to achieve the optimal configuration over the year and decrease the overall energy consumption of the building.

The current Dutch standard for daylight in buildings does not assure good daylight quality.
Designers therefore often do not know when a building has good daylight quality and how they can design a visually comfortable and healthy building.

The new European standard for daylight in buildings is more elaborative and recommends a higher daylight quality. When this standard is introduced, the assessment method must be adopted in the Dutch building regulations. The assessment method however differs a lot from the current Dutch assessment method, which makes it difficult to compare the standards and determine the exact differences.

To make it easier to design buildings with good daylight quality, the goal of this research was to establish a set of recommendations. For these recommendations, it was necessary to compare the Dutch and European standards. Three aspects of the standards were considered in this research: the requirements, the assessment methods and the effects on daylight quality.

Literature review on the standards gave insight in the requirements and assessment methods. The most obvious difference was that the European standard is more elaborative and assess, besides daylight, also sunlight, glare and view. Another big difference is that the Dutch standard is normative and the European standard descriptive. Both standards do not consider the orientation of a building and opposite obstructions.

After a literature study, two case studies were performed. The assessment of daylight in a basement showed that a space that meets the Dutch standard, can have a really bad daylight quality. It also led to the orientation factor which can be used to convert simulated daylight factors. This can be useful to gain insight in the amount of daylight in a space in common situations when the sky is not completely clouded and sunlight influences the daylight quality a lot.

The second case had quite good daylight quality, but still did not meet the European standard. There is not enough daylight, at the south east side there is too much glare, and at the north west side there is not enough exposure to sunlight.

The last part of the research was a systematic study. Variants were simulated according to the Dutch and European standard. Variants with a minimum daylight area from the Dutch standard had a bad daylight quality and showed that the window shape influences the access of daylight. In almost all other variants with bigger windows, higher reflection factors, or less obstructions, it
was not possible to meet the European standard on both side of the building. This means that in a dense area the European standard is almost unachievable. Because of the many influencing factors, there is no clear relation between the equivalent daylight area and the daylight factor.

For designers it is recommended that they consider the orientation, surroundings and reflection factors, even though it is not required according to the standards. This gives a more realistic insight in the daylight quality. Rooms should comply with a minimum daylight factor of 0.8% in 50% of the area and an average daylight factor of 1.5% also in 50% of the area. Besides the amount of daylight, sunlight, glare and view also influence the daylight quality and should be taken into account during the design process.

Of course, there might be more factors that should be considered by designers. Those are not mentioned in this research, but can be investigated in future research.

In the development of the lighting practice, progress has been made to eliminate bad lighting and to contribute to a visual comfortable scene. Metrics, and subsequent recommendations, have been established to provide uniform horizontal illuminance. In addition, performance-based metrics are developed. For example, various lighting levels for different tasks. However, the conventional metrics and current lighting standards fail to describe the spatial quality of light that provides a human observer with information about its surroundings contributing to one’s well-being. And so, increased emphasis is on three-dimensional light distribution in a space creating good lighting. Currently, renewed attention goes to the application of a theory to examine the visual appearance of light in a space: the light field. The light field can be subdivided in the light intensity, the light direction and diffuseness simultaneously. Hence, it is wondered to what extent the analysis of the light field is an effective alternative to predict visual comfort in a daylit office meeting space?

The research answers this main question in three parts, using literature review, in-field measurements and simulated data. The first part of the research concentrates on literature about the conventional visual comfort metrics (luminance Contrast Ratio and Daylight Glare Property), and the (mathematical) description of the light field. The second part of research deals solely with the light field. It examines how its properties can be measured and visualised, in researching the application of tool use. In part three knowledge about the conventional performance-based measuring techniques and the analysis of the properties of the light field (light intensity, light direction and diffuseness) are brought together and compared in a case study of a visual uncomfortable experienced office space.

Based upon the results obtained during the research, it is proven that the analysis of the light field is a promising candidate describing an uncomfortable setting in terms of light direction and diffuseness rather than luminance and illuminance. It is a view independent metric that can predict visual uncomfortable situations generated by a strong directional lighting combined with a low diffuseness, resulting in disturbing shades. Simultaneously, it is found that the current metrics for luminance Contrast Ratio and the simplified Daylight Glare probability, that try to predict the likelihood of visual comfort, lack a full description of the perceived level of visual comfort. Finally, the level of visual comfort for the human observer in the office space of the case study has been improved.

Keywords: daylight, light metrics, visual comfort, luminance contrast ratio, daylight glare probability, light field, light direction, light intensity, diffuseness, light field,