Identifying suitable design options requires good documentation of the design opportunities – their advantages and disadvantages – the energy performance and the user perceptions – and finally the suitability to different climates - some obstacles to good daylighting: costs, drawbacks, lack of knowledge, etc

• documentation of exemplary buildings, and their performance(LINK)
• design ideas and principles (LINK – source book Task 21)
• document the most appropriate design of the electric lighting and its controls (LINK)
• document the most appropriate blinds and external shades (LINK)

smart glazing systems
In recent years light redirecting materials – LINK to industry sources?? - have become common in well-designed daylit buildings. LINK – to examples These systems typically bounce light from the sun, and sometimes even diffuse light from the sky deep into a room above head height making the ceiling a light source for people further back in the room than the window alone can achieve. They also function to reduce glare and intensity of illumination near the window, making the light levels more even in the room and thus making it far less likely that people in the back of the room will turn on the lights just to reduce glare by evening up the illumination rather than because they are poorly illuminated.
The development of these systems has far outstripped our ability to measure their performance in the laboratory and to predict their performance in computer simulations. It is still possible to model many of these systems with physical models, as all one needs is a large enough model to be able to place samples of the material into the window apertures. LINK – physical model guide In fact, many of the best designers mix physical and digital models – using the physical model to calibrate the digital – to ensure a reasonable level of Quality Assurance.
good daylight is not just good glazing, but also glare and shading control
Increasingly the design response to achieving good day lighting is a combination of large areas of insulated but clear glazing with adjustable shading systems that also function to redirect the light from outside deeper into the building. At the experimental edge, adjustable shading in daylight systems includes electrochromic glazing. At a the high end of practice, one of the most extensive specifications of automatic controlled blinds in a perimeter daylight system is the New York Times building. LINK – LBNL work on NYT. This work is not only developing with the client a performance specification for the daylighting but has involved the owner in full scale mock up testing of the combinations of blinds and windows and exterior shading that simultaneously permit good visibility of computer screens and desktops, low glare and view.
shading systems require good controls for optimal daylight
Exterior shading systems have long been identified as optimal light and shade modifiers in buildings, particularly if they are adjustable to account for the movement of the sun. However, for many reasons these are often found to be impractical (wind induced noise, planning laws, maintenance of moving parts) Developing blind systems that preserve views, adjust all the time not just when someone is there or when they remember is the focus of this research project and of blind and control manufacturers worldwide. Of particular interest in this has been the interaction between the responses of users of offices and the blind controls systems. LINK: subtask A work. Ingenious systems not only for measuring the amount of light in a space but for measuring the tilt and the position of blinds have been used to measure the building. Similarly, careful and scientifically replicable, surveys have been conducted of the user preferences. LINK Subtask A It would appear that as with electric light people are very good at operating the blind controls when they enter the office. However, the ongoing adjustment of the light levels across the day is rather better handled with automated controls.
user responses to daylight and daylight systems
The user response seems to be that if the light levels are continuously dimmed in response to the available daylight and glare from the windows, then users responds favourably. Switched systems, even those that only switch a lamp at a time in a 3 or 4 lamp light fitting so do not just switch off and on, are less favourably viewed by building occupants. LINK – Subtask A What works best for the users and for low energy use is a combination of some external shade, to keep the solar heat rejection outside the offices, some glazing that is as clear as possible above eye height for good light penetration, some glazing at eye height for view, some blinds that work to provide extra adjustable shading, some light redirection especially above the eye height and some view at eye height even when fully closed (say, via small perforations). LINK – SubTask A – LBNL work on NYT All good systems of this type require a measure of user-override.
intelligent controls work best
Of interest in the near future are adaptive controls. These are controls that have intelligence. They measure the glare and the lighting conditions; they detect the user override response; they measure blind settings and they correlate them. These settings are remembered and reused when similar outdoor lighting conditions are encountered in future. The goal is to ensure that the “building” responds to the users’ needs and wishes as closely as possible. This of course automates the “negotiation” that often happens when more than one person shares an office with a window: what are optimum blind and lighting settings for one person are not optimum for the next. Research is focusing on issues of how to deal with the automation of the “voting”. The lessons from the research thus far are: LINK – SubTask A
controls – recommended best practice Link Subtask A

exemplary buildings
During the Task the participants have built up a library of example buildings, technology illustrations and computer renderings. The images from these are available for download either as a pdf version of a powerpoint presentation, as a jpeg picture format file, or as a powerpoint presentation. They are free for use, so long as their source is appropriately acknowledged, the IEA logo is not removed from the picture itself, and they are presented with, not divorced from, the accompanying text notes.
the value of daylight
Buildings with good daylighting satisfy the visual requirements of the occupants as often as possible with daylight, without generating drawbacks such as glare, overheating or losing excessive quantities of heat. LINK – SubtaskB – LINK – ENTPE Euro per MegaLumen paper
OECD electric lighting savings
Today, in OECD countries office buildings could be designed so that the electric lighting could be turned off 40% of the time. LINK – Subtask B
single storey buildings and top-lighting
Single storey buildings are easy to daylight. All single storey non-residential buildings can save on high cost electric light and gain productivity by installing top lighting from say skylights. This is already happening extensively in places like California where the opportunity is high because around 80% of retail floor area is single storey. There Title 24 from October 2005 requires facilities of 3000 sq m (~30000sq ft) or greater to have at least 30% of the floor area daylit with appropriate electric lighting controls. Subsidies are also offered by utility companies to go even further: to be eligible for a financial incentive the design needs to exceed Title 24 by at least 10%. Within limits, the greater the saving the greater the incentive. Experience seems to show that this rewards those who were looking at these options, but does not encourage people otherwise. LINK CEC web site?
multi-storey – sidelit - buildings
Sidelit buildings are more difficult. The research evidence seems to indicate that people are more productive (make less mistakes, work faster and for longer) when they have a view. Whether the daylight itself has as significant an effect is unknown at present. Much of the research difficulty – the applications of new technologies, control systems and variatons in human response – derive from the problem of delivering daylight by sidelighting from the perimeter wall. Large windows are helpful in ensuring whatever light that is available from the sun or sky reaches the interior. However, large windows often introduce excessive light.