Mathias Wambsganß: "The elderly and sick are part of a vulnerable group—what do we do for them?"

Daylight is the best light source of all, and lighting planning must start with it. It is dramatic when, as a planner, you join a project and realize that had you been involved earlier, much could have been improved in terms of daylight. Daylight is a dynamic light source, but we can modulate it to some extent. For me, good daylight planning is one that can respond to this dynamic. 

When I say ‘respond’, I don’t mean using static solar control glazing! This may help get you through the hottest six weeks of the year, but it also means a poorer transmission rate in the remaining 46 weeks. In addition, I am voluntarily depriving myself not only of part of the daylight quantity but also of its spectral quality. 

The use of large amounts of glass in the façade does not automatically ensure good supply of daylight, as a lot of glass can also cause a lot of problems. Good façade design can thus prevent an excess of light. We must therefore learn to place openings judiciously: in the right places, with the best possible glass. And by “best possible”, I do not only mean in terms of thermal building physics. 

The boundary conditions are the same everywhere, but there is differentiation. In hospital construction, there are, to put it bluntly, two classes of patients: those close to the windows and those far from the windows. Studies have shown that patients with more daylight exposure are discharged faster. Nevertheless, patient rooms in modern hospital buildings are generally oriented toward the light. In hospitals, my concern is more about the staff, who work there 24/7, especially those working in shifts. 

I’ll give you an example: We are currently working on a project for an emergency room. When a patient arrives here, decisions have to be made quickly, regardless of the time of day. Nevertheless, these areas should not be operated in full brightness at all times, because in normal operation, the staff needs to be protected from excessive blue light components in the evening and at night, which have a negative impact on the circadian rhythm¹.

Taking this into account must be part of everyday planning today. We can easily plan specific concepts today, and it hardly costs any more money. I see this issue more as a problem of willingness and ‘clever implementation’. For example, in a patient room, if someone comes in at night to check on things, a different light should come on than during the day or in critical situations requiring full lighting. This way, we can better meet the needs of patients, at least in this area, although we cannot influence the necessary time schedules of hospitals. 

Studies show a possible positive influence of (day)light on people with sleep problems or the mentioned depression. The first step is to make good use of the available daylight. Particularly in the morning, a biological window opens during which we are especially receptive to larger amounts of light with blue components. This morning activation also positively affects our sleep quality the following night. For healthy people, this means: don’t buy an expensive lamp, but spend at least half an hour outside in the morning. 

However, the elderly and sick are part of a vulnerable group that may no longer be able to do this—what do we do for them? In the planning, we can ensure that the main areas where the affected individuals spend time are as close to the façade as possible. If there is not enough daylight on dark days, artificial lighting can provide the needed light. Several factors need to be consider here, such as the fact that extensive luminous surfaces have a greater effect than small, more selected small light sources, even if the amount of light reaching the eye is comparable. All in all, it is not enough to just select a luminaire; the rooms need to be planned holistically, including the materials used for the surfaces enclosing them. 

We can strengthen the circadian rhythm through these measures, but we must also realize that the requirements to achieve this are higher for older people. The lenses in the eyes become cloudy and yellowish with age, a process that significantly changes color perception and sensitivity to glare. The pupil diameter also decreases with increasing age, and for some older people, activation by light is no longer possible. 

This is precisely where we encounter a conflict of objectives: The planner who only considers non-visual effects wants to stimulate circadian synchronization for elderly people. This involves a higher amount of light in the morning hours. However, if I assess the scene visually, I know that this amount of light is suitable for tasks like knitting or solving crosswords. If the entire room is this bright and the surfaces reflect the light strongly, it can quickly lead to irritation and glare. Lighting design must therefore take into account both non-visual effects and perception-based issues. Where are the important visual tasks, and how can we minimize the risk of glare? 

A central task in room planning therefore is to analyze where people sit or lie in hospitals and what are their sightlines. If rooms are illuminate from above, this is ideal for staff, but someone who lies down a lot may be constantly blinded. The industry provides us with wonderful lighting tools, but above all we need lighting designers who know how to use them correctly.

Let’s start with the latter. It is true that for planning to be successful, clients need to understand the relevance of the topic. Only then, there is a shared interest in addressing the aspect of ‘light and health’ equally with other requirements. This can generally be achieved through broader dissemination of knowledge to the general population, as well as through embedding planning recommendations or guidelines in relevant regulations. Initial steps have already been taken and more will follow. For those already actively involved in planning, further training on the topic is a good idea, and for students in various relevant disciplines, this knowledge must be part of their education. In the four different degree programs I teach at TH Rosenheim, the topic of ‘light and health’ is, of course, an important component.

First and foremost, I wish for more awareness of the value of daylight. We typically discuss the U-value and g-value of transparent building components, both of which are also included in regulations for thermal protection in summer and winter. The transmission of the light spectrum, on the other hand, is nowhere to be found. It is, so to speak, the ‘byproduct’ once the calculations for thermal building physics are completed. And that is unfortunate, as there is an imbalance. It is important to me that the topic of light is discussed in planning tasks already in the early planning phase. That we think together about the building’s shape and discuss which rooms need which type of façade and how the right amount of daylight reaches the rooms and users at the right time. This is followed by consistent planning of artificial lighting that is based on design, ergonomics and also non-visual requirements, weighted differently depending on the task. This is my wish, and not just for hospitals or care facilities, but for all types of buildings.