Der Himmel über die Bücherwelt



The Austrian National Library, with its impressive State Hall, is part of the Hofburg, probably the most important architectural and cultural landmark of Vienna. How important is light to emphasize the artworks and architecture of such an important project?

As you know, without light there is simply nothing visible. The previous lighting was based on metal halide technology and big flood lights were placed on the gallery. These fixtures had a terrible quality of light and colour rendering – it must be said, however, that in the past, there were not that many other options available for such a big building. We needed to find something that, in addition to achieving an excellent colour rendering, would also bring out the warmth of the colours in the space, including in the artwork and frescoes.  This was, indeed, quite a challenging  demand, and we had to prepare a huge mock-up of this project – one-third of the State Hall was used as a 1 to 1 scale mock-up on site – to test the different possibilities and to show the client how our solution will really work.

Which architectural or structural constraints were there? The first thing that comes to mind is probably the difference in colours between the warmth of the wooden surfaces, such as boiseries and book shelves, and the cooler tones of the Baroque frescoes…

Actually, the frescoes, the shelves, and the books are quite similar in tone. The frescoes have a lot of warm colours, but this only became noticeable after the change in lighting. A lot of the frescoes, in fact, have very small golden touches that were not visible before, not to mention the 3D features of the paintings, but this was lost due to the previous lighting being very flattening. These were just two of the areas where our solution improved the project. The real constraint was the architecture itself, as we were not allowed to drill any holes or screw anything into the structure. Therefore, we had to use the cable routes that were previously available. In the end, we had to redo the entire cabling along the gallery balustrade, including using the existing holes and screws to secure the new cable trails and to support the new DALI track system holding the lights. This happened through tedious planning and execution. On the lower floor, where all the books are being kept in vitrines, we developed a special base that could be placed on the ground with no damage caused to the historical structure. The cable trails were then fixed with double-sided tape.

So these elements can be removed without leaving any trace…

Exactly. That is the main challenge of historical buildings, and this is not our first.  We have a great deal of experience and expertise in tackling such challenges and being able to provide the client with a solution that matches exactly what the client wants. I think this is one of the reasons why we were chosen for such a challenging project.

What lighting goals did you set for this project?

One of our primary goals was to achieve top quality lighting consistently throughout the project, while, concurrently, we had to consider the historical rules. For example, we were not allowed to light the shelves with more than 50-60 lux, due to the light radiation that could damage the books and the wooden structures. As a consequence of needing very low lux levels for the books and shelves, the lighting of the ceiling frescoes had to be considered to achieve a balance of light in the space. Additionally, we had to position the lamps in a discrete way that the visitors would not experience any glare while walking through the hall nor would they notice the fixtures. These were the main goals, in conjunction with excellent colour rendering, a long-term system, and low energy consumption.

Why did you choose to mainly use indirect light? How did you achieve an efficient ambient lighting, also in terms of functionality?

This choice was based on the mock-up we developed which was contingent on the project restrictions provided, as well as the light distributions of our chosen fixtures. Thus, we knew exactly which areas could be lit up. As for the safety and ambient lighting in the space, we knew, through our experience, that the reflection of light off of different surfaces would provide the necessary lux levels. Nevertheless, the primary aim was to highlight the architectural elements, bookshelves, and frescoes for the visitors. Our focus was not the lux levels on the floor, but on the historical artefacts which have a higher importance. Besides, for museums, you are not strictly bound to the European standard lux levels.

The collection on display counts more than 200,000 volumes, many of which have a highly historical value. What is the best light to illuminate ancient books in total safety? How did you approach this problem and how did you solve it?

As I said, one of the requirements coming from the historical and preservation department was to limit the lux levels. Another condition was to reduce the UV radiation as much as possible. Let me say, that the most arduous elements to light were the four globes in the centre oval of the State Hall, which we were obligated to light with less than 50 lux. The lighting effect here is managed by the overall control system and they are programmed to switch on only on certain occasions, so, during normal visiting times, the globes are only lit by the ambient lighting. Normally, they have below 25 lux, but despite the lack of extra (direct) lighting, if you look at the globes you won’t notice that they are almost dark. The very important books, paintings, etc., are kept in special vitrines, thus there is one extra glass layer of protection between our lighting and these artefacts. Plus, there is an additional special lighting inside the vitrines themselves. The other books and frescoes are, of course, critical too, but reducing the UV radiation and the lux levels was enough.

Were the expectations met?

Yes! I would say that it does not happen very often, but on this project we were able to get 99% of all the effects we were looking for, but also thanks to a very cooperative client. It was a tough time. I was there during winter for about three weeks, every night, to make the adjustments and to program the dimming with a colleague, who was responsible for the software. Nevertheless, in the end, we were able to get to a point in which everyone, right up to the top management, was happy with the outcome.

Did you also customize the lighting fixtures you chose?

My background is from the theatre, so I am used to working with light in a way that, let’s say, favours the mechanical and light quality side, rather than solely the design of a fixture, especially on projects where I try to hide the lighting sources as much as possible. We ran around a lot with a photographer to take photos and nice pictures of the fixtures, because when you are walking down the regular visitors’ pathway you are not able to see them much. Nevertheless, this library is still in use, so there are a lot of people from the staff who are going to take books and bring them back, all day, every day. They are walking along the gallery and along the ground floor, moving ladders to reach the books, and so on. Therefore it was a priority for us to get standard fixtures that could be modified, especially in terms of anchoring them.  If someone, maybe a worker, is moving along the gallery by the bookshelves, and there are 300 fixtures placed without being properly secured, the sought-after effect would be lost in no time. The same could happen with the cleaning process, the events, and the exhibitions, which sometimes requires temporary walls to be placed behind or above our lighting fixtures. So, for me, securing the fixtures is one of the most important things. In order to achieve something like this, you need a very simple fixture, which is why we chose these elements and why we removed the track adapter and changed it with a more suitable fastening element.

These are the two huge, but very simple developments we made. There was nothing too time consuming, but through these changes we were able to fix the aiming as required, and, up till now, we have had zero trouble. Our office works mostly with standard fixtures, redeveloping them a little bit to what is needed. We like to solve problems with smaller design changes. It is also cost saving because to develop something new from scratch would cost much more, as well as have a longer delivery time.