Planning practice with LED

Renovations at the town hall in Schorndorf near Stuttgart, a project ­involving LED lighting supplied by ERCO, are nearing completion. In September 2012, we talked to architect Gunter Fleitz (­Ippolito Fleitz Group) and lighting designer Prof. Stefan Hofmann (Lichtwerke) about their experiences and deductions regarding the use of LED lighting in a real-life ­situation.

Martin Krautter:
Mr Fleitz, why don’t you start by telling us a bit about Schorndorf’s town hall?

Gunter Fleitz:
The town hall dominates the historic marketplace in the heart of the old town and is the town’s “landmark”, built around 1730, and is now a listed building. The semi-basement with its distinctive arcade windows used to be an open hall where the market took place. The arcades were later closed to produce a foyer that is now used for many purposes including tourist information and events. There are also two multifunctional rooms – the large Council Chamber is used for events such as technical committee meetings and seminars. Above it lies the built-in Wedding Chamber, which also serves as the session room for the Lord Mayor and his team.

Martin Krautter:
What state was the town hall in when you first saw it?

Gunter Fleitz:
When we started the project in 2007, the building was in desperate need of renovation due to significant shortcomings in terms of fire protection and building infrastructure. The young Lord Mayor was also keen for the town hall to get a makeover that would give it, and so the town itself, a new image. When the economic crisis hit in 2008, the project was put on hold until funds came in again for its energy-efficient refurbishment. The last restoration in the 1980s had left it with many features in dark wood as well as terracotta-coloured flooring. We wanted to get rid of these and have a more open façade again to create transparency from the marketplace into the building. The Wedding Chamber now sits, as it were, as a glass structure inside the building. Separated by glass walls, the foyer and chamber converge into a single room differentiated by filters such as curtains and point grids printed on the glass. The acoustic ceiling throughout is curved around the perimeter and has continuous holes to maintain this space continuum.

Martin Krautter:
How did the contract come about, was there a competition?

Gunter Fleitz:
No, we were directly contracted for the project. We had a number of projects in Schorndorf, the most recent ones a radiology practice and a care home. At the opening, we were introduced to the Lord Mayor. He wanted to renovate the town hall with external experience and a new, uninhibited attitude. The good thing was that the Lord Mayor, the Town Councillor for Building and Construction and the head of the Building Department all knew what to expect and were all on the same page.

Martin Krautter:
What specifically were your clients looking for?

Gunter Fleitz:
The functional requirements did not change substantially. We have a variety of complex uses, but we did not want to design a multifunctional room as a sort of “jack of all trades and master of none”. Special focus was given to creating a stately entrance and transparency, also to the Chamber. Closed sessions required the option of appropriate discretion. Relatively early on, we presented a visual concept that would considerably change the character of the room. Our clients were highly enthusiastic about it, and it allowed us to show them what the concept could offer.

It was obvious, for some areas, that we would use LEDs.

Martin Krautter:
Which brings us right to the point – transparency always has a lot to do with lighting. How did you come to cooperate with Stefan Hofmann as a lighting designer?

Gunter Fleitz:
We had already worked on a restaurant project together. We had urged our clients to hire a lighting designer. Our basic interior design concept included initial ideas on lighting, which we expanded together. We often use 3D software for our designs, so very early on we had visual simulations of the room to hand. At the same time, when we got to the detailed lighting design with Stefan Hofmann, all options were still open in terms of exact definition.

Martin Krautter:
Mr Hofmann, what was your first impression?

Stefan Hofmann:
I knew from our previous project how the architects worked, what was important to them, and how they approached things. The lighting is always only as good as the architecture and in the best-case scenario it reduces itself to enhancing superb architecture. As lighting designers, it helps us, of course, when the architect communicates his philosophy, what room is to have which function, and how you move through the rooms.

Gunter Fleitz:
We had a strong design vision that we were able to work on together.

Martin Krautter:
When was the first time that you entertained LEDs during the discussions?

Stefan Hofmann:
It was when we designed the sculpture-like ring pendant luminaires in the foyer, which were only feasible with LED lamps.

Gunter Fleitz:
We knew here that it would boil down to using LEDs, yet not initially for the room’s overall lighting concept. The issue then arose in meetings with the client, who was open to the idea, so Stefan Hofmann explored it in more detail.

Stefan Hofmann:
It was obvious, for some areas, that we would use LEDs – for vertical illuminance, for instance, specifically for effective illumination of the curtains. The next question was how we would handle the lighting in general. Should we use conventional lamps or opt for modern LED technology? We have open, transparent architecture – would the lighting move in the same forward-looking direction? At the end of the day, we conducted an analysis calculating the energy and maintenance costs for two lighting concepts – one for conventional light sources using metal halide lamps or dimmable halogen lamps and the other for LED.

Martin Krautter:
You actually calculated these costs?

Stefan Hofmann:
Yes, and compared them to the acquisition costs. In 2010, LED lighting systems cost around a third more than conventional lighting. We presented these figures with the architect to the Lord Mayor. We were quite frank and said it may take a few years to pay off these additional costs, but he would have a building that demonstrates responsibility and progressiveness. It didn’t take long for him to decide on LED lighting for the whole project.

Martin Krautter:
Did you ever, at any point during the planning, feel that LEDs would compromise on quality?

Gunter Fleitz:
No, but I must admit I have never really seen the light at night. What really impressed me was the colour rendering and the very agreeable light colour everywhere.

Stefan Hofmann:
Similar to low-voltage halogen lamps, LEDs are point light sources. Their superb integration into optical systems produces intense and brilliant light exactly where it is needed. You can see under the Wedding Chamber, for instance, that it works really well now with LED lighting.

Martin Krautter:
What is the light quality of the LED like in terms of visual comfort or glare?

Stefan Hofmann:
A single, finger-sized lamp previously produced a very high lumen package. To achieve the same luminous flux you would need a grid of several light-emitting diodes. Only in conjunction with a sophisticated lens technology, such as ERCO’s, would you get the result you are looking for. We questioned various scenarios with LED spotlights in this project. For instance, is it possible, from a height of 10m, to illuminate the desktop of a single workplace precisely? The result shows that yes, it is possible. Glare control is ensured using a completely different technology, but it is available. There are areas, however, where we could not install LED technology because the right luminaires here simply don’t exist yet – ceiling washlights, for example, or recessed floor uplights.

Martin Krautter:
But how do you ultimately decide on one specific supplier, a specific brand like ERCO?

Gunter Fleitz:
We were completely open when we started, but Stefan Hofmann recommended your products for many situations, as they are simply ideal here. But with so many specific lighting situations, you can’t get it all from one source.

Stefan Hofmann:
It was relatively simple. Apart from the odd decorative and functional exception, most of the lighting comes as point light sources from the ceiling. As a lighting designer, I prefer to use a manufacturer that offers a range, a complete portfolio. ERCO provides LED downlights, wallwashers and directional luminaires all with an exact and consistent design, and these are the very luminaires we needed: with the same diameters and a unified appearance.

Martin Krautter:
So there are design aspects and technical aspects. Was it also a question of service?

Stefan Hofmann:
Initially it was a question of portfolio. For the Chamber we needed LED directional luminaires with a narrow beam angle of 10°. The market, in this segment, is relatively underdeveloped. ERCO was the pioneer, and that ultimately tipped the scale for us. Fortunately ERCO also quite recently changed the light colour from warm white to really warm white.

Martin Krautter:
That means we use LEDs with a colour temperature of 3000K in the project?

Gunter Fleitz:
Yes, this significantly increases acceptance. I don’t believe our architectural style is plain and sober, we use coloured, albeit quite dark, textiles, complemented by natural stone. Nonetheless, the unusual stylistic features, the modernity of the glass architecture – the warm light makes it easier, it simply feels nice.

Hendrik Schumacher:
The colour rendering properties are also excellent. The colour scale with its beige and brown tones is well-served with this colour temperature.

Martin Krautter:
The town hall has not been officially opened yet, what phase are we currently in?

Gunter Fleitz:
The offices on the upper floors are now moving back in. Official business in the town hall will resume on Monday, but not on the ground floor yet. The grand opening is scheduled for 8 October.

Martin Krautter:
Mr Hofmann, you have already seen the lighting at night – what is your opinion?

Stefan Hofmann:
It is exactly as we had hoped it would be. The light of the downlights illuminating the various areas is intense and brilliant, but also highly uniform. The same goes for the directed light. The change from conventional lighting to LED sources was a success – it works. It was a rewarding project and helped us gain further experience. We will know in future projects what wattages, what characteristics, what systems to use.

Hendrik Schumacher:
You are starting to get a feel for LEDs?

Stefan Hofmann:
Yes, and you get ideas what the next step could be. We already have custom-built luminaires in the project that are fitted with a mix of LEDs in 3000K and 4000K. We can therefore either produce warm light or complement daylight with neutral white light as needed. We want to see the same for downlights and wallwashers, that they can easily be switched between these light colours. Finally, a directional luminaire with a light colour of 3000K that gets warmer still when dimmed – that would be perfect for restaurants, for instance.

Gunter Fleitz:
I think it’s only nuances that are currently still missing. When we had a recent tour of the project with the Lord Mayor and the Town Councillor for Building and Construction, we could still sense some nervousness about the generally half-finished work, but they did say, “The light is superb, sensational, let’s hope the rest is the same...”

Martin Krautter:
That’s what one likes to hear!

Gunter Fleitz:
It’s true, there were still things not quite finished yet, but you could sense the ceremonious atmosphere already.

Stefan Hofmann:
It only works when you have good architecture. When you trust each other, listen to one another – then you can work in fruitful partnership.

Gunter Fleitz:
It also helped that we weren’t too short of time. The dry construction work on the floating ceiling panels was time critical. The luminaires and the mounting rings needed to be available on time here. It all worked out fine though. Or, when we were talking beam characteristics, you said, “I had actually imagined it a little softer”...

Stefan Hofmann:
The 10° option was simply too narrow in a few places, where the ceiling was much lower because of ceiling joists. There were, however, other lens options, from spot and flood through to wide flood. We tried these and ended up changing them.

Martin Krautter:
The Spherolit lenses actually do make LEDs more flexible than conventional lamps – does that make it easier for the designer?

Stefan Hofmann:
That was an interesting experience – I phoned ERCO on Wednesday, the lenses arrived by 10 a.m. on Thursday, and on Friday, I was in Schorndorf to replace them. That’s what I call stellar service.

Martin Krautter:
Mr Hofmann, is there anything else you would like to see in terms of product information, product documentation for LED products?

Stefan Hofmann:
Clear standards for technical data and measurements would be helpful for designers and manufacturers. With ERCO, I know that such data as luminous flux or luminance on the target surface are realistic. At the same time, I guess it will take a few years yet for a standardisation of data. Another issue, if I may, is the enormous price pressure because of a changed market situation with altogether new providers. Not all clients are prepared to spend a third more initially on LED solutions.

Hendrik Schumacher:
We all know what it’s like – new technologies cost more at the start before the price comes down. The expectations for LED technology are the same, and, as suppliers, we need to deal with that.

Stefan Hofmann:
Well, conventional lighting systems will likely soon be replaced by LED systems, but the market setup here is completely different. That makes the question of price and product portfolio a legitimate one. Of course, it would be nice to get a simple LED downlight at a reasonable price – with ERCO’s quality.

Martin Krautter:
We are definitely taking a close look at all these issues. The sector at the moment is indeed undergoing enormous changes. Would you say that the LED has become a focal point in lighting design, and also believe LEDs to be the way into the future, as other lamps will cease to be available or be banned?

Gunter Fleitz:
What I have seen in Schorndorf, so far, has really encouraged me and shows me that we can choose LED for future projects without hesitation. The project will reach a new standard of quality.

Stefan Hofmann:
Same from my side – this experience makes me optimistic. If the beam of the LED directional luminaire is too narrow, you simply exchange the lens and don’t need to install new luminaires. This flexibility gives you certainty. I have a good feeling about this.

Martin Krautter:
So you believe architecture with 100% LED is a positive, realistic vision?

Stefan Hofmann:
Absolutely, yes.

Gunter Fleitz:
This project has certainly paved the way here.

Martin Krautter:
Thank you both for the interview and for the nice closing comment!

Lichtbericht 95, November 2012