VELUX Daylight Symposium 2015

The Location: The event was held at the Tobacco Dock, a reminder that some reused buildings provide stunning locations for events, and in this particular case the event was held in daylight. It may sound obvious, but most conferences are still held in locations where daylight is excluded, in case it interferes with the presentations. The usual result is a lot of sleepy attendees watching a lot of fairly tedious slides. When light levels are lowered, our bodies natural inclination is to go to sleep, a fact that the designers of most auditoria seem to have ignored. 
The lantern lights of this tremendous building were modified by simple banner-like screens to prevent glare and the two days were spent with the delegates bathed in full daylight but still able to view the screens. I cannot emphasise enough how much nicer an experience it is to spend a day in this way, rather than buried in the bowels of some convention centre.


The Content: The Daylight Symposium is a unique event, bringing together the worlds leading experts in daylight research and practice. It happens every two years and brings together the authors of CEN standards, the authors of daylight calculation software, the research community working on the effects of daylight on productivity and well-being, and the authors of guidance on the provision of daylight in design. There were also a few architects like me who tried to keep up with the science and not make fools of ourselves by asking really stupid questions, like, ‘what is the difference between lumens and luminance?’*

Some Conclusions

Over the two days I listend to a diverse range of speakers, from all over the world, many technical, some beautiful, all of them interesting. There were some particular highlights for me.

Daylight Autonomy, The CEN Daylight Standard draft appears to signal that the time has come to move on from Daylight Factor as a means of measuring daylight in architecture. Daylight Factor is a simple metric that predicts the amount of daylight in a room expressed as a percentage of the daylight available from an overcast sky. There are several problems with this.

Daylight Factor is not comprehensible to most people, including many professionals. It doesn’t relate either to the location of the space being examined or to the likely weather conditions in that location. So a room of the same size will achieve the same results in Iceland as in Uganda, despite the available daylight being quite different in the two locations. It doesn’t take into account the availability of greater amounts of daylight and sunshine available under typical weather conditions, so a part of the country where there is routinely a lot of sunshine will appear to perform as well as an area that has much less sunshine. As overheating becomes more of a problem, this is counterproductive. 

The CEN recommendation, based on several presentations during the event, is that we move to a measurement based on the availability of light in the room for a proportion of the day. This is similar to Daylight Autonomy, the US standard used in the LEED sustainable buildings assessment method. The draft CEN standard will suggest that we use a measure of the light levels in lux in the room expressed as the time that a desired light level is exceeded in a proportion of the space. The example given as a minimum is 300 lux in 50% of the room for 50% of the time. 300 lux is enough light to read, write or carry out office work, so it is adequate for many activities likely to be carried out at home. 50% of the space allow for variations in the lighting, particularly spaces only lit from one side. 50% of the time allows for variations over the day, so a room that is well lit in the morning can still comply with the requirement, as well as a room that is well lit in the afternoon, or early evening.

The draft CEN standard suggests that there could be three levels of such a standard, a minimum, set at 300 lux, a good at 500 lux and a high at 750 lux.

Rendering with Daylight: A particular bugbear of mine is architectural rendering that shows interiors bathed with light, when in fact such light is either impossible or unlikely at best. This doesn’t do anyone any good. Architectural rendering has a purpose, but that purpose should not be to mislead the designer or the client. It was heartening to see a presentation of Keyshot, a photorealistic lighting tool that can interface quickly with the VELUX Daylight Visualiser. They are both written by Luxion and they are now capable of interacting with each other. The VELUX tool can check the daylight in the room and Keyshot can produce a verifiably accurate daylight render. It can also deal with materials,textures and artificial light, but the important point is that it renders daylight accurately so that designers can check what actual difference their design changes make to the spaces rather than being fooled by a rendering engine that allow the designer free rein with the amount of light available. (In case you think that software doesn’t mislead, and I am overstating the point, one well-known and widely used rendering tool allows the designer to make the sun bigger!)

Thought Provoking: Paul Bogard: The organisers, VELUX, like to intersperse the hard science with some thought provoking speakers, and this time there were two presentations, one at the end of each day. The first by Paul Bogard was not about daylight, but about darkness. His book, The End of Night concerns the fact that most children in developed countries have no idea what a starry sky looks like. I was lucky enough to grow up in a rural area where starry skies were often visible, and the full majesty of the universe could be felt by anyone coming outdoors after dark. Today there are few places in the Western world where this is possible without having to get into a car and drive long distances. Will we end up in a world where fewer children want to become astronomers because they are unaware of the possibilities, or fewer philosophers because they haven’t seen how small and insignificant we are in the grand scheme of things. Paul points out that much of the problem is caused by security concerns and homeowners and property owners being sold lighting systems that waste a lot of light, and don’t even provide good security.

Thought Provoking: Olafur Eliasson: The presentation at the end of the second day was by Olafur Eliasson an Icelandic artist who, among other works, has filled the Tate turbine hall with a sun, and put large chunks of Arctic ice outside a hall where one of the COP talks was taking place. Bizzarely, one of the delegates contacted him a year later to ask him to bring the ice to the next COP. He had to tell the delegate that sadly, the ice had melted, but that there was more available in the Arctic.

He presented his kickstarter project with Little Sun which aims to bring artificial light to countries where children currently cannot read or study after dark unless they use kerosene lamps. His talk was deeply contemplative, almost mystical. His use of language was amazing, given that he works in Berlin and was born in Iceland, so must use at least three languages every day to express the most complex of thoughts. Two thoughts that stayed with me are:

The Shaping of the world is the creative act, and not the work itself.

Cultural institutions allow people to share without agreeing.
* ‘Lumen is the total luminous flux emitted by a light source, and luminance is the amount of light emitted from a surface in a particulat direction’ Obviously!


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