How to light a building facade

Design criteria

Modern building facades can be just as worthy of floodlighting as historic ones. It’s the quality of architecture that counts rather than the age of the structure.

Floodlighting a building façade is a classic case of 'it’s not about the numbers' design. Of course, you can always calculate the vertical illuminance, luminance and uniformity values for a building but that’s not the primary goal.

That’s not say you can use any old floodlight. You will need good quality optics and tight beam control to achieve the effect you want. WE-EF are one of just a few companies who offer such a wide range of beam control accessories, visors, snoots and filters. Also, for the technically minded, their photometric files are easy to understand.

When floodlighting a façade, there are many non-engineering decisions to be made such as do you want the building to stand out or blend in with its background? Do you want a subtle or 'in your face' effect? Which parts of the building are worth highlighting? Do you want colour on the building? My default answer to this last question would be no, not unless you are sure of what you are doing. My own opinion is that colour on buildings is more often a blight than a benefit.

A related point is that you can save a great deal of energy by highlighting the attractive and architecturally important areas of a building rather than flooding the whole façade with uniform light. Similarly, switching off the lights (maybe after midnight) when no-one is around to see the building makes a lot of sense and can halve your energy cost.

The various options are meant to show different effects and styles of approach. The illumination level required to achieve the effect would depend on the location of the building. I.e. you would need a higher illumination level on a building in a city centre compared with the same building in a rural village. You decide on the effect first and crunch the numbers after. 

Our façade is about 35m wide and six storeys high, say 20m high.

The eagle-eyed amongst you will notice that some of the internal lights are on and some are off. That’s what happens in real life and means the building never appears as you planned it! 

Twin beam NTY100 bollards are used in all the options. 

This scheme is designed to balance the various masses of the building. The main emphasis is on lighting all the front faces uniformly across the width. Recessed, ground mounted ETV140 units are used in an almost continuous line. We have used narrow beam units to achieve greater height.

Lighting a façade in this way means that there is a lot of reflected light on to the pavement and can avoid the need for extra lighting from columns which might obscure the view. You can see that the seating is clearly illuminated.

In the roof garden, we have used the IP rated DOC200 series recessed downlight to illuminate the flowers and shrubs. Beam spreads are available from 5° to 25° so you can precisely highlight just the plants and nothing else.

The window reveals, themselves, have been left unlit.

Tech Spec 

Luminaires

ETV140 recessed linear plus DOC200 downlight

Optical control

Asymmetric and symmetric pmma lenses

Pros

Creates a big impression

 

 

 

 

 

 

The front faces of the building are unlit. Instead, the main purpose of this scheme is to emphasise the window recesses. The large outer ones are grey-green in colour. The VLR100 surface mount unit has been fitted with Cool LEDs to provide contrast with the white face of the building. 

The windows either side of the entrance are illuminated in the same manner. The VLR100 is ideal for small window recesses because it is available in widths down to < 330 mm.

Note that as part of the night-time appearance, the client has provided a small amount of illumination in the roof garden.

Tech Spec 

Luminaires

VLR100 surface mount linear, NTY100 bollard

Optical control

pmma lenses

Pros 

Low energy and subtle
 

 

 

 

 

 

 

 

 

 

 

 

This scheme is designed to emphasise the vertical and horizontal elements of the façade. The verticals are illuminated using the circular in-ground ETC100 series. This is a powerful range with five different beam widths, some as narrow as 2 x 3°, which can be coupled with a 150w HIT lamp. We have used LEDs with a 2 x 7° beam which is easily sufficient for a building 15m – 20m high.

The ETC series has the option of gimbals so that you can adjust the tilt of the beam from 0° to 30° off axis. Recessed luminaires have to be tough and these are IK10+ and drive-over up to 5 tonnes.

The windows in a horizontal line at the top are illuminated from below using recessed ETV140. These are just 48 mm wide and 50mm deep so it can be fitted on a tiny ledge. Various lengths are available and 2 x 14° or 2 x 29° beam widths.

Small FLC121 spotlights are used on the topmost pillars. 

Tech Spec

Luminaires

Recessed, gimbal ETC100-GB, ETV140 and FLC121 series circular spotlight

Optical control

pmma lenses

Pros

Good for tall buildings and large structures

 

 

 

 

 

 

 

 

 

 

 

Comments

No comments yet.

Leave your comment