DAY LIGHTING IN MUSEUMS

LIGHTING IN THE MUSEUMS:

DAY LIGHT   

v  Most museum visitors prefer to  see  objects which  are  displayed  under  daylight

v  The  daylight may  be  provided  by  side windows  or

roof lights, be highly controlled or partially controlled.

v  The impression of daylight in a space is much more

noticeable  from side windows  than  roof lights but  is

more  difficult  to  control  to  avoid  glare  and  poor

viewing  conditions

v  Highly  controlled  roof lights,

however,  may  cease  to  give  an  impression  of

daylight and it must be questioned whether they are

simply  worth  the  cost.

ROOMS FOR SENSITIVE OBJECTS

v  With  lower  levels  of  light,  the  use  of  a  dark

background reduces the adaptation level of the eye, thereby  increasing  the  apparent  brightness  of  the

viewed  object.             

v  The illuminance  on  the Objects  should maintained at 50  lux, a  low  reflectance should maroon background is used.   

v   

v  The  choice of background  reflectance and,  indeed,

v  colour plays an important role in the visibility of the

v  objects.

v   Backgrounds of high chroma (strong colour

intensity)  impose  their  own  colour  on  a  room. 

v  Neutral  surfaces  (except  white)  tend  to  produce  a gloomy,  cold  appearance.

v   

v  The  best  compromise  is usually a low chroma background with a reflectance  chosen  according  to  the  necessity  to  reduce  the

adaptation level of the eye (20%-60%).

APPROACHES TO LIGHTING CONTROL

v  With highly sensitive objects  it  is almost  impossible

to  use  daylight.  Control  of  artificial  light  to  levels

below  50  lux  precludes  any  daylight  appearance. 

v  With medium  sensitive  objects  a highly  controlled  approach  may  be  adopted, requiring  automatic  shutter  control  of  the  louvres  that  control  the  daylight  and  artificial  light

v  A more  passive  approach might be  adopted  where  daylight might  provide  between 40%-70% of the total yearly lighting demand.

v   Such a system would have differential louvre controls on the day lighting  for  summer  and winter,  being  relatively  more transparent in winter than summer

CONTRAST

v  Diffuse illumination, where light comes equally from

all directions, will allow an object to be seen, but will

do little to reveal the form or texture because of the

lack of shadows.      

THE MUSEUM OF DELPHI 

v  The  museum  at  Delphi  had  two  distinct  types  of

gallery.  

v  In  most  galleries  the  objects  are  not sensitive. The clerestory-lit galleries  (eg Apollo and the Athenians) tended to suffer from sun patches on the  objects,  particularly  from  the  east-facing

windows during the morning.

  

v  The  Siphnian  room  had  a  traditional  roof light, with

light penetrating through the roof into the roof space

and  then  through  diffusing  glazing  into  the  room

v           

v  There  was  no  control.  An  even  level  of  light  was

produced  in  the  room  with  poor  contrast. 

v   In  the vertical  plane,  the  walls  had  a  higher  illuminance  than the large objects in the room (generally placed  toward the centre of the room).

v   The clerestories are occluded,  being  partly  replaced  by  north-orientated screened  rooflights,  which  are  to  be  integrated  within  a  new  artificial  lighting  system.  

v  This  uses  a combination  of  fluorescent  and  spot  lamps  with  ceiling-reflected light.   

INTERVENTIONS

 

v     The diffusing ceiling in the Siphnians room is being

replaced  by  an  egg-crate  based  internal  system,

with  external  shading  louvres  allowing  no

penetration  of  sunlight,  reducing  the  luminance  of the background while maintaining the illuminance on the objects.  

    

WHY DAY LIGHT

v  Natural light is the most universally valued in museum ,despite difficulties with environment requirements of housing art.

v  Day lighting,  artificial  lighting  provide specific  conservation  problems  in  Museums

v  Controlling  the  ultra-violet  light  is  somewhat  easier

because it is not contributing to vision so ultra-violet

filters can be used  

v  continuous monitoring of  ultra-violet  light  should  take  place  wherever sensitive  objects  are  displayed  within  museums 

v  Direct  exposure  to  sunlight,  while  potentially  very

detrimental  to  the object and the ability  to see it, is

unfortunately  still  too  common  in  European

museums  

EFFECTS OF LIGHT IN THE MUSEUMS:

v  Light is on one hand a destructive

force and thus conflicts with the museums role in preserving our heritage on the other it  is essential to vision, the principal means of communicating the information held within and around 

LIGHT DAMAGE IN THE MUSEUM

In respect of potential light damage museum objects can be considered in three broad categories:

1. Extremely susceptible to light damage 
2.  this category includes works on paper, textiles, naturally occurring dyes, Natural history exhibits

including fur, feather, insect and plant material etc. This category of object requires  
strictly controlled lighting conditions.

 1 .Susceptible to light damage

 This includes Oil paintings on canvas, most wood bone and Ivory and other materials

painted or coloured.

2. Not susceptible to light damage

 Metal most Stone , most ceramics and glass, wooden objects that have largely been used

out doors or have otherwise lost their natural colouring through design or use etc.

the objects in the museums collection, it is a key element in providing a context in time and space

for the museum visitor, in an architectural sense as well as the relationship with the collection and

it provides a key interpretive tool to extend the possibilities in communication.