Interior Lighting is a complex problem depending on various factors such as
• Purpose intended service,
• Class of Interiors.
• Luminaire best suited,
• Color effect and
• Reflection from ceiling, walls, floors.
Good Lighting means intensity should be ample to see clearly and distinctly. The light distribution should be nearly uniform over a part of the room at least. It should be diffused that is soft and well diffused. Color depends on purpose and taste source but should approach daylight / yellow. Source location should be well above range of vision. To avoid glare intrinsic brightness is reduced by diffused glass ware and by remaining objects of secular reflection from range of vision. Shadows are a must for accentuating depth but should not too apparent abruptly or dense, they are not to be harsh and should toned down.
Standard practice is to have general lighting in all areas at a level comfortable to eye. It should eliminate dark shadows and avoid sharp contrast. In order to emphasize on parts that should be shown. Light sources located such that visual importance of object is kept in mind. Lamp may be concealed or counter lighted with a very low attention value to itself. Glare minimized by diffusing.
American Institute of Architects Recommends for Good Illumination.
1. General. Lighting – effectively illuminate all objects/areas with due regard to relative importance in the interior composition. Adequate for eye comfort throughout the room elimination of dark shadows and sharp contrasts – preserve soft shadows for roundness/relief – lighting emphasis on those parts that need first attention.
2. Light sources be subordinated in visual importance to the things intended to illuminate, except rarely when itself is a dominant decorative element. Unless – concealed/counter lighted, that they are not apparent they have extremely high attention value – dominate the scheme. If visible – so disposed – to attract eye to major feature of room than themselves.
3. Glare must be eliminated. Result of intense brightness in concentrated areas within the line of vision. Produced by excess brightness of visible light. reflection of bright lights from – Polished – low diffused surfaces - extreme contrast of light/shade Employ – means of diffusing – at source or finish the room - with Diffusing/Absorbing materials rather than reflecting material.
4. Level of illumination to be adequate for the type of eye work. Local lighting to supplement general lighting adequate illumination – working at m/cs – desks – reading tables High level local lighting is always to be accompanied by general lighting to avoid eye strain and minimize controls. If glare is avoided there is no over illumination. Natural light limits are for outdoor 107600 lux and 1076 lux for indoor. Level should be adequate for eye task expected.
5. General lighting is to be related and controlled to suit the mood. While worship, meditation, introspection need low levels. Gaiety, mental activity, physical activity or intense activity needs high levels. Theaters, homes and restaurants may need levels varied according to mood. Shops level should be appropriate to woo customers through psychological reaction. Offices, factories and schools adequate illumination to work w/o eye strain.
6. Light source must suit interior in style, shape and finish in all architectural aspects.