Calculation of mean illuminance
In practice, it is often necessary to obtain an estimate of the mean intensity of illuminance (En) for a given level of electrical power supplied, or the electrical power P required for a given level of illumination. En and P can be estimated from the formula in
En=100/A* P/P

En= Nominal illuminance (lx)
P = Connected load (W)
P* = Specific connected load (W/m^2)
A = Room floor area
k = Corection factor

The specific power p* required for this calculation depends on the type of lamps used and relates to direct illumination. The correction factor k depends on the size of the room and the reflection levels of the walls, ceiling and floor.

If the calculation is to be made for rooms with different types of lighting, the components are calculated individually and then added together.

Calculation of the illumination using the specific power is also applicable to offices, In the example, a rectangular room with an area of 24m^2 is equipped with 4 lights. From above formula with 2 x 36W lamps (connected value, including 90W ballast), an illuminance of ca.375lx is achieved.

In offices, in addition to conventional louvered mirror lighting, square louvered lighting with compact fluorescent lamps or structured lighting are frequently installed. Lighting structures use a combination of power supply rails to carry spotlights.

Floodlighting buildings
The luminous flux required for lamps used to floodlight a building can be calculated from the formula in
Ø =π x L x A / Ƞʙ x ϱ
Ø = Luminous flux required
L = Mean luminance (cd/m^2)
A = Surface to be flooding
Ƞʙ= Lighting efficiency factor
ϱ = Reflection factor for the material
The luminance should be between 3cd/m^2 (free standing objects ) and 16dc/m^2 (objects in very bright sorroundings)

Designing of Liberaries: Part -I

Public libraries offer general literature and other information media which are directly accessible on open shelves.
Systematic collections and subject searches of material in print and in other media are limited to the larger public libraries.
Public libraries have no academic collection obligations or archiving functions, and are usually without accessible to the public, a and are used by children, adolescents and adults.
Public libraries orientate their level and choice of stock and services to the needs of their users.
As a communication ‘market-place’ for all population groups, in addition to the traditional provision of books, the library may have browsing areas, a citizens advice/inquiries desk, a cafeteria, music listening facilities, recreation and meeting rooms, and study seating for groups and individuals.
It may also include a music library, an art lending library and a mobile lending service.
Include periodicals, brochures, games, or new media (CDs, videos, PC software) to be used in the library or borrowed.
The room design should encourage adults, children and young people to spend time in separate open-plan spaces where activities take place.
The floor area depends on the size of the collection.
There should be 300 squired meters of usable floor area for every 10 000 units of media in the collection.
The objective is to have a minimum of two media units per occupant.
Ideally, the design should include large open, extendable multipurpose areas, which are roughly square, and organized horizontally rather than vertically, and an inviting entrance.
Areas for adult users can have 5 or 6 shelf shelves (maximum reach 1.8m)
In the children’s area there should be four shelf levels with a reach height of around 1.20m.
shelf aisles should should not be more than 3m long. and can also be used to produce niches and exhibition stands.
Book transport should be with book trolleys 920mm x 990mm x 500mm (DxHxW).
The goods elevator should be at the service entrance, and larger libraries should also have book conveyors.
Floor loading in public libraries should not exceed 5.0k/m2, in archive storage and similar open access areas with closely spaced stacks they should be 7.5Kn/m2 maximum, and with compact storage (mobile shelving) 12.5 or 15.0Kn/m2.