Illuminance

When it is necessary to access lighting objectively and quantify the lighting ambience of a space, i.e. Low, soft or strong lighting, the concept of illuminance is used. For instance, the luminous intensity which is provided on a single gray wall by a lamp of identical power decreases according to inverse of the square of the distance. The illuminance, in other words the quantity of light incident upon this surface, is a function of the distance to the source (d), its luminous intensity (I), and the angle that exists between the incident light which reaches the material and the perpendicular to the surface.

The illuminance is expressed in terms of lux (lumen/m²). This is a means of comparison which lighting engineers often use to describe the functionality of lighting.

Common Light Levels Outdoor

Common light levels outdoor at day and night can be found in the table below:

Condition	Illumination (lux, lumen/m2)
Direct Sunlight	100000- 500000
Full Daylight	10000-40000
Overcast Day	20,000
Twilight	400
Full Moon	100
Quarter Moon	0.01- 20
Starlight	0.001-10
Overcast Night	0.0001

 Common and Recommended Light Levels Indoor

The outdoor light level is approximately 10,000 lux on a clear day. In the building, in the area closest to windows, the light level may be reduced to approximately 1,000 lux. In the middle area its may be as low as 25 - 50 lux. Additional lighting equipment is often necessary to compensate the low levels.

Earlier it was common with light levels in the range 100 - 300 lux for normal activities. Today the light level is more common in the range 500 - 1000 lux - depending on activity. For precision and detailed works, the light level may even approach 1500 - 2000 lux.

The table below is a guidance for recommended light level in different work spaces:

Activity	Illumination
	(lux, lumen/m2)
Public areas with dark surroundings	20 - 50
Simple orientation for short visits	50 - 100
Working areas where visual tasks are only occasionally performed	100 - 150
Warehouses, Homes, Theaters, Archives	150
Easy Office Work, Classes	250
Normal Office Work, PC Work, Study Library, Groceries, Show Rooms, Laboratories	500
Supermarkets, Mechanical Workshops, Office Landscapes	750
Normal Drawing Work, Detailed Mechanical Workshops, Operation Theatres	1,000
Detailed Drawing Work, Very Detailed Mechanical Works	1500 - 2000
Performance of visual tasks of low contrast  and very small size for prolonged periods of time	2000 - 5000
Performance of very prolonged and exacting visual tasks	5000 - 10000
Performance of very special visual tasks of extremely low contrast and small size	10000 - 20000

Reference Efficacy Info

 The  following is a guide of efficacies one might expect from common lamp and luminaire combinations:
Lamp Efficacy:

Incandescent General Service lamps:
50 watts or less-- 11 L/W
50 to 125 watts-- 17 L/W
Over 125 watts-- 20 L/W
Halogen lamp to 250 watts-- 18 L/W
Fluorescent Lamps (based on mean lumens, all at 3,000k color):
Up to 26 watts, retrofit screw base-- 48 L/W
Up to 42 watts, plug in triple tube -- 55 L/W
Long Twin Tube-- 57 L/W
T12 Energy Saving-- 72 L/W
T8 Energy Saving-- 87 L/W
T5 Energy Saving-- 90 L/W
T5 HO -- 86 L/W
High Intensity Discharge Lamps (based on mean lumens):
Up to 100 watt Metal Halide, coated lamp-- 40 L/W
150 to 250 watt Metal Halide, coated lamp, pulse start-- 55 L/W
400 watt Metal Halide, coated lamp, pulse start-- 72 L/W
Up to 250 watt High Pressure Sodium-- 98 L/W
400 and 1000 watt High Pressure Sodium-- 114 L/W

Luminaire Efficacy:

Incandescent downlight with 60W A19 lamp-- 9 to 11 L/W
Incandescent reflector lamp downlight with PAR lamp and reflector trim-- 9 to 17 L/W
Incandescent reflector lamp downlight with PAR lamp and black baffle-- 5 to 12 L/W
Halogen downlight with elliptical reflector and baffle --10 to 15 L/W
CFL Downlight 42W triple lamp-- 28 to 36 L/W
Metal Halide downlight-- 32 to 37 L/W
Fluorescent lensed troffer with T12 lamps-- 41 to 47 L/W
Fluorescent parabolic troffer with T8 Lamps-- 60 to 67 L/W
New generation direct/indirect recessed fluorescent with T5 lamps-- 82 L/W
High Bay Industrial reflector, Metal Halide lamp-- 36 to 47 L/W
Low Bay Industrial reflector, Metal Halide Lamp-- 40 to 50 L/W
Parking Garage luminaire, Metal Halide Lamp-- 38 to 45 L/W
Parking Garage luminaire, High Pressure Sodium Lamp-- 64 to 80 L/W
Decorative wall sconce-- white acrylic diffuser, CFL plug-in lamp-- 13 to 20 L/W
Decorative wall sconce-- white acrylic diffuser, incandescent lamp-- 4 to 7 L/W
Fluorescent under-cabinet light, T5 lamp-- 35 to 47 LW

Comparison Matrix Between LED versus HPSV Street Light

 

Item	60 w LED Street Light	150w HPSV Street light
Cost of electricity (KWh)	8	8
Operations in hrs(1 day)	10	10
Operations in days(1 year)	365	365
Annual KWh	219	547.5
Annual Cost of Electricity	1752	4380
Lifetime	30000 hrs/3000 days	6000 hrs/600 days
Comparative Cost	21000	4500
Total Cost of Ownership over LED lifetime keeping cost of electricity same	35400	49500

Over All 40% cost saving in LED street Light

 

Salient features of LED lighting

 

1. High energy efficiency & savings- High power factor> .95
2. Safe light- no UV or IR in the beam
3. Low heat dissipation/sink
4. Vibration resistance- no filament to break.
5. Instant on - reaches full brightness in nanoseconds.
6. Long lifespan- 30000- 100000 hrs.
7. Low -temperature friendly-no issue starting in cold temperature.
8. Excellent colour rendering
9. High Brightness- no compromise between efficacy and CRI.
10. Option of colours
11. Eco friendly green products-contains no mercury, lead or other heavy metals.
12. No maintenance cost.
13. Directional - no wasted light; any pattern possible.

LED Lighting

The use of LED, an acronym for Light Emitting Diode, has greatly spread in the last few years within many diverse fields of application, from traffic lights to infrared TV controls. The increasing use of LED within industry is primarily due to technological progresses, which have permitted LED to be produced in colours other than the original red (which in the beginning was the only colour available), as well as the  fundamental characteristics which LED can boast: being trustworthy, highly efficient and with a long-life span. 
LED today also plays an ever increasing role in the field of technical lighting, as LED lighting systems offer various advantages in respect to traditional sources of illumination:

• long life
• no maintenance costs
• greater efficiency in contrast to halogen and florescent lights
• secure operation
• a clean light as it is without IR and UV components
• easy of installing light points
• absence of mercury
• the possibility of a strong spotlight effect
• no problems switching on
• insensitivity to humidity and vibrations
• ease of achieving efficient and effective optics in plastic or glass

LED illuminations have the following characteristics:

• small
• dynamic effects (variations of the RGB colours)
• cost effective shape and size
• long life and robust
• concentrated colours

Due to the characteristics of LED and of the LED lighting systems, light is increasing its value in its ability to create diverse ambiances both publically and privately: such as in the illumination of museums, restaurants, health centres, bars, road signs, safe routes as well as becoming increasingly useful in the naval sector.
The versatility of LED lighting systems make this form of technical lighting particularly adapted to scenography and set design as well as creating original and personalised spaces. Monochrome or multi-colour LED systems perfectly integrate with buildings and their surroundings, becoming an integral part of the design, offering solutions for internal space as well as external spaces, whether in humid environments or very hot atmospheres.
Choosing an LED lighting system brings with it numerous economic advantages in terms of lower costs; the possibility to achieve four times as much light in respect to tungsten flurescent and filament lamps; the increased effeciency and reliability of led is also highlighted in its life span, which is one to two times greater than that of cl;assic lighting sources. 
The Geospec technical team produces and sells a wide range of led lighting systems, which include:

• LED light fittings
• LED lighting profiles
• LED devices
• LED spotlights
• Path lamps
• LED spotlights for swimming pools
• LED spotlights for gardens and small paths
• Spotlights for light fittings and/or lighting for stairways and steps
• Monocrome SMD LED stips
• SMD RGB Led strips
• Internal and external Wall Washers
• Supplies
• Colours for RGB spotlights