Daylights Product Economics

The Economics of Daylights

Daylights have found usage across a wide range of industries and more new customers are willing to install daylights at their premises. The use of daylight has several advantages. This article highlights the advantages of daylights in terms of lighting, energy saving and heat reduction by comparing Skyshade Norikool Double Glazing Daylight with LED Lights and Metal Halide lamps.

Light Simulation and Energy Cost Comparision

Site Details

Area2,000 Sq.m.
Average Height12 m
Daylight ProductSkyshade Norikool Double Galzing
Aperture Area 1.25 Sq.m.
Design illuminanace275 lux

Daylight Simulation Report

Parameters Values
Daylight Autonomy
9 hours
Average Daylight hours10 hours
Uniformity Ratio-0.4 to 0.5
SFR (Skylight to floor area ratio)0.015
Daylight - Simulation Report

Observations from Metal Halide and LED Light Simulation

Parameters Metal Halide Lamp LED Light
Wattage of each light400 W150 W
Total wattage required for 2,000 Sq.m.22.4 Kw8.4 Kw
Illuminance Uniformity0.4410.45
Lighting Power Density11.2W / Sq.m.4.2W / Sq.m.
LED Light Simuation
Metal Halide Light Simulation

Energy Savings - Daylights Vs Electrical Lights

ParametersSYSKA Norikool Double Glazing DaylightLED LightMetal Halide Lighting
Lux Level250 - 300 Lux250 - 300 Lux250 - 300 Lux
Aperture Area1.2 Sq.m.NANA
Lighting LoadNA8.4 Kw22.4 Kw
Average Daylighting hours10 hoursNANA
Average Factory Working days per year360 days360 days360 days
Unit Electricity CostNARs.9.0 / unitRs.9.0 / unit
Energy Savings per Year30,240 Kwh 80,640 Kwh
*Calculated by multiplying the total load, daily usage hours and the total no. of days per year
Energy Cost Savings per YearRs.2,72,160.00Rs.7,25,760.00
#Energy savings per year x Unit Electricity Cost Note: 1. Add bulb replacement costs 2. Add cooling load reduction cost
Approximate Payback Period2 years 1 Year

Heat Comparison Study

Building Details

Building locationHyderabad
Roof area2000 sq.m
Overall heat transfer coefficientU w/sq.m°k
U value of insulated metal roof [UR]0.032 w/sq.m°k
U value of Norikool DGZ0.74 w/sq.m°k
Temperature difference ( T) between ambient air to
inside air
15 deg Celsius
Electrical lighting load22.4 kw
Lighting power density11.2 w/sq.m
Norikool™DGZ proposed25
Skylight to floor ratio with Norikool1.50%
Illuminance required250 lux
Under deck roof installationYes

Heat Comparision - Daylights Vs. Electrical Lights

Parameters Daylights LED Lights Metal Halide Lamps
Heat transfer rate through insulated roof 1.278 Kw 6.84 Kw10.49 Kw


Formula to calculate Heat transfer = Area x Heat Coefficient x Temperature Difference.

In case of Daylights, the heat coffecient is calculated by considering the SFR and the Roof with skylight to Floor ratio.

The calculation in this case is as below.

Heat Transfer Through Skyshade Double Glaze Norikool = 2,000 X 15[0.985 X 0.032 + 0.015 X 0.74] = 1.278 Kw

In case of the Heat transfer in roof without daylight, the heat transferred through roof and the heat gained from electrical lights are summed up.

The Heat transferred through insulated roof with no daylight = 2,000 x 0.032  x 15 = 0.96 Kw

The heat gained in case of LED Lights = 70% of the light load = 8.4 x 0.7 = 5.88 Kw

The total heat transfer in the case of LED Lights = 0.96 +5.88 = 6.84

The heat gained in case of Metal Halide Lamps = 28% of Light Load + Ballast Wattage = 28% x 22.4 + 3.36 = 9.531 KW
The total heat transfer in case of Metal Halide Lamps = 9.531+0.96 = 10.49 KW
It can be easily inferred, that the heat transfer through Skyshade Double Glaze Norikool is the lowest.
Considering the energy saving and heat transfer calculations, it can be easily concluded that Skyshade Double Glaze Norikool reduces the heat transfer and energy cost.

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