Energy Saving: Lighting Calculation (Unpredictable But Significant)

When I ask to all my friends, my clients and my customers, are you have been saved energy from lighting system? All of them answered the result of saving from lamps or lighting system was not significant. Why? Because lamps just a little loads compare than others loads (motors, fans, pumps, etc). Yes, that's true. But otherwise, it's FALSE!!!

Why? Let's see the calculation example below after you read where are the energy saving placed.

In Lighting Systems, there are many way's to save the energies if we know and how to do that. I'll try to explain it in details.



Where are the saving placed ?



1. Lighting Control

• Timer Switches to turn off lights after a fixed period has passed
• Occupancy sensor / movement detectors to turn off lights when no movement has been detected for a certain period
• Photoelectric cells / daylight harvesting sensor to control lights near windows. When bright exterior light is available, lamps are turned off or dimmed
• Programmable timers to switch lights on and off at predetermined times
• Dimmable light to maintain a low level of illumination at off-peak periods
• Voltage regulators to optimize the power consumed. Ballast perform this function on fluorescent lighting. Voltage regulators are also available for other lighting types such as high pressure sodium lamps.

2. Types of Lamps

Nowadays, there are a lot of types of lamps. But, we not realize that each of lamps have different characteristic and specification. For the example, the old fluorescent lamp, with T12, usually have rated power up to 40W. Today, with same intensity output of light, you can use T8 with rated power up to 36W. The conclusion is you must know about the characteristic and the specification of lamp that will be used.


3. Reflectors



Around 70% of fluorescent tube's light is directed sideways and upwards to the light fittings surfaces.


High efficiency reflector has a spectral efficiency of over 90%. This means two lamps may be replaced by a single lamps. In this way it's possible to reduce energy costs attributed to lighting by 50% or more.




4. Changing Conventional Ballast (Electromagnetic) With Electronic Ballast

Conventional Ballast have power factor (cos phi) up to 0.45.
Electronic Ballast have power factor (cos phi) up to 0.95.
What are the differences? See the calculation in end of this page.


5. Don't want to change Conventional Ballast (Economics reasons), Use Special Capacitor For Lamps

If you don't want to change Conventional Ballast because you have economic reasons (usually for home application), I have the alternatives. Use Special Capacitor for lamps. This capacitor had special schematic wiring diagram, so why you must use Special Capacitor for lamps.

Conventional Ballast without special capacitor have power factor (cos phi) up to 0.45.
Conventional Ballast with special capacitor have power factor (cos phi) up to 0.95.
What are the differences? See the calculation in end of this page.



Near from the end, The Real Calculation...

When I go with my friend to one of his customer, I just ask for their existing lighting system. They says that using all systems as similar as my design system before I explain my design to them. But they have some systems that still not applicable yet. They said that after used the lighting system, they can save the electrical bills up to 50% / months. I'm aghast with their statement. It's same with my calculation that shown below.

For this calculation, electricity rate was from my region / my country electricity goverment factory. The calculation was only in one point that include two lamps in one housing / fitting. Power of each lamp was 4o Watt, works in 220VAC 50Hz. And applicable for industrial and home applicances.

• USING CONVENTIONAL BALLAST NOR SPECIAL CAPACITOR AND T12 40W LAMP (pf = 0.45)

I = (2 x 40W) : (220 VAC x 0.45) = 0.808 A
P = 0.808 x 220VAC = 177.76 Watt
Electricity used per month (1 kWh = Rp. 480.-)
12 hours / day x 30 days x 177.76 Watt = 63,993.6 Watt.Hours = 63.994 kWh
Electricity bill per month (exclude basic load type value bill):
Rp. 480.- x 63.994 kWh = Rp. 30,716.93

• USING ELECTRONIC BALLAST OR SPECIAL CAPACITOR AND T8 36W LAMP(pf = 0.95)

I = (2 x 36W) : (220 VAC x 0.95) = 0.344 A
P = 0.344 x 220VAC = 75.68 Watt
Electricity used per month (1 kWh = Rp. 480.-)
12 hours / day x 30 days x 84.26 Watt = 27,244.8 Watt.Hours = 27.245 kWh
Electricity bill per month (exclude basic load type value bill):
Rp. 480.- x 30.334 kWh = Rp. 13,077.6

TOTAL SAVING PER MONTH
Rp. 30,716.93 - Rp. 13,077.6 = Rp. 17,639.33

It's means you can save 57.43% / month

If you needs the details, please contact me.

How To Achieve Energy Saving???

30% savings are available through existing EE solutions, but to really understand where these opportunities are, let’s understand first the main differences between Passive and Active EE.

Passive EE is regarded as the installation of countermeasures against thermal losses, the use of low consumption equipment and so forth. Active Energy Efficiency is defined as effecting permanent change through measurement, monitoring and control of energy usage. It is vital, but insufficient, to make use of energy saving equipment and devices such as low energy lighting. Without proper control, these measures often merely militate against energy losses rather than make a real reduction in energy consumed and in the way it is used.

Everything that consumes power – from direct electricity consumption through lighting, heating and most significantly electric motors, but also in HVAC control, boiler control and so forth – must be addressed actively if sustained gains are to be made. This includes changing the culture and mindsets of groups of individuals, resulting in behavioural shifts at work and at home, but clearly, this need is reduced by greater use of technical controls.
- 10 to 15% savings are achievable through passive EE measures such as installing low consumption devices, insulating building, etc.
- 5 to 15% can be achieved through such as optimizing usage of installation and devices, turn off devices when not needed, regulating motors or heating at the optimized level…
- Up to 40% of the potential savings for a motor system are realized by the Drive & Automation
- Up to 30% of the potential for savings in a building lighting system can be realized via the lighting control system
- And a further 2 to 8% can also be achieved through active EE measures such as putting in place a permanent monitoring and improvement program

But savings can be lost quickly if there is:
- Unplanned, unmanaged shutdowns of equipment and processes
- Lack of automation and regulation (motors, heating)
- No continuity of behaviors

Energy Efficiency is not different form other disciplines and we take a very rational approach to it, very similar to the 6Sigma DMAIC (Define, Measure, Analyze, Improve and Control) approach.

As always, the first thing that we need to do is to measure in order to understand where are the main consumptions, what is the consumption pattern, etc. This initial measurement, together with some benchmarking information, will allow us see howgood or bad we are doing, to define the main improvement axis and an estimation of what can be expected in terms of gains. We can not improve what we can not measure.

Then, we need to fix the basics or what is called passive EE. Change old enduse devices by Low consumption ones (bulbs, motors, etc), Improve the Insulation of your installations, and assure power quality reliability in order to be able to work in a stable environment where the gains are going to sustainable over time. After that, we are ready to enter into the automation phase or Active Energy efficiency. As already highlighted, everything that consumes power must be addressed actively if sustained gains are to be made.

Active Energy Efficiency can be achieved not only when energy saving devices and equipment are installed, but with all kind of end-use devices. It is this aspect of control that is critical to achieving the maximum efficiency. As an example, consider a low consumption bulb that is left on in an empty room. All that is achieved is that less energy is wasted compared to using an ordinary bulb, but energy is still wasted!

Responsible equipment manufacturers are continually developing more efficient products. However, while for the most part the efficiency of the equipment is a fair representation of its energy saving potential - say, in the example of a domestic washing machine or refrigerator - it is not always the case in industrial and commercial equipment. In many cases the overall energy performance of the system is what really counts. Put simply, if an energy saving device is left permanently on stand-by it can be less efficient than a higher consuming device that is always switched off when not in use.

Summarizing, managing energy is the key to maximizing its usefulness and economizing on its waste. While there are increasing numbers of products that are now more energy efficient than their predecessors, controlling switching or reducing settings of variables such as temperature or speed, makes the greatest impact.