Other Energy Efficient Lighting systems

Light Level Abatement (LLA)
Light Level Abatement is another option for lighting retrofitting. LLA technology can save energy by reducing over illumination. Dimming control is an effective LLA technology but it is not common for fluorescent lighting systems due to the cost reason. If properly selected, the following technique can reduce excessive lighting level and save energy.

(a) Use shorter tube
One of the LLA technologies is to replace the standard T8 tube in the existing luminaire with a shorter tube in the existing luminaire with a shorter tube and a QEB extension adaptor. For example, the existing 1200mm T8 tube can be replaced by a 900mm T8 tube with a QEB extension adaptor or even by a 600mm T8 tube for more energy saving.

How much energy can be saved
The estimated amount of energy that can be saved from the conversions and the estimated payback are as follows:

Scope of work

Energy saving

Payback period

Resulting lighting level

Conversion of a 1200mm T8 EMB to:

900mm T8 EB
29%
3.5 years
75%
600mm T8 EB

60%

1.7 years

45%

(b) De-lamping
Energy can be saved directly by taking down tubes from lighting fittings if the area is over illuminated. In general, the lighting level will be reduced by the same proportion (note: some electronic-ballast-driven luminaires do not allow de-lamping). Should the lighting level be over reduced by de-lamping, you may consider to replace the standard tubes with [tri-phosphors tubes] or adding [reflectors] to bring the lighting level back to the desired level.

How much energy can be saved
The amount of energy saved in two real cases of applications and the estimated payback periods are as follows:

Scope of work

Energy saving

Payback period

Resulting lighting level

Conversion of a 3x1200mm T8 EB to:

2x1200mm tri-phosphors T8 with redirection
33%
1.5 years
109%
Conversion of a 3x1200mm T8 EMB to: 2xPnE for T5 with redirection

56%

1.8 years

89%

To view project example, please click here.

Light pipes
Light pipes are a device which allows the increasing use of daylight in buildings. They use the principle of high efficiency reflection to introduce light into interior of a building. They are simply empty tubes which can be straight or angled assemblies. The internal surface of the light pipe is coated with highly reflective material such as anodized aluminum or coated plastic films to enhance the efficiency of light reflection. The figure below provides the typical structure of a light pipe.

Schematic of a typical light pipe. The text above describes the image.
Schematic of a typical light pipe

How much energy can be saved:
The amount of energy saving by the use of light pipes greatly depends on the number of light pipe used. Usually straight light pipes perform better than angled ones as light energy decreases with increased reflections. The light pipe that illustrates in the above figure is usually integrated on the roof of a building. There is another type of light pipe that can be integrated in a building fa?ade to capture daylight and distribute it into the deep zone of a building as shown in the following figure. Considerations on building structure, space allocation of building services installations and architectural design of the building have to be taken into account when making the decision of light pipe applications.

Light pipe integrated in the building façade. The text above describes the image.

Light pipe integrated in the building façade

To view project example, please click here.

Mirror reflector
The light rays are emitted uniformly in all directions from a fluorescent tube. Redirection technology makes use of reflector can direct most of the light emitted form the tube towards the area to be illuminated. Mirror reflectors coated with silver/aluminium alloy or anodized aluminium are effective reflectors.

How much energy can be saved
When properly designed with dimension and curvature, the use of mirror reflectors can increase the illumination level by 35%.

A Mirror reflector. The text above describes the image.
A Mirror reflector

Nano-technology reflector
This is another type of redirection technology. This type of reflector coated with nano-technology material that can increase the illumination level by 25% with a more uniform distribution of light than the mirror reflector.

A nano-technology reflector. The text above describes the image.
A nano-technology reflector

To view project example, please click here.

Further sources of information:
1. EMSD website, Retrofit with Energy Efficient Fluorescent Lighting System: This web page has hyperlinks which may transfer you to third-party website.http://www.emsd.gov.hk/emsd/e_download/pee/ lighting_retrofit.pdf

   
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