40% Energy Saving for Signboards
at Cosmetic Counters in Department Stores (Corton Boxes)
With trough-type lighting fixtures used for signboards (Corton boxes) we see at cosmetics counters in department stores, etc.
, MCPET can achieve 40% energy saving. If MCPET is combined with the existing lighting fixtures based on the same configuration,
illuminance can be increased by 60%.
Also, MCPET has the effect of correcting “irregular brightness of lamps.
” Fig. 3-[1] is a simplified illustration of how Corton boxes are normally used at cosmetic counters in department stores.
Here, 32-watt fluorescent lamps are set in trough-type lighting fixtures. The depth of the signboard is 200 mm,
lamp pitch is 200 mm, and distance from the fluorescent lamp center to the back sheet is 70 mm. Mitsubishi Rayon’s #432
(total light transmittance: 58%, diffusion coefficient: 84%) is a representative brand of surface acrylic sheet.
In applications where MCPET is used for the first time, MCPET is sometimes attached to the back sheet between
lighting fixtures using heat-resistant double-sided tape. However, this method is not effective with trough-type lighting fixtures.
This is because the distance between the fluorescent lamp and back sheet is longer. Due to a long distance of 130 mm
or more between the fluorescent lamp and back sheet as measured from the center of the fluorescent lamp, light quantity,
which is inversely proportional to the square of distance, decreases before light is reflected on MCPET.
In Fig. 3-[2], MCPET is guided through the gaps between the fluorescent lamps and lighting fixtures.
This method alone increases the average illuminance by as much as 60%, from 3,250 lx to 5,200 lx.
As a precaution, a strategy must be planned beforehand for replacement of glow lamps in accordance with the specific lighting design.
Alternatively, glow lamps can be replaced with electronic glow mechanisms, in which case there is no longer a need to replace glow lamps.
Fig. 3-[3] shows an example that achieves 40% energy saving with two less fluorescent lamps than the configuration
illustrated in Fig. 3-[1]. Here, the average illuminance is 3,220 lx, which is roughly the same as the illuminance of
the current lighting design.
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Introduction of MCPET
Furukawa Electric successfully developed the world’s first industrial production process for microfoamed PET light-reflective sheet (MCPET),
and began sale of the new sheet. The process uses clean carbonic acid gas as a foaming agent to make PET (polyethylene terephthalate),
which can be used for recyclable drink containers, etc., by foaming the material to five times the original volume (bubble fraction: 80%)
and then shaping the foamed material into a white foamed sheet with a thickness of 1 mm. In particular,
bubbles in the sheet have an average size of 10 μm or less. In fact, this small bubble size that could not be heretofore achievable
with conventional foamed sheets is one key feature of our new MCPET.
These fine bubbles result in excellent optical characteristics,
such as an overall visible light reflectivity of 99% or higher and a diffuse reflectance of 95% or higher
(both are relative values compared to white barium sulphate sheet).
Furthermore, while conventional reflective sheets (white-coated steel sheet and metal reflective sheet with mirror surface) have a lower reflectance
for visible light with longer wavelengths (red light) than for light with shorter wavelengths (blue light),
which causes the object irradiated by reflected light to look less reddish and more bluish thus darker,
our MCPET reflects both red light and blue light at equally high reflectance levels (Graph 1).
Also, MCPET is a plastic reflective sheet, which means that it is flexible and can be easily bent,
cut or otherwise processed, or have bend lines marked on it. Since the diffuse reflectance is very high at 95% or above,
MCPET does not require extra consideration regarding angle of reflection, which must be designed with strict precision in many cases,
and this feature also makes MCPET very simple to use.
MCPET can be effectively utilized with all types of surface light sources using fluorescent lamps,
cold-cathode tubes, etc., as well as in other applications such as where a light source is located inside a box-shaped
lighting fixture whose front side is open. This paper describes the effect and usage of MCPET in each lighting
or signboard application by introducing familiar situations where MCPET can be utilized.
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30% Energy Saving for Built-in Lighting in Offices and Stores
Lighting in offices as well as fast-food and other restaurants uses built-in lighting fixtures made with a milky-white
translucent acrylic surface sheet having glare-cutoff feature to produce an exclusive ambiance.
For example, one 450 x 450-mm square lighting fixture uses three compact fluorescent lamps,
each having a power output of 36 watts. When MCPET is used as a reflective sheet, however,
only two lamps are needed to produce equivalent or greater illuminance compared to a three-lamp lighting fixture
using a conventional reflective sheet (white-coated steel sheet), which leads to 33% energy saving.
To compare illuminance, a simple example is presented where illuminance was measured using an illuminance meter
positioned at the center of each surface acrylic plate sheet in a manner contacting the acrylic sheet.
While three lamps produce 17,000 lx with the conventional lighting fixture, two lamps achieve 19,000
lx with the MCPET lighting fixture.
When MCPET is used as a reflective sheet while keeping the number of lamps at three, illuminance increases 50%.
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Showcase Lighting in Supermarkets
– Saving Illuminance by 30%
- Making Products Look Fresher and Tastier
with the Effect of Red Light
MCPET is used for lighting in supermarket showcases displaying fish, meat, vegetable, milk, etc.,
as well as showcases in convenience stores, cake shops, etc., achieving 30% greater illuminance.
Fig. 2-[1] is a typical showcase used in supermarkets, etc. When current showcases are examined,
it is found that brightness is different in different areas of the case. Accordingly, stores are
selecting products they want to promote more, and placing them in brighter areas.
Fluorescent lamps produce white light, which is actually a combination of different colors of light from blue to red.
However, normal reflective sheets (white-coated steel sheet and aluminum sheet with mirror surface) partially absorb
red light among the spectrum of light produced by fluorescent lamps, and consequently reflected light becomes bluish and darker.
Such light makes even fresh sashimi look older than it actually is.
In Fig. 2-[2], MCPET is used as a curved surface. In some cases, bend lines are marked with appropriate dimensions and MCPET
is bent along the lines in the shape of a reverse “C” to encase fluorescent lamps. In the prototype stage,
you can draw bend lines using a ballpoint pen, etc., and then bend the sheet along the lines
(use of a cutting knife is not appropriate, because stress may concentrate along the lines to make the sheet break).
Since the quantity of light loss increases as the reflective surface is moved farther away from the fluorescent lamp,
in some cases it is more efficient to make a curved surface with MCPET by utilizing its elasticity.
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50% Energy Saving for Storefront Signboards of Convenience Stores
Traditionally, convenience stores use pairs of 40-watt fluorescent lamps arranged side by side for their storefront signboards
(façade signboards). If MCPET is used, the number of fluorescent lamps can be reduced to just one, to save energy by 50%.
The width of a typical façade signboard is 1,300 mm, in line with the length of a 40-watt fluorescent lamp being approx.
1,200 mm. The height is 900 mm on average, while the depth is mostly 200 mm.
However, there is a recent trend for slimmer lighting designs with a depth of as small as 80 mm or so.
An average convenience store has ten signboards connected side by side, with each signboard having a height of 900 mm and width
of 1,300 mm. These signboards come in various heights, from 600 mm with the shortest ones to 1,100 mm with the highest ones.
Use of MCPET allows for creation of a façade signboard having the maximum height dimension of 1,100 mm (depth: 200 mm)
using a single fluorescent lamp and still achieving 50% energy saving.
Photograph 2-[1] shows a MCPET signboard using a single fluorescent lamp, and a conventional signboard,
placed side by side with their surface acrylic sheets removed to expose the inside.
Photograph 2-[2] is a side view showing how MCPET is used.
MCPET is guided through the gap between the fluorescent lamp and lamp holder directly below the fluorescent lamp,
and is open toward the front at the top edge and bottom edge.
In Photograph 2-[3], the decorative acrylic sheet is removed and a plain milky-white translucent acrylic sheet is
set to measure the illuminance distribution of the surface sheet.
Graph 2 shows the illuminance distribution measured in the longitudinal direction at the width center on the surface of a
signboard having a height of 1,100 mm. A MCPET signboard with a single fluorescent lamp is compared with a conventional signboard.
In general, the signboards of convenience stores are expected to have 1,000 lx or more at any point on their surface.
Although not shown in Graph 2, the surface illuminance of a conventional signboard is around 600 lx at edges in the width direction.
On the other hand, the surface illuminance of a MCPET signboard is 1,000 lx.
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Correction of “Irregular Brightness of Lamps”
in Advertising Signboards at Subway Stations
MCPET is used to correct “irregular brightness of lamps” and save energy for advertising signboards at subway stations (Photograph 3).
Some of these signboards are produced without adhering to “Relationship of Lamp Pitch and Distance at Which Lines of Light
from Light Sources Become Unrecognizable” (“Outdoor Advertising Handbook,” issued by the Federation
of All Japan Out-door Advertising Associations.) Accordingly, oftentimes we see signboards having “irregular brightness”
of fluorescent lamps used inside.
One way to correct this “irregular brightness of lamps” in signboards is to increase the number of lamps
and reduce the lamp pitch. However, this directly contradicts the notion of energy saving.
When MCPET is used, the problem of “irregular brightness of lamps” can be resolved without having to increase the number of lamps.
“Irregular brightness of lamps” occurring in signboards with a notably small thickness
can be solved by means of using, along with MCPET, a “diffusion cap” that is placed over each lamp to eliminate its
“brightness irregularity.”
Photograph 4 shows an example of how effective these diffusion caps can be.
“Relationship of Lamp Pitch and Distance at Which Lines of Light from Light Sources Become Unrecognizable” is a graph illustrating
the relationship of the lamp pitch needed to suppress “irregular brightness of lamps” on one hand, and the distance from
the lamp center to the surface acrylic sheet on the other, for each type of acrylic sheet. By using MCPET, this distance can be
reduced to create a slim signboard, or the lamp pitch can be extended to save energy. This graph showing the above relationship
provides a clear illustration of the benefits of using MCPET, and is often presented to customers as a reference.
However, the level of “irregular brightness of lamps” depends on how a person perceives it at the actual location using his
or her visual sense, and wrong use of MCPET can lead to problems. Due to this concern, application examples of MCPET for correction of
“irregular brightness of lamps” are not provided in this paper. If you are interested, please contact us. We will give you appropriate
information after understanding your specific application.
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Slim Signboards
Bright, slim signboards having minimal “irregular brightness of lamps” can be produced
at affordable cost using MCPET, diffusion caps and high-diffusion acrylic sheets.
Slim signboards with a depth of 60 mm, thickness of 28 mm for the cold-cathode tube type or 45 mm for the T5 slim tube type,
and outer diameter of 32 mm, can be designed. Fig. 3 shows how to construct a slim signboard using T5 slim tubes.
Roughly the same method can be employed for signboards using cold-cathode tubes or Ø32 fluorescent lamps.
With T5 slim tubes, Mitsubishi Rayon’s #430 milky-white translucent acrylic sheet with a depth of 3 mm is used.
T5 slim tubes are each fitted with a diffusion cap and arranged at a 150-mm pitch.
MCPET is shaped in a triangle with an apex angle of 90° by adjusting its height not to exceed the height of the lamp
when viewed from the back sheet side. Slim signboards can be used effectively in small spaces and draw more attention of,
or give more impact to, people who see them. They have become an increasingly popular choice at exhibition venues,
in women’s clothing stores, for menu boards, as outdoor poster panels, and at gas stations and carparks, among others.
One way to correct this “irregular brightness of lamps” in signboards is to increase the number of lamps
and reduce the lamp pitch. However, this directly contradicts the notion of energy saving.
When MCPET is used, the problem of “irregular brightness of lamps” can be resolved without having to increase the number of lamps.
“Irregular brightness of lamps” occurring in signboards with a notably small thickness
can be solved by means of using, along with MCPET, a “diffusion cap” that is placed over each lamp to eliminate its
“brightness irregularity.”
Photograph 4 shows an example of how effective these diffusion caps can be.
“Relationship of Lamp Pitch and Distance at Which Lines of Light from Light Sources Become Unrecognizable” is a graph illustrating
the relationship of the lamp pitch needed to suppress “irregular brightness of lamps” on one hand, and the distance from
the lamp center to the surface acrylic sheet on the other, for each type of acrylic sheet. By using MCPET, this distance can be
reduced to create a slim signboard, or the lamp pitch can be extended to save energy. This graph showing the above relationship
provides a clear illustration of the benefits of using MCPET, and is often presented to customers as a reference.
However, the level of “irregular brightness of lamps” depends on how a person perceives it at the actual location using his
or her visual sense, and wrong use of MCPET can lead to problems. Due to this concern, application examples of MCPET for correction of
“irregular brightness of lamps” are not provided in this paper. If you are interested, please contact us. We will give you appropriate
information after understanding your specific application.
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Slim Double-sided Surface Light Source
Current double-sided surface light sources such as those used in side signboards at banks are very thick,
having a thickness of 300 mm or more, except for edge-light types having a small screen.
When MCPET and double-sided diffusion caps are used, however, slim double-sided surface light sources with a thickness of
60 to 100 mm can be produced easily using Ø32 fluorescent lamps. Photograph 5 shows an example of the effectiveness of a
100-mm thick double-sided surface light source using MCPET, while Fig. 4 illustrates the method to construct this surface light source.
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Others
We are examining use of MCPET for Schaukasten, simple studios, strobes,
illuminated ceilings, illuminated walls, illuminated shelves for clothing display,
illuminated curtains, illuminated overhead banners, game machines, and down lights, among others.
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Energy-saving Potential of Hundreds of Millions of Yen in Electricity Bills for Restaurant Chains
Lastly, let’s calculate the specific electricity savings that can be achieved with the energy-saving effect of MCPET.
(Power factors of stabilizers, etc., are not considered.)
(Restaurants)
Electricity savings are calculated for restaurants based on the 450 x 450-mm square built-in lighting fixture explained in 2.
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Annual energy savings per lighting fixture
The current lighting fixture using three 36-watt lamps is changed to a MCPET type using two 36-watt lamps.
Annual electricity savings = Power consumption per day x Electricity rate per 1 kWh x Number of operating days a year
= 36 watts x 1 lamp x 10 hours per day / 1,000 x 27.5 cents per kWh x 330 days = $27.00 per year
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Annual energy savings per restaurant
Assuming that the restaurant has average 20 lighting fixtures, the annual electricity savings are calculated as follows:
Annual electricity savings = [1] x 20 units = $540.00 per restaurant
(-2,376 kWh per year per restaurant)
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Annual energy savings for the entire restaurant chain
Assuming that the restaurant chain has 2,000 outlets, the annual electricity savings are calculated as follows:
Annual electricity savings = [2] x 2,000 restaurants = $109,090.90 per year
(-4.75 million kWh per year)
(Convenience Stores)
Savings are calculated based on the façade signboard explained in 5.
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Annual energy savings per lighting fixture
The current lighting fixture using two 40-watt lamps is changed to a MCPET type using one 40-watt lamp.
Annual electricity savings = Power consumption per day x Electricity rate per 1 kWh x Number of operating days a year =
40 watts x 1 lamp x 10 hours per day / 1,000 x 25 yen per kWh x 365 days = $33.18 per year
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Annual energy savings per store
Assuming that the convenience store has average 10 lighting fixtures, the annual electricity savings are calculated as follows:
Annual electricity savings = [1] x 10 units = $331.81 per store
(-1,460 kWh per year per store)
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Annual energy savings for the entire convenience store chain
Assuming that the convenience store chain has 5,000 outlets, the annual electricity savings are calculated as follows:
Annual electricity savings = [3] x 5,000 stores = $1,636,363.63 per year
(-7.3 million kWh per year)
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