1. Natural Lighting System to Promote Energy Efficiency and Reduce Cost
Lawore Olufemi Micheal
1 of 7
ICEPT 2015
LAWORE OLUFEMI MICHEAL
Natural Lighting System to Promote Energy Efficiency and Reduce Cost
Telephone: 07033503402 | Amaff Technologies Limited, Ibadan | laworemike@yahoo.com
A Technical Paper
Presented during NIEEE's International Conference and Exhibition on Power and Telecommunications
(ICEPT 2015)
Abstract
Natural daylight illumination is an outstanding approach to minimize the loads on local power systems thereby
promoting the use of both artificial and natural lighting system for better power management of electricity. Sunlight and
artificial lights are employed, distributed and controlled to give adequate luminance needed for a space.
Here, the paper seeks to explore the possibility of modern day lighting technique in Nigeria with a prove that with a
minimum irradiation average estimate of 357.52W/m2 it is wise to explore the option of daylight means and build
structures that accommodates its use so as to promote good health, better energy use, enhance green environment.
Keywords: Hybrid Solar Lighting, Heliostat, Irradiation, Tubular Daylight Guidance System, Illuminance, Energy-Saver
Introduction
Literature and Problems
Since the advent of natural illumination in the middle of 1980s, introduction of natural light into buildings makes users
consume lesser amount of energy. Natural lighting can be supplemented with artificial illumination to increase luminance
and promote better visibility. Apart from visibility, Natural lighting also supports increase in productivity, good health
life and higher sales. In Nigeria, Natural lighting system could be a way to reduce cool load consumption thereby
reducing demands on the national grid and as well increase productivity in offices and add to aesthetics. It is important
that Nigeria utilizes her solar resources to provide natural lighting system for building for improved energy efficiency
and conservation. At daylight period, the electric light is out or minimized while the sun is allowed to penetrate using any
of the available means of day light harvesting techniques.
When considerations are made on lighting for new building, illumination costs are not limited to fixtures prices but also
installation, retrofitting and maintenance. For retrofitting the argument persists on cost and for maintenance it is vital that
hybrid systemcost little if any more than today’s acceptable systems (FEMP, n.d.).

2. Natural Lighting System to Promote Energy Efficiency and Reduce Cost
Lawore Olufemi Micheal
2 of 7
ICEPT 2015
Artificial lighting affects the human psychology and physiology because the energy spectrumof the incandescent, energy
efficient lamps and fluorescent lighting does not give a full spectrum that is well accustomed to by the human body.
According to liberman, cool white fluorescent are concentrated in the yellow to red region of the visible light spectrum;
incandescent lamps are concentrated in the orange to green portion of the spectrum while energy efficient lamps are
concentrated in the region of yellow to green portion of the visible spectrum (Liberman.J, 1991). Majority of people
prefer sunlight due to its balance in spectrumof colours.
Hathaway et al (Hathaway, et al., n.d.) answer to biological effects of sun light draws this conclusion that the
photobiology action spectra of greatest importance to humans ranges from 290nm to 770nm. Skin reddening and vitamin
D synthesis occurs in the range of 290nm to 375nm. Tanning or pigmentation of the skin and reduction of
dental…[cavities]occurs in response to band light in the band from 280nm to 400nm. Vision is the most sensitive to light
in the 500nm to 650nm range (yellow to green light). Billirubin degradation occurs in response to light in the 400nm to
500nm range (blue light).
Purpose and Contribution
Considering the light bill for the industrialized world today, there is a financial incentive to use higher efficiency lighting.
The real problem then boils down to cost and degrees of user friendliness (Mayhoub, et al., 2010). The goal of hybrid
lighting is to find a practical balance between the cost that is manageable and the future savings that significant
(Mayhoub, et al., 2010). It must be noted that a lighting installation needs to conform to lighting demands for a specific
area without sacrificing good lighting comfort which requires careful consideration regarding appropriate lighting
systems and the use of daylight. Most Nigerians homes and offices depend on bulbs whose illuminant capacity is overtly
wrong for environment with enormous health implication. One of the prevailing problem aside these two in Nigeria is the
issue of architecture designs to accommodate natural light illumination which can be supplemented with artificial
lighting to save cost and enhance productivity: an enhancement of energy sustainability. Also the consideration of leaks
through roofs have necessitated further research that have made skylights, arthelios, roof-lamps less effective to the
modern designs of heliobus, Tubular daylight guidance system heliostat and hybrid solar lighting. These later methods
which have improved in design and best suited for our condition can be employed in offices, hospitals, libraries, homes,
stores and restaurant to enhance visibility, reduce cost, increase sale and improve well-being.
From the cost point of view, energy bill increases overtime due to cost involve in generating, transmitting and
distributing power. Taking Ibadan for example, the MYTO 2 (NERC, 2012) estimate as a continuous increase every year
as attributed in the table below

3. Natural Lighting System to Promote Energy Efficiency and Reduce Cost
Lawore Olufemi Micheal
3 of 7
ICEPT 2015
Table 1: Energy Charges-Ibadan Disco
Source: MYTO 2 provided by NERC 1
Figure 1: Irradiation Values for some years (IITA office, Ibadan)
Result and Discussion
Typical luminous efficacy values for full spectrum fluorescent bulbs are 55lm/W and energy efficient fluorescent bulbs
can approach 100lm/W. About half of the power in natural light is in the visible range with the other half in the infrared.
Large luminous efficacies of about 100lm/W results at 555nm (Frank W.B, n.d.).
From the data got from International Institute of Tropical Agriculture (IITA) analyzed and shown in figure 1& 2, the
average estimated solar irradiance for a year between 800hours to 1800hours is 357.52W/m2. This means that out of the
global irradiance directed to the South West city, Ibadan, a minimal total of 357.52W/m2 (89.022lux) was harvested on
earth with average temperature of 27.37oC around Ibadan, Nigeria and out of which can be utilized for daylight
illumination using techniques like heliostat, heliobus and tubular daylight guidance system. These natural light harvesting
techniques can be incorporated with electrical lighting for interior illumination. One square of bright sunlight
(1000W/m2) can in theory light up 20 rooms or offices (FEMP, n.d.). If the roof area of a building is taken to be
approximately the floor area of any one of its floor, enough light strikes the roof on a sunny day to light every room in

4. Natural Lighting System to Promote Energy Efficiency and Reduce Cost
Lawore Olufemi Micheal
4 of 7
ICEPT 2015
the building even if it is more than a hundred stories high, though the problem facing its outstanding possibility is
collection of light and channeling it to the needed areas.
Figure 2: Charts shows Values of Irradiation for hours and days of the year using Matlab R2012b.
The distribution and availability of power supply is one of the focus of this paper as 24hours power supply is not yet
feasible in the country but what could enhance productivity and improve luminance is Natu ral Lighting System (NIS) to
which lots of research and developmental works have been improved on, incurring heavy funding with major successful
development at the oaks Ridge National Laboratory (ORNL, 2015)that has demonstrated the technical feasibility of an
entirely new, highly energy-efficient ways of lighting and heating buildings using the power of concentrated sunlight.
ORNL is currently developing techniques for transporting the sun’s energy [visibility light and radiant ultraviolet (UV)
and IR energy] into buildings for use not only for interior lighting but for novel hybrid application such as solar hot water
heating and space heating. Though the initial cost is still very high but there are other methods of day -lighting system
that can be used and are explored in Nigeria to minimize cost and for redistribution of little power generated to remote
place:
Tubular Daylight Guidance System (TDGS): this is greatly an improved and modern technology that serves as option
for residential, commercial, school, store etc and provides suitable illumination needed for a space. They make natural
light more productive for use and overtime reduces the cost of lighting which consumes a quarter of energy cost for
commercial areas and 10-20% for industry (FEMP, n.d.). They are passive, cheap to manufacture, effective for overcast
and clear skies with relatively easy to install which can be done in couple of hours by a professional with a tube
telescoping system, reduces glare and inconsistent light pattern. The design has been so much under perfection that the
risk of leak is greatly reduced. The cost of TDGS ranges from $399 for a 200ft2 to $549 for a 1600ft2 (minus installation
cost) of which in addition with a smart LED will help provide lighting till night time with a mounting height of about
15ft. The initial cost can be above a N100000 but it would after 10-12 years start saving a building of a great energy cost
and provide a more friendly and suitable environment for home, office, study or workshop. 160DSe Solatube type
TDGS can also be used in kitchen, hallways, bathrooms, and closets with a coverage area of 200ft 2 at a cost of $399

5. Natural Lighting System to Promote Energy Efficiency and Reduce Cost
Lawore Olufemi Micheal
5 of 7
ICEPT 2015
with when implemented with SmartLED will provide energy for the whole night. TDGS with electric lighting can be
used to maximize the harvest of sunlight during sunny days (Anon., n.d.).
Source: Solatube International
Figure 3: TDGS method of Dayighting with SmartLED for Interiors (Anon., n.d.)
Heliostat: Another method to save cost in building is to make use of mirrors which are projected at some angles to
capture the movement of the sun and direct the reflection to a particular direction. Heliostat can be employed to project
sunlight directly through window or skylight, or into any structural arrangement of optical elements, example are light
tubes that projects an amount of sunlight where it is needed. It is quite more expensive than TDGS and would require
digital control, motor-drives to rotate the mirrors at degrees/time to positions of the sun’s ray. H1 heliostat 48” Rigid
reflector of quantity 1-3 can deliver 1300watts of energy to a target or over 15000lumen for lighting application (Anon.,
n.d.). Aside lighting, this can also be channeled for heating purpose. The larger the mirror mounted, the larger the light
delivered.
Hybrid Solar Lighting (HSL): Another alternative to other day lighting method is a new technology by Oak Ridge
National Laboratory which uses power of concentration of the sun’s energy [visible light, ultraviolet and radiant energy]
into building for interior lighting and heating purpose. It has been proposed that HSL should be saving the nation more
than 50million KWh/year in the US (FEMP, n.d.). Hybrid lighting components include radiation collection system, the
light distributive system, the controls and the luminaires. The light transmission system currently used is of flexible low
cost and large core optic fibers. The visible light is focused into the tubes and light is transmitted to locations in the
building. This method is the most effective for tall buildings because of the high efficiency and possible direction it has
better than other day light mechanism (ORNL, 2015).

6. Natural Lighting System to Promote Energy Efficiency and Reduce Cost
Lawore Olufemi Micheal
6 of 7
ICEPT 2015
Figure 4: Hybrid Solar lighting Model and Distribution for Interiors (FEMP, n.d.)
Conclusion
We can reduce the demand of power on national grid by exploring natural lighting system with supplements from
electrical means so as to help communities without power access get illuminated since Nigeria power system has a quota
estimate given to each states and sector based on power generation availability. Aside, health impact to types of light
fittings through the use of electric lamp has hazardous gas, and its disposal is another reason to promote the use of
daylight techniques in residence, schools and commercial centers.
In order to save more cost, sustainable architecture needs to be put in place to accommodate new means of lighting
system that reduces energy cost and helps for better focus and aesthetics for health reasons. The initial cost though may
be high but the benefits are huge especially in areas like eateries and stores where it can attract customers. The use of
daylight in offices, libraries, and workshop can minimize a third of energy cost, improve health life and promote better
work condition since only natural light produces all possible energy spectrumfor good use.
With a minimum of 300W/m2 irradiation value in Nigeria, natural lighting technique can be used to help bring a brighter
atmosphere in the country. The Abundance of Sun’s light is an opportunity to improve on building architecture and
promote natural illumination.

7. Natural Lighting System to Promote Energy Efficiency and Reduce Cost
Lawore Olufemi Micheal
7 of 7
ICEPT 2015
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