Glare Causes and Reduction in Building Design: Construction Tech 5

This assignment delves into the crucial aspects of lighting design within the field of construction technology. It begins by examining the differences between rods and cones in the human eye and how these variations impact our vision and influence lighting design for diverse tasks. The assignment then identifies and explains five key considerations that affect required light levels in a workplace, supported by illustrative diagrams. Furthermore, it discusses how to determine appropriate light levels for specific workplaces, providing examples of different visual tasks and acceptable illuminance ranges. The document also explores the factors influencing the amount of natural light in buildings and concludes by analyzing the causes of glare and methods for its reduction. This comprehensive study is essential for understanding and optimizing lighting in construction environments. Desklib provides past papers and solved assignments for students.

CONSTRUCTION TECHNOLOGY 5
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Question One
The eye's retina has two types of photoreceptors. They include cones and rods. The present
understanding of cones is that they can be divided into green cones that account for over 32%,
red cones at 64% and blue cones at 2%. They are known to provide the color sensitivity of the
eye. The concentration of the green and red cones is at the fovea centralis (Matusiak 2013). The
blue cones are known to have the highest sensitivity despite the fact that they are found outside
the fovea. This leads to a specific distinction on how the eye perceives the blue color.The cones
are very less sensitive to light than rods in any comparison of the daylight. The cones are
responsible for all high-resolution vision. Rods are not much sensitive to color. These
components are usually triggered by individual photons but only under optimal conditions.
The condition that is considered optimal is normally obtained after a considerable period of
darkness. The respond of rods to blue color is very sharp. However, its response to red is very
poor. In the video of Paul, the driver has instruments of red lights. Since the rods do not respond
to red, the driver possibly gains full dark-adapted vision with the rods that is later used to watch
obstacles (Mueller 2013). This is why it is normally undesirable to examine objects by the use of
white light just for a short time. This is because the attainment of optimum night vision takes up
to half an hour. In general, rods will see perfectly in white, black and shades of grey thus
communicating the shape and the form of the object. Their super sensitiveness allows us to see at
night. In the design of the lighting system, the scotopic vision is achieved by the guidance of
rods that are responsible for vision at low light levels. Also for the photopic vision, reference is
drawn from cones that have active levels of light (Ghosh, Norton and Duffy 2016).

Question Two
The type of lighting design will be dependent on the following factors:
1) The suitability for use
In most of the cases, specific activities will demand a specific amount of light. In offices where
paperwork is common, the user may prefer little reflections from other sources. In fact, natural
light sources are to be contained and controlled to avoid reflections and its consequences like
glare.
Figure 1: Distraction reflections to be avoided in paperwork (Matusiak 2013)
2) The safety factors for use
People spend most of their time in the workplace as opposed to other places. This means that
safety standards must be adhered to in such places. Safety measures will ensure that the vision of
the workers is not interfered with (Suk, Schiler and Kensek 2013).

Figure 2: Checking for the presence of veiling reflections (Matusiak 2013)
3) The area size to be covered
Workers should not strain to see objects because of the light source. Sufficient sources should be
provided in the ratio of the space available. Also, small area coverage should be provided with
just enough light sources to avoid too much glare.

Figure 3: Stored goods causing obstruction as a result of one light source (Matusiak 2013)
4) The general physical constraints of the place
In the event that the area of the location of the office is too congested for access to the natural
light, artificial light sources may be embraced. This implies that even the small sources of natural
light will be blocked to avoid glare. The provision of artificial light must be able to meet the
requirements of the activities that are being carried by occupants in the room.

Figure 4: Natural light is blocked and replaced with an artificial light source (Matusiak 2013)
5) The purpose for which the light will be used.
In places of work where minute objects like needle are handled for the repairs of electronics,
local lighting system may be required. The local lighting system is used where there is a
requirement of high-level illumination but within the small area. Also, the lighting system must
be flexible so that it can be focused on specific points.
Figure 5: Local lighting providing flexible light (Matusiak 2013).
Question 3
Level of illuminance and tasks
i. The public areas with very dark surrounding with be provided with illumination lux,
lumen/m2 between 20-50. This is because the activities in such a place are very general
and people do not need a source of light that draws attention.

ii. At homes, warehouse and theaters range 140-150 as illumination lux, lumen/m2 will be
recommended. This is basically to allow people to see objects that would otherwise
knock down.
iii. For the case of the office work and classes, books and other paperwork are handled.
Reflections should be avoided and as such a illumine range of 250 illumination lux,
lumen/m2 will be recommended.
iv. Detailed mechanical work and detailed drawing work involves checking of very minutes
bur crucial components. A flexible light source with arrange of 1500 to 2000 as
illumination lux, lumen/m2 will be required.
v. The performance of a very special visual task that has extremely low contrast and small
size will require much light. The illuminance rage of 10000 to 20000as illumination lux,
lumen/m2 is normally used(Hirning, Isoardi and Cowling 2014).
Question Four
Factors that affect the amount of natural light falling on a work surface inside a building
Size and location of the windows
When the windows are located in such a way that they are exposed to natural light. The number
of skylights is normally reduced by the windows (Van 2014). Actually, they impact the location
of the skylights.The light from the windows, however, diminishes as the sun moves across the
sky.

Figure 6: Size and location of the window (Van 2014).
Interior obstructions
The distribution of natural light within the building is normally affected by the interior walls that
are known to obstruct light. Also the presence of bright objects in the house will always facilitate
continuous reflections.
Figure 7: Light from windows obstructed by chairs and shelves (Fasi and Budaiwi 2015).
Spatial dimensions
The shape and the size of the space that is to be lit normally influence the number of skylights
that are needed. This particular factor normally affects even the number of bulbs used in the case

of artificial lighting. Big halls will require more number of bulbs as opposed to small sized store
rooms
Figure 8: Effects of spatial dimensions (Van 2014)
Heat gain and loss
It is important to remember that light May is not the only factor of consideration in the
calculation of energy saving. In the installation of the skylights, there is the removal of thermal
insulation of the materials for roofing. The great loss and gain must, therefore, be accounted for
in the selection of the natural system of lighting.
Figure 9: Heat gain and loss effects (Day and Gunderson 2015)
The intended use of the space

It is important to understand how the occupants will be using the building and the timing as well.
Activities that are to be carried out in the morning would natural light being tapped from the east
and the vice versa for the evening program.
Figure 10: Lecture hall allowing much natural light in the morning hours (Van 2014)
Question 5
Causes of glare
Discomfort glare refers to that pain which is caused by very high luminance in the field of view
of the worker. The degree of this discomfort will depend on the number, size, and position of the
luminance sources. Disability glare, on the other hand, is caused by scattering of light within the
eye thereby reducing visibility and contrast a condition called veiling luminance. The reduction
of visibility is attributed to light scattering (Konstantzos, Tzempelikos and Chan 2015)

Figure 11: Light scattering concept (Van 2014)
The magnitude of the disability can be estimated using the equation below
Figure 12: Disability glares (Yun, Yoon and Kim 2014).
Reduction of glare in a building
The glare in the building can be controlled by the use of translucent plastic binds on the
windows. When these components are used, the incoming sunlight will be diffused instead of
being reflected like for the case of the wood and metal surfaces.

Figure 13: Use of solar binds for windows to control glare (Yun, Yoon and Kim 2014)
From the figure shown above, it is evident that glare is too much from the section that does not
have solar binds. After the bind has been introduced, the glare reduces significantly.