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Familua O. S. ARC/05/5609

AN

ASSIGNMENT

ON

TYPES OF SUN SHADING DEVICES IN

NIGERIA

PREPARED BY

FAMILUA O.S.

ARC/05/5609

SUBMITTED TO

DEPARTMENT OF ARCHITECTURE

IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR

THE AWARD M.TECH IN ARCHITECTURE

FEDERAL UNIVERSITY OF TECHNOLOGY, AKURE.

AUG, 2011


INTRODUCTION

Well planned external shading is the most effective method of reducing solar heat gain. In

addition, it offers possibilities for incorporating day lighting and passive heating. Some types of

external shading interfere with view, while other types make it possible to exploit view that

would otherwise be impossible because of solar glare.

External shading is much easier to integrate into the design of a new building than it is to

retrofit. External shading has a major effect on the appearance of the building, and it must be

anchored strongly to the building structure to resist wind loads. In retrofit, both of these factors

are serious challenges.

Each face of a building requires a different shading treatment because sunlight strikes each

side from different angles. A south face is best shaded with horizontal shading. East and west

faces require shading that blocks sunlight entering at low angles. A north face can often be left

unshaded.

Shading can be adapted to virtually all sizes of windows and skylights. The most common

limitations are high cost and the effect on the building’s appearance.

Effective external shading blocks all or most direct sunlight, although it admits indirect light

from the sky. It typically reduces solar heat input by 80% to 90%. In buildings where solar load

dominates the cooling requirement, shading may reduce a building’s total cooling load by as

much as half.

All interior systems are less effective than a good exterior system because they allow the sun’s

heat to enter the building. They also depend on user behavior, which can’t be relied upon.

LIMITATION

This study seeks to identify various types of sun-shading devices available in Nigeria.

Shading and daylighting.

East, west and south building facades call for a different approach to solar control. The high

summer sun is partially blocked by horizontal aluminum shading device on the south façade

(Figures 1).


Shading on the south façade prevents direct solar radiation from high altitude sun from

penetrating the building envelope during critical times of the day.

East and west facades use a perforated Venetian blind within the glazing cavity to provide

needed shading.

The shading device also serves as an external lightshelf by reflecting light onto the ceiling near

the window. The standard ceiling height is 9 ft [2.8 m] and the ceiling in office areas near the

window angles up toward the window to maximize daylight in the work zone. The low altitude

of the sun on the east and west facades during the early morning and late afternoon demands

almost 100% blockage. In response, motorized blinds are installed within the triple-glazing

system on the east and west facades and are controlled by light sensors.


Types of Sun-Shading Devices

Basically there are three type of sun-shading devices in Nigeria, viz;

Horizontal devices

Vertical devices

Egg crate devices

Horizontal devices: This is the most suitable for overhead sun. They are best suited southern

and northern elevation and their performance is measured by vertical shadow angle. The simplest

form is a roof overhang, a projecting floor,or a projected balcony.

Shading Methods

Sun-Shading is a general technique that you can accomplish with many different types of

architectural features. Shading may be fixed or movable.


Projecting horizontal shelves.

These can be a primary method of shading south faces. They must be built into the building’s

structure, and hence they are limited to new construction. To be effective, they must be much

wider than the windows, in the direction along the wall, to account for the sun’s motion from

east to west. Typically, they are installed above the level of the windows, If the windows are

closely spaced, shelves typically are installed along the full width of the south face. Smaller

shelves can also be built into tall windows at various levels.

Adun House Ilorin kwara state


Balconies.

These have the same effect as horizontal shelves, but more so. They are deep enough to provide

significant shading even if they do not face in a southerly direction. They provide major

additional value as usable space and as an ambiance feature.

Private Hospital Ilorin kwara state


Eaves and overhangs,

Which can provide effective shading for the floor level directly under the eave. They merit

strong consideration as shading devices, and they can provide major additional value in

protecting the wall finish and reducing below-grade moisture problems.

Staff Quarter Kwara Poly, Ilorin kwara state


Awnings

Awning which project downward over the windows. These may be fully effective on south faces,

and provide partial shading of windows on east and west faces. A common mistake is making

awnings to fit the width of the window. Such awnings are too narrow, allowing an excessive

amount of sunlight to enter from the sides.

Residential Building Ilorin kwara state


Horizontal shelves integrated with windows

These are effective cooling load control devices on a south face. Otherwise, they are mainly a

decorative touch. This building must be at southerly latitude for shelves this shallow to provide

much benefit.

Works Department Kwara Poly, Ilorin kwara state


Vertical devices:

This is the best shading for low sun. They are commonly referred to as fins and are most

effective on western and eastern elevation. Their performance is measured by the horizontal

shadow.

Vertical array of louvers

These provide effective shading of full-height windows across a narrow walkway. They are high

enough to avoid obstructing the view.

Sterling Bank Building Ilorin kwara state


Inset windows.

In effect, the entire wall acts as a shading device around the window. This is obviously a feature

that is limited to new construction. It is usually done as a stylistic element, rather than as a

rational approach to controlling sunlight. As a method of shading, it is very expensive and

wasteful of occupiable space. However, it can be effective if it is used properly, namely, on

southerly exposures at low geographic latitudes.

Lecture Theatre Kwara Poly, Ilorin kwara state


Fixed louvers

It may be useful on any exposure of a building, except north. The best orientation for the louver

blades depends on the direction that the glazing faces. On the south side, the blades should be

horizontal. For the north side, louvers are vertical. For other directions, they may be tilted.

Louvers can be arranged in a horizontal array, like a shelf. Or, they can be arranged in a vertical

array, like a venetian blind. Or, they can be installed at an angle, like an awning. Louvers

interfere with the view if they are installed in the line of sight, but they may not block the view

entirely. For example, a vertical stack of horizontal louvers in front of a window interferes with

the view upward and horizontally, but they are not too bad when viewing downward.

Obafemi Awolowo University Health Center Ile Ife


Vertical fins

Fins are useful for shading north faces from summer sunlight early and late in the day. Figure

below shows a building with fins molded into the wall surface.

Computer Centre Kwara Poly, Ilorin kwara state


Miniature fixed-louver materials

These are supported in frames and installed directly over glazing. They are useful on all faces.

One product is made from aluminum sheet punched to create tiny louvers. Another product

consists of tiny bronze strips woven into a louver with wires. Within limits dictated by the

manufacturing process, the manufacturer may offer a variety of louver spacings and tilt angles.

Some fixed louver materials can be oriented vertically for use in east-west shading, or to any

other angle.

Kwara Hotel Ilorin kwara state

Egg crate devices:


This is the combination of vertical and horizontal devices. This type exclude more radiation than

either vertical or horizontal element alone. They are usually in the form of grill blocks or

decorative screens. Their performance is determined by both the horizontal and vertical shadow

angle.

Egg crate decorative Screen

The egg crates block sunlight from all directions. They are attached to the wall. This rather

massive construction and the irregular placement of the screen may have been motivated by an

appearance concept as much as by sunlight control.

University of Ibadan Health Centre, Ibadan

DESIGN STRATEGIES

• Use exterior shading, either a device attached to the building skin or an extension of the skin

itself, to keep out unwanted solar heat. Exterior systems are typically more effective than interior

systems in blocking solar heat gain.

• Design the building to shade itself.

If shading attachments are not aesthetically acceptable, use the building form itself for exterior

shading.

Set the window back in a deeper wall section or extend elements of the skin to visually blend

with envelope structural features.

• Use a horizontal form for south windows.


For example, awnings, overhangs, recessed windows .Also somewhat useful on the east and

west. Serves no function on the north.

• Use a vertical form on east and west windows.

For example, vertical fins or recessed windows. Also useful on north to block early morning and

late afternoon low sun.

• Give west and south windows shading priority.

Morning sun is usually not a serious heat gain problem. If your budget is tight, invest in west and

south shading only.

• Design shading for glare relief as well

Use exterior shading to reduce glare by partially blocking occupants’ view of the too-bright sky.

Exterior surfaces also help smooth out interior daylight distribution.

• If interior devices are the only shading, specify light colors

In order to reflect the sun’s heat back out. Light-colored blinds or louvers are best. Light-colored

woven or translucent shades are acceptable, but may not control glare under bright summer

conditions.

• Use devices that still allow daylight in

Blinds and openweave shades are good choices for filtering but not blocking all light.

• Interior shading alone has limited ability to control solar gain.

REFERENCES

D. R. Wulfinghoff, 1991 Reducing Cooling Load: Window and Skylight


Laouadi, A. 2010, Guildlines for Effective Residential Solar Shading Devices. National Research

Council Canada

K. O. Kadari and J. Okosun 2006 Thermal Performance in Building Without Shading Devices,

Journal of Applied Science

Ogunsote O.O. 1991 Introduction to Building Climatology. A basic course for Architecture

students. First Edition, Ahmadu Bellow University Press Limited Zaria Nigeria

Olufowobi M. B. 1987, A Simple Approach to the design of effective horizontal shading device.

Nigeria Institute Of Architect

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