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Examples of Sun Shading devices at the Oba Kekere Campus, FUTA

INTRODUCTION

Sunlight passages into building impacts on the building energy utilization in a number of

ways and through hot and cold climates. In all seasons of the year, the sun improves

daylight quality and proper designed shading devices can appreciably lessen building cooling

load consumption and further enhance daylight utilization.

What type of shading device is best soothed for our buildings?

The shading requirements vary according to climate and building orientation. There is an

acceptable rule of thumb which suggests as shown below:

ORIENTATIONSUGGESTED SHADING TYPE

NORTH fixed or adjustable shading placed horizontally above window

EAST & WEST adjustable vertical screens outside window

NE & NW adjustable shading

SE & SW Planting

Orientation is quite critical; some shading methods are extremely specific to compass

orientation (azimuth). For example, fixed horizontal shading may leak sunlight into the

building during the morning or afternoon unless it is used on a face that is oriented almost

exactly due south. The same is true of vertically oriented shading that is installed on east

and west faces.

Examples of Sun shading devices at the Oba Kekere Campus, Federal University of

Technology, Akure

The study area Oba kekere campus is located within Federal University of Technology,

Akure. It lies between latitudes 7o18′03′′N - 7o18′06′′N and Longitudes 5o08′02′′E - 5o08′05′′E.

The site is located within the sub-equatorial climatic belt with tropical rain-forest

vegetation. The mean annual temperature is 240C-270C, whiles the annual rainfall varies

between 1500mm and 3500mm (Adeleke and Goh Cheng Leong, 1978). The Federal

University of Technology, Akure is underlain by rocks of the Precambrian Basement Complex

of Southwestern Nigeria (Rahaman, 1989).

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plate 1

Most building in Oba kekere campus are shaded using predominantly fixed shading devices.

Fixed, in this case, means attached to the building. It is acceptable for the shading device to

move and respond to solar angles, as louvers do.

The challenges with cost, energy generation and technology have made it impossible for the

designers of these buildings to specify such devices.

Installing fixed shading devices can be an efficient way to provide thermal and visual

comfort to building users. The design of fixed shading devices should depend on the daily

and yearly variation of solar position. This isn’t the case with most of the buildings in Oba

kekere campus.

The designers of these buildings have given proper consideration to their orientations; the

layout of most of them is North-South with the longer axis facing East-West. There are little

or no openings on the north-south elevations except for a few (Great Hall, etc).

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A great number of these buildings are single bank with large fenestrations allowing for

adequate ventilation.

This exercise employed the use of Revit building information module to generate some of

the models (developing 3-dimensional blocks for the oba kekere buildings. See plate 2)

while subjecting them to the exact climatic conditions by in putting the latitude and

longitude for Federal University of Akure to generate the shading pattern at 12noon of 21

June 2011 for the various buildings.

Plate 2 (Please note the oval highlight)

Determining the azimuth for simulation is a big challenge! It will require knowing the actual

orientation of the building faces within an accuracy of about 10°. Therefore, all buildings

examined have been placed as shown in the location map in plate 1 and the latitude and

longitude applied as shown in Plate 2.

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Oba Kekere buildings

1. Industrial Design Department Building

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plate 3

The use of vertical fins, an “after thought” roof overhang and a projecting concrete canopy

at the entrance are the major shading element on this building.

plate 4

Revit simulation of IDD building showing the shading devices

Roof overhang: The shadow pattern shows that the “after thought” roof overhang of this

building is effective in keeping direct sunlight out of the windows. They can provide major

additional value in protecting the wall finish and reducing moisture problems

plate 5

Section through IDD building

2. The Post Graduate Hostel

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plate 6

The design of the Post Graduate Hostel Oba Kekere employed the use of balconies and roof

eaves, doors and windows are set back deeper into wall sections while extending other

elements of the skin to visually blend with envelope structural features.

plate 7

Revit simulation of The Post Graduate Hostel building showing the effect of balcony as a

Shading device

plate 8

A section through the balcony

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3. Prototype Staff Quarters

plate 9

The design of staff quarters in oba kekere employed varying combination of shading devices.

Vertical fins, eaves and insert of windows and entrance

Plate 10

Revit simulation of a prototype staff housing in Oba Kekere showing the effect of sun-

shading devices

plate 11

Section through the eaves

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4. Oba Kekere bus-stop

plate 12

Oba kekere bus-stop. Shed concept have long been used as sun-shading devices.

plate 13

Revit simulation of sun-shading of the bus stop in Oba kekere

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plate 14

Section through the bus-stop

5. Classroom Block at Oba kekere

plate 15

Inset windows of classrooms at Oba kekere

The shadow patterns show that deeply inserting windows are shaded from solar heat gain.

In effect, the roof acts as a shading device around the window. 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 useful space.

However, it can be effective if it is used properly, namely, on southerly exposures at low

geographic latitudes.

plate 16

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Revit simulation of classroom in Oba Kekere

plate 17

Section of classroom

6. Laboratory Block at Oba Kekere

plate 18

Corridors and roof over-hangs are common shading techniques used in most Oba Kekere

buildings. Classrooms and Laboratories are designed in similar manner i.e. single banking,

cross ventilation and large fenestrations.

plate 19

Revit simulation of Laboratory building in Oba Kekere

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plate 20

Section through the corridor

7. Electronic Test Centre

Plate 20

This building relies mainly on the eaves to provide sun-shading on the long side of the

building while the corridor provided shade for the entrance.

Plate 21

Revit simulation of Electronic Test Centre in Oba Kekere

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plate 22

Section through the corridor

8. Great Hall

plate 23

Entrance into great Hall with concrete canopy, the roof eaves is not adequate to prevent

solar heat gain.

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Plate 24

In the design of classrooms, laboratories and offices, it is well recognized that appropriate

solar shading devices can control indoor illumination from daylight, solar heat gains and

glare while maintaining the view out through windows, thus saving lighting and thermal

energy and maintaining visual comfort. Therefore, designers should have a thorough

understanding of the performance of shading devices to enhance the success of their

projects.

Nevertheless, the geometric aspects of shading design are rather complicated, especially if

one wishes to study alternatives or seasonal performance. A solid modeller like REVIT can

make things much easier.

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REFRENCES

ISO. 2003a. Standard 15099: Thermal performance of windows, doors and shading devices -

detailed calculations. International Standard Organisation, Geneva, Switzerland.

ISO. 2003b. Standard 9050: Glass in building-determination of light transmittance, solar

direct transmittance, total solar energy transmittance, ultraviolet transmittance and related

glazing factors.

K.N. Agarwal* and V.V. Verma* (2003) Thermal characteristics of glazing and shading

materials

Laouadi A., Galasiu A.D. 2009. Window shadings reduce residential cooling energy. Solplan

Review; 144. pp. 18-19.

Laouadi A. 2009a. Thermal performance modelling of complex fenestration systems. Journal

of Building Performance Simulation, 2(3), pp. 189 — 207.

TPUB (2006 ) Example of architectural shading devices. Retrieved November, 2009

www.tpub.com

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http://www.tpub.com/

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