this upload will give an overall knowledge about the designing and making of sun shading devices.

1. nachiket vyawahare
B170835CE CIVIL ENGINEERING
DEPARTMENT-FUNCTIONAL
DESIGN OF BUILDINGS
SUNSHADING DEVICES

2. SUNSHADING DEVICES
WHAT ARE SUNSHADING DEVICES?
Sun shading devices are any mechanical equipment or textiles that
are used either internally or externally or between the internal and
external building space.
They can be any mechanical equipment like dynamic facades,
projections(chajja), cantilevers, louvres, fins, jails, or even textiles.
They can be fixed, manual, and automatic moveable.
PURPOSE OF PROVIDING SUNSHADING DEVICES
The primary objective of providing sun shading devices is of creating
a comfortable internal environment, that is, cool in the summer and
warm in the winter.

3. The other purposes can be listed as follows
1. As solar radiation is an important factor of thermal comfort, the
sun shading devices help in improving the internal environment
and provide greater comfort for occupants.
2. Use of shading devices can improve the energy performance of
a building by reducing the heat gains during summers and by
promoting heat gain during winters thus reducing the HVAC
(heating, ventilation, air conditioning) loads and therefore
minimizing energy costs.
3. Preventing glare which can cause discomfort or disability of
vision.
4. Their effective use can increase the useful daylight availability.
5. They can create a sense of security knowingly or unknowingly,
for example, providing internal shading devices like curtains
and windows, with their primary objective also create a sense
of privacy.
Types of sun shading devices
On the basis of their position in a building:-
 Internal
 External
 Interpane
INTERNAL SUN SHADING DEVICES

4. The devices which are connected to the interior of the building to
limit the glare resulting from solar radiation. They are usually
adjustable and allow occupants to regulate the amount of direct light
entering their space.
Generally, they are in the form of horizontal and vertical blinds
attached above the windows.
Some types of internal shading devices are listed below-
Curtains
It is the most commonly used internal shading device used in the
residential buildings. It is economical as well as it can be found in
different textures, colours and varieties that with its primary use it
also enhances the aesthetics of the room.
Venetian blind

5. They are basically slatted blinds suspended by a strip of cloth called
tapes, all slats in unison can be rotated through nearly 180 degrees.
Slat width can be between 16 and 120 mm, with 25 mm being a
common width.
Vertical louvre blinds
They are highly functional and cost effective window coverings which
can be used in larger windows and doors too to control heat light
and glare.
Roller blinds
Roller blinds are usually stiffened polyester, mounted on a metal
pole and operated with a side chain or spring mechanism. Roller
blinds are practical blind for everyday use.
Pleated blinds
Pleated blinds are shades made from a pleated fabric that pull up to
sit flat at the top of a window to hide from sight when open.
Blackout blinds
Blackout blinds are shades made of specially treated woven fabrics
whose whole purpose is to block any external light from entering the
room.
External sun shading devices

6. The shading devices provided or available on the exterior of a
building to keep it comfortable thermally.
Their general functions include
 Allowing a view out
 Protection from rain
 Protection from direct solar radiations
 Protection from sky glare
They can be roughly subdivided as
 Horizontal, vertical or inclined projections
 Vegetation and other building
Vertical shading devices
Vertical shading devices consist of pilasters, louvre blades or
projecting fins in a vertical position. Their performance is based on

7. horizontal shadow angle (HSA). They are commonly referred to as
fins and are most effective on western and eastern elevations.
Horizontal shading devices
Horizontal shading devices are usually in the form of canopies, long
verandas, movable horizontal louvre blades or roof overhangs. They
are best suited to southern and northern elevations and their
performance is measured by vertical shadow angle(VSA).
Egg-crate devices
These are combinations of vertical and horizontal devices. They are
usually in the form of grill blocks or decorative screens. Their
performance is determined by both HSA and VSA.
Design of shading devices
There are certain steps to be followed in the design of shading
devices –
Step one
It is necessary to determine when shading is required, that is at what
times of the year and during what hours of the day. That is usually
done by defining the overheated and under heated periods.
The overheated period is that period when there is hot discomfort
while the underheated period represents cold discomfort. The
overheated and underheated periods are determined with the aid of
a thermal index. The climatic data needed are the monthly minima
and maxima of dry-bulb and wet-bulb temperatures as well as the
mean monthly wind velocity. The wet bulb temperatures are not
always available and in such a case they should be calculated from
the monthly minima and maxima of relative humidity, this can be

8. done by taking the help of psychometric chart and also by the
computer program PSYCHRO.

10. Step two –use of sun path diagrams
The next step in the design of sun-shading devices is to determine
the position of the sun at the times when shading is required. The
position of the sun is defined by two angles – the solar altitude
(measured from 0 to 90 degrees above the horizon) and the solar
azimuth which is measured from the south and is measured from 0
to -180 degrees(westward) and 0 to +180 degrees (eastward). The
position of the sun can be determined by various ways, in which one
of the best ways is by using sun-path diagrams

11. The sun path diagram is a projection of the hemisphere of the sky.
The observer is assumed to be in the centre of this hemisphere and
the sun to travel on the surface of the hemisphere. There are two
types of projections used to obtain sun path diagrams. The first is the
stereographic projection of the hemisphere onto a horizontal circle
Further detailed use of sun path diagrams can be learned by
observing the diagrams.
Step three
The next step is to assign the proper type of shading device and
determining the dimensions of the device for its effective use.

12. The performance of shading devices is specified by two angles which
are horizontal shadow angle and vertical shadow angle.
HORIZONTAL SHADOW ANGLE
HSA is required for the vertical shading devices which is the
horizontal angle between the normal of the window pane and the
azimuth of the sun.
HSA= WALL AZIMUTH-SOLAR AZIMUTH
VERTICAL SHADOW ANGLE
VSA is required for the horizontal shading devices and it is the angle
between the ground line and altitude of the sun

13. SHADE DIMENSIONS
The determination of the size of the shading devices can be done by
taking the help from the horizontal and vertical shadow angles. If the
height value refers to the vertical distance the shadow and the
window sill, then the depth and the side can be determined using
simple trigonometry.
Shade depth= height/tan(VSA)
Shade width= depth x tan(HSA)
Step four
The choice of prefabricated devices or the design of the new ones.
The design takes not only the required geometry but also the
aesthetic and structural factors.
In recent years, there has been a dramatic increase in the variety of
shading devices and glazing available like canvas awnings to solar
screens, roll down blinds, shutters and vertical louvers.
Various specifications of glasses are also available for the shading.
They should be prepared to specify glass U-value, SC, Tvis and net
window value for all fenestration systems. The SC of a glazing
indicates the amount of solar heat gain that is admitted into the
building, while the visible transmittance of a glazing material
indicates the percentage of light available in visible portion of the
spectrum admitted into a building.
Disadvantages of sun shading devices
The disadvantages if considered are very mere compared to its
advantages and its contribution towards thermal comfort.
Some of the disadvantages can be listed below

14. 1. If the building is highly stylized , shading will block some of the
part of the building and might affect the high aesthetics of the
building.
2. Handling of the internal shading devices can be sometimes
difficult in maintaining like curtains and blinds.
3. In the use of shading devices like light shelves, problems with
low angle winter sunlight penetration can give rise to glare.
REFERENCES
WWW.WBDG.COM- WHOLE BUILDING DESIGN GUIDE
WWW.SDECNG.NET
ANDSOME MORE..