Presentation on Sun Shading Devices

Presentation on Sun Shading DevicesPresenters: Binisha Gurung Nishu ShresthaPrabal DahalRojina NakarmiSuchitra Bhatta

Introduction Sun Shading Devices are any mechanical equipment or textiles that are used either internally or externally or in between the internal and the external building space.

The primary objective of creating a comfortable internal environment, that is, cool in the summer and warm in the winter.

Need of Sun Shading DevicesTo reduce the heat gains during summer, reduce the cooling loads and therefore minimize energy costs. Sun Shading Devices improve internal environment in order to provide greater comfort for occupants. Likewise, internal sun shading devices like curtains help to beautify internal space and create a sense of privacy. Therefore, it is highly essential for the architects and engineers to incorporate these shading techniques.

Types of Sun Shading DevicesOn the basis of their position in a building:-

InternalExternalInterpane

Internal Sun Shading DevicesLimit the glare resulting from solar radiation. Usually are adjustable and allow occupants to regulate the amount of direct light entering their space. Most commonly these shading devices take the form of horizontal or vertical blinds attached above windows. Internal shading devices should be made or designed to be durable.

Curtains: It is the most commonly used shading device, mostly used on residential buildings. It is cheaper in comparison and can be found in various varieties, colours and texture. A curtain also acts as a decorative item.

Venetian blind: Venetian blinds are basic slatted blinds made of metal or plastic, wood or bamboo can also be used. 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 120mm, with 25mm being a common width

Vertical Louvre blinds: Suitable for many applications in commercial and public buildings where the control of heat, light and glare are of concern. It can be used in larger windows and doors too.

Roller blinds: Roller blinds areusually stiffened polyester, mounted on a metal pole and operated with a side chain or spring mechanism. Roller Blindsare a practicalblindfor everyday use, Block Outs, Sun Screens and Translucent with a metal or plastic chain available, that operates theblindthrough an aluminum tube to roll up and down.

Pleated Blinds: Pleated blindsareshadesmade from apleatedfabric (which helps to add texture to a room) that pull up to sit flat at the top of a window to hide from sight when open.

Blackout binds: Blackout blinds stop light from passing through thanks to special treatments and extra tight woven fabrics to help control the light levels in a room. It is designed to block the external lights to enter the room.

External Sun Shading DevicesConsidered better than internal

Horizontal, Vertical or inclined projections

Vegetation and other buildings

Horizontal Devices: to shade a window during hot summer months, but to allow sunlight to shine through a window in the winter, to help warm a building.

Vertical Devices: Primarily useful for east and west exposures to improve the insulation value of glass in winter months by acting as a windbreak.

Slanted Vertical FinVertical Fins

The egg-crate: A combination of vertical and horizontal shading elements commonly used in hot climate regions because of their high shading efficiencies. The horizontal elements control ground glare from reflected solar rays. The device works well on walls

Shading from External Environment

Shade from buildings

Designing a Shading Device

Select Shading Type

Identify Design Dimensions

Identify Category

Select Shading TypeOrientationSuggested Shading TypeNorthfixed or adjustable shading placed horizontally above windowEast and Westadjustable vertical screens outside windowNE and NWadjustable shadingSE and SWplanting

Climatic zonesRequirementsHot and dryComplete one year round shadingWarm and humidComplete year round shading , but design should be made such that ventilation is not affectedTemperatureComplete year round shading but only during major sunshine hoursCold and cloudyNo shadingCold and sunnyShading during summer months onlyComposite Shading during summer months only

Sun paths

Our device should be such that:

i. It reduces glare.ii. It reduces cooling load.iii. It allows us to see the view that we like to watch.iv. For doing presentations, complete shut off of lights is possible.v. There is limited reduction daylight.

Identify Design Dimension Shading type: Horizontal OverhangShading category: fixedDesign dimensions: Relationship between the overhang Depth (L) and the opening height (H).L=H L=3H/4 L=H/2 L=H/3L=H/4Shading type: Vertical OverhangShading category: fixedDesign Dimensions: Relationship between the overhang Depth (L) and the opening width (d).L=dL=3d/4L=d/2

Example of a calculation:

Identify CategoryFixedAdjustableMovableDynamicManualAutomatic

Importance and Advantages of Sun Shading Devices

Maintain a comfortable indoor temperature. Shading is a simple method to block the sun before it can get into the building. Shading minimizes the incident solar radiation and cool the building effectively and hence dramatically affect building energy performance. Reduce building peak heat gain and cooling requirements and improve the natural lighting quality of building interiors. Peak electricity demand is also reduced by exterior shading devices, resulting in lower peak demand charges from utilities and reduced mechanical equipment costs. Likewise, trees when used as shading devices can beautify landscape and provide oxygen. Internal Shading devices also help to create a sense of privacy.

Disadvantages of Sun Shading DevicesDifficulties can be experienced in handling the internal shading devices like curtains and blinds. In the use of shading devices like light shelves, problems with low angle winter sunlight penetration can give rise to glare.If the building is highly stylized (e.g. Neoclassical or glass cube), it may be impossible to reconcile external shading with the original style. Shading always blocks a part of the view. As a minimum, it blocks the portion of the sky where the sun travels.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.

National Case Studies

Trees used as Sun Shading Device for the East face of a commercial building in Durbarmarg.We can also see Vertical Blinds used in the internal space.

In the same building, on the top, a restaurant is using a space created by interesting sun shading devices.

In Lainchaur, Malla Hotel, Horizontal sun shading device is used in the north facade of the building. The windows are also having panes that reduce glare in the internal environment.

In Jyoti Bhawan, Kantipath, Jamal, vertical external sun shading devices have been used on the East Facade.

On the way to Jyatha from Jamal, a hotel is using eggcrate device on the western facade.

On the Eastern facade (receiving maximum amount of Sunlight throughout the day) of Suraj Arcade, Kathmandu Durbar Square area, Vertical Sun shading devices have been used.

Horizontal in North Face (receiving less sunlight) of a commercial building in Makhan Tole.Eggcrate type device in Jamal. East facade.

Formal National Case Study IName of the building: Janak Nath Memorial School, previously Kanya School.Location: LainchourDate Established: 2043 B.S.Type of Building: Public School Use: Students, teachers, staffs and administrative people use this building generally from 10 am to 4 pm on weekdays.Type of Shading Device: External Shading DeviceType of External: Egg CratePosition of Device: East Facade

Effectiveness: The Eggcrate system has been used not only around the window openings, but also on walls. The shading device has therefore been converted into design element as well. The length of projections are 1 feet and have provided very good shade. Therefore, this can be considered good use of shading device.

The internal view of a classroom in third floor. Students feel comfortable both in summer and winter as per the information provided by a staff member of the schoolWindows themselves have been placed at a height likely to prevent students from outside distractions. Eggcrate patterns visible on the interior space as well.

Formal National Case Study IIName of the building: Kathmandu Durbar Square Cafe, previously shops and storage.Location: BasantapurType of Building: PublicUse: Staffs and customers use the place throughout the whole day 7 am to 9 pm. Type of Shading Device: External Shading Device and Internal Shading DeviceType of External: EggcrateType of Internal: StickersPosition of Device: South Facade

Effectiveness: On the ground floor, there are glass panes windows where stickers have been used. Stickers are serving the purpose of preventing excessive glare from entering the internal space as well as giving a sense of privacy. On the first floor, external eggcrate shades have been used. The windows are small probably because the building was built when traditional Newari building style was popular in the area. Addition of shades seems useless. However, the first floor, if used for storage could have required shades.

Internal shades, stickers used behind the cash counter. Serving both as shading and privacy creating device.

Space of the first floor. Little or no use of sun shading device in today's context

Secondary National Case Study Name of the building: Mahendra Bhawan School Administrative block when used by Kathmandu AcademyType of Building: Educational InstitutionUse: Students, teachers, staffs and administrative people use this building generally from 7 am to 4 pm on weekdays.Type of Shading Device: Internal Type of Internal: Pleated BlindsPosition of Device: Eastern Windows of 1st floor, Southern Windows of ground and 1st floor, Northern Window of Ground floor.

Lounge and teacher's lounge.

Preventing glare and creating a sense of privacy in the north window of computer room

Blinds on the first floor in a winter morning. In summer, the desks nearby the windows are generally left vacant due to heat.

International Case StudiesFormal International Case Study I:Name of the Building: National Library, SingaporeLocation: Victoria Street, SingaporeDate: 2004Associated Names: Kenneth Yeang (architect/planner), T.R. Hamzah & Yeang (architect/planner)Building Types: educationalBuilding Usage: library

Hot humid climateWidest shading device (1.8m)Made of light metallic material similar to wings of aircraftOriented away from east-west solar exposure (to cut down solar penetration)Sunshading devices on the west sideBlinds used at building faade (Adjusts automatically through day light sensors depending on the light intensity)Motion sensors and energy efficient lighting are used throughout the buildingFaade has double-glazed, high quality, low-emissivity glass to reduce head transfer

Formal International Case Study II:

Name of the Building: SUR YAPI OFFICESLocation: Istanbul, TurkeyDate: July, 2010 Associate names: Gkhan Aktan Altug,TAGO ArchitectsBuilding type: OfficialUse: Sur Building Construction Industry. TIC. LTD. STI.

The building is oriented to maximize the generous south light, while dramatic, faceted louvers act as a solar shading device. The louvers become part of the dynamic skin of the building.

Interior space

Secondary International Case Study

Name of Building: Ebril Metro StationLocation: Ebril, IraqDate: Under constructionAssociated names: Mohammed SiyamandBuilding Type: Metro stationBuilding Usage: Metro stationShading type: Dynamic

Recommendations:When deciding which devices to use and where to use them, the designer must consider a whole range of issues, whether they will be opened and closed daily as needed or just put up for the hottest season, whether they will adversely affect natural lighting level or even produce more glare, and how they might affect any natural ventilation strategy.On average, external products are twice as good as internal products in reducing peak cooling loadsIn selecting shading products, one should also pay attention to the transmitted daylight and the effect on the view out.

ConclusionThe team found out that there are various types of shading devices used in Nepal and in international buildings. Importantly, the team members realized that projections around the windows in buildings are not just design elements but also serve the purpose of shading devices. Comparatively, the national devices were less good looking and effective than the international. This, the team conjectures to be a result of poor design ideas and techniques in the national buildings. The team realizes that the importance of proper designing of sun shading devices and therefore willing to incorporate the devices in their design works.

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