The desire to limit the quantity of sunlight that enters a structure might be motivated by a variety of different factors. Controlling and dispersing natural light will improve daylighting in almost all climates. In warm, sunny climates, excessive solar gain may lead to high cooling energy consumption. In cold and temperate climates, winter sun entering south-facing windows can positively contribute to passive solar heating.
What are shading devices all about?
The interior illumination quality of buildings may be significantly improved by properly designed sun control and shading systems, which can also significantly decrease peak heat gain and cooling needs. There have been reports of yearly cooling energy consumption savings ranging from 5% to 15%, depending on the location and degree of fenestration. By minimizing glare and lowering contrast ratios, sun control and shade technologies may also enhance user comfort visually. This often results in higher productivity and happiness. Building facades may be distinguished from one another using shading methods. An otherwise uninteresting design might benefit from this to provide interest and human scale.
The importance of having shading devices
Many energy-efficient building design solutions include the use of sun control and shading equipment. Particularly, well-designed sun control and shading systems are often required in buildings that use passive solar heating or daylighting.
External window shading is a great strategy to keep unwelcome solar heat gain out of conditioned spaces during cooling seasons. Natural landscaping or architectural features like awnings, overhangs, and trellises may provide shading. Some shading tools may also serve as light shelves, which are reflectors that bounce sunshine deep into building interiors.
The solar direction of a certain building façade will affect how effective shading devices are designed. For instance, in the summer, when sun angles are high, simple permanent overhangs are a particularly efficient way to shade south-facing windows. During the summer’s peak heat gain hours, the same horizontal device is inefficient at keeping low afternoon light from penetrating west-facing windows.
Devices for outside shading are very useful when used with glass facades. Louvretecperth noted that high-performance glazing with very low shading coefficients is now accessible (SC). These innovative glass options lessen the requirement for outside shading devices when they are specified. As a result, a variety of building materials may provide solar control and shade, such as:
In general, small commercial buildings are best suited for fixed outside shade elements like overhangs. The size of the window and the proportional significance of heating and cooling in the structure determine the ideal length of an overhang.
How to install shading devices?
- Peak sun angles for the summer season are on June 21, the summer solstice, whereas peak temperatures and humidity are more likely to occur in August. Keep in mind that an overhang large enough to completely shade a south-facing window in August will also do so in April, when a little sun heat may be preferable.
- Understanding the sun’s location in the sky during the cooling season is crucial to appropriately build shade devices. The altitude and azimuth angles are used to describe the sun’s location.
- The angle of the sun above the horizon, which reaches its greatest on a particular day at solar noon, is known as the altitude angle.
- The sun’s angle of projection onto the ground plane with respect to south is known as the azimuth angle, often referred to as the bearing angle.
- Architectural Graphic Standards, 12th Edition, available from John Wiley & Sons, Inc. Publishers, is a readily accessible source of information on sun angles and solar path diagrams.
Building look may be significantly affected by shading mechanisms. This effect may have a positive or negative outcome. The likelihood that shading devices will be appealing and seamlessly incorporated into a project’s overall architecture increases the sooner in the design process that they are taken into account.
The degree of window shading is a key factor in ANSI/ASHRAE/IES Standard 90.1 Energy Efficient Design of New Buildings Except Low-Rise Residential Buildings (on which the Federal counterpart 10 C.F.R. 435 is based). When employing the alternate component packages envelope design method, it is necessary to analyze both the projection factor (PF) for outside shading and the shading coefficient (SC) of glass.
Shading System Design
It is challenging to draw broad conclusions regarding the design of shading devices given the large diversity of structures and climates in which they might be found. The following design suggestions, however, are typically accurate:
On south-facing windows, use permanent overhangs to reduce direct sun radiation. Other methods, such low-e glass, should be used to limit indirect (diffuse) radiation. Limit the quantity of east and west glass as much as you can since it is more difficult to shade than south glass. Think about using landscaping to provide shade for east and west exposures.
In the continental United States, north-facing glass gets relatively little direct solar gain, thus there is no need to bother about shading it. This maxim should not be followed in the tropics since a structure will get more direct solar gain on its north side. In addition, because the roof is a significant source of transmitted solar gain into the structure in tropical climates, think about darkening it even if there are no skylights.
Tips for effective shading device installation
Keep in mind that shade has an impact on daylighting; take both into account. For instance, a light shelf may block out lower windows while reflecting natural light into a space via high windows. Since the work area has already been exposed to solar gain, interior shading devices like Venetian blinds or vertical louvers won’t be able to lower cooling demands. However, these indoor gadgets do provide glare reduction and may help with optical comfort and sharpness at work.
Understanding sun angles is essential for many design considerations, such as choosing shading equipment, positioning solar collectors, or building integrated photovoltaic (BIPV) panels, and figuring out the fundamental building orientation.
Be sure to give the strength of shading equipment careful thought. Operable shading equipment may need significant upkeep and repairs over time. Always take into account the life-cycle cost of landscape care and upkeep when depending on landscape features for shade. Strategies for shading that are effective at one latitude may not be suitable at all for other locations at other latitudes. When transferring shade concepts from one project to another, use caution.
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