As windows and doors complement your existing heating and cooling systems, external and internal shading devices greatly help to improve the energy efficiency of a home. When properly installed, energy star rated doors, windows, and skylights supported by canvas awnings, solar screens, roll-down blinds, shutters, and vertical blinds all reduce energy consumption and result in great savings over traditional window treatment systems. They increase your comfort by maintaining a steady indoor temperature throughout the year, reduce condensation compared to a conventional model and protect interior furnishings from fading or sun rot.
Why External and Internal Shading is Necessary
Shading windows, doors and skylights is the simplest as well as the most energy-efficient way of controlling the way the sun’s energy is allowed into your home. It results in saving on cooling in the summer and utilizing ‘free’ heating in the winter.
Shading is designed to deflect the sun’s rays before it can reach a window or door. Made of rounded individual fibers that are a combination of PVC, fiberglass and cellulose, exterior shades are best used on eastern, western and southern oriented windows. They are equally useful in winter to keep the warmth in. In summers, they are an excellent way to prevent unwanted solar heat gain from entering a conditioned space.
Internal shading is almost always adjustable or retractable and is typically in the form of a roller or Venetian blinds or curtains. It is easily adjusted and maintained, and sometimes can provide night-time blackout. It is also generally cheaper and is particularly effective at controlling diffuse and reflected light, the major causes of glare. Curtains and blinds can moderate brightness, and Venetians and louvers can redirect the light.
Advantages of Shading Devices
Shading devices allow you a lot more control over the light and temperature you want to allow into your house.
They can be equally effective when used with proper insulation and automation that make it easy to control and maximize thermal control through the fenestration.
There is a variety of internal shading solutions such as drapes, shades and blinds to choose from, depending on your window orientation and privacy requirements.
Many shades like cellular shades and roller shades come with a reflective coating that would efficiently deflect the sun’s heat back through the window before it can cause any harmful effects.
In nearly all climates, controlling and diffusing natural illumination goes a long way in improving daylighting.
Well-designed shading devices can dramatically reduce building peak heat gain and cooling requirements and improve the natural lighting quality of building interiors.
Shading devices can also improve user’s visual comfort by controlling glare and reducing contrast ratios. This often leads to increased satisfaction and productivity.
Shading devices offer the opportunity of differentiating one room from another. It can impart a distinctive character to an otherwise undistinguished design.
Buildings that employ passive solar heating or daylighting often depend on well-designed shading devices.
Types of Shading
Shading devices can be supported by natural landscaping or by building elements such as awnings, overhangs, and trellises. Some can also function as reflectors, called light shelves, which bounce natural light for daylighting deep into building interiors.
Solar control and shading can also be provided by a wide range of building components including:
• Landscape features such as mature trees or hedgerows;
• Horizontal reflecting surfaces called light shelves;
• Low shading coefficient (SC) glass; and,
• Internal shades such as Venetian blinds or adjustable louvers.
• Aluminum architectural sunshade, horizontal sun control device, vertical fins.
Tips for Shading
Use fixed overhangs on the south-facing glass to control direct beam solar radiation. Indirect (diffuse) radiation should be controlled by other measures, such as low-e glazing.
You will do well to limit the amount of east and west glass since it is harder to shade than south glass. Consider the use of landscaping to shade east and west exposures.
Shading affects daylighting; consider both simultaneously. For example, a light shelf bounces natural light deep into a room through high windows while shading lower windows.
Window treatments like Venetian blinds or vertical louvers offer glare control and can contribute to visual acuity and comfort in the workplace. They admit diffuse light while excluding direct sunlight, and can also act as a daylighting device by redirecting light onto the ceiling.
Carefully consider the durability of shading devices. Over time, operable shading devices can require a considerable amount of maintenance and repair.
When relying on landscape elements for shading, be sure to consider the cost of landscape maintenance and upkeep on life-cycle costs.
Shading strategies that work well at one latitude, may be completely inappropriate for other sites at different latitudes. Be careful when applying shading ideas from one project to another.
While shading devices often perform well, their practicality is limited by the need for manual or mechanical manipulation. The solution is to combine internal shading with automation.
The use of both external and internal shading is an important aspect of energy-efficient building design strategies. In recent years, there has been a dramatic increase in the variety of shading devices and glazing available for use in buildings. A wide range of adjustable shading products is commercially available to add to user comforts and energy-efficiency of your house.