Angular selective shading systems

[edit] Introduction

Angular selective shading systems are generally static, energy efficient window treatments that are suitable for new construction or retrofit projects. They block or filter direct sunlight while allowing diffuse daylight to pass through windows within a specific range. Static, angular selective shading systems offer a potentially low-cost option to reduce window heat gains and control glare while permitting the admission of useful daylight and access to views.

These passive systems are optically complex, designed to have characteristics that allow them to selectively assume different properties related to the transmission of light.

[edit] Types of angular selective systems

There are generally single and double layer systems. The single layer systems tend to manage visual glare through angular selective control but have moderately high transmittance in the near infrared and a high emittance. Two layer systems tend to offer low emittance and better solar control, but still offer good visible angular selectivity.

They can be made from a wide variety of materials and produced in a broad array of shapes, sizes and colours that can be installed at angles that preserve views (both in and out of windows), reduce solar heat gain and controlling glare and excessive light.

[edit] External

Examples include woven metal screens or punched metal scrims for building exteriors. In certain instances, these products can be mechanically manoeuvred (either manually or electronically) into the ideal position based on conditions and preferences.

[edit] Between pane

There are also between-pane options, including micro-louvred systems (in metal, fabric or mirrored materials) or highly reflective sculpted mesh. These systems tend to have wider application possibilities and may last longer than their exterior counterparts, with lower maintenance requirements, but they may not offer the same flexibility in terms of deployment.

They must also be designed in a manner that does not interfere with - or possibly damage - low-e window coatings. Low-e glass is a type of glass that has a coating added to one or more of its surfaces to reduce its emissivity so that it rejects a higher proportion of long-wave infra-red radiation.

[edit] Glass treatments

Angular selective fritted or etched glass is another method of reducing window heat gain while preserving the transmission of natural daylight.

There are also certain types of oblique thin metal and metal insulator coatings that can be spectrally selective. As a type of smart window system, these coatings are configured as a grating made from parallel strips of material. The strips serve to manage solar radiation through angular selective light transmission based on predefined preferences.

[edit] Related articles on Designing Buildings

• Emissivity.
• Fritting.
• Glazing.
• Low-e glass.
• Solar shading.
• Types of window.
• When hospital buildings are not healthy.