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Using Integrated Louvers for Optimal Daylight and Energy Management

Integrated Louvers in Skylights at Ohzuma Gakuen University in Tokyo, Japan. PHOTO CREDIT: Unicel Architectural

We know two things for sure – the impact of daylight on people is overwhelmingly positive and sunlight generates an incredible amount of energy.

For architects, this presents the challenge to design for optimal daylight conditions while controlling solar heat gain. The best daylighting design allows for adjustable sunlight filter and control.

Diffused daylighting creates uniform and consistent lighting, and helps ensure that daylight is a primary source of illumination. One of the most effective ways to manage solar heat gain and sunlight is integrated louvers - hermetically sealed glass units combining louvers within glass for exterior glazing applications.

Integrated operable louvers typically deliver flexible heat and light control, and manage the quantity and quality of light transmission through fenestration. Motorized louvers or sunblades can provide maximum daylight control. The best daylighting and privacy results can be achieved by installing windows with advanced louvered glazing technologies. Eliminating strings and cords ensures lifetime alignment and zero maintenance. 

Louvers may be installed either horizontally or vertically. They are typically made of rigid, extruded aluminum and come in a variety of sizes and shapes. These interlocking blades offer utmost privacy, heat and light control when closed.

The Right Reflective Balance

Mitigating glare and getting the right reflective conditions is key to optimal daylight control. Integrated louvers will always maintain the right balance between reflection and diffusion.

Specular reflection is the mirror-like reflection of light from a single angle. With specular reflection, daylight can cause a significant glare problem. Diffuse reflection is the reflection of light from a surface where a ray is reflected at many angles rather than at just one angle.

Standard louvers or blinds collect dust and grime which jeopardizes diffusion and impedes daylighting performance, whereas painted integrated louvers promote intermediate reflection which achieves the right balance between reflection and diffusion for superior daylighting benefits. As the louvers are integrated, grime cannot settle on their surfaces to impede daylighting performance.

Adjustable Sunlight Control

Indoor lighting preferences can be controlled by adjusting integrated louvers.  Fully open and maximum daylight will penetrate; angled up and light will reflect off ceilings creating a diffused effect; fully closed and light blockage and complete privacy can be achieved.

Integrated louvers typically feature precise control mechanisms that can rotate 180 degrees horizontally or vertically to distribute and diffuse light with simple louver rotation. They can filter sunlight for thermal and human benefits, or reflect light back outside to block UV rays, unwanted glare and solar heat gain.

Specifically, louver positioning can block solar heat gain while still filtering daylight into interiors. Blocking solar heat gain through glazing guarantees an optimal Solar Heat Gain Coefficient (SHGC); utilizing integrated louvers ensures simultaneous transparency options. In the summer, adjustable integrated louvers can block direct sun light to significantly reduce cooling requirements. In the winter, integrated louvers can be angled parallel to the sun rays to leverage solar energy for interior heating. Integrated louvers therefore offer variable SHGC that can be adjusted according to seasonal requirements.

When installed in exterior applications, integrated louvers can significantly reduce energy consumption in support of LEED® requirements. For example, louvers can help you earn EA credits for optimizing energy performance, IEQ credits for thermal comfort, daylight, and views, as well as ID credits for controlling solar heat gain and enhancing daylighting.

Advantages Over Double- and Triple-Glazed Windows

The benefits of daylighting design using integrated louvers deliver a measurable advantage over double and triple-glazed windows. For example, in a 14-story office building with fully glazed facades in Toronto, test results indicated that integrated louvers can deliver over $182K in total capital cost savings and $127K in total energy savings annually over the double-glazed alternative. Additionally, a university in Baltimore used integrated louvers as part of a new construction project for a 124,800 square foot facility, and life cycle cost analyses have found that their use has decreased the building’s operational outlays and has increased savings over the life of the product.  Integrated louvers also offer three times as many savings every year in operational costs compared to triple glazing in terms of reduced energy consumption. This is especially pertinent for peak cooling demand as less air conditioning is used during the summer.

Today, managing daylight is no longer a design afterthought, but rather a strategic architectural consideration toward better leveraging and mitigating the power of sunlight for optimal energy efficiencies. LEED-friendly integrated louvers are proven to deliver the required daylight and heat control to ensure vastly improved thermal performance, making them an attractive solution for sustainable design.

Viviane Chan is head of business development for Unicel Architectural.

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