Ultimate Daylighting

Windows, glass and digital innovations
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Sponsored by Guardian Industries Corp., Pella Commercial, EFCO, a Pella Company, and Panda Windows & Doors
Celeste Allen Novak AIA, LEED AP

The evolution of glazings and glass performance has shown dramatic improvements in visible light transmission, U-values, SHGC, and shading coefficients. See the online version of this course for a chart that demonstrates the performance enhancements to a ¼-inch monolithic lite with the addition of high-performance coatings.

Prior to low-E coatings, tinted glass was used as a means of solar control. As technology advancements continue, low-E coated clear glass offers better insulating performance and solar control than tinted glass, along with potentially truer color transmission as expressed by the color rendering index (CRI). The CRI is a measure of color accuracy ranging from 1-100, with a rating of 100 representing the truest color transmission as it relates to natural daylight.

From the inside looking out at a simulated streetscape, the architect can compare the visible light transmission from a wide range of coated products on clear glass as they relate to an uncoated clear glass unit that has 85% visible light transmission.

Photo courtesy of Guardian Industries

High-Tech Calculators Guide Performance Selection

New web-based IG performance and building energy calculators that are capable of producing BIM content are now available to help architects guide performance selection. These powerful tools populate BIM content with manufacturer data for thermal and optical performance values for use in project-specific integrated mockups and building models. This digital tool creates highly detailed content representing the correct thickness and color of the inboard and outboard lites. Users can control the level of detail depending on the scale of the drawing and views on the computer. The generated report compares energy cost, utility consumption, and the financial payback of different glazing options. By simulating alternatives along with the cost of those alternatives, architects can clearly demonstrate to their clients the economic and performance advantages of choosing a higher-performance window even if it has higher initial costs.

In addition, a simple box energy model also assists the architects in “tuning” windows based on climate or on building orientation. A digital building energy calculator can easily model the nuances of selecting a different type of window for the north side of a building versus south, east, or west side. Based on the project location, the architect can select different types of coatings with similar visual appearance but different energy performance criteria to optimize each elevation of a building. The cost of tuning the windows for orientation can be modeled and the payback period often will show that the extra expense (if any) to optimize each glazing scenario per elevation is a good bargain.

To reduce patient exposure to airborne allergens and to provide sun control, high-performance aluminum-clad wood windows with integral blinds were used at the Vollum Institute for Advanced Biomedical Research in Portland, Oregon.

Photo courtesy of Pella Commercial

Too much uncontrolled daylight can cause glare and provide occupant discomfort. As Terry Zeimetz, AIA, CSI, CCPR of Pella Commercial, states: “It is important to understand how to control solar energy. Where is it going to be stopped, through exterior sunshades, on different panes of glass, inside the glass system with in-between blinds or shades or inside the building with some type of window treatments. The most effective strategy is to block solar energy before it enters the building. Second best is to stop it with between-the-glass blinds or shades before it gets past the inner piece of glass. The least effective way to stop heat gain is with room-side window treatments since the heat has already passed through the glass and must be dealt with.”

Sometimes the solution to adding interior sun controls can have the unintended consequences of causing health problems. As an example, the use of room-side curtains or blinds collect allergens on the surface materials. New research by the Department of Occupational and Environmental Health at The University of Iowa demonstrates the potential for designing window treatments that can improve health for allergy sufferers.2

Researchers at the Vollum Institute for Advanced Biomedical Research, designed by Zimmer Gunsul Frasca Architects LLP, studied the collection of allergens on window blinds. They documented results that demonstrated that windows with ordinary room-side blinds accumulated 200 times more of certain airborne allergens than some high-performance windows with between-the-glass blinds.

Large door or window openings create a sense of freshness and serenity that makes you feel like you are one with your natural surroundings.

Photo courtesy of Panda Windows & Doors

 

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Originally published in Architectural Record
Originally published in September 2013

Notice

Academies
Ultimate Daylighting
Buyer's Guide
New Advanced Architectural Glass
Guardian's new advanced architectural glass, SunGuard Neutral 78/65, helps architects meet energy codes in heating-dominated climates with abundant daylighting. It has the highest visible light transmission of any SunGuard product, a high solar heat gain coefficient, and neutral color. Neutral 78/65 is available on clear or UltraWhite low-iron float glass.
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Guardian Industries
www.sunguardglass.com
Revolutionary Lift & Slide System
The all-new TS .13 Aluminum/Wood Clad Thermally Broken Lift & Slide features easy lift and slide functionality and incredible comfort. This model's added wood insulation guarantees structure interiors are warmer in the winter and cooler in the summer, and its isolated aluminum frame makes it strong and resistant to the harshest elements while drastically reducing the need for finish maintenance.
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Panda Windows & Doors
www.panda-windows.com
New Factory-Applied Exterior Aluminum Trims
Pella now offers additional factory-applied exterior aluminum trims in custom or standard profiles for Pella® aluminum-clad wood windows and doors.
Circle 9
Pella Commercial
www.pellacommercial.com