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I N S I G H T : H igh - P e r f o r man c e Facade Solutions b y L E A H B . G A RR I S Adapted from the April 2006 edition of Buildings, published by Stamats Business Media. According to the Lawrence Berkeley National Laborator y in Berkeley, Calif., high-performance commercial building facades are comprehensive systems that incorporate daylighting, solar heat-gain control, ventilation, and space conditioning. Examples include: Solar-Control Facades Spectrally selective solar control is window glass that permits some portions of the solar spectrum to enter for daylight purposes while blocking others associated with solar heat. Low-E coatings control solar heat gains in summer, prevent loss of interior heat in winter, and reduce electriclighting use. Solar filters, such as overhangs, fins, light shelves, or secondary exterior skins made of filter material, indiscriminately absorb or reflect a portion of both direct and diffuse solar radiation and are applied to exterior walls to reduce solar radiation levels and diffuse daylight. Exterior solar control helps to stop direct sun from entering the building and can be provided by overhang, fin, or full window-screen geometries. Examples include louvers and blinds. Daylighting Facades Sunlight-redirection systems rely on reflection, refraction, diffraction, or non-imaging optics to modify the distribution of incoming daylight. Benefits include not only the potential to offset lighting requirements, but to improve lighting quality and visual comfort. Light shelves, one example of a sunlight-redirection system, are horizontal, exterior projections that use a highreflectance, diffuse, or semi-specular upper surface to reflect sunlight to a certain interior depth from the window wall. Skylight redirection systems, designed for diffuse skylight, are intended to increase overall interior daylight levels with less emphasis on the depth of light redirection. Double-Skin Facades and Natural Ventilation Heat extraction double-skin facades systems consist of a single exterior layer of heat-strengthened or laminated safety glass, with exterior air inlet and outlet openings. A second layer, the interior 52 t e x a s a r c h i t e c t D e sign facade, consists of fixed or operable, double- or single-pane casement windows. In between these two facades are retractable or fixed blinds, or roller shades. During cooling conditions, the blinds/shades cover the full height of the facade and are tilted to block direct sun. The heat absorbed is released within the intermediate space and drawn off through the exterior skin by natural or mechanical ventilative means. Nighttime ventilation can be used to cool a building, reducing air-conditioning loads. Heat gains generated during the day are absorbed by furnishings, walls, floors, and other surfaces and released over time. With nighttime ventilation systems, the building is often shaped to minimize air-flow obstructions. Mixed-mode ventilation is a space-conditioning approach that combines natural (passive) ventilation with mechanical (active) ventilation and cooling. to draw in fresh air at a low level and exhaust air at a high level.) THORNTREE Supplying architects with the finest natural stone selection for 27 years. slate.marble.granite F R O M T H E great quarries O F T H E W O R L D Your main source for Architectural Concrete Masonry Units in Texas. Showroom & Warehouse 10105 West Gulf Bank. Houston, Tx. 77040 (713) 690-8200 www.thor Palestine Concrete Tile and Southwest Concrete Products are committed to sustainable business practices and products, and participate in the US Green Building Council’s Leeds program. Beauty and Durability in Building Products P.O. Box 2508, Palestine,Tx. 75802 800.594.7967 Fax: 903.729.2219 1109 Upland Drive, Suite C, Houston, TX. 77043 Fax: 713.365.9004 713.365.9077 See our new website at 1 1 / 1 2 2 0 0 6

Texas Architect Nov/Dec 2006: Place Making

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