DAYLIGHTING AND WINDOWS
Daylighting forms the cornerstone of resource efficient, high performance design for schools. Affecting individuals on both conscious and subconscious levels, it provides light to see the work environment, a natural rhythm that determines the cycles of days and seasons, and biological stimulation for hormones that regulate body systems and moods. In addition, it offers opportunities for natural ventilation and, if properly integrated with the electric lighting
system, can provide tremendous energy savings. The Gentle, diffuse daylight permeates a classroom with both advantages of daylighting translate to higher sidelight and toplight. Note that all surfaces are painted performance in schools. Research has shown that white to distribute light more efficiently and reduce contrast glare. NREL/PIX 11392 children achieve significantly higher test scores in classrooms that are daylit than in those that are not,1 making daylighting one of the best building-related investments for the learning environment.
This chapter provides an overview of daylighting and fenestration design. It also presents eight daylighting guidelines for specific sidelighting and toplighting schemes.
View Windows (Guideline DL1) High Sidelighting—Clerestory (Guideline DL2) High Sidelighting—Clerestory with Light Shelf or Louvers (Guideline DL3) Classroom Daylighting—Wall Wash Toplighting (Guideline DL4) Central Toplighting (Guideline DL5) Patterned Toplighting (Guideline DL6)
Linear Toplighting (Guideline DL7)
Tubular Skylights (Guideline DL8)
To fully daylight most spaces, the guidelines should be combined with each other or repeated as a pattern across the space. For example, Wall Wash Toplighting (Guideline DL4) on an interior wall could be combined with High Clerestory Sidelighting (Guideline DL2) and View Windows (Guideline DL1) on an
1 Heschong Mahone Group, “Daylighting in Schools—An Investigation into the Relationship between Daylighting and Human Performance,” prepared for Pacific Gas & Electric Company and funded by California utility customers, 1999. Heschong Mahone Group and New Buildings Institute, “Re-Analysis Summary: Daylighting in Schools, Additional Analysis.” February 2002.
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exterior wall to fully daylight a classroom. Since daylight is additive, the total amount of daylight in the space is the sum of the daylight available from each individual pattern. Each guideline represents a daylight delivery system with inherent advantages and disadvantages, which are summarized below in Table 1.
Table 1 – Selection Criteria for Daylighting Strategies
High Central & View Sidelight w/ Wall Wash Patterned Linear Tubular Windows Light Shelf Toplighting Toplighting Toplighting Skylights Design Criteria (DL1) (DL2 & DL3) (DL4) (DL5 & DL6) (DL7) (DL8) Uniform Light Distribution / Low Glare / Reduced Energy Costs Cost Effectiveness Safety/Security Concerns / Low Maintenance