Page 323 - The Engineering Guide to LEED-New Construction Sustainable Construction for Engineers

LEED Indoor Envir onmental Quality 285

LEED 2009 OPTION 4—COMBINATION
LEED 2009 IEQc8.1 allows for any combination of LEED 2009 Options 1, 2, and 3 that meets
the minimum 75 percent daylight illumination requirement.
For all the options in LEED 2009 glare control is required to avoid high-contrast situations
that could impede visual tasks. Some allowance (minimum 10 fc) is given for dedicated
theater spaces and other spaces where daylight might hinder tasks may be given exceptions
on a case-by-case basis. Regularly occupied areas also include those areas occupied by
animals for veterinary, and animal boarding and shelter facilities.

Calculations and Considerations
The definitions for glazing, glazing factor, daylighting, incident light, nonoccupied spaces,
nonregularly occupied spaces, regularly occupied spaces, and visible light transmittance T are
vis
listed in App. B. The most important definition is that of regularly occupied areas. Regularly
occupied areas are spaces where most occupants actually work on a regular basis.
Maintenance work is not included. In residential facilities, they are the living or family
areas. In these areas, having daylighting from more “indirect” sources is promoted.
Figure 6.8.1 depicts some of the typical types of daylighting glazed surfaces and
their locations. To obtain this credit, there are restrictions on these various locations for
daylighting and views so that glare is controlled. Typical glare control practices are
listed in the LEED-NC 2.2 and 2009 Reference Guides.
In both versions of LEED, there are three main options for credit compliance, with
a forth option which combines any of the three compliance paths in LEED 2009. In both
versions, the first two are by some form of lighting model, and the third is based on
actual measurements. The first in LEED 2.2 and the second in LEED 2009 are based on
glazing factors, which are dependent on the window types and orientations. The second
(version 2.2) or first (LEED 2009) and third options in either are based on an estimate
(model) or measurement, respectively, of horizontal footcandles (illumination) in the
regularly occupied areas.

FIGURE 6.8.1 Sidelighting and toplighting.