Home lighting design policy for most any house these days:
let the daylight in. . .
with qualifications – maybe not too much, not too little, depends on where, depends on how, how about when, depends what it’s shining on, etc. This is about a Daylighting Schedule.
Home lighting design code: IRC 303.1 presents effectively and round-about that, at least in a sleeping room, “aggregate glazing area" should be not less than 8% of that room's floor surface area. (CABO’s tougher, fewer exceptions.) [Please note that this presentation has no direct connection with emergency egress.]
Home lighting design practice: who knows; the author has had reactions from "exactly, right" to "not so important around here" to "what are you talking about" from building authorities having jurisdiction.
Before The Architect develops a home lighting Daylighting Schedule to address code and a whole lot more.
AGGREGATE GLAZING AREA
To start, the term aggregate glazing area – otherwise undefined – is interpreted to mean translucent surface – glass, clear plastic, etc. and not associated frame, sash, muntins, trim, and the like….
what Marvin Windows and Doors defines as “Lite", Pella as “Visible Glass", Loewen as "Exposed Glass Area," etc.
Note, please, that if some folks weren’t interested in these surface areas, the big players in windows wouldn’t work it out in print. Before The Architect is interested.
THE HOME DAYLIGHTING SCHEDULE FOR INTERIOR DAYLIGHTING
A home lighting Daylighting Schedule, or Illumination Schedule –
Defines the proportion of aggregate glazing area to interior surface area in each major space of a residence, including habitable rooms, halls, walk-in closets, utility spaces for workshop and laundry and such, garage(s), etc.
Compares actual aggregate glazing area to calculated code target for each major space and presents the difference either in square feet of glazing area or, increasingly likely, in percent of glazing area target – the latter seems easier to usefully understand.
Comments selectively by suggestion, indication, and definition about daylighting aspects of importance as designers’ opinions warrant.
Provides an opportunity to identify persistently darkish spaces or parts of spaces sufficiently distant from a natural light source so as to be considered unlighted, or not penetrated, by a natural light source, e.g., a space considerably back from the daylight from a covered porch, an exceptionally deep interior space.
Home Interior Daylighting Schedule, Excerpted
Home lighting experts put definable limits on the extent of useful daylighting that can penetrate a space, e.g., including but not limited to
Lighting Design Basics by Mark Karlen and James Benya, John Wiley & Sons, Inc., 2004, p.34 and
Interior Lighting For Designers 4th Edition by Gary Gordon, John Wiley & Sons, Inc., 1957, p.53ff.
While this aspect of daylighting analysis can be judgmental, consideration of related adjustment to natural illumination is, in the author’s opinion, well worth the effort as a pre-emptive design alert to convenience and safety
Presents several bases of analysis –
Of itself for natural light, in the house’s compass orientation and, possibly, its adjustment and in personal assessment of infiltration and adequacy in daylighted spaces
Ventilation, particularly as an indicator in cross-venting of sleeping areas and longer occupied rooms plus sizing and siting both supplies and returns
UV intrusion indicator of where it may be less welcome and its power may need to be diminished
Natural heat-build indicator for HVAC professional attention and various design means to lessen
Daylight glare definition especially in areas, such as stairways, where glare could threaten safety
Qualification for code-compliance of aggregate glazing area to space surface area in sleeping areas, notably more problematic in such spaces within story-and-a-half structures
Suggestive guide to artificial lighting throughout, particularly ambient lighting and lighting controls
Definitive cross-check on window and door size and site in both elevation and plan view
Excellent perspective on the consequences of exterior design on interior functionality, occasionally leading to design changes ranging from marginal to major
Guide to increased layering in low-daylight spaces
Guide to continuous service rating in no- and very low-daylight spaces
Motivation in single-storied deep spaces with exterior covers to penetrate those covers with niches in the roof, sunscreen, skylight, clerestory, etc.
Motivation in single-storied deep spaces with or without exterior covers to add clerestories and light wells by way of dormers and other fenestration design modifications
Motivation, particularly in story-and-a-half designs, to necessarily add dormers, skylights, skylight tubes, clerestories, and other fenestration design modifications
Comment: Note please that latter-day fixing of major mistakes to attain convenient and safe sizing and siting of windows, exterior door composition, luminaires, and light-reflecting and -absorbing features can be a remediation expense and physical inconvenience bigtime.
Before The Architect designs and drafts custom home plans nationwide. Its principals Ralph and Jean Pressel have worked hands-on together since the ‘60s in custom home design, drafting, consulting, plus building and repair in every major trade.Their plan sets are extraordinarily detailed; their clients' active involvement throughout is essential.
Home Design Standards - Home Building Standards 4Q08 Edition e-book at 823 pages and the website www.beforethearchitect.com at nearly 1000 pages of text and illustrations are enterprises of Before The Architect’s principals.
The author of this article has chosen to make this article available with free reprint rights. Click here to copy this article.
Disclaimer: All information on this site is provided for informational purposes only! By no means is any
information presented herein intended to substitute for the advice provided to you by any health care or other professional
or organization.
.jpg)
