Light Flutter

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BEFORE THE ARCHITECT – DREAM HOME DESIGNING BACKGROUND – UNIQUE HOME DESIGN ARTICLES

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LIGHT FLUTTER - A SYSTEM OF DREAM HOME LIGHT DESIGN

By Before The Architect  Copyright 2002, 2003, 2007, 2009 Before The Architect

When you're ready, teach  your craft to others.  This is best done personally.  This is most often done with clients.   You don't need a podium or tenure to perform; if you get really good at what you do at this or that, folks who give a damn will seek you out.  Teach with both honor and humility.  And answer each question you're asked.  You'll be continually surprised at how much you don't know about what you know when keenly inquiring minds start inquiring.  Before The Architect

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Light flutter comes from ceiling fan blades interrupting a view of home light rays – natural or mechanical source.  This is about mechanical source interruption and its avoidance by a home light, fine home design system. 

Light flutter can be divided in two categories – primary and secondary. 

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Primary home light flutter puts a fan blade directly across the beam at close range to the viewer – pulses home light and shadow enough to hurt vision almost painfully
 

bulletSecondary home light flutter puts a blade across more distant home light rays to both blade and viewer, enough sometimes to be only barely noticeable for the viewing disruption, like death by duck nibble 

Both flutters are inconvenient, signatures of poor interior light dream home design in this dream home designer's opinion.  Both can be home-designed-out reasonably. 

Who cares?  In our dream home design experience – forces converge. 
 

bullet Aging eyes - -if you don’t have them, you will – need more illuminance than generally home-designed.  Light and shadow variance is no friend to aging eyes
 
bullet Ceiling fans are a trademark of warmer climes – retirement climes
 
bullet Recessed home light is broadly popular and applied
 
bullet Compact fluorescent lamps (CFLs) in downlight are not only Green, they can produce ageing-extra illuminance that is tougher to match with incandescents
 
bullet Finally, by experience and the expressions of others, ceiling luminaires are commonly sited by tradesmen onsite, which, in the author’s opinion, is neither as it should be nor need be.  Electrical installers are a segment of the building business, not the home design business.

The physics of it: a ceiling fan blade can intersect a ceiling-sourced home light ray anywhere there’s a line of sight, not just right below or right by the spinning fan. 

The physiology of it: height counts.  The higher the base point for line of sight, the longer is the blade-intersected view, i.e., the less ceiling space on which to apply downlights.  Our fine home design uses a base point for line of sight 70.3” above floor level – upper end of U.S. male eye level (Architectural Design Standards, 10th Ed., Ramsey/Sleeper, p.2), adjusted for actual height metrics of clients whose heights vary from the norm. 

The geometry of it: apply room and fan dimensions to scale.  Each space with a ceiling fan will return its own particular results for major and minor axes separately (unless the space is square).  Let’s try on, as example, the 20’ major axis to a room with a 9’ ceiling, and a 44” diameter ceiling fan with a “standard” application, putting the blade plane 12” below ceiling level.  The dream home drawing to follow develops these metrics into prescripts of where and where not to install downlights at either end of the space. 

 Light Flutter Avoidance, Section, Part 2B

Source: Home Design Standards-Home Building Standards 3Q10 desk copy draft, currently page 244 of 421 at 1/8/07 

What’s learned?  From 7’-4 5/16” outside the fan’s centerpoint and through 2’-7 11/16” to the major axis terminus at the space’s wall, recessed downlights appear to be applicable without primary or secondary flutter.  Derivatively, with increasing length of downrod, ceiling-sourced opportunities for illuminance shrink, effectively expanding primary flutter ceiling surface area while reducing secondary flutter exposure. 

This approach to avoiding home light flutter has significant upsides – 

bulletCalculations are not complex and can be executed quickly
 
bulletMethodology addresses a space’s major and minor axes separately and without an averaged generalization subject to useful space foregone
 
bulletOutcomes can be demonstrated and defined on the order of dead-reckoning
 
bulletModel relies on well-known values early-on in dream home plans development – space dimensions and, by derivation, ceiling fans metrics
 
bulletControllable variables abound, including height of base point, site of base point relative to the space, blade diameter (limitedly), downrod length (less limitedly)
 
bulletPractical refinements are possible, including adjusting eye level to owner’s physiometrics; adjusting the site of base points respectful of a given space’s realities, e.g., built-ins, steps up, wall-loaded furniture, etc.; rounding the corners of the rectilinear standoff space the
model inevitably produces, giving up more useable space
 
bulletPhysical dynamics are such that home light flutter avoided will never be more closely defensed than at a space’s perimeters – the farther one travels into the space interior, the farther apart are lines of sight between blade diameter and home light source
 
bulletNone of the other our other home light options is diminished, including
bulletwall-aimed luminaires of any sort, wall lanterns, valances, soffits, coves, pendants at or below blade plane, table lamps, floor lamps
bulletflood-light a space so as to overwhelm shadow overall
bulletrecess the fan, as though in its own tray, where the blade plane is not lower than the surrounding ceiling in which or on which luminaires can be applied
bulletsuspend luminaires at or below blade plane
 
bulletCan apply to surface-mounted luminaires, too

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This analysis, fan by fan, downrod by downrod, ceiling surface area by ceiling surface area, axis by axis, space by space determines the approximate extent of ceiling area for downlight excepting home light flutter.  This dream home designer, then lays in a hatching pattern in each affected space right on the Electrical and Light Plan.  To wit -

Key:  CLG=CEILING; DR=DOOR; DRD=DOWNROD; EL=ELEVATION; ENG.LAT.=ENGINEERING LATITUDE; HR= (WIRING) HOME RUN; INS FL=INSULATE FLOOR (IN THIS INSTANCE, MOSTLY TO ABATE SOUND TRANSMISSION FROM L0); K=KING-SIZED; l=LUMENS; LI=LINER INCH; PRM=PERIMETER; SD=SINGLE-POLE DIMMER; S3D=3-WAY DIMMER; S4=4-WAY SWITCH INTERIM TO BRANCH ELECTRICAL CIRCUIT WIRING; S4D=4-WAY DIMMER INTERIM TO BRANCH ELECTRICAL CIRCUIT WIRING; SHWR=SHOWER; TYP=TYPICAL

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