Environmental Controls I/IG Lecture 18 Daylighting Design & Analysis Design Strategies Glazing and Reflectors Sidelighting Analysis Method Lecture 18 Daylighting Design & Analysis Design Strategies Glazing and Reflectors Sidelighting Analysis Method

Daylighting Design & Analysis

Orientation and Slope Vertical vs. Horizontal Time of year Sun position DL-5 F p. 79

Daylighting Components SC=Sun + Sky IRC 1 IRC2 ERC S: F p. 590

Daylighting Factor (DF) The quantity of interior illuminance on a horizontal work plane expressed as a percentage of illuminance of an exterior unobstructed horizontal plane DF (%) = (E INT /E EXT ) x 100

Daylighting Factor (DF) If E INT is 20 foot-candles and E EXT is 1000 foot-candles, then what is the daylighting factor? DF(%)= (E INT /E EXT ) x 100 DF (%)=(20/1000) x 100 DF (%)=2.0%

Isolux Contours Lines of similar lighting levels Expressed as DF Darwin College Library, Cambridge, England

Isolux Contours Example E EXT = 2000 fc 1: 20 fc 2: 60 fc 3: 100 fc 4: 40 fc 5: 80 fc 6: 140 fc 7: 20 fc 8: 60 fc 9: 100 fc DF(%)= (E INT /E EXT ) x 100

Isolux Contours Example E EXT = 2000 fc 1: 20 fcDF=1 % 2: 60 fcDF=3 % 3: 100 fcDF=5 % 4: 40 fcDF=2 % 5: 80 fcDF=4 % 6: 140 fcDF=7 % 7: 20 fcDF=1 % 8: 60 fcDF=3 % 9: 100 fcDF=5 %

Isolux Contours Example E EXT = 2000 fc 1: 20 fcDF=1 % 2: 60 fcDF=3 % 3: 100 fcDF=5 % 4: 40 fcDF=2 % 5: 80 fcDF=4 % 6: 140 fcDF=7 % 7: 20 fcDF=1 % 8: 60 fcDF=3 % 9: 100 fcDF=5 %

Isolux Contours Lines of similar lighting levels Expressed as DF Darwin College Library, Cambridge, England

Illumination Gradient An illumination gradient through a section Ludwig Museum, Koln, Germany

Design Strategies

Selection Parameters Daylight availability Task orientation Space orientation

Daylighting Graphs 10’ Ceiling 30” Work plane DL-5: F10-2 p. 80

South Facing Walls Solid Overhang a: translucent glazing b: horizontal overhang c: 30º sloped clear glazing d: 45º sloped clear glazing DL-5: F10-5 p. 82

South Facing Walls Diffusing Awnings a: translucent glazing b: translucent awning clear glazing c: white vertical slatted awning, clear glazing d: white, horizontal slatted awning, clear glazing DL-5: F10-6 p. 82

Light Shelves W: With light shelf WO: Without light shelf DL-5: F10-18 p. 89

Skylights Effect of skylight above roof a: flat horizontal b: half-round barrel, white opaque ends c: steeply sloped A-frame, white opaque ends DL-5: F10-21 p. 91Typographic Error In Reading 

Roof Monitors North-South Monitors a: translucent panel b: north monitor, clear glazing c: south monitor, translucent glazing DL-5: F10-30 p. 95

Roof Monitors Sun Control Baffles/Louvers Light Wells DL-5: F10-35 p. 97

Roof Monitors Graphic Design Approach DL-5: F10-37 p. 98

Glazing & Reflectors

Fenestration Window or Fenestration?

Clear Glazing Maximum VLT DL-5: F11-1 p. 105

Gray/Bronze Glazing Gray glass preferred where color rendition is important DL-5: F11-2 p. 106

Heat Absorbing Glazing Green is more common Blue is becoming more available DL-5: F11-3 p. 107

Solar IR Reflective Film Low-E Glass DL-5: F 11-6 p. 109

Multiple Glazing Combinations of individual paned glazing Mylar/Film layer Inert gas (argon or krypton) “Superwindow”

Exotics LED Windows Aerogels Kalwall Prototype House and Studio Thomas Herzog

Sidelighting Method

Subscripts w=window k=sky g=ground u=sun

Parameters RgRg TgTg

Illumination (E) E kw Illumination from sky on window E kg Illumination from sky on ground E uw Illumination from sun on window E ug Illumination from sun on ground E kuw Illumination from sky and sun on window E kug Illumination from sky and sun on ground

Illumination (E) E gw Illumination from ground on window E kwp Illumination from sky (and sun) on work plane E gwp Illumination from ground on work plane R g Reflectance of ground surface A g Window area of transmittance T g Transmittance of glass

Coefficients of Utilization (C,K) C os and K os overcast sky C cs and K cs clear sky C us and K us uniform sky C sv and K sv sky with venetian blind C ug and K ug uniform ground C gv and K gv ground with venetian blind

Daylighting Components Illumination on window E kuw = E kw + E uw Illumination on ground E kug = E kg + E ug

Daylighting Components Illumination from sky (and sun) on work plane E kwp = E kuw x A g x T g x C x K

Daylighting Components Illumination from ground on window E gw = E kug x R g x 0.5 Illumination from ground on work plane E gwp = E gw x A g x T g x C x K

Total Daylighting Components Illumination from ground on window E TOT = E kwp + E gwp