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Environmental Controls I/IG

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Presentation on theme: "Environmental Controls I/IG"— Presentation transcript:

1 Environmental Controls I/IG
Lecture 9 Solar Geometry Shading Strategies

2 Sun Position Can be described by two angles: Altitude Azimuth
S: p. 1514, T.C.12

3 Solar Angles Describe the sun position relative to a vertical surface

4 Solar Altitude: β (beta)
Vertical angle to sun position

5 Solar Azimuth: Φ (phi) Horizontal bearing angle from south

6 Surface Azimuth: Ψ (psi)
Surface horizontal bearing angle from south

7 Surface Solar Azimuth: γ (gamma)
Angle between solar and surface azimuths γ = Φ - Ψ

8 Sign Conventions Angles east of south are negative
Angles west of south are positive 90º -90º S 45º -45º

9 Calculating Surface Solar Azimuth
γ = Φ – Ψ For example: Building façade is oriented south east (Ψ =-45º) Solar azimuth (ϕ) is 30º west of south γ = 30º – (-45º) = 75º Note: |γ|≥ 90º, façade in shade -45º 30º

10 Profile Angle: Ω (omega)
Defines limits of shade conditions For horizontal projections: TAN(Ω)=TAN(β) / COS(Y)

11 Profile Angle: Ω (omega)
For horizontal projections: SH=PH TAN(Ω) where, PH: width of enclosing side of horizontal projection SH: height of shadow below horizontal projection

12 Profile Angle: Ω (omega)
Defines limits of shade conditions For vertical projections: TAN(Ω)=TAN(Y)

13 Profile Angle: Ω (omega)
For vertical projections: Sw=Pv TAN(Y) where, Pv: width of enclosing side of vertical projection Sw: width of shadow beyond vertical projection

14 Sizing Horizontal Projections
Establish fenestration pattern and determine size of openings

15 Sizing Horizontal Projections
Determine cut off date and time for solar penetration Mar AM solar time Determine surface azimuth Due south, Ψ=0º Determine required shadow height SH=6’ ?

16 Sizing Horizontal Projections
Establish profile (Ω) angles for the solstices at solar noon using surface solar azimuth (Y = Φ –Ψ). At solar noon (Φ=0º) and for L=40º, Ψ=0º: 12/21 β= L=26.5º TAN(Ωw)=TAN(β)/COS(Y) Ωw=26.5º 6/21 β= L=73.5º TAN(Ωs)=TAN(β)/COS(Y) Ωs=73.5º

17 Sizing Horizontal Projections
Establish profile (Ω) angles for cut off date and time using surface solar azimuth (Y = Φ –Ψ). At 10 AM solar time and for L=40º, Ψ=0º:

18 Sizing Horizontal Projections
Mar AM Solar Time β= 41.6º Φ= -41.9º Y=Φ-Ψ Y=-41.9º-0º=-41.9º S: p. 1514, T.C.12

19 Sizing Horizontal Projections
Establish profile (Ω) angles for cut off date and time using surface solar azimuth (Y = Φ –Ψ). At 10 AM solar time and for L=40º, Ψ=0º: 3/21 β=41.6º Y=-41.9º TAN(Ω)=TAN(β)/COS(Y) TAN(Ω)= 0.888/0.744= 1.19 Ω=50º

20 Sizing Horizontal Projections
Given SH = 6’ and SH=PH Tan(Ω) Solve for PH PH=SH/TAN(Ω) PH=6/1.19=5.04’ ~ 5’-0 ½” say 5’-0”

21 Solar Envelope Ω Louver Spacing Ph Sh Reduce horizontal projections by adding horizontal louvers in a vertical screen

22 Sizing Horizontal Projections
Use the summer solstice profile angle (ΩS) to determine spacing of vertical louvers ΩS H S Spacing (S)= H/TAN(ΩS) If H=12’’, then S=12/TAN(ΩS)=3.55” say 3½” Note: method does not include louver thickness

23 Sizing Horizontal Projections
Use the summer solstice profile angle (ΩS) to determine spacing of reverse inclined louvers H ΩS S 2S Spacing (S)= H/TAN(ΩS) If H=12’’, then S=12/TAN(ΩS)=3.55” say 3½” Note: method does not include louver thickness

24 Lateral Penetration Mar 21 at 10 AM solar time
β When Y≠0º, lateral penetration occurs at an angle = β

25 Lateral Penetration Solutions
Extend projection bilaterally β

26 Lateral Penetration Solutions
Install vertical component bilaterally

27 Critical Angle Analysis
Critical angles define solar aperture height (SAH) ΩW SAH Ω ΩS

28 Solar Aperture Sizing Insolation desired: 2600 Btuh
Determine initial size Insolation desired: 2600 Btuh Available insolation* : 269Btuh/sf Initial area(AI)= 2600 Btuh/269 Btuh/sf= 9.7 sf *(S: p. 1649, T B.12; South Facing at solar noon on 12/21) Percent sunshine(SS%) 45% or 0.45 (L: p. 89) Solar Heat Gain Coefficient (SHGC) Single glazed clear=0.79 (S: p. 171 T 4.13)

29 Solar Aperture Sizing Interior filters (IF) Drapes full open= 1.00
(S: p. 179, T 4.21) Exterior filters (EF) Cottonwood Trees= 0.68 (S: p. 111, T 3.5) Determine final Aperture Area(AAF) AAF=AAI/(SS% x SHGC x IF x EF) AAF=9.7/(0.45x0.79x1.00x0.68)= say 40 sf

30 Sizing Vertical Projections
SW =|PVTAN(Y)| or PV=|SW/TAN(Y)|

31 Sizing Vertical Projections
On Mar 10 AM (Y=-41.9º), if SW=6’ what should PV be to shade window PV=|SW/TAN(Y)| PV=|6/-1.115|=5.4’ ~5’-5”

32 Shading Strategies

33 Shading Devices – Overview
South Façade: Horizontal overhang or Brise-soleil San Cristobal Stables The Capital (Chandigarh)

34 Shading Devices –Overview
East/West Façade: Vertical fins angled to the north and/or Brise-soleil Keio University Graduate School Research Center Monastery of Ste Marie de La Tourette

35 Shading Devices –Overview
North Façade: Vertical fins (used in hot climates only) Phoenix Central Library L: p. 559 fig b

36 Shading Devices – Tectonics
Vertical Louvers or Screens John Deere Headquarters, Moline IL Jewett Art Center, Wellesley, MA

37 Shading Devices – Tectonics
Horizontal Solid and louvered planes, projections or recesses Paimio Sanatorium, Finland Getty Center Los Angeles, CA

38 Shading Devices –Tectonics
Sculptural Form Thickness Projections Screens Reynolds Aluminum Building, Detroit, MI Unity Temple, Oak Park, IL Beach House, Lido Shores, FL Obayashi Tokyo Design Center

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