ARCH 309-F24 Lecture 7 Solar Geometry + Shading PDF

ARCH 309-F24 Lecture 7-Solar Geometry + Shading Environmental Control Systems I Lecture 7 SOLAR GEOMETRY + SHADING HYOJIN KIM, PH.D. Associate Professor...

ARCH 309-F24 Lecture 7-Solar Geometry + Shading Environmental Control Systems I Lecture 7 SOLAR GEOMETRY + SHADING HYOJIN KIM, PH.D. Associate Professor New Jersey Institute of Technology All materials in this course are intended solely for the use of students currently enrolled in this course and solely for purposes related to this course. Students are strictly prohibited from sharing any of the course materials with third parties. These materials may be protected by copyright law, and any additional use beyond the scope of this course may constitute a violation of federal copyright law. LEARNING OBJECTIVES After this lecture, you should be able to Understand Earth’s relationship to the Sun and how that relationship affects thermal comfort. Define basic solar geometry terminology and explain in layman’s terms. Define sunpath diagram and explain in layman’s terms. Understand different types of shading devices and their different applications. Design shading devices using Climate Consultant’s shading calculator. Estimate solar heat gains through windows. Associate Professor Hyojin Kim, Ph.D. Lecture 7 SOLAR GEOMETRY + SHADING 2 1  ARCH 309-F24 Lecture 7-Solar Geometry + Shading READINGS FOR LECTURE 7 Required Readings for Lecture 7: – MEEB Chapter 8 Associate Professor Hyojin Kim, Ph.D. Lecture 7 SOLAR GEOMETRY + SHADING 3 WHY DO WE CARE? Associate Professor Hyojin Kim, Ph.D. Lecture 7 SOLAR GEOMETRY + SHADING 4 2  ARCH 309-F24 Lecture 7-Solar Geometry + Shading WHY DO WE CARE? Le Corbusier La Cité de Refuge (or Salvation Army) in Paris Associate Professor Hyojin Kim, Ph.D. Lecture 7 SOLAR GEOMETRY + SHADING 5 WHY DO WE CARE? Le Corbusier La Cité de Refuge (or Salvation Army) in Paris Associate Professor Hyojin Kim, Ph.D. Lecture 7 SOLAR GEOMETRY + SHADING 6 3  ARCH 309-F24 Lecture 7-Solar Geometry + Shading FRIEND AND ENEMY The sun, by Le Corbusier 1938-1944, V 4. Associate Professor Hyojin Kim, Ph.D. Lecture 7 SOLAR GEOMETRY + SHADING 7 SUN’S POSITION Before you decide what can be done at a given site you need to know something about solar radiation and shading. The easiest way to understand solar radiation Source: MEEB Fig. 8.2 and shading is to chart the Summer solstice Winter solstice sun’s path following the hemisphere projected on the earth. Earth’s axis of rotation 23.5° causes earth’s seasons. Source: MEEB Fig. 8.8 Associate Professor Hyojin Kim, Ph.D. Lecture 7 SOLAR GEOMETRY + SHADING 8 4  ARCH 309-F24 Lecture 7-Solar Geometry + Shading SUN’S POSITION The easiest way to do this is by measuring the altitude (vertical angle above the horizon) and azimuth (horizontal angle measured from the South) of an object in regards to the sun’s position. Source: MEEB Fig. 8.12 Associate Professor Hyojin Kim, Ph.D. Lecture 7 SOLAR GEOMETRY + SHADING 9 SUN’S POSITION Maximum summer sun altitude is 90° minus latitude plus 23.5°. Minimum winter sun altitude is 90° minus latitude minus 23.5°. Thus, for all latitudes the yearly difference between maximum and minimum altitudes is twice 23.5°, or 47°, as shown. – Vernal, autumnal equinox = 90° – latitude – Winter and summer solstice = ± 23.5° Maximum Sun Altitude at Various Latitudes for Both Solstices and Equinoxes Source: MEEB Fig. 8.4 Associate Professor Hyojin Kim, Ph.D. Lecture 7 SOLAR GEOMETRY + SHADING 10 5  ARCH 309-F24 Lecture 7-Solar Geometry + Shading SOLAR TIME Solar Time varies from Clock Time due to: – Daylight Savings Time – Location in the time zone (longitude) – The earth’s speed in orbit varies (i.e., equation of time) We will use Solar Time which is the time based on the sun’s position in our discussion. All charts and tables use solar time. Associate Professor Hyojin Kim, Ph.D. Lecture 7 SOLAR GEOMETRY + SHADING 11 SOLAR TIME Solar time = Local time + E + 4(Lst - Lloc) E = equation of time Lst = standard time zone longitude Lloc = location longitude Calculate for Eugene, OR if it is 2:30 PM on Jan. 31st: Local Time =2:30 PM* E= -14 mins Lst = 120˚ W Lloc = 123˚ W *During DST (March-Nov), you’ll need to subtract 1 hour to get Standard Time. -14 Associate Professor Hyojin Kim, Ph.D. Lecture 7 SOLAR GEOMETRY + SHADING 12 6  ARCH 309-F24 Lecture 7-Solar Geometry + Shading SOLAR TIME Solar time = Local time + E + 4(Lst - Lloc) = 2:30 PM – 14 min + 4(120- 123) = 2:30 PM – 26 min = 2:04 PM -14 Associate Professor Hyojin Kim, Ph.D. Lecture 7 SOLAR GEOMETRY + SHADING 13 SUN CHART There are many different methods of projecting the sun’s path onto a useful diagram. The origins of this work can be traced back to the 1500s where astronomers and mathematicians projected celestial movement onto a sphere. Associate Professor Hyojin Kim, Ph.D. Lecture 7 SOLAR GEOMETRY + SHADING 14 7  ARCH 309-F24 Lecture 7-Solar Geometry + Shading SUN CHART Cylindrical Chart Equidistant Chart Orthographic Chart Stereographic Chart Associate Professor Hyojin Kim, Ph.D. Lecture 7 SOLAR GEOMETRY + SHADING 15 SUN CHART Associate Professor Hyojin Kim, Ph.D. Lecture 7 SOLAR GEOMETRY + SHADING 16 8  ARCH 309-F24 Lecture 7-Solar Geometry + Shading SUNPATH DIAGRAM Each point on the sun path diagram represents an instantaneous location of the sun. Sunpath combines – Month – Time of day – α = solar altitude – αs = solar azimuth Associate Professor Hyojin Kim, Ph.D. Lecture 7 SOLAR GEOMETRY + SHADING 17 SUNPATH DIAGRAM Azimuth Altitude Sun time Sun path Associate Professor Hyojin Kim, Ph.D. Lecture 7 SOLAR GEOMETRY + SHADING 18 9  ARCH 309-F24 Lecture 7-Solar Geometry + Shading SUNPATH DIAGRAM Example: March 21st at 12 PM and 3PM 30º 44º 55º Sun path 0º Associate Professor Hyojin Kim, Ph.D. Lecture 7 SOLAR GEOMETRY + SHADING 19 SUNPATH DIAGRAM Associate Professor Hyojin Kim, Ph.D. Lecture 7 SOLAR GEOMETRY + SHADING 20 10  ARCH 309-F24 Lecture 7-Solar Geometry + Shading SUNPATH DIAGRAM Azimuth Altitude Sun time Sun path Associate Professor Hyojin Kim, Ph.D. Lecture 7 SOLAR GEOMETRY + SHADING 21 SUNPATH DIAGRAM Example: March 21st at 12 PM and 3PM 44º 30º Sun path 0º 55º Associate Professor Hyojin Kim, Ph.D. Lecture 7 SOLAR GEOMETRY + SHADING 22 11  ARCH 309-F24 Lecture 7-Solar Geometry + Shading SUNPATH DIAGRAM Associate Professor Hyojin Kim, Ph.D. Lecture 7 SOLAR GEOMETRY + SHADING 23 HELIODON Heliodons visually teach the basic concepts of solar geometry that is affected by latitude, time of year, and time of day, as related to a building that will allows them identify opportunities for energy savings through solar-responsive architectural design. Associate Professor Hyojin Kim, Ph.D. Lecture 7 SOLAR GEOMETRY + SHADING 24 12  ARCH 309-F24 Lecture 7-Solar Geometry + Shading HELIODON Associate Professor Hyojin Kim, Ph.D. Lecture 7 SOLAR GEOMETRY + SHADING 25 HELIODON NJIT ASHRAE built a heliodon. Associate Professor Hyojin Kim, Ph.D. Lecture 7 SOLAR GEOMETRY + SHADING 26 13  ARCH 309-F24 Lecture 7-Solar Geometry + Shading SUN PATH VISUALIZATION IN BIM https://knowledge.autodesk.com/support/revit- products/getting-started/caas/simplecontent/content/sun- path-visualization-bim.html Associate Professor Hyojin Kim, Ph.D. Lecture 7 SOLAR GEOMETRY + SHADING 27 SUN PATH VISUALIZATION IN BIM Check the sunpath chart tutorial on Canvas! Associate Professor Hyojin Kim, Ph.D. Lecture 7 SOLAR GEOMETRY + SHADING 28 14  ARCH 309-F24 Lecture 7-Solar Geometry + Shading GOALS OF SOLAR SHADING Understanding of solar geometry is CRITICAL in this balancing act. Bring enough daylight into the building to provide adequate light levels, without the use of electric lighting. Maintain views. Shading devices need to respond to thermal conditions (i.e., overheated and underheated periods in a given climate with a given building design), not only solar geometry. Do not bring in so much that it causes overheating of the building. East and west windows should be avoided if possible. Associate Professor Hyojin Kim, Ph.D. Lecture 7 SOLAR GEOMETRY + SHADING 29 TYPES OF SOLAR SHADING Horizontal vs. vertical: Horizontal shading is most effective for south orientation when sun angles are high, while vertical shading (i.e., fin) is most effective for east or west orientation to block low-angle sun. Solid vs. louvered: Louvered horizontal shading has less snow/wind loads with textured aesthetic design. Internal vs. external: External shading is more effective than internal devices (x4). Associate Professor Hyojin Kim, Ph.D. Lecture 7 SOLAR GEOMETRY + SHADING 30 15  ARCH 309-F24 Lecture 7-Solar Geometry + Shading TYPES OF SOLAR SHADING Movable vs. fixed: Operable shading (e.g., movable awning, rotating fins or louvers, deciduous trees) effectively responds to daily and seasonal variations. Can be highly effective even if only moved 2x/ year. Source: HCL Fig. 9.4d, 9.4g, and 9.5i Associate Professor Hyojin Kim, Ph.D. Lecture 7 SOLAR GEOMETRY + SHADING 31 SOLAR SHADING EXAMPLES Each orientation requires different shading strategy. Langford A Architecture Building, Texas A&M University Associate Professor Hyojin Kim, Ph.D. Lecture 7 SOLAR GEOMETRY + SHADING 32 16  ARCH 309-F24 Lecture 7-Solar Geometry + Shading SOLAR SHADING EXAMPLES Phoenix Central Library, AZ – Adjustable, horizontal louvers on the south façade. – Fixed vertical shading (i.e., sail-fins) on the north façade to block early morning and late evening sun during summer months. Source: https://www.archdaily.com/255208/burton-barr-central-library-will-bruderpartners Associate Professor Hyojin Kim, Ph.D. Lecture 7 SOLAR GEOMETRY + SHADING 33 SOLAR SHADING EXAMPLES Langley Academy, UK Source: https://www.fosterandpartners.com/projects/langley-academy/ Associate Professor Hyojin Kim, Ph.D. Lecture 7 SOLAR GEOMETRY + SHADING 34 17  ARCH 309-F24 Lecture 7-Solar Geometry + Shading SOLAR SHADING EXAMPLES Inland Revenue Center, Michael Hopkins, UK – Integrated light shelf shades space and reflects light into space. – Light-colored ceiling improves reflectance of daylight. – Triple glazing and shading devices. Source: https://www.hopkins.co.uk/projects/5/88/ Associate Professor Hyojin Kim, Ph.D. Lecture 7 SOLAR GEOMETRY + SHADING 35 SOLAR SHADING EXAMPLES Unique shading devices provide dramatic shadow patterns. Source: MEEB Fig. 8.21 to 8.23 Associate Professor Hyojin Kim, Ph.D. Lecture 7 SOLAR GEOMETRY + SHADING 36 18  ARCH 309-F24 Lecture 7-Solar Geometry + Shading SHADING EXAMPLES 37 More examples are: http://www.2030palette.org/shading- devices/ Associate Professor Hyojin Kim, Ph.D. Lecture 7 SOLAR GEOMETRY + SHADING 37 HOMEWORK 5 Associate Professor Hyojin Kim, Ph.D. Lecture 7 SOLAR GEOMETRY + SHADING 38 19  ARCH 309-F24 Lecture 7-Solar Geometry + Shading HOMEWORK 5 Associate Professor Hyojin Kim, Ph.D. Lecture 7 SOLAR GEOMETRY + SHADING 39 SHADING MASKS Shading Calculator in Climate Consultant – Vertical Shadow Angle (= Profile Angle) for an overhang – Horizontal Shadow Angle for a fin Without Shading Calculator With Shading Calculator Associate Professor Hyojin Kim, Ph.D. Lecture 7 SOLAR GEOMETRY + SHADING 40 20  ARCH 309-F24 Lecture 7-Solar Geometry + Shading SHADING MASKS Vertical Shadow Angle (= Profile Angle) is the angle cast by the leading edge of an exterior shading device in a plane normal to the face of the building. Leading Edge Normal to Window Associate Professor Hyojin Kim, Ph.D. Lecture 7 SOLAR GEOMETRY + SHADING 41 SHADING MASKS Determine the Vertical Shadow Angle (VSA) of your horizontal shade to meet the thermal needs of a building. VSA 50° VSA With Shading Calculator Associate Professor Hyojin Kim, Ph.D. Lecture 7 SOLAR GEOMETRY + SHADING 42 21  ARCH 309-F24 Lecture 7-Solar Geometry + Shading SHADING MASKS Determine the dimension (i.e., depth) of your horizontal shade based on the Vertical Shadow Angle. Overhang depth = Window height / tan(VSA) VSA 50° window height VSA With Shading Calculator Associate Professor Hyojin Kim, Ph.D. Lecture 7 SOLAR GEOMETRY + SHADING 43 SHADING MASKS Determine the Horizontal Shadow Angle (HSA) of your side fin to meet the thermal needs of a building. Outer Edge HSA Vertical Edge of the Window HSA Associate Professor Hyojin Kim, Ph.D. Lecture 7 SOLAR GEOMETRY + SHADING 44 22  ARCH 309-F24 Lecture 7-Solar Geometry + Shading SHADING MASKS Determine the Horizontal Shadow Angle (HSA) of your side fin to meet the thermal needs of a building. HSA HSA 45° Circle and triangle Associate Professor Hyojin Kim, Ph.D. Lecture 7 SOLAR GEOMETRY + SHADING 45 SHADING MASKS Determine the Horizontal Shadow Angle (HSA) of your side fin to meet the thermal needs of a building. HSA 45° Circle and triangle HSA Associate Professor Hyojin Kim, Ph.D. Lecture 7 SOLAR GEOMETRY + SHADING 46 23  ARCH 309-F24 Lecture 7-Solar Geometry + Shading SHADING MASKS Determine the dimension (i.e., depth) of your horizontal shade based on the Vertical Shadow Angle. Fin depth = Window width / tan (HSA) 45° HSA HSA 45° Associate Professor Hyojin Kim, Ph.D. Lecture 7 SOLAR GEOMETRY + SHADING 47 SHADING MASKS You can display shading obstructions (e.g., trees or neighboring buildings). Fin depth = Window width / tan (HSA) 45° 45° HSA HSA 45° Medium-Height Tree Associate Professor Hyojin Kim, Ph.D. Lecture 7 SOLAR GEOMETRY + SHADING 48 24  ARCH 309-F24 Lecture 7-Solar Geometry + Shading SHADING MASKS Make sure your proposed shading strategy will work in both seasons (i.e., Summer/Fall and Winter/Spring). Summer and Fall Winter and Spring Associate Professor Hyojin Kim, Ph.D. Lecture 7 SOLAR GEOMETRY + SHADING 49 SHADING MASKS Sunpath diagrams are useful for visualizing shading effects when combined with shading mask protractor. Associate Professor Hyojin Kim, Ph.D. Lecture 7 SOLAR GEOMETRY + SHADING 50 25  ARCH 309-F24 Lecture 7-Solar Geometry + Shading SHADING MASKS Determine the overhang dimension based on the profile angle normal with the bottom of the window. Associate Professor Hyojin Kim, Ph.D. Lecture 7 SOLAR GEOMETRY + SHADING 51 SHADING MASKS UN Habitat’s Sun Shading Catalogue: https://unhabitat.org/sun-shading-catalogue-adequate- shading-sizing-overhangs-and-fins Associate Professor Hyojin Kim, Ph.D. Lecture 7 SOLAR GEOMETRY + SHADING 52 26  ARCH 309-F24 Lecture 7-Solar Geometry + Shading HEAT GAIN THROUGH WINDOWS 𝑄ሶ = 𝑈 × 𝐴 × ∆𝑇 Where, 𝑄ሶ = sensible heat gain (Btu/hr) 𝑈 = 1/ σ 𝑅 (Btu/h·ft2·F) 𝐴 = window area (ft2) ∆𝑇 = indoor-outdoor temperature difference (F) Window U-factors available from Tables E.13 to E.15 Valid if there’s no solar radiation! Associate Professor Hyojin Kim, Ph.D. Lecture 7 SOLAR GEOMETRY + SHADING 53 HEAT GAIN THROUGH WINDOWS 𝑄ሶ = 𝑈𝐴∆𝑇 + 𝜏𝐼𝐴 + ℎ𝑖 𝐴∆𝑇𝑠𝑜𝑙 = 𝑈𝐴∆𝑇 + 𝐴 × 𝑆𝐻𝐺𝐹 × 𝑆𝐶 Where, 𝑄ሶ = sensible heat gain (Btu/hr) 𝜏 = transmissivity 𝐼 = solar irradiance (Btu/h·ft²) ℎ𝑖 = heat transfer coefficient (Btu/h·ft²·F) ∆𝑇𝑠𝑜𝑙 = temp. rise of the glass from absorption of solar radiation SHGF = Solar Heat Gain Factor (Btu/h·ft²) SC = Shading Coefficient (= SHGC/0.87) Associate Professor Hyojin Kim, Ph.D. Lecture 7 SOLAR GEOMETRY + SHADING 54 27  ARCH 309-F24 Lecture 7-Solar Geometry + Shading HEAT GAIN THROUGH WINDOWS SHGF (Solar Heat Gain Factor, Btu/h·ft²) represent the solar radiation gain through one layer of double-strength (1/8-in.- (3-mm)-thick) single clear glass. SC (Shading Coefficient) is the ratio of the total solar heat admittance of a given glazing product relative to SHGF at normal solar incidence. SHGC (Solar Heat Gain Coefficient) is the ratio of the total solar heat admittance of a given window product relative to the solar heat incident on the projected window surface at normal solar incidence. – SC x 0.87 = SHGC – SHGC can range from 0 to 1, with 1 representing no resistance and 0 representing total resistance. – Real products range from 0.2 to 0.9. Associate Professor Hyojin Kim, Ph.D. Lecture 7 SOLAR GEOMETRY + SHADING 55 MEEB TABLES C.1 TO C.10 Associate Professor Hyojin Kim, Ph.D. Lecture 7 SOLAR GEOMETRY + SHADING 56 28  ARCH 309-F24 Lecture 7-Solar Geometry + Shading QUESTIONS? All materials in this course are intended solely for the use of students currently enrolled in this course and solely for purposes related to this course. Students are strictly prohibited from sharing any of the course materials with third parties. These materials may be protected by copyright law, and any additional use beyond the scope of this course Professor Hyojin Kim, Ph.D. may constitute a violation of federalCUA copyright ARPL law. 736, Lecture 4 INTERNAL LOADS 57 29