LIGHT 2 May 2009, Yeoh OonSoon Architect/Lecturer Sun-Path Diagrams Refer Szokolay pp 116, 117 & 119, 120

Tracking the Sun - Measurement of Time & Time Zones Mankind has divided the time it takes to complete one revolution of earth into 24 hours. The Earth is virtually divided through the North-South axis into longitudes spread over 360deg. Thus for each 15 deg longitude the earth revolves, the time this takes is measured as 1 hour. World time is organized generally into 1 hour time zones with Greenwich, London, United Kingdom as the reference point. The longitude passing through Greenwich (0deg 0min) is noted as 0 hour and time zones are referred to as (Greenwich Meridian Time) “GMT + hours” if to the East and “GMT – hours” if to the west. This Time is based on the geographical location but is subject to adjustment by countries for their administrative convenience. Peninsular Malaysia was originally GMT + 7 hours, but the Malaysian government has moved the Federal Time forward 1 hour (called “daylight saving” in temperate countries) to synchronize with Sabah & Sarawak. Thus Malaysia is now administratively in Time Zone GMT +8 hrs instead of GMT +7hrs. The implication is that the sun’s location in the sky is calculated based on solar time, thus adjustments should be made for local time zone changes or daylight saving. Penang Island is at latitude 5deg 20min North and longitude 100deg 12 min East. (solar time GMT +6.67hrs ) The sun’s location in the sky is tracked by it’s horizontal (azimuth) angle and it’s vertical (altitude) angle. The two angles specify the sun’s position in the sky in geographical coordinates i.e. North is taken as 0 deg, and horizontal is 0 deg. The sun’s location in the sky can be calculated or determined using sun-path diagrams.

altitude = (, azimuth = "

SZOKOLAY, S.V. (1980). “Environmental Science Handbook for Architects and Builders”, The Construction Press, UK By calculation; sin ( = sin D x sin L + cos D x cos L x cos H cos " = cos L x sin D - cos D x sin L x cos H cos ( where, L = geographical latitude (south negative) H= hour angle (15deg for each hour from noon; am = negative) D= declination (0-23.5deg) D = 23.45 sin ( 360 x 284 + n ) ( 365 ) = 23.45 sin {0.986 (284 + n) } where,

n = number of day in year from January 1.

Pp 116, SZOKOLAY, S.V. (1980). “Environmental Science Handbook for Architects and Builders”, The Construction Press, UK

Methods to determine(predict) sunlight penetration (insolation).

1. Calculation using trigonometric equations 2. Sunpath diagrams. Mainly graphical.

2.1 Stereographic sunpath diagrams and associated shadow angle protractor; manual or computerized.

2.2 Orthographic projection 2.3 Equidistant projection – used exclusively in United States 2.4 Gnomonic projection – derived from sun-dials 2.5 Waldram projection

3. Physical or Computer modeling & prediction can also be done, 3.1 sun-dials 3.2 heliodon 3.3 solarscopes

Method 2.1 Stereographic sunpath diagrams and associated shadow angle protractor; manual or computerized; is the favoured technique here and in other commonwealth countries. Other Sun-path diagrams are less common, further reference SZOKOLAY, S.V. (1980). “Environmental Science Handbook for Architects and Builders”, The Construction Press, UK; pp139-141, pp311-313, To determine insolation, we need to know the sun’s position in relation to the building face/façade. The orientation of the building face is the horizontal angle of a perpendicular line/plane projecting from the façade.

HSA = * = 20 deg; VSA = , = 35 deg.

SZOKOLAY, S.V. (1980). “Environmental Science Handbook for Architects and Builders”, The Construction Press, UK The horizontal shadow angle (HSA)(*) or azimuth difference is; * = " - w where w = orientation of building face/façade The vertical shadow angle (VSA)(,) is the projection of the solar altitude angle onto a plane perpendicular to the building face/façade. Thus, when the sun is directly opposite the façade, i.e. w = ", then sun altitude angle = vertical shadow angle i.e. ( = , The sun altitude is (. 1. Calculation using trigonometric equations

tan , = tan ( x sec * = tan ( cos *

Stereographic sunpath diagrams and shadow angle protractor. Manual or Computerized. Mainly graphical

Stereographic sun-path diagram for someplace United Kingdom. SZOKOLAY, S.V. (1980). “Environmental Science Handbook for Architects and Builders”, The Construction Press, UK The shadow angle protractor gives the azimuth difference or HSA (horizontal shadow angle), * and the VSA (vertical shadow angle), , for a given building face/façade orientation. This is a manual graphical method where the shadow angle protractor is placed over the appropriate sun-path diagram at the building façade orientation over the desired time point. The HSA and VSA are then read off the protractor. (pp317, SZOKOLAY, S.V. (1980). “Environmental Science Handbook for Architects and Builders”, The Construction Press, UK)

A useful free Sun Position Calculator program (SUNTOOL) by MARSH, A.J. can be downloaded from the Website “www.squ1.com” (Aug 2006) Stereographic sunpath for Penang Island.

5 Sept.2006; Solar time = 15:42, GMT+7=16:00 Local Time = 17:00 (daylight saving) Azimuth = -85.0deg., Altitude = 34.7deg.

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Location: 5.3, 100.2 Azimuth: -85.0° Altitude: 34.7° HSA: 5.0 V SA: 34.8

Time: 16:00 Date: 5th September

Stereographic sunpath. Sun Position Calculator program by MARSH, A.J.

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Orthographic Sunpath for Penang Island Sun Position Calculator program by MARSH, A.J.

Latitude: 5.3° Date: 5th SeptemberLongitude: 100.2° Julian Date: 248Local Correction: -17.9 mins Equation of Time: 1.3 minsLocal Sunrise: 06:15 Declination: 7.1°Local Sunset: 18:20 Orientation: 270.0°

Local (Solar) Aziumuth Altitude HSA V SA 06:30 (06:12) 83.2° 3.7° 173.2° 176.3°07:00 (06:42) 83.8° 11.1° 173.8° 168.9°07:30 (07:12) 84.3° 18.5° 174.3° 161.4°08:00 (07:42) 84.7° 25.9° 174.7° 154.0°08:30 (08:12) 85.0° 33.4° 175.0° 146.5°09:00 (08:42) 85.2° 40.8° 175.2° 139.1°09:30 (09:12) 85.3° 48.3° 175.3° 131.7°10:00 (09:42) 85.2° 55.7° 175.2° 124.2°10:30 (10:12) 84.8° 63.1° 174.8° 116.8°11:00 (10:42) 83.7° 70.6° 173.7° 109.3°11:30 (11:12) 80.8° 78.0° 170.8° 101.9°12:00 (11:42) 67.8° 85.2° 157.8° 94.4°12:30 (12:12) -59.0° 86.5° 31.0° 87.0°13:00 (12:42) -79.7° 79.4° 10.3° 79.5°13:30 (13:12) -83.3° 72.0° 6.7° 72.1°14:00 (13:42) -84.6° 64.6° 5.4° 64.7°14:30 (14:12) -85.1° 57.1° 4.9° 57.2°15:00 (14:42) -85.3° 49.7° 4.7° 49.8°15:30 (15:12) -85.2° 42.2° 4.8° 42.3°16:00 (15:42) -85.0° 34.8° 5.0° 34.9°16:30 (16:12) -84.7° 27.4° 5.3° 27.5°17:00 (16:42) -84.4° 19.9° 5.6° 20.0°17:30 (17:12) -83.9° 12.5° 6.1° 12.6°18:00 (17:42) -83.3° 5.1° 6.7° 5.1°

Sunpath Table for Penang Island Sun Position Calculator program by MARSH, A.J.

Drag nodes or double-click to edit dimensions.

Date: 5th SeptemberLocation: 5.3, 100.2

Penetration: 3019 mmEaves Depth: 0 mmEaves Height: 2200 mmWall Width: 150 mmSill Height: 900 mm

V SA: 34.8HSA: 5.0Sun Pos: -85.0, 34.7Time: 16:00

Wall is a North-South Vertical Plane i.e orientation of Building Face is 270 deg. Sun Penetration Window Section on Penang Island Sun Position Calculator program by MARSH, A.J.

Drag nodes or double-click to edit dimensions.

Date: 5th SeptemberLocation: 5.3, 100.2

Penetration: 7925759488 mmEaves Depth: 0 mmEaves Height: 2150 mmWall Width: 150 mmSill Height: 900 mm

V SA: 0.0HSA: -82.9Sun Pos: -82.9, 0.0Time: 18:20

SUNSET Note that sunrays are always parallel and never fall below horizontal, i.e.they never shine directly at the ceiling no matter how high or tall the building.

Sun Shading Devices. SZOKOLAY, S.V. (1980). “Environmental Science Handbook for Architects and Builders”, The Construction Press, UK

Sun Shading Devices. SZOKOLAY, S.V. (1980). “Environmental Science Handbook for Architects and Builders”, The Construction Press, UK A shading mask demarcates the time when the location is shaded. When the shading mask is placed over the sun-path diagram, at all times within the mask, the point considered will be in shade. Another more sophisticated commercial software for sun shading by MARSH, A.J. called Solar Tool is available at www.squ1.com Note sun shading considerations in calculation; GBI ver.1 2009 -NRNC EE1 Minimum EE Performance • Meet the following minimum EE requirements as stipulated in MS 1525:2007:

OTTV ≤ 50, RTTV ≤ 25. Submit calculations using the BEIT software or other GBI approved software(s)

Physical modeling & prediction

SZOKOLAY, S.V. (1980). “Environmental Science Handbook for Architects and Builders”, The Construction Press, UK Computer modeling & prediction Insolation (sun penetration) modeling of digital 3D building using MicroStation (Bentley) CAD program

Aerial View from North-East.

Bay Window Insolation prediction of corner bay window facing East and North with near full height windows.

East Façade 21 Dec 9:00am No Shades East Façade 21 Dec 9:00am With Shades

East Façade 21 Dec 10:00am No Shades East Façade 21 Dec 10:00am With Shades

East Façade 22 Jun 9:00am Part Shade East Façade 22 Jun 10:00am With Shades

Site Over-Shadowing In many temperate countries, eg the U.K., there exists statutes/laws and guidelines to protect the publics’ right to light. This means that spaces in a building must not be shaded entirely from the sun (called over-shadowing) by another building throughout much of the year. Site over-shadowing is not a problem in this country, in fact in some cases, it may be desirable.

INDUSTRIAL/COMMERCIAL APPLICATIONS • Sun shading devices eg. louvers, fins, canopies, etc. Example Sun Shading installations at the following buildings in Penang, PISA - Sq Ara, eGATE - East Coast Expressway, UMNO Building - Jalan Macalister.

http://www.hunterdouglas.com.my/ http://www.luxalon.com.my/

http://www.luxalon.com.my/product.aspx - Horizontal Sun Louvers

http://www.luxalon.com.my/product.aspx - Vertical Sun Louvers http://www.luxalon.com.my/product.aspx - Product Installation Information A variety of carrier systems are available allowing the optimal solution for their application. � The fixed SL-2 and SL-4 stringers � The self supporting extruded carrier system SLR-10/40/60/60V/100 with adjustable panel brackets � The stringer can also be mounted on the SLR carrier rail Stringers

Carrier rails

SLR 10 SLR 40 SLR

60 SLR 60V SLR 100 End

cap Bracket

Horizontal bracket 84R

Spacers

48 mm

63 mm

88 mm Different modulations (pitch)

Spacer 48 mm, X= 74 mm, a= 67° Spacer 63 mm, X= 89 mm, a= 57° Spacer 88 mm, X= 114 mm, a= 45°

DAYLIGHT Daylighting analysis examines the flow of light into buildings and the development of

prediction techniques; i.e. to predict the daylight achievable indoors given a configuration of openings. It depends on whether the sky is clear or overcast as this will determine the quantity of source light.

GBI ver.1 2009 -NRNC EQ8 Daylighting Provide good levels of daylighting for building occupants: • Demonstrate that ≥ 30% of the NLA has a daylight factor in the range of 1.0 – 3.5% as

measured at the working plane, 800mm from floor level, OR • Demonstrate that ≥ 50% of the NLA has a daylight factor in the range of 1.0 – 3.5% as

measured at the working plane, 800mm from floor level

Another different approach is to establish standard sky models i.e. representative skies for clear

and overcast conditions. This is approach taken by the Commission Internationale de l’Eclairage (CIE).

CIE skies are theoretical representation of standard clear and overcast skies and predict sky luminance rather than exterior illuminance falling on a horizontal or vertical surface. (CIE 1970).

Daylighting system includes everything needed to make daylighting function as an environmental system in the building – daylight apertures, glazing media, shading and sun control and electric lighting controls. Daylighting concepts can be grouped into 7 categories;

1. Sidelighting / Vertical 2. Roof and top (horz) lighting 3. Angled lighting 4. Beam Lighting 5. Indirect lighting 6. Atria, light courts, and reentrant lighting 7. Combinations of above.

Sidelighting or Vertical windows are the most commonly used type of daylighting system. Many rooms have windows only on one side, however light levels fall off quite quickly as you move deeper into the space. As a general rule of thumb, useful daylighting will only reach a distance of 2.5 times the height of the top of the window above the work plane (usually taken at a desk height of 600mm). In a standard office building with a window height of 2.5m, this means a maximum of about 5-7metres.

Square One , www.squ1.com

Vertical or Sidelighting / Window ROBBINS, Claude L. (1986). “Daylighting : Design & Analysis”, Van Nostrand Reinhold Company, New York.

Clerestory Light on right wall

Sawtooth

Horizontal Rooflight

Atrium Light Predicting the quantity of natural light that can be achieved indoors. Daylight can be handled quantitively in 2 ways;

1. by using luminous quantities ( flux, illuminance) i.e. by assuming a set of outdoor values and calculating th resulting interior illuminances.

2. by using relative values (daylight factor) . Technique No.2 is the more commonly accepted method; although I am of the opinion that it is of not much significance in our part of the tropics where clear skies are common and sunlight plentiful. The Daylight Factor (DF) is defined as the ratio of illuminance due to daylight at a point indoors on the work plane to the simultaneous outdoor illuminance on a horizontal plane obtained from an unobstructed hemisphere of overcast sky. DF is usually expressed as a percentage. DF = Ei x 100% Eo

SZOKOLAY, S.V. (1980). “Environmental Science Handbook for Architects and Builders”, The Construction Press, UK Exterior illuminance prediction model – where exterior illuminance striking a surface set at any

orientation over a given time frame (hourly) can be determined, based on measured or calculated weather or climatic data that are used to estimate the local atmospheric conditions affecting daylight availability. Model can be applied anywhere in the world simply by introducing the local weather or climatic data. Examples;

1. Dogniaux Prediction Model 2. Gillette Prediction Model 3. Robbins-Hunter Prediction Model

Sky illuminance Models - considerable difference of opinion worldwide as to the best method of defining it.

Some techniques are locale (locality) specific. Calculate the proportion of clear and overcast sky

– may use some form of percent sun. Szokolay identifies 7 methods of daylight prediction (to predict natural light achievable indoors);

1. the total flux method 2. the split flux method : protractors 3. simplified daylight Sky Component tables 4. daylight graphs 5. Waldram diagram 6. pepper-pot diagram 7. model studies

Method 2 : the split flux method Of the above, probably the most commonly used is Method 2 : the split flux method developed by the British Research Establishment (BRE previously known as BRS-Building Research Station). Model studies now can be by means of physical or digital models. The split flux method : protractors The flux is split 3 ways;

1. the sky component (SC) 2. the reflected light from external surfaces (ERC) 3. reflected light from internal surfaces of the room (IRC)

DF = SC + ERC + IRC

“New Metric Handbook”, ed. TUTT, Patricia & ADLER, D., The Architectural Press, London

1979

Square One , //www.squ1.com/archive BURBERRY, Peter. (1979). “Mitchell’s Building Series: Environment & Services”, B.T.Batsford, London.

Square One , //www.squ1.com/archive