Solar Geometry and Time Quiz

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Questions and Answers

What factor does NOT affect the difference between Solar Time and Clock Time?

Daylight Savings Time

Location in the time zone

Equation of time

Earth's tilt on its axis (correct)

What does 'E' represent in the solar time formula?

Equation of time (correct)

Time zone offset

Time adjustment due to daylight savings

Longitude of local location

Using the formula, what is the result of Solar Time when the local time is 2:30 PM and E is -14 minutes?

2:56 PM

2:30 PM

2:14 PM

2:04 PM (correct)

Which of the following charts is NOT used to project the sun's path?

Thermal Chart Signup and view all the answers

What is the primary purpose of solar time calculations in architectural design?

To figure out shadow patterns and sunlight exposure Signup and view all the answers

In the formula for solar time, what does the term '4(Lst - Lloc)' specifically account for?

The difference in local and standard time zone Signup and view all the answers

When calculating solar time for a location observing Daylight Savings Time, what adjustment should be made?

Subtract 1 hour Signup and view all the answers

Which of the following best describes the historical significance of sun charts?

They trace back to work by ancient astronomers and mathematicians. Signup and view all the answers

What is the primary function of the light shelf mentioned in the Inland Revenue Center?

To reflect light into the space Signup and view all the answers

Which feature helps improve the reflectance of daylight in the Inland Revenue Center?

Light-colored ceiling Signup and view all the answers

What do shading devices create as per the examples provided?

Dramatic shadow patterns Signup and view all the answers

Which of the following tools is used for determining shading masks?

Climate Consultant Signup and view all the answers

What is the purpose of the Vertical Shadow Angle in the context of shading?

To determine the angle of an overhang Signup and view all the answers

What is indicated by the term 'Horizontal Shadow Angle'?

The angle for a vertical shading fin Signup and view all the answers

How are shading devices beneficial in architecture?

They enhance aesthetic appearance and functionality Signup and view all the answers

Which project is specifically mentioned as having integrated light shelf shades?

Inland Revenue Center Signup and view all the answers

What is the maximum summer sun altitude calculated using latitude?

90° minus latitude plus 23.5° Signup and view all the answers

Which angle is referred to as azimuth in solar geometry?

Horizontal angle measured from the South Signup and view all the answers

What determines the yearly difference between maximum and minimum sun altitudes?

Latitude and Earth’s axis tilt Signup and view all the answers

During the vernal and autumnal equinox, how is the sun's altitude calculated at any latitude?

90° minus latitude Signup and view all the answers

What is the minimum winter sun altitude based on latitude?

90° minus latitude minus 23.5° Signup and view all the answers

What is the total angular difference in sun altitudes throughout the year?

47° Signup and view all the answers

Why is it important to chart the sun's path for a specific site?

To understand solar radiation and shading Signup and view all the answers

Which seasonal event corresponds to a sun altitude of 90° - latitude?

Vernal equinox Signup and view all the answers

What is the Horizontal Shadow Angle (HSA) required for thermal optimization in shading design?

45° Signup and view all the answers

Which formula correctly calculates the fin depth for horizontal shading?

Fin depth = Window width / tan(HSA) Signup and view all the answers

What factors can be considered when displaying shading obstructions?

Shading obstructions such as trees and neighboring buildings Signup and view all the answers

How does the Horizontal Shadow Angle influence the design of a shading mask?

It helps calculate the fin depth to meet thermal needs. Signup and view all the answers

What is the outcome of using a Horizontal Shadow Angle greater than 45°?

Decreased shade and possible thermal loss. Signup and view all the answers

What is the function of the Vertical Shadow Angle in shading design?

To calculate the depth of horizontal shades. Signup and view all the answers

What effect might displaying shading obstructions have on shading calculations?

They improve the accuracy of the shading simulation. Signup and view all the answers

Which angle is utilized to help achieve the necessary shading depth?

Vertical Shadow Angle Signup and view all the answers

What does SHGF stand for in the context of heat gain through windows?

Solar Heat Gain Factor Signup and view all the answers

How is the Shading Coefficient (SC) defined?

The ratio of the total solar heat admittance relative to SHGF Signup and view all the answers

What is the range of the Solar Heat Gain Coefficient (SHGC)?

0 to 1 Signup and view all the answers

If a window has an SC of 0.75, what would be the calculated SHGC using the given formula?

0.82 Signup and view all the answers

What does an SHGC value of 0 represent?

Total resistance to heat gain Signup and view all the answers

Which of the following statements about real products is accurate?

Real products generally range from 0.2 to 0.9 Signup and view all the answers

Which measurement represents the solar heat admittance of a window product relative to incident solar heat?

SHGC Signup and view all the answers

What is the primary purpose of determining SHGF, SC, and SHGC?

To evaluate potential heat gain through windows Signup and view all the answers

Study Notes

Solar Geometry

Earth's axis of rotation is 23.5 degrees, causing seasons
Sun's position is determined by:
- Altitude (vertical angle above the horizon)
- Azimuth (horizontal angle measured from South)
Maximum summer sun altitude is 90 degrees minus latitude plus 23.5 degrees
Minimum winter sun altitude is 90 degrees minus latitude minus 23.5 degrees
Maximum and minimum altitude difference is 47 degrees
Vernal and autumnal equinox sun altitude is 90 degrees minus latitude
Summer and winter solstice sun altitude is ± 23.5 degrees

Solar Time

Solar time differs from clock time due to:
- Daylight Savings Time
- Location within a time zone (longitude)
- Earth's speed in orbit variation (i.e., equation of time)
Solar time is used for charts and tables
Solar time equation:
- Solar time = Local time + E + 4(Lst - Lloc)
- E = equation of time
- Lst = standard time zone longitude
- Lloc = location longitude

Sun Chart

There are different methods for projecting the sun's path on a diagram:
- Cylindrical Chart
- Equidistant Chart
- Orthographic Chart
- Stereographic Chart

Solar Shading

Langley Academy, UK, features a curved roof with integrated shading
Inland Revenue Center, UK, utilizes a light shelf for shading and reflecting light into space
Light-colored ceilings improve daylight reflectance
Unique shading devices can create dramatic shadow patterns

Shading Masks

Climate Consultant provides a shading calculator
Vertical Shadow Angle is used for overhangs
Horizontal Shadow Angle is used for fins
Fin depth = window width / tan(HSA)
Trees and neighboring buildings can be considered as shading obstructions

Heat Gain Through Windows

SHGF (Solar Heat Gain Factor) represents solar radiation gain through single clear glass
SC (Shading Coefficient) is the ratio of solar heat admittance of a glazing product relative to SHGF
SHGC (Solar Heat Gain Coefficient) is the ratio of solar heat admittance of a window product relative to solar heat incident on the projected window surface
SC x 0.87 = SHGC
SHGC ranges from 0 to 1, 1 representing no resistance, and 0 total resistance
Real products range from 0.2 to 0.9
MEEB Tables C.1 to C.10 provide information on SHGF, SC, and SHGC

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Description

Test your knowledge on solar geometry, including the Earth's axial tilt and the factors affecting sun position. Dive into how solar time differs from standard clock time and the implications for navigation. This quiz will challenge your understanding of concepts like altitude, azimuth, and equinoxes.