ARCH 215 : Lecture 10

Define Solar Constant vs. Surface Solar Radiation

Solar Constant: The amount of solar radiation / power that lands on the outer edge of the Earth atmosphere

Surface Solar Radiation: The amount of energy that is actually reaching the Earths surface.

Thermal Radiation Ruling Principal

The determinant of how much how much energy is transferred is wrens displacement law.

Solar Radiation varies because of what 5 characteristics

1. Geographic Location

2. Time of the Day

3. Season

4. Local Landscape

5. Local Weather (clouds)

Irradiance Definition vs. Irradiation Definition

Irradiance: The intensity W/m² or kW/m²

Irradiation: The sum over a period of time kWh/m²

The 3 Kinds of Light on the Solar Radiation Spectrum

1) UV. 3 tiers: A. Healthy, B. Fine/Tanning, C. Cancer fs

2) Visible. The daylight spectrum

3) Infrared

Illuminance vs. Irradiance

Illuminance: The amount of luminous flux per unit area. How much visible light is measure per unit area.

Irradiance: The flux of radiant energy per unit area (directional flow through a medium). How solar energy is measured. How much incident light illuminates the surface. Human brightness perception

How many Lumens in 1m² of window

100,000 Lumens. 1m² of window is 13m² of electric light.

What percentage of energy do buildings consume? How is the division between residential and commercial

39%. (42% of that is residential, 57% is commercial)

List 4 people based goals in regards to Solar Radiation

1. Avoid Visual Discomfort

2. Block direct view of Solar Disc

3. Avoid Sharp contrasts in the laminae

4. Avoid the sensation of Direct sun

Direct vs. Diffused vs. Global Solar Radiation

Direct: Solar radiation that passes directly passes through the earths surface.

Diffused: It has been scattered out of the direct beam (this is why the sky is blue - the blue radiation beams scatter when they hit the atmosphere)

Global: Its both - haha bet you didn’t see that coming

What is the Sky Component

Indirect radiation / light

What are the 3 outcomes when radiant energy hits glass

1. Reflected

2. Absorbed

3. Transmitted

What is a SHGC? What is the CA Residential Max?

SHGC: Solar Heat Gain Coefficient. The amount of transmitted radiation through the glass, the higher the more that is transmitted.

CA Residential Max: 0.23

What is a VT rating for glass?

The Visible Light Transmittance

What is Spectrally Selective Glass and how does it manifest in a hot climate versus a cool one?

Spectrally Selective glass tries to strategically balance the SHGC and the VT

Hot Climate - Low SHGC and high VT

Cool - High SHGC and High VT

What is WWR? What is the California maximums percentage range?

WWR - Window Wall Ration. The percentage of glazing / fenestration facing a certain face.

California has a maximum of 5-20%

What is the Angle of Incidence

Indicates weather the surface is in the sun or not. The “normal” is the peak.

What is the Cosine Effect?

Because not all points can be perpendicular to the suns rays, the less perpendicular to the rays the more the ray is dispersed and therefore the strength is decreased.

Explain the difference between exterior screen, massing, dynamic facade, and surface shading as passive cooling strategies.

you got this!