1. What is Solar Heat Gain Coefficient?

The Solar Heat Gain Coefficient (SHGC) is the fraction of incident solar radiation admitted through a window, both directly transmitted and absorbed and subsequently released inward. It measures how well a window blocks heat from sunlight.

2. How Does the Calculator Work?

The calculator uses the SHGC formula:

Where:

• \( Direct\ Trans \) — Fraction of solar radiation directly transmitted
• \( Absorbed \) — Fraction of solar radiation absorbed and released inward
• \( Total \) — Total incident solar radiation

Explanation: SHGC values range from 0 to 1, with lower values indicating better shading performance.

3. Importance of SHGC Calculation

Details: SHGC is crucial for energy efficiency calculations, building design, and selecting appropriate window treatments for climate control.

4. Using the Calculator

Tips: Enter all values as fractions between 0 and 1. The total must be greater than 0 for valid calculation.

5. Frequently Asked Questions (FAQ)

Q1: What is a good SHGC value?
A: It depends on climate. In hot climates, lower SHGC (0.3 or less) is better. In cold climates, higher SHGC (0.5-0.7) helps with passive solar heating.

Q2: How does SHGC differ from U-factor?
A: U-factor measures non-solar heat flow, while SHGC measures solar heat gain. Both are important for window performance.

Q3: Can SHGC be greater than 1?
A: Normally no, as it represents a fraction of incident radiation. Values >1 would indicate measurement error.

Q4: How is SHGC measured?
A: In laboratory conditions using spectrophotometric measurements and computer modeling.

Q5: Does SHGC account for different angles of sunlight?
A: Standard SHGC values are for normal incidence. Performance varies with sun angle.