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. SHGC is expressed as a number between 0 and 1.

2. How Does the Calculator Work?

The calculator uses the SHGC formula:

Where:

• Transmitted Solar — Solar radiation passing through the window (W/m²)
• Incident Solar — Total solar radiation hitting the window (W/m²)

Explanation: The SHGC measures how well a window blocks heat from sunlight. The lower the SHGC, the less solar heat it transmits.

3. Importance of SHGC Calculation

Details: SHGC is crucial for energy-efficient building design, helping to determine how much heat gain will occur through windows, which affects cooling loads and energy consumption.

4. Using the Calculator

Tips: Enter both transmitted and incident solar values in W/m². Both values must be positive numbers.

5. Frequently Asked Questions (FAQ)

Q1: What is a good SHGC value?
A: It depends on climate. In hot climates, lower SHGC (0.25-0.40) is better to reduce cooling loads. In cold climates, higher SHGC (0.50-0.60) 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: No, SHGC is always between 0 and 1. A value of 1 would mean all solar radiation is transmitted.

Q4: How is SHGC measured in real windows?
A: It's typically measured in laboratories using specialized equipment that simulates solar radiation.

Q5: Does SHGC account for different angles of sunlight?
A: Standard SHGC values are for normal incidence. Performance varies at different angles, which is considered in more detailed analyses.