Solar Heat Gain Coefficient and Visible Light Transmission
Access to know-how
SHGC Overview
SOLAR HEAT GAIN COEFFICIENT

WHAT YOU NEED TO KNOW

  • How well the door prevents or allows heat from the sun passing through to the interior of the building
  • Selectable depending on whether you want the heat from the sun in to warm a space or block it to keep it cool
  • Warmer climates want a low SHGC (.06-.31) because they want to keep their buildings cool
  • Colder climates want this number to be higher (.45-.57) because they benefit from the free solar heat
  • Dependent on climate zone, shading and orientation

REFERENCE NUMBERS

SHGC Guide
SOLAR HEAT GAIN COEFFICIENT

1: 0.06 – 0.18 Recommend: Bi-part 168” x 92” or Single Slide 96” x 92”, no transom, 1” glass, 10” bottom rail, 2” muntin, narrow stiles. Center of glass SHGC before door frame 0.05-0.025

2: 0.21 – 0.31 Recommend: Bi-part 168” x 92” or Single Slide 96” x 92” no transom, 1” glass, 10” bottom rail, 2” muntin, narrow stiles. Center of glass SHGC before door frame 0.30-0.45

3: 0.45 – 0.57 Recommend: Bi-part 192” x 92” or Single Slide 108” x 92” with transom, 1” glass, 4” bottom rails, no muntins, narrow stiles. Center of glass SHGC w/o door frame 0.60-0.75

VT Overview
VISIBLE LIGHT TRANSMISSION

WHAT YOU NEED TO KNOW

  • How well the glass allows sunlight to pass through it
  • VLT is important for determining daylighting (the illumination of indoor space by natural light).
  • VLT can improve occupant wellbeing and productivity while lowering artificial lighting costs
  • Tied to SHGC
  • Dependent on unit size, glass-to-frame ratio and transmittance of the glass

REFERENCE NUMBERS

  • Prevents = lower VT and SHGC
  • Allows = higher VT and SHGC
  • Based on IECC C402.4.3 / ASHARE 90.1 / NFRC 200: 0.3 - 0.6
  • Dura-Glide GreenStar: 0.04 - 0.56
Visible Light Transmission
VISIBLE LIGHT TRANSMISSION

WHAT YOU NEED TO KNOW

  • How well the glass allows sunlight to pass through it
  • VLT is important for determining daylighting (the illumination of indoor space by natural light).
  • VLT can improve occupant wellbeing and productivity while lowering artificial lighting costs
  • Tied to SHGC
  • Dependent on unit size, glass-to-frame ratio and transmittance of the glass

REFERENCE NUMBERS

  • Prevents = lower VT and SHGC
  • Allows = higher VT and SHGC
  • Based on IECC C402.4.3 / ASHARE 90.1 / NFRC 200: 0.3 - 0.6
  • Dura-Glide GreenStar: 0.04 - 0.56
NFRC Ratings
NFRC RATINGS AND AUTOMATIC DOORS

All simulations are performed by an NFRC Accredited Lab