visible light transmission
Visible Light Transmission (VLT) is a measurement of the amount of visible light waves that transmit through a material. Measured as a percentage, VLT values for vision glazing, like insulated glass units (IGU) that transmits a direct beam of light, typically range between 40-70%. Utilizing the power of diffusion, Kalwall transmits much lower percentages of visible light but produces superior daylight levels by scattering light waves deeper into spaces without glare or hot spots. As a result, common VLT values for Kalwall are between 12-20% although some applications may call for somewhat higher or lower VLT values. The comparison below shows the distinct behavior of visible light transmitted through Kalwall versus an insulated glass unit (IGU) using our daylight modeling software. Want to optimize your daylighting design? Want to compare vision glazing with Kalwall? Submit your design, via your local sales representative, for this complimentary service.
Kalwall = Glare-free Daylighting
Insulated Glass = Glare-filled Daylighting
Performance Data: 2-3/4” (70mm) Panel
| FRP Face Sheet Combinations | Visible Light Transmission (VLT) % | Solar Heat Gain Coefficient @ 0° | |||||||||
| Exterior FRP | Interior FRP | 0.53 U | 0.29 | 0.23 U | 0.22 | 0.14 U | 0.18 | 0.10 U | 0.05 U | 0.53 U | 0.29 | 0.23 U | 0.22 | 0.14 U | 0.18 | 0.10 U | 0.05 U |
| Crystal | White | 35% | 20% | 12% | 8% | 20% | 0.52 | 0.28 | 0.17 | 0.13 | 0.25 |
| White | White | 20% | 15% | 8% | 5% | 14% | 0.38 | 0.23 | 0.15 | 0.11 | 0.18 |
| Crystal | Crystal | 50% | 30% | 15% | 10% | N/A | 0.65 | 0.33 | 0.18 | 0.13 | N/A |
| Aqua | White | 29% | 17% | 6% | 4% | 15% | 0.45 | 0.24 | 0.14 | 0.1 | 0.21 |
| Rose | White | 30% | 18% | 6% | 4% | 16% | 0.46 | 0.24 | 0.15 | 0.1 | 0.21 |
| Ice Blue | White | 35% | 20% | 8% | 6% | 21% | 0.54 | 0.28 | 0.17 | 0.12 | 0.26 |
| Greenish Blue | Crystal | 25% | 14% | 5% | 3% | 14% | 0.5 | 0.23 | 0.14 | 0.1 | 0.19 |
Performance Data: 4” (100mm) Panel
| FRP Face Sheet Combinations | Visible Light Transmission (VLT) % | Solar Heat Gain Coefficient @ 0 | |||||||
| Exterior FRP | Interior FRP | 0.55 U | 0.15 U | 0.08 U | 0.05 U | 0.55 U | 0.15 U | 0.08 U | 0.05 U |
| Crystal | White | 35% | 14% | 7% | N/A | 0.52 | 0.09 | 0.04 | N/A |
| White | White | 20% | 12% | 5% | N/A | 0.38 | 0.06 | 0.04 | N/A |
| Crystal | Crystal | 50% | 17% | 8% | N/A | 0.65 | 0.10 | 0.07 | N/A |
| Air Gap Only | Fiberglass ‘Batts’ | Lumira® Aerogel |
U-value SI conversion: 1.0 W/m²K = 0.176 Btu/hr/ft²/°F
U-values shown in bold denote thermally-broken grid core panels.
Approximate Visible light transmission (VLT) values by ASTM E-972. VLT values over 30% are not recommended for most Kalwall applications.
Panel U-values include panel grid-core by NFRC 100 or 102. NFRC certified system U-values vary depending on framing.
Shading Coefficient (SC) is equal to 1.15 times the Solar Heat Gain Coefficient (SHGC).
