The visible transmittance (VT) is an optical property that indicates the amount of visible light transmitted..
The NFRC's VT is a whole window rating and includes the impact of the frame which does not transmit any visible light. While VT theoretically varies between 0 and 1, most values among double- and triple-pane windows are between 0.30 and 0.70. The higher the VT, the more light is transmitted. A high VT is desirable to maximize daylight.
Select windows with a higher VT to maximize daylight and view.