Pilkington Spectrum is a Windows-based glass performance model which enables you to quickly and efficiently calculate key properties of insulating glass units without the need to construct and measure them. You can use Pilkington Spectrum to provide the following information: - light and solar properties (transmittance, reflectance, absorptance, g value, etc.) in accordance with EN 410, - centre pane U-value in accordance with EN 673 (with an option to display the U-value to two decimal places)