Glass for Europe has launched a new communications series examining how the solar factor (g-value) is incorporated into national building regulations, highlighting the growing importance of solar control glazing in improving thermal comfort and reducing cooling demand as Europe faces more frequent and intense heatwaves.

The initiative follows the publication of the organisation’s technical paper, The Role of Solar Control Glazing in Passive Cooling of Buildings, and provides a comparative overview of regulatory approaches in England, Germany, Greece, Italy, Portugal, Romania, Spain and Turkey. The series analyses how each country integrates the solar factor into building codes, revealing significant differences in methodology.

While some regulations establish maximum allowable g-values depending on climate zone, façade orientation or building type, others adopt performance-based assessments that require designers to demonstrate compliance through overheating risk analysis and building energy simulations. The campaign illustrates how glazing selection has become an essential design parameter alongside insulation in modern building envelopes.

The g-value measures the proportion of total solar energy transmitted through glazing into a building. Higher g-values allow greater passive solar heat gains, which can be advantageous during colder periods, whereas lower g-values reduce unwanted solar heat ingress, helping prevent overheating during summer months. Selecting glazing with an appropriate solar factor can significantly improve indoor thermal comfort, reduce reliance on air conditioning, lower energy consumption and support the development of climate-resilient buildings.