HeKa Herzog GmbH from Oldenburg is increasingly focusing its portfolio on energy-efficient window systems. This step comes against the backdrop of increasing requirements for U-values of building envelopes and the targeted increase in the renovation rate of existing buildings. The mid-sized company does not mention specific technical specifications or frame materials used (wood-aluminum, plastic multi-chamber, passive house certified) in its announcement. The positioning reflects an industry-wide trend: window manufacturers must prepare for GEG-compliant systems with Uw-values significantly below 1.0 W/(m²K).