Wood naturally has excellent thermal efficiency and aluminium is also far better insulated today than many people think. In order to be considered suitable for passive houses, a U-value of 0.8 W/m²K or lower for windows and doors is recommended. The window profiles of our ECO series achieve Uw-values of up to 0.72 W/m²K – thanks to additional insulating foam between the wood and aluminium shell and triple thermal insulation glazing.