Difference Between Aluminium Windows and uPVC Windows Material: Aluminium windows are made from metal, while uPVC windows are made from unplasticized polyvinyl chloride, a type of plastic. Durability: Aluminium is generally more durable and resistant to warping and corrosion than uPVC. Energy Efficiency: uPVC windows typically offer better insulation properties, making them more energy-efficient. Maintenance: uPVC requires less maintenance (no painting or sealing), whereas aluminium may need periodic treatment to prevent corrosion. Aesthetic Options: Aluminium windows can have a sleeker profile and offer a wider range of finishes, while uPVC comes in various colors but with a bulkier frame.