the deffirences of aluminum double hung window and UPVC double hung window. 

UPVC windows are known for their excellent insulation properties and resistance to weathering and corrosion, while aluminum windows are highly durable and offer a sleek, modern look. UPVC frames are generally more energy-efficient and have better thermal insulation compared to aluminum frames. Aluminum windows, however, are often preferred for their strength and slim profile, which allows for larger glass areas and a more contemporary aesthetic.

Both UPVC and aluminum double-hung windows feature two operable sashes that slide vertically, allowing for flexible ventilation. They both can be equipped with energy-efficient glass and offer ease of cleaning with tilting sashes.