My new buy to let house has had most of the old sash windows removed and replaced with uPVC windows. They are far preferable as they are less draughty than wooden ones. They also require no painting, which reduces maintenance costs over the years. These types of windows have been around for nearly thirty years now, and they certainly seem to be the favoured choice in our area for any home owner who decides to make Home improvements. There are hundreds of companies around who offer to install new wndows, but it is a good idea to use only the long established ones, and make sure that you can see other properties where they have installed windows to make sure they do a good job.