hi, doing an extension and some of the windows can be potentially re-used. How easy will it be to remove and re-install?. in terms of sizing the extension is not ready yet so in theory we can make the new windows similar in size to existing ones to fit the old uPVC. At least some of them. \n\nAlso is there a recommended size for bifold doors. I have it down as 5m wide but little bit worried about too hot in summer too cold in winter and also door stability. 5m is quite wide. Costs too! Thank you.