We were called out to this property in Windsor because the homeowner believed their windows were causing drafts in the home and were responsible for the higher than usual energy bills. All modern UPVC frames are designed to expand in the cooler and hotter months, but over time these changes in the outside temperatures can cause the seals to become loose. Weather damage is also another common cause of broken or damaged UPVC window seals. 
We established the cause of the problem and replaced the double-glazed sealed unit quickly. We also needed to renew the UPVC window mechanisms, completely ensuring the drafts from the upstairs windows were eradicated.