Britain has for many decades had a weird kind of affinity with the double glazing salesperson. Ever since the 1980 when the technology first started to make its way out in a generally affordable and accessible sense, homeowners are bombarded with slogans and calls-to-action on a pretty relentless basis. Of course, the benefits of double glazing demand no real explanation as they’re common knowledge to most people these days. However, even so many years down the line there’s still one huge question that plagues those on the lookout for new windows and doors:…