Change the regulation of mandatory trickle vents and go back to the original regulations but with better education for consumers and window companies so people can advise and install them where necessary. But the choice should be the consumers and not mandatory by the government.
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It's completely unfair to half the population of compentent companies + consumers who know how to use a window properly. The consumer should have a choice. If the company surveying the job is Fensa / Certass registered then they should be able to advise properly. Bad landlords + poor housing, resulting in condensation / mould problems are not going to be solved with trickle vents. Why should responsible home owners loose they're right to say yes or no a to trickle vents being installed.