Knowing how the EU works, it's therefore no surprise to learn that they have forced the British government to increase the 5% VAT rate on energy efficiency products to 20%.
VAT is an EU-mandated tax with the EU setting the rates and taking a cut of the proceeds. The money the EU raises from VAT doesn't go into its budget to cut the cost to the taxpayer, it goes into it's propaganda slush fund called "EU own resources". So you can imagine how keen they are to abolish any exemptions or discounts such as on children's clothes, books, fresh food and - of course - all these energy efficiency products they've forced builders to use.
So, having created a market for energy efficiency products with new laws and big fines for missing targets the EU is now quadrupling the tax on those products with the proceeds going straight into their slush fund.