Are conservatories a good idea?

In a word - NO! (but with qualification)

They all overheat in the summer and are too cold in the winter. They cannot be used throughout the year as a dedicated room unless you fill it full of blinds & heating systems (which is not allowed).

Many home owners wanting a quick fix bolt on extension to an existing roof often consider a conservatory. Most are demolished or replaced for a more substantial proper habitable room extension within 15 years so why bother?

If you have already lived with a conservatory you will already either love them or hate them. The ones that seem to work often face north, are of a size that allows for good use of space (larger than 3M x 3M) & have an illegal heating system installed.

Many homeowners open up the conservatory into the existing home which is not allowed under Building Regulations due to the excessive loss of heat & additional CO2 into the air for the extra heating demand.

The newer and more useful form of a conservatory design is the highly glazed extension that still retains about 50% of the walls and roof for up-rating of insulation values as compensation for the extra glazed areas beyond the 25% floor area limit under Building Regulations. Many traditional styles have now re-emerged such as the orangry glazed roof within a flat roof for example. New contemporary fenestration such as long runs of glazed high efficiency bi-fold doors have taken the place of sliding patio door sets.

This is a much better and more sustainable solution to a highly glazed room area rather than a plastic framed bolt on conservatory serving little functional use to the home owner.