Yes, a modern conservatory with a UPVC frame offers excellent insulation against cold winter days, meaning that you can use it as a complement to your living space all year round.
Older conservatories had a reputation for being cold and draughty in the winter and getting too hot to use in the summer without the doors adn windows being open, but this no longer needs to be the case.
Modern UPVC framed conservatories offer excellent thermal efficiency without the ability for draughts to get in through any gaps, and with double glazed windows, heat loss is minimal meaning that you can enjoy the view from your conservatory on the coldest days.
Controlling heat during the hot summer months is also possible in a modern conservatory. Your installer will be able to advise about different types of glass that can be more heat reflective and prevent the space from overheating. Good ventilation through a variety of window options in the conservatory also help to manage heat properly on warmer days and make your conservatory an enjoyable place to be during the summer.