We often get asked advice on insulating conservatories both to keep them warm in Winter and cool in Summer. The most obvious answer is to design it into the conservatory in the first place. The roof is only one part of the equation. You to need ensure that building is well constructed and that the doors etc are well insulated. Once that is done the roof is the next thing to look at. About 75% of polycarbonate roofs today are made from 25mm mutiwall sheets. However the use of thicker polycarbonate is rapidly increasing. When you look at the "U ratings" it is easy to see why. The U rating is an indication of the products insulation capabilities and the lower the better. As is demonstrated in the table attached
In summary 35MM polycarbonate is a much better insulator and lighter than both double glazed glass and argon filled double glazed units. It is also considerably cheaper both on the cost of the panels but also in the construction cost of the conservatory itself.
It is available in various colour options and can be supplied cut to size for your conservatory. If you would like to see a sample please email email@example.com
If you want to insulate your roof even further you should consider solar inserts. Whilst there is no published information on their insulation properties they do reflect heat back into the conservatory. They can be supplied pre fitted into your roof or can be retro fitted at a later date. I will be publishing more data about them at a later date.