Orangeries have their roots in the big houses of the 18th and 19th centuries and were used for – growing oranges (or at least citrus fruit). In the modern world they tend to have a heavier structure than a conservatory. You will often see that the lower parts of their walls are made of solid materials. The roofs are often flatter and tend to have roof lantern to let in the light. Orangeries may be heavier to construct and are often easier to warm in Winter and to cool in Summer. They can be better at giving you all-year round access to your new extension. One way of thinking of them is that they help move part of your living space into the garden. Because of their relatively solid construction you may have to think more carefully about planning regulations.