In general, there are three different types of conservatories and greenhouses which are mutually separated by temperature in winter.
Cold conservatory has winter temperature around 5 degrees Celsius. It is not heated except in exceptional cases when outside temperatures are very low. It is primarily intended for overwintering plants that can not tolerate freezing temperatures, such as citrus and other plants of the Mediterranean.
Moderate conservatory has winter temperature between 12 and 17 degrees Celsius. It is intended for overwintering plants that need a slightly lower winter temperatures and for overwintering Mediterranean plants and some tropical plants. It is useful for plants, that can not stay outside over winter. It is necessary to install heating system that will be running on very cold winter days and nights. Moderate conservatory gets warm in the spring very quickly and can be used for activities such as meals, relaxation, reading etc.
Warm conservatory has always temperatures between 18 and 24 degrees Celsius. It is used mainly for tropical plants. We can use it for our activities all year-round. We can put in it dining table, work desk, or couch to relax. In summer it can represent a link between living room and garden. It can be used over whole year, and is usually an extension of a living room.
It is important that the structure has a good thermal insulated glass with sufficiently low thermal conductivity. The heating system must be of sufficient capacity to maintain the desired temperature in cold winters. If conservatory is well insulated, we can save some money for heating in the winter as it retains warmth of winter sun.