A cellar is a storage area for wine in barrels or bottles and is normally built underground. It is a necessity in a quality winery to provide a favorable environment to ensure that the wines stored there remain fresh even after many years of storage. This means that the temperature and humidity in the cellar must be regulated to levels that allow the wines to age slowly and develop complexity.

If a cellar is built on the ground, it could best be described as a wine room and if it contains less than 500 bottles and is on the ground, it could be identified as a wine cabinet. The main objective of building a winery is to protect the wine from environmental factors that will compromise the quality of the wine. Factors such as light, high temperature or low humidity will adversely affect the wine. Wine is a living being that must be protected from fluctuations in temperature, heat and light, as well as vibrations. With proper storage, wine not only maintains its freshness but also improves the quality of its aroma, complexity and flavor.

Therefore, a quality winery must not only maintain the vitality of the wine, but also enhance it. The proper temperature in a basement should be between 13 and 18 degrees C and should be free of vibrations. If temperatures change from season to season, it should vary by less than 10 degrees C. For centuries, the French have stored their wines in underground caves at these temperatures and this is how people measure the temperature level for wine storage. . To ensure that the final product has the qualities of a well-matured wine, temperatures should not exceed 18 degrees C, as the wine will mature too quickly. Wines that ripen too quickly will often taste more like vinegar and will not have the refined, delicious taste of a good wine.

Active or passive describes the cooling system used in the cellar. A warehouse with an active cooling system requires insulation and a vapor barrier installed. Then a special wine cooling unit is installed on the wall to ensure that the temperature and humidity are kept at the correct levels. Many elevated cellars will require a cooling unit to maintain a constant temperature. Geographical areas that are naturally very cool are often suitable for a passively cooled cellar. Most underground basements are passively cooled, and a well-built, well-insulated basement can often be passively cooled. A passive cellar does not require energy to function. Therefore, they are cheaper to build and run, although they are sometimes unreliable in extreme weather conditions.