In moderate climate-zones there is a need for heating in
the winter period, while in the summer cooling of the buildings is necessary.
For a long time mechanical installations were used to achieve this. But
these use too much energy and moreover, they require hermetically closed
buildings to work well. However it is possible to naturally cool or heat
buildings by using a conservatory or atrium.
 The atrium of Galleria Emanuelle II in Milan |
 The flow of air pulled trough the Galleria's cool basement ventilates the atrium |
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An atrium is an open, central area in the complete height of a building, which is surrounded by residence areas. In many old building cultures the atrium is used as traffic place, as meeting-place and in warmer climates as shaded inner area. When such an atrium is covered with glass the atrium can, when it has enough height, be used as a natural cooling tower. By the so-called chimney effect, in which rising warm air is removed from the area in the roof (possibly after having passed heat exchangers and possibly returned to the building after cooling). Because of the lower pressure that is created by the chimney effect externally supplied air can be led through the residence areas. In theory an atrium can contribute to the heating of a building in the winter, when the air isn't removed. But in practice it appears that the air temperature becomes too high too fast. Moreover in the current highly insulated buildings there is more often a need for cooling than heating - also in the winter months.
A conservatory is comparable to an atrium, but is situated on the façade of a building and has at least one glass wall. Which means that heating by the sun can become a problem faster. But a conservatory can - by a correct construction and usage - be used as a natural heater and cooler in a way comparable with the atrium. When the sun shines in the winter period the area, even if it freezes outside, will be heated to a comfortable temperature. In the summer the conservatory can be used as a natural cooler by the chimney effect in combination with cross ventilation from the cool side of the building.
Conservatories or atriums are often completed with plants
and/or water features.
These respectively take care of an increased oxygen level and filtering
of fine dust particles from the air and an increase of the air humidity.
Which substantially increases the quality of the air in a building. Moreover
those large, central areas form informal meeting areas - comparable to
squares in a city - that can contribute to an improvement of the social
climate in a building.
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