Ventilation efficiency may be defined as the capability of a given ventilation system to achieve the best balance between indoor air quality and energy conservation requirements:

The paper reviews some problems of theory and practice of energy conservation in buildings. The necessity for a policy of energy

This paper details a set of guidelines for the design of thermally efficient houses in the generally temperate climate of Greece, using the common construction materials of Greek contemporary housing and employing simple passive design techniques. The guidelines should be of use to the designers of climate sensitive housing in Greece. The relationship between heat capacity· levels of thermal insulation and size of openings are considered in detail. The Building Bioclimatic Chart devised by Givoni and the Energy Simulation Computer program ESP are the mai tools of the study.