During the year 2000, energy-efficient buildings for low-income students at La Pampa University were designed and constructed. Buildings are located at the centre of La Pampa province, in a temperate semi-arid region of central Argentina Socio-economic, educational and environmental reasons have driven the design. Energy conservation devices, passive solar heating, natural ventilation and solar protection were the main strategies. The resulting design comprises two blocks of apartments with a useful floor area of 700 m(2) and main spaces. Two bedrooms, a dining room and essential services make up each apartment. Solar windows are provided for all main spaces. Northern shading devices and metallic pergolas protect all windows in summer. Once the building was finished, a monitoring plan started on December 2000. This paper shows the results of the thermal and energy behavior of apartments. The evolution of internal temperature was different in each apartment. The consumption of natural gas varied among dwellers, but the volume consumed was lower than that of conventional dwellings. Without extra building cost dwellers live under good higrothermal conditions at 50% of the auxiliary energy consumed by conventional dwellings. (c) 2004 Elsevier Ltd. All rights reserved.