The aim of this research was to investigate the potential of the well-established principles of Passive Solar Design when applied to the specific cultural, economic and climatic contexts of Cyprus. The principal element of the study was the design, construction and monitored inhabitation of an Experimental Solar House at Lefkosia. In order to establish the parameters for this design detailed investigations were made of the following: • The climate of Cyprus • The energy economy of Cyprus • Thermal comfort in Cyprus • Passive solar systems and methods • The history of architecture in Cyprus. The research into thermal comfort concluded that, for Cyprus, an average 19.5°C – 29°C is an acceptable temperature and an average of 20-75% is the acceptable range of relative humidity. The psychometric chart, Olgyays’ bioclimatic chart, Humphreys’ comfort chart and Szokolays’ equation were adapted for Lefkosia. Through monitoring the Experimental Solar House from the 27/11/1999 until 18/12/2001, using computer data loggers. The results show that all heating requirements are satisfied by solar energy, while natural ventilation or ceiling fans meet all the cooling needs. However, it is concluded that it is impossible to accurately specify final temperatures and relative humidity for the average person, because of the psychological, physiological and practical factors. Passive solar design elements have been found in constructions created since 7000B.C. and are now fundamentally used in passive architecture. These illustrate strong characteristics of historical and traditional architecture, which serve as exemplars for energy-saving architecture today and are used on the Experimental Solar House. The best-known applications of passive solar systems were researched taking into consideration their relevance for Lefkosia and it is concluded that the passive systems that are most suited for Cyprus and, therefore, are used in the Experimental Solar House are: Direct Gain, rectangular shape but compact design (aspect ratio 1:1.33) with the longer axis pointing East and West, external insulation on walls and roof, overall U-value of walls 0.6W/m²K and roof 0.3W/m²K, low emmisivity double-glazed argon-filled, interior thermal storage constructed from brick blocks and concrete frame, glazing- for direct gain systems, south facing window area greater than about 10-12% of floor area require thermal mass, well distributed over floors, walls and ceilings to reduce temperature swings, 5% north wall openings are sufficient for cross ventilation during summer nights, optimum of south wall openings 40% mountainous areas, 24% coastal region, 18% inland region, permanent external shading devices, vegetation (shade deciduous trees are excellent for shade in summer while allowing sun through the winter), use of cross ventilation, stack effect, night ventilation and ceiling fans. Comparative annual energy use of the Experimental Solar House versus traditional house, contemporary house and a low energy case was performed using computer simulation software Energy 10, WeatherTool and Ecotect. Results showed that the application of passive design techniques increased the comfort percentages from 10 to 45%. The annual energy use of the Experimental Solar House (121KWh/m²) is less than the contemporary house (368 kWh/m²) the traditional (243 kWh/m²). The research concludes that Passive Solar Design may be successfully applied in the design of modern buildings in Cyprus.