Overheating, high cooling energy demand and glare are recurrent problems in office buildings in Santiago. It is necessary to know the influence of different architectural strategies in energy demands to meet thermal comfort of the users and energy efficiency. Based on dynamic simulations, cooling and heating demand are estimated for an office building located in Santiago. It is shown that the size of envelope's glazed areas highly influences the energy demand. A totally glazed facade building might reach up to 155 kWh/m(2) year for total cooling and heating demands. On the other hand, in a building with a window-to-wall ratio (WWR) of 20%, external solar protection and selective glazing, demand might be as low as 25 kWh/m(2) year. If night ventilation is applied during cooling periods an additional reduction of 37% can be achieved. A WWR of 20% is enough to keep a useful daylight around 80% of the time throughout the year. Main conclusions are: (i) for the climate conditions of Santiago, completely glazed facades are not recommended, even with selective glazing; (ii) night ventilation shows to be highly effective to reduce cooling demand; and (iii) lower WWRs with solar protection can achieve a better daylight performance than larger WWRs due to prevention of glare. (C) 2011 Elsevier B.V. All rights reserved.