A comparative analysis of summer meteorological data measured in the Geneva region over the 1990-2005 period yields following results [1], as illustrated in fig. 1:

• As well in urban as in rural areas, classified summer temperatures are very similar from one year to another, never exceeding 35°C. As a notable exception, 2003 however characterizes by around fifteen days with peak temperatures exceeding this threshold.

• Night temperature always drops lower in rural than in urban areas, whereas day temperatures do rise to similar peaks.

• To the contrary of the dry temperature, the wet bulb temperature of 2003 remains close to that of other years. This indicates a stable potential of evaporative cooling, to the contrary of direct night cooling and other techniques examined further down.

2. Building

Representative of the administrative building stock, the architectural typology is that of a low depth building, with 20 m2 / 50 m3 offices distributed on both sides of a broad central corridor. In terms of simulation, this typology results in a thermal model made up of three zones: two offices, on opposite facades and separated by the central corridor, with lateral boundary conditions given by identical interior climate (neighbor offices).

The parameters that govern the thermal behavior of the building are as follows:

• Thermal mass is mainly determined by 28 cm thick slabs, in heavy option (full concrete: 510 kJ/K. m2) or medium option (combined wood structure with concrete filling: 350 kJ/K. m2). In both cases, separation walls between offices add an additional 170 kJ/K. m2 (relative to ground surface).

• Thermal insulation is any of low 1980’s quality (6 cm, double glazing windows), or high quality as given by the Swiss Minergie standard (20 cm, triple glazing insulating windows).

• Solar access is determined by an E-W orientation on a low 5° horizon, along with a 50% window-to-wall ratio. Efficient external solar protection (overall g-value: 13% with 1980 windows, 7% with Minergie windows) are activated when direct radiation on the facade exceeds 10 W/m2.

• Internal gains are 10, 20 or 35 W/m2 (during occupation: 8-18 h).