In the temperate latitudes, air-conditioning installations are necessary only because architectural design neglects to take the indoor climate into consideration. As a consequence of high energy costs in Europe, the idea of natural air-conditioning was introduced into the planning of office buildings, with smaller rooms illuminated by daylight, windows that can be opened, low heat-transfer rates on the outer walls, and massive inner walls and ceilings, instead of intensely glazed curtain facades, and large, open-plan offices with high artificial illumination levels. This structure, typical for historic buildings, allows heat to accumulate in the daytime and then be emitted during the night through ventilation. Less heat dissipation by using compact fluorescent lamps and reduced outside air exchange by indoor air quality control are some other attributes. All of them should be adapted to a new museum architecture.