To remedy these conditions, small Brazilian museums, often housed in historic buildings, are often naturally ventilated and lit. In hot and humid regions, buildings can be open to benefit from ventilation, because the climate is mild and allows for it, internal conditions being almost the same as those external. Only a few museums are air conditioned in Brazil, mainly the large and national ones. In the case of Northeast Brazil, the misuse of these systems is notorious, since the institutions often operate their plants solely for the visitors' comfort. They are switched on during working hours, and switched off at the end of the day.
Nobody knows yet, for little is known about hot and humid museums.
To know more about hot and humid museums, a case study was set up in the coast of Northeast Brazil, and the two types of internal environment control were examined. Firstly, the degree of environment stability was assessed in three local museums. This paper thus looks at internal climate fluctuation, and discusses each building's performance in safeguarding museum collections. Not only to have an overall view of hot and humid museums, but also to evaluate architectural changes, in concept and detailing, covering both period of construction and type of environmental control, three museum buildings were chosen as a small but representative sample. Two are naturally ventilated historic buildings from the 18th and 19th centuries, and the third, a modern air-conditioned one, from the 1960s.