One of the most acclaimed architects of the twentieth century Alvar Aalto (1898 – 1976) was also educator and critic of his time. In particular, he voiced strong concerns about emerging technologies and remained a vivid supporter of humane architecture. Thus this research project investigates Aalto’s approach to active and passive environmental control systems and their spatial integration. Using wind analysis and computational fluid dynamic (CFD) studies, this paper analyzes natural ventilation flow paths in two of Aalto’s major works: The Alvar Aalto Viipuri Municipal Library (1935), which accidentally operated for years on stack ventilation, and Alvar Aalto’s Säynätsalo Town Hall (1952), which uses a raised courtyard to shelter the inner space from strong winds enabling the operation of windows in the courtyard. Both buildings highlight a distinct flow path strategy which enhances air flow through and around the building, reaching from pure wind induced ventilation strategies to combinations of wind and stack ventilation.

The courtyard atrium or inner landscape, Aalto’s major spatial devices act as an interface to create an intermediate microclimate. This microclimate mediates between the severe outside climate and a more moderate, comfortable, or even delightful interior. The courtyard has to be inside, i.e. protected in order to protect; the surrounding building thus acts as its own interface. The house acts as a climatic membrane. The main material needed to create this interface is air and its ventilation patterns, which are shaped through the spatial composition.

One of Aalto’s early essays ‘porraskiveltä arkihuoneesen’ for the Aitta 1926 sample issue hinges on the idea of inner paradise using Fra Angelico’s (1400 – 1455) painting L’Annuziazione as a metaphor to describe and envision the inside-outside relationship of space and climate in his beginning design work (Schildt 1984: 214). Aalto’s essay hinges on the way one enters a room and how the room is connected to the exterior climate and the light of the sky. I argue with Göran Schildt that the roof lights Aalto first explored at Paimio and Turun Sanomat, and elaborated at Viipuri Municipal Library, are the open sky over a modern version of a classical amphitheatre (Passe 2008). Thus, Säynätsalo Town Hall with its green raised courtyard of low height to area ratio captures the sun while still protecting the inner space from the winds and allowing the low angle of the Northern sun to penetrate and warm the whole inner space. At Viipuri, Aalto, nevertheless experimented with novel environmental control technologies, and challenged basic physics by introducing both heat and ventilation air from above, in spite of his intrinsic critique of inhumane technologies in the USA. This paper thus critically compares some of Aalto’s key texts on technology with the actual design and environmental performance strategies of the two buildings.