Coupled sashes were used in the 1930s, but this was not a traditional solution. A
typical double-sash wooden window would have been an inward-outward opening,
painted wooden window. Kilpi’s reprimand to Kolhon Saha (Kolho Sawmill), stating
that a professional craftsman should immediately be able to see from the drawings that
the solution required premium-quality windows, was fair. Aalto used steel windows
in the public spaces such as staircases, dining halls and patient corridors. Apparently
he attempted to use oak windows in the dining hall, or at least he considered them a
possible alternative. Varnished oak windows were considered especially distinguished
in the architecture of the day.
Aalto also wanted to use steel windows in the patient room, which was of particu-
lar ideological value to him. The window was eventually realised as a hybrid made of
wood and steel. In the Finnish context, wooden-framed windows were less expensive
than the steel ones: Finnish-made steel windows were not mass-produced and were
available only to order although they were made from industrially produced steel
profiles. Designers took pains to develop a wooden window standard that, quite nec-
essarily, incorporated steel elements.
The patient room windows were an essential and salient architectonic feature in
the sanatorium, and underwent a complete overhaul in the time leading to the final
realisation. Besides changing from a steel window to a hybrid window, Aalto also
developed the window as a holistic concept, integrally linked with heating, ventila-
tion and the amount of daylight benefitting the patient. He wrote in a publication
aimed at Swedish architects in 1932: “The patient room has, among others, the
following characteristics: morning sun on the patients’ beds, afternoon sun on the
front part of the room, in front of the window. Double glazed windows in wood
with L-shaped frames, with permanent ventilation through glass panes with vertical
openings. Exposure to the sun can be adjusted using the external blinds ...”.^806 Aalto
discussed the idea of continuous ventilation, and considering that he was addressing
his professional peers, this question may be interpreted as a sign of his intention to
design a wall-sized sliding window for the patient room. With this rhetorical gesture,
he wanted to demonstrate his expertise about the overlapping trends in health care
and architecture. Naturally, the timber-framed window was not designed to be kept
continuously open in the Finnish weather conditions.
The ventilation took place horizontally through the central row of windows, which
is why there could be no mullions. The wooden-framed large window opening would
have required a sturdier frame for structural reasons had the frame been wooden. Now
that the frames were built equal in strength to the sash, they had to be reinforced with
steel profiles both on the exterior and interior window. A window combining wood and
steel was genuinely a hybrid. Wooden windows were not of any interest to the media.
This was why Aalto highlighted in all publicity wooden windows reinforced with steel
806 Aalto 1932, p. 30.