Le Corbusier did not design a 'solar house' by its strict definition, and he is not discussed at length in the book.* But if the subject had been broadened to include the sun-responsive (or heliotherapeutic) architecture of the 1920s, I certainly would have ranked Le Corbusier among the major figures and written about him at length.
Le Corbusier's interpretation of sun-responsive architecture took on powerful mytho-poetic dimensions. For starters, every attentive architecture student notices the inscription “Soleil” on the aerial sketch of the Villa Savoye (Poissy, 1929), and learns that the grand promenade through the house reaches its monumental conclusion at the solarium. I tend to agree with Richard Hobday's claim:
"That the Villa Savoye is a temple to sunbathing is beyond question."
(Incidentally, the Villa Savoye was oriented diagonally to the cardinal points, as was Palladio's Villa Rotonda.)
Le Corbusier’s thinking about the sun was vitally shaped by the 1930 CIAM congress and others that followed. At that meeting he presented the Ville Radieuse, and according to Kenneth Frampton, he realized the “heliothermic limitations” of the cruciform skyscraper that populated his ideal city. By 1933, Le Corbusier discarded the cruciform and introduced a new “sun-inflected high-rise form,” where most of the spaces could face south. Le Corbusier, as Frampton revealed, explained this design in a footnote in the Antwerp Plan:
"During these past few years, I have reworked the design of the crossplan skyscraper and evolved a more living form with the same static safety margin: a form dictated by sunlight.… There are no longer any offices facing north. And this new form is infinitely more full of life."
When Le Corbusier formulated the Athens Charter for CIAM between 1933 and 1941, he encoded heliotherapeutic principles in the larger agenda of modern architecture and planning. Here is article 26 of the Charter in full:
"Science, in its studies of solar radiations, has disclosed those that are indispensable to human health and also those that, in certain cases, could be harmful to it. The sun is the master of life. Medicine has shown that tuberculosis established itself wherever the sun fails to penetrate; it demands that the individual be returned, as much as possible, to ‘the conditions of nature’. The sun must penetrate every dwelling several hours a day even during the season when sunlight is most scarce. Society will no longer tolerate a situation where entire families are cut off from the sun and thus doomed to declining health. Any housing design in which even a single dwelling is exclusively oriented to the north, or is deprived of the sun because it is cast in shadow, will be harshly condemned. Builders must be required to submit a diagram showing that the sun will penetrate each dwelling for a minimum of two hours on the day of the winter solstice, failing which, the building permit will be denied. To introduce the sun is the new and most imperative duty of the architect."
The most striking property of this passage—besides its polemical strength—may be its lateness. This is a full generation after the ‘Davos-type’ sanatoria and Auguste Rollier’s publications La Cure de Soleil in 1914 and L’Heliotherapie in 1923, and a decade after the completion of the Zonnestraal sanatorium. (The antibiotic cure for tuberculosis would be developed in 1946.)
Le Corbusier did not explicitly design for solar heat gain. Rather, his experience with the power of the sun’s energy had been decidedly negative. His Cité de Refuge for the Salvation Army (Paris, 1933), with its inoperable south-facing curtain wall, “proved disastrous in summer due to thermal gain.” He was forced to retrofit the building with operable windows. In general he “reluctantly accepted” the necessity of the brise-soleil, according to Paul Overy. His experience was remarkably similar in substance, and uncannily parallel in time, to Fred Keck’s ‘discovery’ of solar heat, though Keck turned his negative experience for good in designing solar-heated houses. Also, Le Corbusier drew his first two-dimensional shading diagram (for an Algiers office project) in 1938, a year after Keck published his.
Le Corbusier's Le Poeme de l'Angle Droit (The Poem of the Right Angle), created between 1947-53 and published in 1955, revealed the depth of his identification with the rhythms of the sun. The piece included 19 paintings, each with an accompanying verse.
The first painting, at the top of this page, could be read as an abstraction of the physical path of the sun above and below the horizon, but also an engineer’s graph of heat gains and losses over the course of the day, with the horizon line being the zero line.
He published similar sketches as early as 1942 in La Maison des Hommes. In this example, the shape is inflected to indicate the cumulative experience of solar heat being most profound in the late afternoon, and the progression from summer to winter.
Also in Le Poeme de l'Angle Droit, Le Corbusier painted a tall, narrow building overlaid with the tall parabolic path of the summer sun and the lower curve of winter. The building, with east- and west-facing brises-soleil, clearly refers to the Unité d'Habitation, which was in development at the same time.
The verse corresponding to this image reads, in part:
L'horloge et le calendrier solaires ont apportés à l'architecture le "brise-soleil" installé devant les vitrages des édifices modernes.
Une symphonie architecturale s'apprête sous ce titre: "La Maison Fille de Soleil"
"The clock and the solar calendar brought to architecture the "brise-soleil" to be installed in front of the windows of modern buildings.
An architectural symphony is prepared under the title: 'The House of the Sun's Girl'."
The curious phrase "La Maison Fille de Soleil" (which I'm not sure I've translated correctly), later appeared as the title of an obscure Don Cherry jazz LP, with original (?) artwork by Le Corbusier. More info and hi-res images here. I am hesitant to interpret the astonishing unfolded image, but it seems to be an exhibition of Le Corbusier's work, including the last image above, inside a grand Baroque suite of rooms.
*My book does include a short discussion of Le Corbusier's maxim la fênetre est faite pour éclairer, non pour ventiler---“the window is for light, not for ventilation”---which probably influenced Fred Keck and Paul Schweikher as they developed new forms.
Kenneth Frampton, Le Corbusier, 2001.
Richard Hobday, The Light Revolution: Health Architecture and the Sun, 2006.
Paul Overy, Light, Air and Openness: Modern Architecture Between the Wars, 2007.