Solar Geometry in France, 1961

Even though it’s becoming more and more common to find architectural historians recognizing that environmental concerns were central to the history of modern architecture, the subject of solar heating seems a bit recondite for an institution such as the Cité de l’Architecture et du Patrimoine, the major museum of architecture in Paris, which features full-scale Romanesque portals and Gothic sculptures. So I was surprised to find these solar geometry diagrams on display:

At the museum, the caption read: “Diagrammes solaires C.S.T.B.” and no date was given.

C.S.T.B. refers to the Centre Scientifique et Technique du Bâtiment, France's national agency for building science research, then and now. After some further exploration, I believe these diagrams were first published in 1961. The C.S.T.B. researchers, Pierrette Chauvel and Jean Dourgnon, appear to have been important figures in lighting and daylighting research.

Also of note in the image above: the curved lines are at monthly intervals, with the exception of dashed line, which indicates March 13-October 1. I’m not sure why that would have been a significant date. Please comment if you have some insight.

The diagrams were included in a section entitled: “Protectrice et Climatique: Les Vertus de L'Enveloppe.” Here is the explanatory text:

L'une des premières fonctions de l'architecture est de protéger ses utilisateurs du climat extérieur. Une température agréable et constante s'obtient par le choix des magrtériaux de construction, par la conception même du bâtiment et de son enveloppe et, plus récemment, par l'usage de l'air conditionné.

Aux xxe siècle, la façade en verre devient une réalité. Les baies vitrées offrent des vues plus larges sur l'extérieur et une nouvelle perception de l'espace mais laissent entrer une trop grande quantité de rayons solaires. Dans les années 1950, les brise-soleil apportent une solution technique tout en dotant la façade de nouvelles qualités plastiques.

Aujourd'hui, la sensibilisation aux problèmes environnementaux conduit à concevoir une architecture dite <<écologique>>. Le traitement de la <<peau>> entre alors en ligne de compte comme la question des économies d'énergie.

And here as I've translated:

Protection and Climate: The Virtues of the Envelope

One of the primary functions of architecture is to protect users from the weather. A pleasant and constant temperature may be achieved by the choice of building materials, by the design of the building and its envelope, and, more recently, by the use of air conditioning.

In the twentieth century, the glass facade became a reality. Windows offered a greater views of the outside and a new perception of space but let in too much solar heat. In the 1950s, the brise-soleil provided a technical solution while giving the facade new plastic qualities.

Today, an awareness of environmental problems has prompted an architecture called “ecological.” The treatment of the “skin” then engages the question of energy savings.

In essence, the point of the exhibit is that French modern architects (like Le Corbusier) learned that all-glass structures overheated badly, and that knowledge of solar geometry was needed for proper shading—a major theme in 20th century architecture as I explain in The Solar House.

If diagrams such as those above were only available to French architects beginning in 1961 (and I'm not sure that's the case), then they were a few decades behind. American architects had access to this kind of information in 1938. (See Whit Smith's solar tool.)

Solar Futures: The View from 1973

The history of solar energy is full of lofty goals or aims that were not realized.  Here's an example from 1973:

"Although the sun is the indirect source of all fossil fuels, it has been neglected as a direct source of power. Yet the potential is tremendous: The energy in the sunlight falling on the surface of Lake Erie in a single day is greater than the entire nation's present annual energy consumption.

In recommending a large research effort in solar energy, a joint panel of the National Science Foundation and the National Aeronautics and Space Administration reported last December that by the year 2020 the sun could provide 35 per cent of heating and cooling in buildings, 30 per cent of the nation’s gaseous fuels and 20 per cent of its electricity."

---New York Times, April 18, 1973

(The "large research effort" never occurred, and solar energy currently accounts for 0.32% of US energy use according to Lawrence Livermore National Lab, although I do not believe this figure includes passive solar heating --- see The Clothesline Paradox.)

Jørn Utzon's sun-responsive houses

Here’s an extremely interesting academic paper that was published recently:

“Utzon and the sun path as an organizing element of life in a house”
by Miguel Ángel Rupérez Escribano, Universidad Politécnica de Madrid
Fourth International Utzon Symposium (2014)
Link to pdf

Danish architect Jørn Utzon is best-known, of course, for the design of the Sydney Opera house (and for the fractious collaboration with engineers from Ove Arup's office on that project). His Bagsværd Church (Bagsværd, Denmark, 1968-76) is also a masterpiece of world architecture in the late-modern period. What may be less well-known is that Utzon designed dozens of houses around the world.

Utzon's own house, Hellebæk, Denmark (1950-52)
Photo by Seier+Seier
www.flickr.com/photos/seier/2472346988/

If you’re thinking that the image above looks quite a bit like George Fred Keck's solar houses of the 1940s, you're right, it certainly does. Escribano concludes that Utzon was influenced by some of the main characters in The Solar House, particularly Keck and Frank Lloyd Wright:

“The selected houses designed by Utzon follow a common pattern, which has remarkable similarities with the American solar houses.”

Escribano’ excellent study goes further, looking closely at how Utzon adjusted the solar orientation of many of his homes to the southeast or southwest based on site and climate factors.

Orientation of 20 houses by Utzon.
From the article linked above.  Drawings by the author.

Although Escribano says that Utzon considered the sun “a useful element in heating the house” in cold climates, the paper does not suggest that Utzon aimed to quantify energy savings, or to call his houses “solar,” as Keck and Wright did. 

Solar Principles and Laramie's Hitchcock House

As I explain in The Solar House, the basic principles of solar architecture were broadcast and applied nationwide starting in the mid-1940s, after having been established in the late 30s and early 40s by architects, especially George Fred Keck.

Here’s one striking example of those principles loosely applied: The “Hitchcock House” in Laramie, Wyoming, so-called for the architects Hitchcock & Hitchcock, and built in 1954. Laramie is my hometown currently so I’m quite familiar with the structure and I just happened to catch it at a photogenic moment.

Of special note are the windows in the center-left on the ground level. Here you find the classic arrangement of large panes of fixed insulated glass with a shading device above and ventilated louvers below. This formula was pioneered by Fred Keck and Paul Schweikher in c. 1940 and explained in detail in the book. In the picture above, at about 4:00PM in mid-August, you can see the shading working perfectly to prevent overheating. The roof overhang is doing well for the upstairs windows too. Clearly the architects understood solar geometry. (I wouldn't be surprised if they used Libbey-Owens-Ford's Sun Angle Calculator.)

This is a perfect illustration of the ubiquity of the 1940s solar house. Houses like this—typical but unique—can be found in cities and towns all over America after 1945. The late date here of 1954 shows how trends may be adopted late, or persist longer, in the hinterlands.

Now you probably expect the left side of the image faces south. Where Hitchcock & Hitchcock can be criticized (and why I said “loosely applied” above) is that we’re looking at the southwest corner of the structure, and so the beautifully-composed solar wall is facing west—not ideal orientation. If they had been following the Keck playbook faithfully, the house would have been long and narrow, running east-west, with the large amounts of glass and shading on the long south face. Indeed, it would be better if there were almost no glass on the west. Here the architects compromised and applied a typical south-facing technique to the west. There’s also too much glass on the north.

This is a classic theme in architectural history: techniques are misapplied as a movement or style is popularized and diffuses. As Goethe said, what is useful in one period becomes representational in the next.

Interior showing the ventilated louvers opened for cooling

Today the Hitchcock House is owned by the University of Wyoming. It’s been remodeled, with a significant addition, certified LEED Gold, and renamed the Bim Kendall House. More info here.  Thankfully during the renovation all of the original “solar” features were preserved, especially the ventilating louvers, which still perform their original function perfectly, providing excellent natural ventilation with building security, while those windows don’t need insect screens which would interfere with the view.

On ventilating louvers, see also: Keck's Sloan house II: a new look

A note on the solar architecture of the 1970s

My book The Solar House begins:

"The label ‘solar house’ typically conjures an image, I think, from the 1970s: an eccentrically-shaped structure with an oversized sloped glass wall and diagonal cedar siding.  Perhaps an earth berm.  A Volkswagen van nearby..."

The book then focuses on the period before 1973.  It includes a only broad overview of the solar architecture of the 1970s, with discussion of a few key examples.  I was not able to include every worthy house from that period, simply because so many appeared.

Yet I do think the solar architecture of the 1970s is a compelling subject, of course, and I'm especially interested in the aesthetic questions.  Because solar house design was strongly affiliated with the counterculture, it can be easy to dismiss with a laugh.

A stereotypical example (?)

Or maybe it's beginning to look serious and attractive again now, as our tastes age.  And young people don't seem to find images like this to be ugly.  In any case, there are genuine, difficult issues to unpack when looking at the eccentric solar architecture of the 1970s and my book offers only a few small steps in that direction.  (Not only was there a lot of solar architecture after, say, 1973, there was a lot of discourse about aesthetics.)  I hope somebody else will continue to help us document and understand what happened and when that exists there should be a lot of new interpretations of 70s solar architecture.

I recently came upon a quotation from Susan C. Piedmont-Palladino which caused me to reflect again on some of these larger questions:

"...the trend towards integrated and more sophisticated technology may also allow environmentally responsible architecture of the future to avoid becoming ghettoized like the 'solar architecture' of the past.  The icons of the energy-conscious architecture of the 70s—the single-slope roof with attached solar collectors, the Trombe wall, etc.—became stigmas in the 80s as the reality of scarcity was obscured by the illusion of plenty."*

I generally agree with the premise, that the stereotypical 70s solar house created a 'stigma' which damaged the social movement.  Is the solar house, as a type, still stigmatized?  Probably.  I've spoken of an "Age of Aquarius hangover" on occasion.

Still, it would be a shame, I think, if anyone interpreted the historical lesson to mean that progressive social movements should avoid experimental architecture.   Of all the possible motives for architecture to explore new forms, surely free renewable energy is compelling enough...

What do you think?

*"Building Alternatives," Perspecta 29 (1998).