Calculating Solar Heat in the 1930s

One of the key themes of The Solar House is that both passive and active solar heating began to be scientifically understood in the 1930s & 40s. Hoyt Hottel and his team at MIT calculated solar heat in about 1939 for (what was later called) MIT Solar House I, which used solar-thermal panels on the roof. Then they wrote the equations used by solar engineers going forward. Meanwhile in Chicago, George Fred Keck and his brother William calculated (passive) solar gains for the Sloan house in early 1940. They found that the gains outweighed the losses for the south-facing glass walls, and in fact they found a net “overload,” indicating possible overheating. Additionally, it was in the 1930s that architects using glass in hot climates began to be concerned about overheating and solving that problem through shading (see Le Corbusier and the Sun for example).

So the question arises: If you wanted to calculate solar gains in, say, 1940, what kind of data and methods were available? If you were doing scientific research, like Hottel and his team, you used meteorological measurements and worked from first principles. If you were an architect like Keck or Le Corbusier, or a practicing engineer, these are the main sources of information that would have been available:

• Howard T. Fisher, “A Rapid Method for Determining Sunlight on Buildings,” Architectural Record 70 (December 1931), 445-454.

• R. A. Miller and L. V. Black, "Transmission of radiant energy through glass.” ASHVE Transactions 38 (1932), 63-78.

• H.E. Beckett, “Orientation of Buildings,” Journal of the Royal Institute of British Architects 40 (1933), 61-65.

• P.J. Waldram, “Universal Diagrams” Journal of the Royal Institute of British Architects 40 (1933), 50-55.

• F.C. Houghten, C. Gutberlet, and J.L. Blackshaw, “Studies of solar radiation through bare and shaded windows,” ASHVE Transactions 40 (1934), 101-116.

• Henry N. Wright, “Site Planning and Sunlight,” American Architect and Architecture 149 (August 1936): 19ff.

• Arthur M. Greene, Principles of Heating, Ventilating and Air Conditioning (1936)

• “Figuring Solar Heat Gains of Buildings” by William Goodman, in Heating, Piping, and Air Conditioning, May through October 1938

• “Orientation for Sunshine,” Architectural Forum, June 1938

Jacobsen's SAS Hotel: Facade issues

Arne Jacobsen’s SAS Hotel in Copenhagen was originally built in 1958–60, and it is widely-acknowledged as a masterpiece of mid-century modernism.

© Anthony Denzer

The curtain wall is leaking water pretty badly; I experienced this when I stayed here a few weeks ago. I found this note from the hotel, which says that they are “working on” finding a solution which is sensitive to the building’s protected status. Does this mean a major façade renovation is being planned? Unclear.

© Anthony Denzer

Because of the deep marble sills, the water didn’t cause any issues within the room, but you can bet there are unseen problems occurring. My stay there was wonderful. Here’s a few more pictures.

© Anthony Denzer

© Anthony Denzer

Final note: I find the black columns in the image above to be much too visually strong. Originally they were white. The lobby was renovated in 2017–18 by Space Copenhagen and Fritz Hansen.

Solar Form in the 70s

Last week at the Architectural Engineering Institute (AEI) conference I presented a paper called “The Solar Architecture Taxonomy: A Historical Analysis.” My co-author Jon Gardzelewski and I analyzed 180 solar buildings from the 1970s to see how architects used solar panels when they became commercially-available for the first time. There is very little design theory addressing solar panels. We presume this might have value for designers who wish to use PV in the future.

We found the most common design strategy was to create ‘solar form’—to shape (or distort) the building form so that panels face the south sky. 72% of the 180 buildings in our survey had solar form. In our reading, this design strategy is derived from early-modernist theory (“form follows function”).

We further distinguished between “strong form” and “weak form.” Here’s what we wrote:

…we propose to define strong form as follows: the major form clearly expresses the collection of solar energy, plus the minor forms and other design elements directly support the same theme. We suggest weak form for buildings that have a major gesture which expresses the collection of solar energy, but other forms and elements which communicate other priorities or influences.”

To distinguish between strong form and weak form does not necessarily imply a value judgment. Some examples of strong form are strongly eccentric; they look dated in retrospect. Some examples of weak form certainly represent sophisticated design thinking, as they reflect the influence of Postmodern architectural theory in the 1970s, where the expression of “complexity and contradiction” (Venturi, 1966) became a positive goal for architectural design. 

Other examples of weak form—typically houses—are compromised by an apparent desire to ‘fit in’ to a traditional vocabulary, or to simply not appear eccentric. The magazine Popular Science found “researchers … were trying to make their projects look as much like other houses on the block as possible” (Luckett, 1974).

Previously on the blog:
A note on the solar architecture of the 1970s

In the News: The Dover Sun House

Image from Boston Globe article linked below.

The Dover Sun House (Dover, Mass., 1949) was an important experiment in solar house history, and in The Solar House I tell its story in depth. Because it was created by engineer Maria Telkes, architect Eleanor Raymond, and client Amelia Peabody, it was noteworthy also for being “exclusively a feminine project.”

Andrew Nemethy, who lived in the house as a child, wrote a piece for the Boston Globe this week about the house’s significance and his memories of it. He writes:

“The Sun House had its quirks, not least the daily chore of raising or lowering the shades that covered the seven picture windows. The shades kept warmth from radiating out on cloudy days and (along with a system of louvers) prevented the sun from overheating us.”

As I documented in The Solar House, Telkes’ design for the Dover Sun House used flat-plate air heaters and an experimental method of heat storage with salts. She called it “the Model T of the sun-heated houses.” It operated properly for two winters but then failed, and the technology of salt storage never became prevalent for solar heating*. Nemethy says:

“I recall my mother telling me that we bundled up indoors when the solar heating system began to fail, but my childhood memories are mostly of an odd-looking house in a rural setting 3 miles from my closest friend, not of a scientific landmark.”

Nemethy discusses Telkes’ difficult personality in more length than I did. And he confirms a fact of which I was not certain: The Dover Sun House was demolished in about 2010.

*Note: Today salts are sometimes used in Thermal Energy Storage systems, often cooling systems which produce ice at night (when electricity is cheaper) for air conditioning in the daytime.

Previously on the blog:
Unearthed: Dover Sun House comic

Harold Orr Honored

Just a quick note to mention that Harold Orr was inducted as a member of the Order of Canada last week—a very high honor. Orr, a mechanical engineer, was a key figure in energy-efficient housing in the 1970s, and a member of the team* that built the seminal Saskatchewan Conservation House (1977). In The Solar House I describe the Saskatchewan project as a pivotal historical development when superinsulation and airtightness became more important strategies than passive solar heating and thermal mass. The Saskatchewan Conservation Home is now recognized as an important forerunner of the Passivhaus movement.

In recent years Orr has continued to emphasize the importance of airtight construction for energy efficiency. Did Harold Orr invent the blower door? He says so, here (pdf). I believe it’s more accurate to say that he improved upon fan depressurization methods first developed in Sweden by Arne Elmroth, Ake Blomsterberg and Johnny Kronvall.

Harold Orr’s name is always accompanied by ‘pioneer’, and that is well-deserved! He also received the Pioneer Award at the International Passive House Conference in 2015. By extension, the Order of Canada award offers some welcome recognition for the green building community and its history.

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*The team included:
Project Manager: David Eyre
Ir. E. Hendrik Grolle, Grolle Architect and Engineer
From Saskatchewan Research Council: Dave Jennings, Bernard McArthy, Deryl Thompson
From National Research Council: Harold Orr
From Dept. of Mechanical Engineering, Univ. of Saskatchewan: Robert W. Besant, Robert S. Dumont, Greg Schoneau, Dick Van Ee

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Much more about the Saskatchewan Conservation Home on the Resources page.
Previously on the blog: The Saskatchewan Conservation House: Aesthetic Questions