Is your window "thermally desirable"?

In my research for The Solar House I came upon this statement by a British engineering professor in 1976:

"If during a 24-hr period the incoming heat is greater than the loss, the window is thermally profitable for that day.  Furthermore, if during a year the incoming heat is greater than the loss, the window is thermally desirable.  If overall the window gives a net positive gain, its size should be as large as possible.  Conversely, if the long-term window net gain is negative, its best size is zero.…  On a purely thermal basis there is no optimum intermediate size: The window is either maximum or zero."

The quotation is from Dr. Morris Davies*, an engineer at the University of Liverpool, who was part of a research team that spent about ten years analyzing the performance of the St. George’s School by Emslie Morgan (Wallasey, 1961-62), an immensely interesting building I wrote about in The Solar House.

What an excellent illustration of the difference between scientific optimization and design!  Davies' optimized architecture would typically have an all-glass south wall, and all-solid walls on the east, west, and south.   In my view, this is why computer simulations can contribute to architectural design, but they can not be generative or determinant of architectural design.  Scientific knowledge is one important ingredient in a more complex recipe, and human judgments are essential.

Of course, Davies' position here did not consider that windows have other functions beyond thermal (and he admitted so).  They may be desirable for providing daylight, or views, and they may be undesirable for bringing discomfort due to glare.  St. George’s School did indeed suffer a glare problem, of which Davies was aware.

But even from a purely technical point of view, Davies was wrong.  To focus on annual net gain is too simplistic; it neglects the fact that quite a bit of passive solar heat is collected in afternoons in the Spring and Fall, when it is likely to be unwanted because it causes the building to overheat, depending on the weather and other factors of course.  To make a good window "maximum" is to increase the overheating problem.  Any number of solar house architects learned that lesson the hard way, long before 1976, as I detail in The Solar House. 

Note that overheating does not necessarily imply that the building needs air-conditioning.  Opening some windows may suffice, especially on a swing-season afternoon.  This was most certainly the case in Wallasey.  Still, the solar gains at that time are, for the most part, not beneficial.

Clearly Davies was speaking theoretically, and perhaps he assumed that windows would be shaded at times when the building doesn't need heat.  In practice, shading never works in a theoretically-optimum manner.  Or perhaps he assumed that thermal mass lagtime and carryover effects would effectively redistribute the heat from day to night.  In practice, this is also limited.

Nevertheless, I do enjoy the phrase "thermally desirable," and it wouldn't hurt if most architects adopted a little bit of that mindset when thinking about windows.

*Davies was quoted in Joseph E. Perry, Jr.. “The Wallasey School,” Proceedings of the Conference on Passive Solar Heating and Cooling, 1976.

Previously: Why I care about Building Science

A Paul Siple Quotation

"It would appear that in some cases architects have had a tendency to devote unbalanced attention to style and appearance, much after the fashion of women's hat designers, who strive for the expression of uniqueness until the function of head-cover for protection from weather loses its meaning; and woe be it when such hats are caught out in rain, wind or blizzardy weather."

---Paul Siple, "Climatic Criteria for Building Construction" (1950)
linked here

I love quotations like this, because they demonstrate the distance that developed in the 20th century between the conventions of high architecture and a vernacular approach to building based on well-educated common sense and first principles.  See also: a Reyner Banham quotation from "Stocktaking."  There's a wonderful story to be told about how that distance developed (beginning in earlier centuries).  It should be written by somebody who can be sympathetic to both sides.

Who was Paul Siple?  Today he would be called a climate scientist.  He worked for the military.  He invented the term wind chill factor, and several features in Antarctica are named for him.  See Wikipedia

Siple was closely affiliated with the solar house community.  He attended the 1950 MIT Symposium (which I characterize as "a great summit meeting of solar architects and engineers" in The Solar House), where he gave a paper entitled “Feasibility of Solar Heating Systems.”  Earlier he contributed to the House Beautiful Climate Control Project ("How Many Climates Do We Have in the U.S.?", October 1949).

Book Review: Hyperlocalization of Architecture

How do we come to terms with the fact that Sustainable Architecture can encompass everything from Japanese microhousing to Mexican shopping malls?  The new book Hyperlocalization of Architecture: Contemporary Sustainable Archetypes by Andrew Michler gives us some new tools to understand this vast, disorganized movement.  I recommend it to anyone who wants a richer understanding of what's going on, globally, in architecture.

Michler traveled to several destinations around the globe and found (for the most part) unfamiliar architects working out new ideas about sustainable architecture.  The format, which juxtaposes interviews with the architects and well-illustrated projects, is outstanding, because the reader can toggle back and forth to assemble meaning out of words and images.  The effect is one of discovery.  What does Sean Godsell mean when he talks about "playing with childhood memory"?  I turn the pages and begin to locate what this means in the building images.  Michler also offers some interpretive passages, and rather than being intrusive they tend to offer more clues.

Michler's book is full of wonderful revelations.  The real strength of the book is in its curatorial sense of adventure.  Who knew, for example, about the wonderful Spanish architect Berta Barrio and her projects such as Biblioteca de Can Llaurador?  Now I do!  I love her notion that "We are not comfortable if we are just looking for shape when we design."  (This theme of anti-formalism seems to run through the book.)

Like me, Michler loves Japan and seeks to understand its peculiar customs.  His observant essay "Japan Condenses" begins with this paradox: "A new house may have practically no insulation but the toilet seat is always heated."  What does this mean for Sustainable Architecture?  His answer cleverly touches on everything from building science to urbanism to Japanese shopping habits.  Michler's ability to deftly connect the dots across disciplines results in insights which are both smart and fun.

I wish Michler had included London, which has in my opinion the most well-developed building culture in the world.  I expect he stayed away since he is understandably averse to the 'starchitects' like Zaha and Foster, and because global capital is driving much of the agenda in the city right now.  Still, I think he would have found some smaller firms --- like Cullinan Studio, Waugh Thistleton, and Juice Architects --- doing exceptional work and exploring new ideas with an exciting pragmatism.

Of course Sustainable is a slippery word and it's a common criticism that Sustainable Architecture is interpreted differently in different places.  But I think Michler wants to celebrate that Sustainable Architecture will look different in one place than another.  And his term Hyperlocalization even suggests, I think, that sustainability goals will be achieved differently in one place than another.  In other words, Michler is arguing For a Contingent Architecture, one produced as people respond to the peculiar physical and cultural needs and opportunities of their place. 

I would argue that this is akin to the developmental period of modern architecture in the 1920s.  At that time, architects all over the world explored new ideas about space and form, and though they shared a basic agenda, they produced different kinds of buildings.  California's modernism was different from Paris', which was different from Germany's, and so on.  Did Bijovet and Neutra wring their hands about the fact that their strains of modern architecture were different from one another?  Of course not!

Likewise we shouldn't be anxious about the imprecise definition of Sustainable Architecture.  What Michler's book finally shows us is that the world of architecture is pluralistic and dispersed, and it's at the beginning of a profound revolution; this is really exciting stuff.

Disclaimer: Andrew Michler is a friend.  But I wouldn't write anything here that I don't believe.

Related: Elrond Burrell's review (May 2016)

The Conservatory Effect

As readers of The Solar House know, I discovered that concerns about overheating were central to the development of the solar house.  Early modern architects found that too much glass can easily lead to an uncomfortable house which requires air conditioning; this is the subject of chapter 2, "The Solar House and the Glass House."  Proper shading became central to the definition of the solar house from the 1930s.  Glass house architects like Mies van der Rohe ignored this fundamental issue, and clients like Edith Farnsworth suffered.

It appears that some green homebuilders today are learning the same lessons.  (They should read more.)  British writer Mark Brinkley asks: "Are Eco Homes prone to Overheating?" 

Brinkley calls this by its British term: The Conservatory Effect.  He says the effect is created by large, unshaded, south-facing glazing, plus inadequate ventilation. This produces spaces which are rendered almost uninhabitable during the day time.

Many of the characters in The Solar House would have been well-acquainted with The Conservatory Effect (though they didn't use that term); they worked hard to find techniques to mitigate it. 

I like this label, The Conservatory Effect, because it implies that modern architects should be more familiar with the history of climate control innovations in greenhouses (conservatories) in Victorian Britain (which I recently discussed here).  I'm going to start using it!

Marcel Breuer's Villa Sayer

Here's a project which offers some fascinating insight into problems of environmental control in modern architecture.

Marcel Breuer's Villa Sayer (Normandy, 1972-1974) is currently featured in an exhibit at the Cité de l'Architecture et du Patrimoine in Paris.  It's a house built with a concrete hyperbolic parabaloid roof.  During the design process, Breuer made extensive notes questioning the design problems related to heating and cooling:

There is a persistent notion that Modernists like Breuer were insensitive to issues of thermal comfort.  This is clear counter-evidence: an inquisitive effort to create a 'well-tempered environment'.  Yet it is also telling that Breuer asks his designers "Is this house air-conditioned?" at a relatively advanced stage in the process.  An architect sensitive to energy use would certainly know the answer.  (Energy use was not a concern to architects generally at this time.)

Here's a link to the page about the Villa Sayer at the Cité de l'Architecture.  Also more here.

The Cité de l'Architecture seems to have a strong interest in these issues.  Last summer I wrote about their display on Solar Geometry in France, 1961

Related: Straight from the Desk of Marcel Breuer, at Dwell.com