Never in history has there been a stronger or more eloquent advocate for the use of solar building principles than Socrates. Xenophon, a disciple of Socrates, presented in a Socratic dialogue the philosopher’s belief that the art of “building houses as they ought to be” was firmly based on the principle “that the same house must be both beautiful and useful.” In what has become known as the Socratic method, Socrates began his discourse by asking a question: “When someone wishes to build the proper house, must he make it as pleasant to live in and as useful as it can be?” After his student answered in the affirmative, the master then asked, “Is it not pleasant to have the house cool in summer and warm in winter?” And when the student assented to this as well, Socrates then closed the discussion by affirming, “Now in houses with a southern orientation, the sun’s rays penetrate into the porticoes [covered porches,] but in summer the path of the sun is right over our heads and above the roof, so we have shade….To put it succinctly, the house in which the owner can find a pleasant retreat in all seasons…is at once the most useful and the most beautiful.”1
The second great sage of Greece, Aristotle, provided additional details not mentioned by Socrates. He, too, started with a question: “What type of housing are we to build for slaves and freemen, for women and men, for foreigners and citizens?” And then he answered, “For well-being and health, the homestead should be airy in summer and sunny in winter. A homestead possessing these qualities would be longer than it is deep; and its main front would face south.”2
Socrates’s father worked in the construction industry as a stonemason, and many believe Socrates followed in his father’s footsteps. If he did, he would have known about the remodeling of two houses in downtown Athens — the Agora — where workmen changed the arrangement of rooms so the most important ones would face onto a southern courtyard.3
The fact that Socrates spent the majority of his life in the neighborhood assures that he knew about the solar project in Athens. And less than 2 miles outside of the city, another example of solar design was built in Socrates’s time. This was a large rectangular house that sat on the foot of the northerly slope of Mount Aegaleo, one of several mountains near Athens. According to the archaeologists who excavated it, the farmhouse they discovered, “which faces south and has its entrance and court on this side and its main rooms on the north,” corresponds exactly to the ideas expounded by the great philosopher as recorded by Xenophon.4
Olynthus: A Planned Solar City
Socrates surely also knew about the solar district planned and built as part of the city of Olynthus, northeast of Athens, since its creation was a consequence of a revolt against his beloved city-state.5
People from neighboring towns participating in the break with Athens in 432 bce moved to Olynthus for protection against Athenian retribution. The increase in population forced the Olynthians to establish a new district, which its excavators called North Hill. The latitude was approximately that of New York City and Chicago, and the temperature often dropped below freezing in winter. Approximately twenty-five hundred people settled there.
North Hill was a planned community from the beginning. Starting from scratch, the settlers could more easily implement the principal ideas of solar architecture. The town planners situated the new district of Olynthus atop a sweeping plateau and built the streets perpendicular to each other, just as the Chinese had, with the main streets running east-west. In this way, all the houses on a street could be built with a southern exposure, assuring solar heating and cooling for all residents — in keeping with the democratic ethos of the period. Aristotle later commented that such rational planning was the “modern fashion,” which allowed the convenient arrangement of homes so that they could take maximum advantage of the sun.6
Olynthian builders usually constructed houses in a blocklong row simultaneously. The typical dwelling had six or more rooms on the ground floor and probably as many on the upper floor. These houses were usually a standard square shape and shared a common foundation, roof, and walls with the other houses on the block. The north wall was made of adobe bricks, which kept out the cold north winds of winter. If this wall had any window openings, they were few in number and were kept tightly shuttered during cold weather.
The main living rooms of a house faced a portico supported by wooden pillars running parallel to the south side of the building. The portico led to an open-air courtyard averaging 320 square feet, which was separated from the street by a low wall. The courtyard provided a place where the occupants could enjoy the outdoors with maximum privacy; and sunlight, the home’s primary source of illumination and winter heat, entered the house through the courtyard.
The house’s earthen floors and adobe walls absorbed and retained much of the solar energy that came in through its window openings facing the courtyard. In the evening, when the indoor air began to cool, the floors and walls released the stored solar heat and helped warm the house. To prevent cold drafts from coming through the open portico into the house, some builders constructed a low adobe wall between the pillars of the portico, parallel to the south wall of the house, allowing for the warming rays of sun in winter, while shutting out the cold drafts below.
The Olynthian solar house design worked well in summer and winter. When the summer sun was almost directly overhead — from about ten in the morning until two in the afternoon — the portico’s eave shaded the openings of the main rooms of the house from the sun’s harsh rays. In addition, the closed walls and contiguous dwellings barred the entrance of the morning and afternoon sun into the east and west sides of the homes.
Priene and Delos
About 350 bce, during Aristotle’s lifetime, Mausolus, ruler of the Greek city of Priene, planned to rebuild the city on the steep slopes of Mount Mycale, in what is now western Turkey (Asia Minor). He intended, with the help of Alexander the Great, to make Priene a model city for the Greek world. Luckily for future generations, Priene’s ruins are considered the finest surviving example of an ancient Greek city.
Priene is a good example of how the ancient Greek architects and planners coped with adverse topography to create a solar city. To accommodate Mycale’s steep slopes, the city’s builders devised a checkerboard street plan similar to that used at Olynthus. They terraced the main avenues along the contours of the rocky spur on an east-west axis; the secondary streets ran up the mountain from north to south. Owing to the sharp incline, many of the secondary streets became stairways. Despite Priene’s difficult location, all homes, no matter how large or small, were designed according to what Priene’s excavator, Theodor Wiegand, called the “solar building principle.” The main rooms always opened onto a south-facing covered porch. Even homes belonging to the poorer citizens enjoyed the warmth of the sun in winter and were spared its heat in summer.7
Delos, an important trading center in the Aegean, presented an even greater challenge to solar architects. The irregular rocky terrain of this island precluded the division of streets into an orderly pattern as at Olynthus or Priene. It also prevented the use of uniform house plans. Often the contorted topography determined the design of a Delian home. Nevertheless, the main rooms faced south whenever possible. In some parts of Delos, a new adaptation of solar design took form. Many residents terraced their homes along the sloping terrain so that the important rooms were on the upper level, with a commanding view of the south.8
Diminished Access to Fuel
It is probably no coincidence that construction incorporating solar-building techniques began to appear after miners at Laurion, near Athens, struck a rich vein of silver. The silver mine would lead to the flowering of Athenian wealth and power throughout most of the fifth century bce. Separating the silver metal from the ore required huge amounts of charcoal, however. At the same time, large numbers of people flocked to Athens, and since everyone cooked meals and heated homes with hibachi-like braziers, the growing population, combined with the surging silver production, took a toll on local forests, the only source of fuel for heating, cooking, and smelting.9 Surveying the effect of deforestation, Plato remarked about the land, no longer protected by the canopy of the woodland against the erosive forces of rain, sun, and wind, “What now remains compared with what then existed is like the skeleton of a sick man, all fat and soft earth having wasted away, and only the bare framework of the land being left….There are some mountains which have nothing but food for bees, but they had trees not very long ago, and the rafters from those felled there to roof the largest buildings are still sound.”10
The people of Delos imported all their charcoal, since no trees grew on the island, creating a seller’s market for heating fuel. Realizing the unfair advantage that sellers of charcoal enjoyed, legislators passed laws regulating the trade to protect consumers from price gouging.11
These measures coincided with the popularization of solar architecture there, no doubt also a response to the scarcity of wood.
Later residents of Priene were fortunate that their predecessors had planned the city for solar heating. Farmers rapidly turned the wooded area around the local river — the Maender — into wheat fields. With the forest canopy gone, rains throughout the watershed sent floods of mud into the river. The consequent infilling of Maender Bay with silt transformed the sea formerly adjacent to Priene into dry land, causing the city to lose its coastal location. Although accelerated erosion dashed any hopes of the city becoming a great port, the solar design of its homes at least made the residents less vulnerable to rising charcoal prices.12
How Well Did Solar Design Work?
According to Isomachus, a character in a Socratic dialogue by Xenophon, Greek solar architecture was highly effective. Isomachus brought his bride to his solar-oriented home and “showed her…living rooms for the family that are cool in summer and warm in winter.” He told Socrates, “The whole house fronts south so that it is…sunny in winter and shady in summer.”13
Empirical evidence confirms Isomachus’s praise. The Architect Edwin D. Thatcher studied the solar-heating capability of rooms facing south to determine the feasibility of indoor nude sunbathing during the winter. To simulate actual conditions, Thatcher relied on weather data for a climate similar to that of ancient Greece and western Turkey. He found that a naked person sitting in the sunny part of such a room would be relatively comfortable on 67 percent of the days during the colder months of November through March.14 The room used for this study was not as well protected as an average Greek living room, however — and of course the residents of the latter would have been clothed most of the time. It seems safe to say that for most of the winter the sun would have adequately heated the main rooms of a Greek solar-oriented home during the daytime. When solar heat was insufficient, charcoal braziers could be lit.
The great playwright Aeschylus suggested that a south-facing orientation was a normal characteristic of Greek homes. It was a sign of a “modern” or “civilized” dwelling, he declared, as opposed to houses built by primitives and barbarians, who, “though they had eyes to see, they saw to no avail; they had ears, but understood not. But like shapes in dreams, throughout their time, without purpose they wrought all things in confusion. They lacked knowledge of houses…turned to face the sun, dwelling beneath the ground like swarming ants in sunless caves.”15
Excerpted from the book Let It Shine. Copyright © 2013 by John Perlin. Reprinted with permission from New World Library.
An international expert on solar energy and forestry, John Perlin has lectured extensively on these topics in North America, Europe, Asia, and Australia. Perlin is the author of A Forest Journey: The Story of Wood and Civilization. Perlin mentors those involved in realizing photovoltaic, solar hot-water, and energy-efficiency technologies at the University of California, Santa Barbara (UCSB), and coordinates the California Space Grant Consortium as a member of UCSB’s department of physics. www.John-Perlin.com. MARK Z. JACOBSON, PHD, is a professor of civil and environmental engineering at Stanford University and director of its Atmosphere/Energy program.
Author: Bliss
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