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Passive Solar and Wind

What is it? --- How does it work?--- Cost to Implement ---Statistics ---Other Considerations

History--- Troglodytes--- Moorish Reflecting Pools--- Frank Lloyd Wright

Sun Veins --- Awnings--- Shutters--- Screens--- Veins

Examples--- Greensville--- Braydon House Puslinch--- commercial


What is it?

Passive Solar is using sunlight both to heat the interior of a building and to encourage airflow through a structure. There are no mechanical or electrical systems in place to aid this energy transfer. In contrast, solar panels require both a storage device and the means to transfer and implement the energy in addition to the panels themselves; an initial source of power is needed to get the process moving. With passive solar, all you need is a good design.

How does it work?

Depending upon your position on the planet, the sun will shine directly overhead in the summer, and then at varying angles down towards the horizon as winter approaches. On the winter solstice, December 21 in the north, the sun is very low. On the summer solstice, the sun is very high.

Art Moderne House

Passive solar works best when there are very large windows on the south side of the building with correspondingly large overhangs. In the summer, the roof receives all the light from the sun and the overhangs shade the windows, preventing the sun from entering the room.


In the winter, the sun enters the room and heats up the floor, walls, and furniture. Stone, brick and heavy wood tend to retain more heat than less dense materials. In technical terms, the solar energy is transferred to the thermal mass which retains the heat and then disperses the heat as the solar energy disappears.

If an overhang is impossible to arrange due to the design of the building, planting one or more deciduous trees on the south side of the house and putting in large windows will be effective as well.


In the summer the leaves of the trees will block the sun from entering the rooms.


In the winter, the sun shines through the tree entering the room and heating up the floor, walls, and furniture.

Cost to Implement

If your house is designed with passive solar in mind, it is not in any way more expensive than other designs. In fact it can be less expensive. If you are looking at renovating your house, instead of the relentless beige on beige stucco, huge wasteful roofs and meaningless quasi-Roman detailing, consider looking at Frank Lloyd Wright's work for inspiration. The Robie House is possibly the best example of a very nicely placed large overhang.

For those with a limited budget who want to make a very inexpensive change, put a few very large windows on the south side of your house. Plant a few trees, and the savings in heating will be realized in a few years. You may need to use an awning or window coverings until the trees are the right size. The owner of the Greensville example turns off the heat in the house during sunny days from December to March.


I haven't found any stats yet.

Other Considerations

This method of heating your house is dependent upon sunshine. You will need another method of heating as well. Some areas of Ontario have higher rates of sunshine than others.

This reference gives annual rainfalls for each area of Ontario, but does not give the annual sunshine factor. These factors are very much dependent upon the proximity to both water and "mountains", such as the Niagara Escarpment.

www.climate.weatheroffice.ec .gc.ca/climate_normals/stnselect_e.html

Type of Glass
Plain, untreated double or triple glazed glass is the best. Low-E window glass treated with a coating to lower heat loss and reduce UV rays that fade carpet and furniture will also reduce solar heat gain. You must keep sensitive fabrics and carpets away from the sunlight.


History of Passive Solar

Anyone who has spent time in the Mediterranean, the Caribbean, or other tropical places will have a hard time identifying with this information on passive solar. To tropical people this is second nature. Living outside for a large part of the year, it is only natural to live in harmony with the sun, to use the shade in the hotter months and the warming rays in the winter.

In contrast, most modern Canadians live in an environment very much removed from the natural elements. In the summer we live in air conditioned houses, cars, shopping plazas and offices. In the winter these same places are heated. The temperature outside is a matter of indifference to most people.

Some 40,000 years ago, Cro-Magnons, the precursor to modern man, were starting to develop villages in Africa and parts of Europe. By 3000 BC this process was speeded up by Bronze Age and later iron man. For all theses peoples, the obvious choice of a good permanent address was naturally occurring caves and rock recesses. In many countries of the world, the rock was sufficiently pliable that carving out a niche in a desirable location was an option.

Consider this: if you were going to embark upon a one or two year carving session to whittle out the home of your dreams from a solid rock face, wouldn't you spend a bit of time considering the location?


Les Baux de Provence

One of the earliest homes in Les Baux de Provence, a village near Avignon France, is a very comfortable two room home. The door opens onto the south side of the rock. By December 21, when the sun is at its lowest on the horizon, the sunlight advances across the floor and up to the top of the bench shown.

In the summer, the sun only reaches a few feet into the entrance, the rest of the home remains cool.


Les baux de Provence


Les Baux de Provence

Just up the path is a home that is as well chosen as the last. This photo taken at 4:30 in the afternoon in February shows the sun just drawing away from the inside of the building.

The window at the back opens up to a shear cliff dropping some 100 feet. In the summer the moving sun would cause a breeze to lift out of the valley at the bottom of the cliff an cool the room.

Les Baux de Provence


Les Baux de Provence

Other houses were carved out of the rock face of a southwest facing rise on the plateau. Inside the house, sections of the walls were carved out to form basins for water and oil .The region produces some of the best olive oil in the world, There is evidence in the Bible and other sources, that olive oil was produced several millennia before the birth of Christ.

The image on the right shows a water gully coming down from a plateau higher up. Rainwater was collected on the plateau, then directed down the gully to a stone barrel below.

Small holes on the exterior wall were for pigeons - an original dove cote.

Les Baux de Provence

Castle Zisa
1166 - 1175

This is a Moorish castle, intended as a summer castle, built by Norman William I d’Altavilla and finished for his son, William II. It is a masterpiece of natural air conditioning.

The entrance façade is on the east side. Three large arches on the façade open onto a large pool fed from a fountain inside the large arch.

The morning sun heats the east side, the front façade, and a draft is created up the east side of the building, entering through the arches and proceeding to the Fountain Hall (below).

Castle Zisa

Castle Zisa

The air is drawn through this interior corridor into the cool room of the Fountain Hall shown below. This is a Moorish design. The moors were fluent in methods to accommodate architectural form to the climate. a signature element is always a large pool that helps move air and regulate climate.

The large expanse of water of the pool in front of the façade helped both to decrease the ambient temperature during the hot hours of afternoon and increase air movement. The building is cooled by the simple but effective method of temperature and pressure differential.

The cool, evaporating water of the pool water draws in the relatively warmer air on the lawns surrounding the castle. These are then drawn through the arches and this porch and into the Fountain Hall (below).

Castle Zisa

Fountain Hall
Castle Zisa

This hall has a fountain in the center with a reflecting pool. There is a series of vertical passages that conduct the air up through the building cooling it.

Air passes through hidden passages upwards into the building, implementing an ingenious form of natural air conditioning.

The three open rooms on the room were intended as recipients for rain water, which were channeled downwards through hidden canals within the building towards the fountain in the ground floor and ultimately feeding the outside pool.


Castle Zisa

Castle Zisa - diagram

Note the diagram is not done yet.

Hospital of the Innocents

Temperature and Pressure Differential Iran

The Persians and the Moors were the people who did the most significant work with temperature and pressure differentials.

In almost every castle from Iran through North Africa and into Spain, there is a large body of water in front of the building that creates a breeze into the arcades of the building. This large private house, now a museum, is closed up for winter, the arches are filled with glass, but the reflecting pool is still a visual delight in the inner courtyard. In the summer this pool would help to cool the house.

In mosques and public squares the reflecting pool has a religious significance. Like most conventions attributed to religion, this has a scientific base.

Shiraz Iran


On the east side of the pool, there is an arcade that opens up onto the garden area. Inner courtyards are the norm in temperate climates both for privacy and safety as well as to contain the microclimate that is created by the pools. The air circulates over the water, is cooled, continues along the arcade and then circles back to the water. The air becomes cool as well as humid.

Shiraz Iran

Alcazar Cordoba Spain

Up until 1492, Spain was fortunate to experience a unique cohabitation of Moslems, Jews and Christians, all sharing the knowledge that came from each individual culture. This sophisticated culture spawned some of the best architecture and intellectual thought in Europe. The Alcazar palace was built in 1328 by the Moorish King Alfonso XI. It was later taken over by the Christian Kings. The palace has a continuous river of reflecting pools which start in the palace courtyard.

Cordoba Spain

Alcazar Cordoba Spain

The pool continues to reach out into the garden. The hot air concentrated on the mass of stone and in the surrounding garden is cooled by the flowing water. The temperature and pressure differential cause breezes to flow gently across the terraces and into the surrounding building.

When the Christians took over the building, they recognized the value of the Moorish design and maintained it. Also maintained are a few Arab bath houses.


Alhambra Granada Spain

The many reflecting pools in the Alhambra, Spain, have the same effect. The hot air from the very arid surrounding area is drawn across the pool where it cools and then continues into the arcade where it refreshes the interior of the building.

In many of the reflecting pools fish are kept both to help clean the water and to eat.

Granada Spain

Robie House

Chicago 1908

Possibly Wright's most famous residence, the Robie House has all the distinctive features of a Prairie style home. It is long and low. The roof projects out over the windows and the courtyards to provide privacy and a sheltered area outside. Being directly on the sidewalk, Wright used brick walls to enclose the entrances and clerestory windows for privacy.

Robie House

Robie House

Wright 1908

During the summer the overhang provides a large shadow that keeps the inner courtyard cool. During the winter, the sun heats up the wide expanse of brick and stone making the courtyard a small, relatively warm and protected enclosure just out side the front door.

Robie House

Hill House 1903

The roof on a house with a large overhang does not need to be flat. Here on the Hill House of 1903, the roof has a vaguely oriental look. The windows are still protected from the sun during the summer months and full of sunlight in the winter.

Hill House

Susan Lawrence Dana House 1903 Wright

Again in the Dana House of the same year Wright pursues the idea of an oriental looking roof with a large overhang. In all of these houses Wright also has large brick courtyards that would retain the heat of the winter sun around the house.


Heurtly House
Oak Park 1902

The Heurtly House in Oak Park has has a large overhang and clerestory windows. It is very close to the street, but also very private.

Heurtly House

Heurtly House
Oak Park 1902

The doorway has a Romanesque simplicity. The door itself is recessed, quite a distance from the entrance. It is all masonry, providing good thermal mass to accept the heat from the sun in the winter and heat up the entranceway itself.

Heurtly House



Following are some examples of both residential and commercial properties that have been successful in employing passive solar designs.




This house in Greensville was built in 1955. The design is quite obviously inspired by Frank Lloyd Wright, and the use of passive solar is deliberate.

This photograph taken on the winter solstice, December 21, shows the sunlight flooding the room and extending across the floor and onto the furniture along the far wall some 15 feet into the room.

On sunny days, the owner simply turns off the heat between 9:00 in the morning and 5:00 at night. The curtains are drawn at sundown and the heat is retained for a few hours.



Taken at the same time of day, 12:00 noon, on the spring equinox, March 21, the sun barely enters the room at all.




The Braydon House in Puslinch uses the same principles as those shown above. The overhang on the south side prevents the sun from entering the house during the 'dog days' of July and August. A deciduous tree grown on the same side of the house does the same thing. In the summer the leaves take the sunlight and use them for photosynthesis. In the winter, the tree has no leaves and the sun enters the house directly.

This photo, taken near 12:00 noon on October 3 shows the sun coming down slightly under the overhang.



This photo shows the inside of the room on October 3 at 12:00 noon. The sun enters and heats the floor near the window, but doesn't enter the whole room.

The weather this time if year can be anything from 10 degrees to 25 degrees during the day. The sunlight warms part of the room, but would not be stiflingly hot if it was a sunny, hot day.



The West side of the building is covered with a large verandah which protects the door and windows on the west side of the house from the late day sun in summer. In Winter, the verandah would be the warmest part of the exterior as the setting sun, low on the horizon, would create heat which would be trapped under the verandah and warm the door even in the dead of winter.




Early Renaissance Extra Reading and Films


Giedion, Sigfried, Architecture and the Phenomena of Transition, Harvard University Press, Cambridge, Mass.1971

Sullivan, Chip,Treib Marc, Garden and Climate, tural Press, New York, 1993

Vitruvius, The Ten Books on Architecture, translated by Morris Hicky Morgan, Dover Publications, New York, 1960.



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