Contemporary energy conservation efforts emphasize architectural and engineering solutions. Green building is a trend, still divorced from the landscape and the garden, both which are green to begin with. Integral to any discussion of sustainability or green building should be a consideration of the capacity of the designed landscape to create and modify microclimates and thus conserve energy.
Prior to the oil embargo of 1973 which alerted the world to its overdependence on diminishing fossil fuel reserves, building and growth patterns had become extremely wasteful. In reaction to the prevailing attitudes that our energy supplies were inexhaustible, many architects and landscape architects began to investigate passive design techniques. Unfortunately, our fascination with later Information Age technologies diverted our attention away from these early advances and investigations.
Many of the principles of passive design explored in the 1970s had their origins in the distant past. Throughout landscape history, the harsher the climate, the more ingenious the devices and methods became for creating physically comfortable spaces. A review of historical gardens would reveal many precedents for energy efficient design. In fact, the principles of climatic site planning reach back thousands of years. In Mediterranean climates, such as ours, people lived in close connection with the landscape, adapting their environments to create comfortable living spaces by observing natural patterns and systems. One doesn’t need a complex computer model to understand how the sun moves across the sky.
The move towards an energy responsive ethic provides us with a second chance to incorporate the knowledge and methodologies from our ancient and recent pasts and implement these ideas on a large scale.
EarthAs early 36 BC, Varro identified the southeast-facing hillside as the ideal location for a villa. (The form of the typical “suburban” villa included house and grounds together with the total complex understood as a unit.) The southeast orientation allowed the dwelling and the garden to catch the prevailing summer breezes and block the cold northern winds in winter.
During the Renaissance there existed a “Canon of Horticultural Rule” which presented a format for placing elements in the landscape. According to the canon, the bosco or planted woodland was an integral element of the site plan. A dense plantation of evergreen trees placed on the northern side of a structure not only blocked the winter winds, but also played an important ecological role, providing abundant vegetative mass for photosynthesis and wildlife habitat. This is an extremely important lesson for contemporary design: establishing a ratio of vegetative mass to built form and maximizing tree canopy can provide great climatic benefit. A plantation mass can effectively block the sun, and thus reduce ground level temperatures and insulate buildings. Planting large areas of deciduous trees with broad canopies will produce significant quantities of oxygen, while reducing ambient temperatures in the summer.
Contemporary ideas of passive solar design are also rooted in history. All living material can trace its origins to the heavenly fire. Without the sun we cannot thrive. In the past, solar orientation was a guiding principle in laying out garden and dwelling. Leon Battista Alberti promoted the common-sense use of passive solar design as long ago as 1482. He believed that loggias should be designed not only to capture beautiful views, but also to provide year round comfort by admitting sun or breezes, depending on the season. Alberti even proposed the use of glass to keep out the winter wind and let in the undefiled daylight.
Pliny the Younger’s Laurentine villa near Rome contained a unique solar device called the heliocaminus, or heated sunbath, which was a garden room enclosed on four sides and open to the sky to capture the sun’s rays. The solar-heated heliocaminus of the Romans evolved into the giardino segreto or secret garden, ever popular in Italian Renaissance gardens. Usually a sunken space with decorative stone or stucco walls, the enclosed room deflected cold winds and collected heat from the sun. One of the finest examples of the giardino segreto can be found just outside of Florence on the grounds of the Villa Gamberaia. Located directly across from the central entrance to the villa is a narrow secret garden, hardly more than 20 feet across and 100 feet long. This diminutive garden runs east to west to ensuring exposure to the morning and afternoon sun.
Being aware of the movement of the sun also allowed Renaissance designers to develop garden elements for the year-round growth of crops. The limonaia was one of the first solar-powered spaces in temperate climates that harnessed and stored solar energy for the winter storage of citrus plants. Similar in form to the loggia, the limonaia faced south and was enclosed with large plates of glass, like a greenhouse. Operable windows regulated interior heat. Plants were placed on tiered platforms at the base of the solid north wall to receive plenty of sunlight.
The Villa Medici at Castello, a few miles from Florence, had over 300 varieties of fruit trees in cultivation, essentially making this villa a functioning agricultural landscape set within a beautiful formal garden. The ornate formal gardens of the Italian Renaissance, so often criticized as exercises in geometry imposed on nature, continue to have relevance for designers and planners today. As agricultural centers they provided sustenance for not only their owners, but the families that cultivated and maintained them. Most of the farming villas produced cash crops and could be considered self-sustaining in many respects.
The limonaia, integral to the Italian garden, can be retrofitted into contemporary gardens to serve as the foundation for sustainable communities. Relevant today for its ability to capture and store the sun’s heat, a limonaia can be an instrumental device for growing food as we move towards a more sustainable future where gardens provide not only beauty, but sustenance.
AirGarden designers have sculpted the movement of air and designed air-cooled spaces throughout history, particularly in Mediterranean climates. Today’s designers can exploit the cooling effects of moving air to reduce the energy and environmental costs of using mechanically-cooled air-conditioning systems. Microclimates can be designed to take advantage of the cooling properties of air flow. Air can be directed, funneled, and accelerated with simple landscape and architectural forms such as seats, arbors, pergolas, garden pavilions and porches.
The Alcazar Gardens of Seville contain one of the cleverest air-cooled seats in garden history. This extraordinary bench is situated in the Jardin de la Danza, a small garden room within a series of enclosed patios. Extremely thick walls enclose the garden on the east and west, while the southern wall addresses the prevailing summer breezes with an intimate niche. Between two built-in benches, a small arched window with a decorative metal grill frames a picturesque view of the adjacent lower garden. As the breeze flows, it is forced through the small window, thus increasing its velocity at its point of exit on the opposite side of the opening. (We now understand this phenomenon as the Venturi Effect.) In addition to being naturally air-conditioned, the enclave remains cool in the summer because the thick walls that enclose it act as an insulator, while the white walls reflect the heat produced from the intense rays of the sun. This ingenious form of air conditioning remains effective to this day.
Alleés are parallel rows of evenly planted trees placed on either side of a path, avenue, or roadway, and are usually long enough to create a walk or promenade of some distance. They are commonly used to direct views, organize spaces, create vistas, and unite various parts of a garden. An alleé can also stimulate the movement of air and be used to direct air currents into specific areas of the garden, garden structures and dwellings. When planted along south-facing slopes, alleés benefit from naturally rising air currents that push air from the shaded space into building interiors.
In desert climates garden pavilions were commonly built with a south-facing porch balanced over a large pool. The shaded interior porch with its high ceiling would catch the cooled air that passed over the pool. Many variations were possible, but a connection to the garden was essential. To augment the cooling effect of the porch, the Persians suspended a curtain from the façade of the pavilion to block the hottest rays of the summer sun. The curtain was pulled back in the winter to allow the sun to enter and warm the space. A soft and luminous quality of light filtered through the fabric. When the curtain was fully extended over the pool, it acted as a large air scoop, concentrating the ephemeral breeze, and capturing water evaporating from the pool. In addition, the cloth could be moistened with rose water, cooling and scenting the interior as the moisture evaporated. The Persian garden pavilion and the Italian summer house are both designed for natural coolness. As intelligent passive design devices they represent relevant footprints for reducing energy consumption in the contemporary built environment.
WaterThe importance of water as a commodity cannot be underestimated, especially in California. Without water there can be no life. And in past cultures, the collection, storage, and movement of water was a priority in order to maintain a predictable supply throughout the year. Only then could passive microclimates be enjoyed and the art of the garden flourish.
In California, every drop of water that falls on a site should be captured and stored. Extremely high temperatures combined with lengthy droughts have turned the American west into a tinderbox. In many regions of the world water is being used more quickly than aquifers can be replenished. Water tables are falling. If this trend continues it will have a profound impact on food production and living standards.
The control and disbursement of water in California has become a politically explosive issue. Perhaps only through enlightened watershed management and a change in public attitudes toward consumption can a dependable supply of clean water be preserved. Continued research of both historical precedents and current technologies, combined with the promotion of sustainable agricultural practices, are the first steps towards redefining our relationship with water. Water is not merely a resource to be exploited for human convenience, but rather a nurturing force that links and sustains all life on earth.
In many arid climates cisterns were used as a fundamental method of storing as much rain water and runoff as possible for use during the dry season. In Los Angeles, before aqueducts brought water from the north, residential cisterns were critical elements in a system that had to balance the effects of both droughts and floods. This tradition can be resurrected in the contemporary landscape. Runoff can be directed into insulated closed cisterns built into new structures or retrofitted into existing structures.
Long before modern drip irrigation, the Persian gardener developed a simple yet efficient method for subsurface irrigation. In Yazd, one of the hottest spots on the Iranian plateau, “condensing jars” significantly reduced the amount of water lost to evaporation. Earthenware containers were placed in the soil between rows of plants, set with their narrow necks protruding just above the surface. When filled with water these containers “sweated” moisture through their porous earthen sides, directly irrigating the roots of the vegetation. Condensing jars, removed from exposure to sun and air, effectively conserved water by protecting it from evaporation.
Aerated water was often employed to cool garden structures. Forcing water under high pressure through miniature openings or thin slots would suspend fine drops of water in the surrounding air, humidifying it and lowering the temperature. To produce this effect, water would first be pumped into reservoirs on the roof. With gravity pressure, the water would descend through columns pierced with thousands of tiny holes, creating an almost invisible mist that gently cooled the room. Aerated by thousands of tiny misting jets, these garden rooms were a tranquil oasis for the body and mind.
Many advances have been made in green architecture and alternative building. The US Green Building Council has established standards for sustainable buildings. However, these achievements need to be integrated with energy-conserving, sustainable landscapes that create new gardens on a regional scale. New and exciting opportunities lie ahead for the creation of unified garden and architectural forms that not only conserve energy, water, and agricultural lands, but are also works of art and places for spiritual renewal.