Technical Chamber of Greece 1 st Greek Chinese Forum on the environment 3-4 / 12 /2009 Thematic area: Bioclimatic Architecture GREEK TRADITIONAL BIOCLIMATIC ARCHITECTURE Christos Floros, architect 5 Avlidos Str, Athens 115-27, tel. 0030 210 7220628, e-mail: cfloro@tee.gr Bioclimatic architecture of the 21 st century resets the goal of human living in harmony with the natural environment. Fascinated by the technological achievements of the 20 th century, we built without limits, with the illusion that nature cannot punish us. Now that we understood that we must build ecologically, it is useful to investigate our traditional architecture that was integrated in the ecosystem. At the beginning of this paper, we present briefly the major components of contemporary bioclimatic architecture, with emphasis on minimizing the consumption of energy that is not derived from renewable sources, water saving, anti-heat provisions (considering the forthcoming climate change) and selection of building materials and techniques with ecological criteria. Subsequently, we examine how each one of the above stated components of contemporary bioclimatic architecture, was realized in Greek traditional architecture and we present characteristic paradigms from various Greek areas. This investigation is useful in: a. promoting understanding of Greek traditional architecture through an ecological approach b. enriching the contemporary bioclimatic architecture know-how, so that it can be creatively utilized A THE MAJOR COMPONENTS OF CONTEMPORARY BIOCLIMATIC ARCHITECTURE A1 MINIMIZING THE CONSUMPTION OF ENERGY THAT IS NOT DERIVED FROM RENEWABLE SOURCES Given that the construction and the operation of buildings consume a great percentage of energy that is not derived from renewable sources and they release CO2, we must: o prefer materials that are created and transported consuming the minimum energy that is not derived from renewable sources o apply building techniques that consume the minimum energy that is not derived from renewable sources o design buildings so as to minimize the dependence of their operation upon not renewable energy sources o apply building operational systems that consume renewable energy sources (from the sun, air, water, land) A2 WATER SAVING Water saving in buildings can be attained with the following methods: o collecting rainwater o designing the most suitable hydraulic facilities o recycling waste water 1
Water saving in the surrounding landscape can be attained by permitting the soil to absorb rainwater to enrich the aquifer and allow the function of the hydrological cycle. It is also important to choose planting belonging to the ecosystem of each area, that does not require frequent watering. A3 ANTI-HEAT PROVISIONS Anti-heat provisions are vital due to climate change. In warm climatic areas, active cooling of buildings is more energy consuming than their active heating. A3.a BIOCLIMATIC BUILDING DESIGN A3.a1 minimizing direct solar gain The major source of unwanted summer heat is direct solar gain. One of the primary concerns in design should be minimizing the loads that impact our new buildings, thus ensuring the success of any potential cooling strategies. Buildings should be designed with emphasis on: A3.a1.1 avoiding extensive glazing A3.a1.2 locating window openings with climatic criteria A3.a1.3 thermal insulation A3.a1.4 passive radiative cooling A3.a1.5 external shading A3.a2 natural cooling Natural cooling can be very effective. It can be attained through: A3.a2.1 natural ventilation A3.a2.2 evaporative cooling A3.a3 ground cooling The dissipation of the excess heat of a building to the ground is very effective, when building temperature is higher than ground temperature. It is attained either with passive ground cooling or with hybrid ground cooling techniques. A3.a4 outdoor living Use of sheltered open-air spaces for out-door living (atriums, porticoes, verandas, covered balconies) make life more comfortable during warm days and nights. A3.b BIOCLIMATIC DESIGN OF BUILDING SURROUNDINGS A3.b1 landscape Minimizing site areas covered with pavement is an antidote to the Urban Heat Island phenomenon. A3.b2 natural ventilation routes Buildings must be located so as to create free routes for natural ventilation. A3.b3 appropriate tree planting Trees must be suitable for the ecosystem of each area, provide proper shading and not disturb natural ventilation. Deciduous trees can be utilized more effectively. A4 SELECTION OF BUILDING MATERIALS AND TECHNIQUES WITH ECOLOGIC CRITERIA Building materials and techniques must: o not release great quantities of CO2 o not destroy O3 in atmosphere 2
o not require great consumption of not renewable energy sources Materials, in particular: o must be recyclable o must be users friendly o their extraction must not damage the natural environment B THE MAJOR COMPONENTS OF GREEK TRADITIONAL BIOCLIMATIC ARCHITECTURE B1 MINIMIZING THE CONSUMPTION OF ENERGY THAT IS NOT DERIVED FROM RENEWABLE SOURCES B1.a MINIMIZATION OF ENERGY CONSUMPTION FOR BUILDING MATERIALS TRANSPORTATION Through a disturbed ecological approach, we often choose materials that are friendly to the environment, but are imported from remote areas (e.g. wood imported in Greece from Indonesia). Energy consumed for transportation of materials, is one of the major factors that are responsible for environmental degradation. The modern movement in architecture neglected localism and caused to increase this degradation. Use of local building materials in traditional architecture, was due to limited transportation potential, in older times. Nevertheless, ecologically was a perfect choice, and contributed substantially to the morphological wealth of Greek traditional architecture. When building materials with special properties were required, they searched out to import them from the nearest of the areas where they could be found. B1.b MINIMIZATION OF ENERGY CONSUMPTION FOR HEATING BUILDINGS Minimization of energy consumption for heating buildings can be attained through proper design, minimizing heat loss. Thick stone or brick walls had a great thermal mass. Living spaces (particularly those used during winter) had small external openings. There was often extensive earth contact, not only in semi buried buildings, but also in buildings where some of their walls were in contact to sloping ground. The basement of some houses was used as animal shelter. Animal heat warmed human living spaces on the above storey, as a heat transparent wooden floor separated them. We shall refer to thermal insulation later. B1.c USE OF WATERMILLS AND WINDMILLS Watermills and windmills are some of the most interesting buildings of Greek traditional architecture. Designed with special expertise in the use of renewable energy sources, they are morphologically landmarks of our traditional settlements. B1.c1 Watermills With watermills, waterfall dynamic energy was used to operate machines for grain milling, powder milling, tannery, ice production and marble cutting. Watermills can be considered as ancestors of contemporary hydroelectric projects. 3
B1.c2 Windmills Windmills built from the 12 th to the 19 th century used wind energy for grinding grain. They were mostly built on islands that do not have waterfalls, while they have strong winds. Some windmills were built in the mainland too. B2 WATER SAVING B2.a CISTERNS Water saving in traditional buildings in areas with no rivers and water springs, is realized by collecting rainwater in cisterns. Cisterns were constructed in the basement of the building or in outdoor area near the building. Outdoor cisterns are roofed. Rainwater is mostly gathered on flat roofs. From the roof is driven to the cistern through vertical clay gutters. In some cases, rainwater falling on sloping or vaulted roofs, is driven to the cistern through sophisticated constructions. Traditional building technology makes most cisterns absolutely watertight. Public fountains, built mainly in the 18 th century, are interesting architectural constructions that use water stored in vaulted cisterns. B2.b BUILDING SURROUNDINGS In building surroundings the ground is not paved, where it is not urgently needed. Consequently, rainwater enriches the aquifer and the hydrological cycle functions properly. B3 ANTI-HEAT PROVISIONS In the Greek area, particularly south of the 39 th parallel, one of the main objectives of the traditional architecture was to avoid overheating of the buildings. B3.a BIOCLIMATIC BUILDING DESIGN Almost all components of the contemporary bioclimatic architecture existed in Greek traditional building design. B3.a1 minimizing direct solar gain B3.a1.1 avoiding extensive glazing There is not extensive glazing in traditional Greek buildings B3.a1.2 locating window openings with climatic criteria Since antiquity builders were interested in locating window openings with climatic criteria. In general, they preferred to locate the larger openings on the southern and eastern walls. They tried to avoid openings on the northern and western walls. Nevertheless, they created small openings on the northern walls to attain natural cooling during the warm periods. Arrangements differ depending upon the microclimate of each area. B3.a1.3 thermal insulation There was no special provision for thermal insulation. However, flat and vaulted roofs provided some thermal insulation. Under sloping roofs, wooden false ceilings were constructed, creating a vacant space that helped to insulate the functional spaces underneath. B3.a1.4 passive radiative cooling In Cycladic islands (in the Aegean Sea) building cells are painted absolutely white. Continuous whitewashing maintains this absolute white. Consequently the 4
greatest percentage of long wave sun radiation is reflected and does not over warm the buildings. Recent research worldwise concludes that we must paint white at least the roofs of buildings or apply white coverings. Scientists refer to the successful white painting of buildings, applied in the Cycladic islands and in other Mediterranean areas. B3.a1.5 external shading External shading is attained with projecting canopies, arbors, trees and climbing plants planted in proper places. Loggias shade window openings behind them. Wooden window shutters, either solid or French type regulated entrance of sunlight in building interiors. B3.a2 natural cooling B3.a2.1 natural ventilation Main window openings were placed, if possible, at the southern or eastern external walls of the building and small openings were created at the top of external walls, opposite the main openings and preferably on the northern walls. During summer etesian winds, they left the windows open and wind flow entering from the small northern windows run through the building, cooling it. During summer nights, when external temperature is lower than the temperature inside the building, hot air flows out through the small top windows and through the chimneys. B3.a2.2 evaporative cooling Evaporative cooling was a technique used in ancient Egypt and Persia. In warm Greek areas there is not adequate water, in general and consequently evaporative cooling is not used in traditional Greek architecture. B3.a3 ground cooling Passive ground cooling is provided during the warm periods in semi buried buildings and in buildings where some of their walls are in contact to sloping ground. There are many semi buried buildings in Thira (Sadorini) island where excavation of volcanic earth is easy. B3.a4 outdoor living A famous Greek author wrote that Greek living, is outdoor living. Particularly, south of the 39 th parallel, the climate is so friendly, that people avoid most of the year the internal built spaces, preferring to live in roofed spaces that have at least one of their sides open to the natural environment. Designing semi-open-air spaces with appropriate orientation was a critical bioclimatic option, as it created pleasant and healthy living, when the weather was not bad, without need for expensive constructions and without energy consumption. It is astonishing that semi-open-air spaces exist in Greece continuously from ancient times till now. B3.a5 designing different spaces for winter and summer North of the 39 th parallel in Greece, there is a great difference in temperatures from winter to summer. So, as there were no active systems for controlling building temperature, they had different living rooms for winter and summer. Winter living rooms were positioned in the lower storeys, behind thick external walls with small openings. Summer living rooms were positioned in the upper storey, behind thin external walls with large openings and they had proper orientation. Overheating was avoided through: 5
o cross ventilation o building envelopes with small thermal mass (because the night period is not long enough to cool building envelopes with great thermal mass) B3.b BIOCLIMATIC DESIGN OF BUILDING SURROUNDINGS B3.b1 landscape Limiting pavement area to the minimum essential, overheating is avoided. This also contributes to the proper functioning of the hydrological cycle. In Cycladic islands the perimeters of each paving slab and their joints are whitewashed. This is a great percentage of the total pavement and heat absorption is limited. B3.b2 natural ventilation routes Aristotle, Ippodamos, Xenophon, Vitruvius and other great men have investigated the buildings layout in settlements. One of the criteria in creating the layout of Greek traditional settlements, is the protection from the wind or the utilization of the wind for cooling and clearing the settlement, depending upon local characteristics. In warm areas, traditional settlements have layouts that permit the undisturbed wind flow, so as to create natural ventilation of the streets and to promote natural ventilation of the buildings. The serpentine layout of the narrow streets of the traditional central settlement of Mykonos island, is a characteristic example, as it fully utilizes the etesian summer winds to cool both the settlement and each building and also to remove atmospheric pollutants. B3.b3 appropriate tree planting It is obvious that they selected planting belonging to the ecosystem of each area. They used trees, arbors and other planting to create shadow. Deciduous trees were used to create shadow during summer and not to disturb sun penetration during winter. They never disturbed with planting the wind flow that was required for cooling. B4 SELECTION OF BUILDING MATERIALS AND TECHNIQUES WITH ECOLOGICAL CRITERIA Building materials and techniques used in Greek traditional architecture: o did not release great quantities of CO2 o did not destroy O3 in atmosphere o did not require great consumption of not renewable energy sources Materials, in particular: o were recyclable o were users friendly o their extraction did not damage the natural environment. 6