(This paper presented at INDUSTRIAL ENERGETIC 2004 in Donji Milanovac,
organized by Society of thermal engineers of Serbia and Montenegro, September 2004.)
Nenad B. Miloradovic
THERMOTECHNIC - ENERGY SAVING - BUILDING STOCK - BIOCLIMATIC ARCHITECTURE - PASSIVE SOLAR ARCHITECTURE - NEOLITHIC - LEPENSKI VIR
STATEMENT BY DRAGOSLAV SREJOVIC, ARCHEOLOGIST
NEOLITHIC SETTLEMENT OF VINCA - THERMAL ASPECTS
(with Nenad Tasic, archeologist)
NEW BOOK ON SERBIAN:
THERMAL ASPECTS OF BUILDING CONSTRUCTION - BACKGROUND AND PERSPECTIVES
(SUPPLEMENT TO SUSTAINABLE DEVELOPMENT)
ARCHITECTURE OF LEPENSKI VIR AS A SIGNPOST FOR ENERGY EFFICIENCY IN BUILDING STOCK
Buildings are the greatest consumers energy for heating and cooling; therefore, our energy is highly susceptible to changes in outdoor temperature. Measures which contribute to energy efficiency in this area are thus of great importance.
Some of the measures which are still taken as guidelines for energy efficiency in building stock were already applied as early as in the Neolithic, in the architecture of Lepenski Vir. This relates to the selection of the site, the shape of the building envelop and its compactness, filling in earth and and imbeding the walls which are in the shade, etc. The energy of the period relied only upon fire made by burning wood and the heat from solar radiation. Passive techniques, now long forgotten,may serve as an example and inspiration for modern solutions based on new technologies. The issue of adapting to the climatic environment is still current, as it was long ago.
The book by Dragoslav Srejovic, archeologist, entitled ”Lepenski Vir, a new prehistoric culture in the Danube region”, published by Srpska knjizevna zadruga in 1969, is the major source of information on this pearl of the world architecture.
The energy crisis in 1970s caused an increased interest in solar and bioclimatic architecture. Excavations and research in Lepenski Vir was performed before this crisis. The ”time gap” was the reason why the thermal aspect of the architecture of this important Neolithic field was not paid sufficient attention in archeological research of Lepenski Vir.
The aim of this paper is to present the architecture of Lepenski Vir, which dates back from the Neolithic, in view of the highly organised skills with emphasized bioclimatic aspects. It could also be concluded that the constructors of Lepenski Vir were aware of the construction principles which ideally fit into the surrounding natural and climatic features, so the architecture of Lepenski Vir is an exceptional example for modern architects who wish to construct low-energy buildings (certainly, with some improvements of the long-forgotten skills). Energy may be saved by applying simple techniques and interventions, in case the natural environment is taken into consideration.
The paper consists of the following chapters: the introduction, the location and its natural environment, the description of Lepenski Vir architecture, elements of passive solar architecture and bioclimatic aspects of Lepenski Vir and the conclusion.
Utilization of solar energy is one of the oldest man’s skills. In the past, the man has always fulfilled his needs for energy with fire and resourceful use of solar radiation. The skills thus obtained significantly influenced development and advancement of mankind.
Nowadays, we are returning to solar energy utilization. In almost all countries, energy development plans include the following two items:
1. Development of renewable energy sources (solar energy, wind energy, geothermal energy, using waves, high tide and low tide and waterfall energy, biomass energy).
2. Rationalization of energy consumption (includes deliberation of energy efficiency both in the sense of the whole energy chain and its parts. Particular attention is paid to measures intended for improving energy efficiency).
Buildings, which are the greatest consumers of energy for heating in winter and cooling in summer, have significant impact on energy efficiency of the whole energy chain. Measures contributing to saving energy in this area have important influence on the stability of the energy system.
The objective of this paper is to present the architecture of Lepenski Vir, which originates from the Neolithic, as a highly organised skill featuring emphasized bioclimatic aspects. Passive construction techniques, which may be observed in the architecture of Lepenski Vir, may contribute to saving energy in future, in case they are applied within new, modern solutions which are based on new technologies.
THE LOCATION AND ITS NATURAL ENVIRONMENT
Lepenski Vir is an excavation field located on the right bank of the Danube in the Djerdap Gorge. It is well known for its art sculptures, remains of urbanized houses, graves, general purpose objects and unusual ornaments. This abandoned settlement is estimated to be about 7,000 years old. Professor Dragoslav Srejovic, PhD was in charge of archeological research in the period between 1965 and 1968, performed in order to protect archeological sites, which was necessary due to the fact that the ground was to be sunk for the purpose of setting in operation the hydro power plant Djerdap 1. The findings were excavated and relocated to another site situated just above the original one. The big artificial lake, constructed in 1970, rasied the level of the Danube by 12 meters on the average. Thus, evidence on life of people form the Neolithic was preserved.
The Djerdap Gorge is a natural area unique in Europe. As the Djerdap Gorge stretches in the direction west-east and due to its specific position, shape and relief conditions, it is a habitat of some rare plant species and a rich mixed community. The quick changes of the relief, climate, plant and animal species take place in close areas, both horizontally and vertically. Taking this into consideration, the Djerdap Gorge consists of numerous and various micro-habitats.
Running deep into the Carpathian mountains, the Djerdap Gorge is sheltered from sharp climatic influences from the North and excessive heat from the South. Due to a sharp turn southwards, air currents in the territory of Lepenski Vir are disrupted, so that the area has specific microclimate. This specific ”Djerdap climate” is featured by somewhat milder winters and moderately hot summers, with a later tempereture maximum (see: literature, Misic B., Colic D. and Dinic A (5), discussing meteorological parametres at the site before constructing the accumulation lake). Climatic conditions at the site are more favourable than those in areas out of Djerdap.
The vicinity of the river causes frequent precipitation and high relative humidity of the air; this results in frequent occurence of dew, fog and rainbow.
Due to the terrain configuration, Lepenski Vir is situated on the lee-side, surrounded by a dense forest and high sheer cliffs, and the horse shoe-shaped plateau on which the settelement was constructed is very insolated in the morning. The configuration of the terrain was also the reson for the settlement to be turned towards the river, so that the whole settlement was in the shade in the afternoon, which was pleasant for the summers.
ARCHITECTURE OF LEPENSKI VIR - DESCRIPTION
The book “Lepenski Vir, nova praistorijska kultura u Podunavlju” (Lepenski Vir, a new prehistoric culture in the Danube region), published by Srpska knjizevna zadruga in 1969, is the main source of information on this pearl of the world architecture.
The architecture of Lepenski Vir is the first meaningful architecture, based on a rational approach. It may be classified as original, because it was conceived by the generations which were becoming adapted to living in open spaces having left the caves. This is not about some individual or isolated facility, but a whole urban settlement located at the bank of the Danube.
The architecture of Lepenski Vir was clearly defined during the first phase of construction (Ia). It is this phase in which the manner of construction, the shape and arrangement of the houses, the main communications and the use of construction materials were conceived. Lepenski Vir Ia is the work of an exceptionally talented generation. Almost all the building structures are facing the river Danube and they have almost the East orientation. They follow the shape of the ground, and perfectly fit into the surrounding natural setting and environment. This also relates to the thermodynamical aspect, as the facilities are ”tucked” into the calcarenite base which has considerable thermoaccumulative characteristics. The vicinity of the Danube and the great mass of the river also contribute to the comfortable conditions at the site and damping temperature amplitudes.
All the houses have a trapezoid shape, with the longer base line contorted into an arch. It was established that 22 out of the 85 houses of theis shape were constructed in the first phase. All the houses in Lepenski Vir Ia were constructed in the same manner and using the same materials. Their shape is identical, as well as the arrangement of internal constructions and the proportions; the houses only differ in size. Materials used are wood and some types of coloured sandstone and limestone. The shape of the houses, as well as the manner in which they are connected and their position on the site are a result of elaborated and organised work.
Picture 1 – Photo of bases of houses in Lepenski Vir, taken from on-line literature (8).
The floors of the houses in Lepenski Vir settlement are of extraordinary construction. They are mainly made of arenaceous and marly red limestone, which was extracted above Lepenski Vir, from the slopes of Koršo mountain. The local red limestone was first kilned, and then added water, sand and fine pebbles to obtain a slush mass with properties of lime mortar. Before final thickening, this mass was polished or applied later as coating. Only after a while, after the water had been released, the floor would acquire certain strength. Today it appears petrified. The floor is 1-2 cm thick at the edges, and up to 25 cm thick by the hearth. The hearths were made from heavy stone blocks, 100x50x40 or 60x40x35 cm in dimensions, while the stone thresholds connect the hearths to the front. In literature (1), Ljubinka Babovic, art historian and an active participant in excavation and conservation, claims: “The floor is made from purple-red stone, and its base has a form of a shrine; the hearths are made of gray stone prisms, gray stone slates make the ashery, stone tables, triangular or arrow-shaped symbols around the hearth. Supports – the base and the stone ring encircling the floor of the shrine – marks of the upper construction, are constructed of the same material”. The base gets its final appearance only after the stone constructions are sunk into the ruddy floor mass.
As for the upper construction, only the traces of charred beams could be found on the floors of the houses. Due to the incline, it is certain that the houses had slanting walls, while the roof began form the ground level. As only the bases of the houses remained, the third dimension is unknown. It may be assumed that the roof construction was firm due to the wood beams which were covered in thatch (according to Srejovic) or leather and fur (as the remains of game found in the houses suggested that animals most frequently trapped were martens, badgers and beavers, as well as deer). As the third dimension has not been defined, we know nothing of the manner in which the inhabitants of Lepenski Vir dealt with smoke gasses from their massive hearths. The hearth, which is located at the very entrance of the house, could be directly connected to the atmosphere without a chimney.
As the terrain is sloped, the majority of houses were partly dug in. In the western part of the settlement they were dug in as deeply as one meter, while this feature is almost non-existent by the bank of the Danube. All this relates to phase Ia. The later settlements, constructed upon the rubbles of the old one, were located at somewhat higher grounds and could not be dug in, but had arched support walls up to one meter high. The forms of the bases were not as precise as they were before, and in phase II floors were never covered with lime mortar. This is why they were poorly fixed.
The architecture which appeared as the first comprehensive symbol remained so till the end of the Lepenski Vir culture. The shape created at the beginning of phase Ia became a pattern to be permanently observed. The standard and tradition were conceived, and the later changes did not considerably modify the structure of the settlement. The details which were subject to changes did not threaten the traditional pattern.
ELEMENTS OF PASSIVE SOLAR ARCHITECTURE AND BIOCLIMATIC ASPECTS IN LEPENSKI VIR
Some general rules must be taken into consideration when constructing low-energy buildings. One of the basic rules relates to the choice of site in which the house is to be constructed. In this sense, the architecture of Lepenski Vir fits perfectly into the natural environment. This relates bot to individual houses and the settlement as a whole. The position and the location of the settlement were carefully selected as a result of experience and rational approach, while the site by itself is exceptionally favourable. The vicinity of the river, rich in fish, enabled quick provision of food, and the steep cliffs prevented enemies and wild animals from getting in. Microclimatic characteristics and favourable characteristics of the site could be observed primarily based on the experience and long-term monitoring over natural phenomena, such as draining puddles and melting of snow (primarily under sun radiation).
The shape of the bases of the houses is exceptionally beneficial energy-wise. This primarily relates to the compactness of the form, as comfortable conditions in a facility and energy behaviour of a building depend on the ratio of the surface of the outer walls against the volume. The inside of the house performs heat exchange with the environment through its building envelop which has certain thermoinsulating features. If the surface through which energy transfer is performed is smaller, it is possible to achieve comfortable conditions in the building in the facility, or – as it is more current nowadays – to save energy for heating. The sphere is the most compact geometrical shape, while the cyllinder is the most compact cyllindrical body. Cyllindrical form of a convex trapeze has by 6% smaller ratio of the surface against the volume compared to the cube, and it is even somewhat better than the half-sphere. This is the scope to which energy may be saved, as architecture nowadays is mainly ortogonal (walls are placed at right angles). Comparing certain modern forms which have uinfavourable proportions with the shape of a convex trapeze, energy consumption in them is even greater. Even in modern facilities which have quality thermoinsulating materials it is possible to reduce consumption of energy if the compactness of the shape is taken into consideration. I would like to emphasize that the shape of the bases of houses in Lepenski Vir is a new, yet an old solution which contributes to saving energy. We may only make assumptions on the mathematical skills of the inhabitants of Lepenski Vir, as there are no written traces left. Much of their knowledge was lost in the vortex of time.
Picture 2 – Geometry of the bases of houses in Lepenski Vir according to Srejovic, downloaded from on-line literature (8).
We have already mentioned that the third dimension of the houses remained unknown. However, it is certain that walls were made of materials which may be destroyed by damp. The walls were placed at an angle, and the roof started from the ground level. This enabled fast drying of the materials under the influence of the sun, as slanting surfaces may receive more solar energy than vertical walls. The slope reduced compactness of the shape, but helped preserve the construction materials (possibly leather, furs or brushwood – materials succeptible to decomposition).
Orientation of the houses is also interesting. All the houses were facing the Danube, which was vitally connected to the settlement. All of them, except a few, are orientated towards the east. Bioclimatic architecture, a branch of architecture which takes meteorological conditions – primarily excposure to the sun - into consideration, claims that an ideal orientation towards the south is turned 12 degrees eastwards. (see: literature, (6), Pucar M, Pajevic M i Jovanovic-Popovic M). This relates to the flat terrain, and areas which are not exposed to excessive east wind influence. However, the terrain in which Lepenski Vir is situated is bordering a steep hill on the west, so that the whole site is in shade after 3 p.m. This is why its east orientation is favourable, as the houses are turned in such a way as to gain solar energy as much as possible. This is especially favourable in winters, when solar energy is needed for heating. The energy for heating was most needed in the mornings, when the outside temperatures are lower than maximum day temperatures and when the facility needs to be heated after a cold night. Therefore, in this site, firstly thanks to the configuration of the terrain, the orientation eastwards is more favourable than the theoretically better orientation southwards. This demonstrates well-harmonised relations between the need for energy and the power of solar radiation. Humid climate, where water frequently condensates in the form of dew, especially before the dawn after a cold night, as well as frequent precipitation and high relative humidity of the air result in the need for drying in the morning. Eastward orientation also provides the best comfort in summers, when outside temperatures are high, as the outside temperatures and gains from solar radiation act jointly in the afternoons, when the whole site is in the shade. All these elements have favourable impact on the comfort in the houses throught the year.
Picture 3 – Orientation of the settlement, taken from the literature (1).
The floor is made from lime mortar, which has similar thermal characteristics to those of bricks. Due to light weight of the upper construction, almost the whole mass of the facility is in the floor.
Thermoaccumulative characteristics of the materials used for the base make the floor act as a heat accumulator. I would like to point out that surfaces exposed to solar radiation are important in application in modern solar houses.
Good accumulative features of the floor area provide not only for acceptance of heat from solar radiation, but also enable keeping heat from the fireplace after the fire has been extinguished. As well as in case of all passive heating systems, comfortable conditions are provided using an active heating system. Additional heating in this case is obtained through a fireplace fitted in the floor, as a form of floor heating. The thickest layers of mortar are located around the fireplace. Modern tile stoves and electric thermoaccumulative heaters operate on the same principle.
The ability to absorb heat depends on the colour and roughness of the material. Dark colours absorb, while light colours reflect sun rays. Absorption-wise, the ruddy colour of the floor presents an acceptable solution. Apart from this, it is possible that the original colour faded due to tehrmophysical processes and contacts with air. The literature (1), however, states that the original colour was purple-red.
Vertical assymetry of the houses, as assumed by Srejovic, may also contribute to saving the energy for heating. The walls oriented toward the sun radiation gain are larger in space than the ones in the shade. For the inhabitants of Lepenski Vir, this meant faster drying of the roofs and the walls of the houses.
Picture 4 – The assumed appearance of houses in Lepenski Vir according to Srejovic, taken from literature (7).
Apart from the aforementioned, there is yet another principle of bioclimatic architecture which may be observed at the remains of the settlement. This is digging in or filling in walls with earth. The walls which were turned westwards were up to one meter dug into the ground; the ones close to the bank of the Danube were hardly dug in at all. As it is known that earth is excellent insulating material, this was applied to make use of the favourable thermal accumulation of the ground and reduce heat losses caused by outside air. This reduces the areas exposed to outside air, but to cold winds as well. There are even assumptions that in the future underground construction will be applied increasingly (see: literature, Lukic M (3)).
Picture 5 – Digging in and sloped thatch walls, according to Srejovic, taken from literature (7).
The shrines, which appeared only after the Lepenski Vir architecture was precisely adopted, were exposed to sun rays early in the morning. They first occurred in the phase 1b. It may be concluded that the inhabitants of Lepenski Vir were aware of the imporatnt role the Sun and solar radiation in their lives. Here I shall once again quote Ljubinka Babovic: ”It is certain, however, that one celestial body, the Sun, was the pillar of the culture of Lepenski Vir, and that this culture knew, measured and monitored the movement of the Sun. At symbolic level, it may be concluded that an image of the Universe ruled by the Sun as the supreme Uranic being was in Lepenski Vir expressed through architecture, sculpture, customs and rites. Therefore, Lepenski Vir is Hieropolis, or, more to the point, Heliopolis, thus a town of priests in which the sacred excludes the profane.” It is my opinion that the explicit bioclimatic conditions of the Lepenski Vir architecture in no way contradict the later religious character of the settlement.
The stated principles of passive solar and bioclimatic architecture, a dozen of them, point to the assumption that the architecture of Lepenski Vir could not have possibly occurred by chance, and that its occurrence may be explained through the influence of the Sun and solar radiation. Some of these principles are basic and may be perceived at once, while some of them call for further analysis. Not casting away caution and scientific skepticism, I would like to express my belief that inhabitants of Lepenski Vir had exceptionally comfortable homes for that period. This is corroborated by the already established fact (see: literature (7)) that skeletons of Lepenski Vir inhabitants did not show any other diseases except for spondilose; some of them died in very old age. Therefore, there were no traces of rheumatic processes which occur due to humidity or cold, which could be expected having in mind the humid climate at the site. It could also be concluded that the constructors of Lepenski Vir were aware of the principle of construction of houses which ideally fit into the surrounding natural and climatic setting which makes the architecture of Lepenski Vir and excellent example, even for modern architects who tend towards constructing low-energy buildings (certainly, the long-forgotten skills are to be improved). Simple techniques and decisions may help save energy, in case the natural environment is taken into consideration.
We may ask how useful taking interest in this unusual and mysterious architecture may be. The answer is simple: the energy chain issues are current in ever country and always. Coming up against the meteorological conditions is an ancient problem, and the local energy is quite susceptible to changes in temperature. Needs for heating and cooling largely dictate consumption of fuels. This is why saving and rationalization in this domain may have considerable impact on the quality of life. Long forgotten experiences may also contribute to new ideas in architecture and energetic, with introduction of new technologies, equipment and materials. The architecture of Lepenski Vir may serve as an inspiration for designing new facilities which would consume less energy. I would like to repeat that the eccentric base of the Lepenski Vir dwellings is exceptionally attractive in the energy sense. The time will come when houses will be increasingly perceived as thermodynamic, not only construction facilities.
Picture 6 – Communications in the settlement, taken from literature (7).
The energy crisis of 1970s resulted in increased interest in solar and bioclimatic architecture. Excavations and research in Lepenski Vir were performed before this crisis. This time gap was the reason why the thermal aspect of the architecture of this significant Neolithic site was not taken into consideration in archeological research of Lepenski Vir.
The stated bioclimatic aspects of the Lepenski Vir architecture contribute not only to better understanding of the history of architecture and energetic, but may also serve as a signpost for energy saving in building stock. We should not linger on whether the hunters and fishermen of the Neolithic were able to conceive such an approach to architecture. The explanation, apart from the very architecture, is unlikely to be found. However, their achievements need only to be improved and applied in current conditions.
(1) Babovic Lj, 1997, Položaj i funkcija svetilišta na Lepenskom Viru, Uzdarje Dragoslavu Srejovicu, Faculty of Philosophy, Belgrade, 97-108.
(2) Hawkes J, 1963, Prehistory, Georg Allen and Unwin Ltd. London, 146.
(3) Lukic M, 1994, Solarna arhitektura, Naucna knjiga, Belgrade, 42-49.
(4) Miloradovic N, 1997, Optimalni oblik zgrada u energetskom smislu, Proceedings of the 28 Congress on KGH, SMEITS, Belgrade, 128-140.
(5) Mišic B, Colic D i Dinic A, 1969, Ekološko-fitocenološka istraživanja in: D. Srejovic, Lepenski Vir, SKZ, Belgrade, 207-223.
(6) Pucar M, Pajevic M i Jovanovic-Popovic M, 1994, Bioklimatsko planiranje i projektovanje – urbanisticki parametri, Zavet, Belgrade, 36.
(7) Srejovic D, 1969, Lepenski Vir, nova praistorijska kultura u Podunavlju, SKZ, Belgrade, 42-92,157.
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