“Human being… by nature, as opposed to other animals, didn’t walk inclined towards the ground, but straight and tall in order to behold the magnificence of the skies and the stars; and furthermore, finding themselves proficient with their hands and joints to easily deal with whatever they wanted, started to create their rooves from branches. Others would dig shelters along the slopes of mountains. Some of them, imitating sparrows’ nests, would take cover under clay and mud.

Others, who observed these dwellings went a step further with their inventions and began erecting better huts day by day. Thus, these men of mimical and sharp nature, and nurturing their pride every day from their findings, taught each other about new ways to build their homes; and using their ingenuity with these imitations, they progressively upgraded them in taste” [Book II: Chapter 1: Primitive communities and the origin of buildings. Vitruvius II, I, “Of the origin of buildings”].

Some types of architecture that have remained until the present day have followed strange, untraceable paths, that our curious minds attempt to unveil. We ask ourselves about their origin, their precursors, their influences. We wonder about all the factors that consolidated a certain architectural configuration within them, a morphology and a language.

In our section of Popular Architecture, we research these unusual constructions such as southern Italy’s ‘i trulli’. We do this to let our imagination fly back to distant times, to snatch a piece of history, to try to speak their unique language.

 “I trulli” are an ancient construction typology created entirely from dry stone walls – without the use of mortar –  rounded off with a conical shape coating. This covering forms an overhanging dome which is decorated with lime-painted symbols and is supported by whitewashed walls up to a metre and a half thick. The scenery created by the ensemble of these buildings throughout the small villages of Italian Puglia, speaks for itself about its richness, a richness that, as we shall see, goes far beyond mere aesthetics.

GEOCLIMATIC RESEARCH

Puglia is a region of Southern Italy located between the Appennini mountains and the Adriatic sea, covering more than 20,000 km square. This vast area ranges from low hills and broad plains, to the turquoise waters of the Adriatic sea, whilst basking in a subtropical climate of dry, hot summers and warm, humid winters.

Within its central zone, we find the sub-region of La Murgia: a plateau no more than 700 metres high which extends for 4000 km square. Some years ago, in June, we found ourselves travelling through this little paradise, escaping from the rainy North. Heading towards the highs of the plateau we saw the landscape begin to change. La Murgia, made out of limestone strati (mainly white and ocre limes) offered us a rocky terrain, which we admired from above the distant and green shores of the Adriatic.

As revealed by its Latin name (Murgia → ‘murex’ → “pointy or sharp rock”), this land holds since by gone days, a resource easily extracted and exploited, which has and will forever shape an evolutionary path different to the rest of Puglia, also in terms of architecture.   

HISTORY AND ORIGINS

Thanks to this substratum, we find human settlements with buildings following this particular construction technique of limestone masonry. Villages like Alberobello, Locorotondo, Cisternino, Fasano, Martina Franca, Putignano, Noci, etc. form the so-called “Murgia dei trulli”, one of the most homogenous preserved urban areas in Europe, which is still inhabited today. Alberobello itself, entitled “capital of i trulli” and declared World Heritage Site by Unesco in 1996, has a population close to 11,000 inhabitants, of which 4,000 still live in trulli.

The origin of such buildings, and the etymology of their name “trullo,” remains unclear.  According to Gabriella Esposito – “Architettura e storia dei trulli” (1983), ‘trullo’ could come from the Latin word ‘trullus’, which defines any kind of building finished off with a dome, or from the Ancient Greek ‘torullus,’ meaning dome. Such discussions around the origin of the word are closely linked to the subject of the construction’s origin itself: does it come from Murgia, evolving from the primitive wicker huts? Does it represent therefore, the evolution of a light, portable structure characteristic of a nomadic people, to a stony, stable and durable one, characteristic of a sedentary people? Or was it simply imported from other lands?

It’s important to keep in mind that these trulli aren’t an architectural singularity. Dusting off old history books, we find examples of similar buildings from ancient cultures. Ever since the III Millennium B.C, ‘tholos’ were erected in Egypt and Mesopotamia because of their constructive simplicity, considering they don’t even need trusses to form concentric circles enclosed in a central oculus. Mycenaean culture, which dates back to II Millennium B.C, pioneered the monumental building with a cone-shaped dome: the Treasury of Atreus. But let’s get back to the subject of housing architecture and distance ourselves from monumentality:

The village of Kouem in Aleppo, Syria, for instance, was raised entirely out of trulli-like buildings, in this case with a recoated external façade and crowned with pinnacles similar to the ones found in Alberobello. Could that be related to the ancient presence of Greek, Minor Asian and Egyptian settlements in southern Italy? And what about the constructions found in Digano, southern Istria; in Balearic islands; in Valchiusa, Provenza; or the circular huts in Luguria and Sardinia; or the buildings in Harrán, Turkey?

Regardless of their influences, this discussion allows us to bring up a number of conclusions regarding the origin of such a particular typology – the geological features of the land and its rocky display are the prime factor. In a primaeval step of the process, society adapted the construction into a circular floor plan due to its simplicity. Later on, the agrarian farmer economy would establish it as a housing typology.

CONSTRUCTION, SPACE AND FINAL PORTRAY

Raising a trullo demands just simple and easy architectural logic. When each and every resource is used for what it’s meant to, and urban spaces come from a pure matter of need, the outcome can’t be anything but beautiful. The house will be formed by the progressive addition of trulli with a 30 square meters core surrounded by a 1-meter thick wall and topped by an overhanging dome shaping a pinnacle.

This jointed ensemble – which volume comes organically through a process of “budding” – receives the name of ‘trullaia’, and within its borders lay the core of family life. They are generally formed by a main trullo with direct access to the street, easily identified for having the biggest dome of the house and a symbol painted on the top – the origin of which is still under research. To the main trullo, the rest of minor trulli are assembled – used as spaces for sleeping, cooking or warming.

These housing ensembles are definitory of the urban landscape. A landscape in evergoing dialogue with the scattered trulli in agrarian areas, kept apart by long stone walls made out of gathered stones – stones that are also used in the construction of terraces where vineyards, olive trees and several other fruit trees can be sown. Thus, mortarless limestone masonry becomes the basic ingredient in both anthropized landscape and urban planning.

SUSTAINABILITY AND ENERGETIC EFFICIENCY

Speaking in terms of sustainability, the materials used subscribe the three following premises:

• Low energetic cost – both during the production process (the land itself provides the resources) and transportation (its abundance renders importation unnecessary). Rather often, the usage of stone comes with a big impact not only because of the amount of energy required for the extraction but also because of the transformation it brings to the land, the landscape and the environment. Puglia, however, stands as an exception.
• Durability – estimated useful life has become nowadays one of the main concerns when it comes to selecting the materials that are to be employed. The raw stone is the “everlasting resource”, having an extremely low rate of erosion and its weather endurance.
• Wastes – stone will be used for almost every single element in a trullo: foundations, walls, coating… Disposing of any kind of mortar, a trullo’s fall – be it by nature or human hands – will only leave a mound of stones behind. In fact, its construction is so fast and cheap that very usually an old trullo will be destroyed in order to raise a new one – instead of dealing with restoration works. The trullo rises from its ashes.

Familiarizing ourselves with the top concern for today’s society – sustainability, which became the quest sought by the new paradigm of architecture – it’s compulsory to go deeper into the matter of trullo’s energetic behaviour. This matter – aside from its formal beauty and “picturesque friendliness” – is the one that can “rescue” said typology to be adapted to present times, bringing it back to the evolutive path of architecture and thus preventing it to be left as an antiquity to be “restored”.

As a reminder, energetic efficiency is directly defined by savings in climatization and resource use – such as sunlight or water. The desired human comfort comes mainly from air temperature, solar radiation, air currents and humidity. Regarding trulli – circular constructions with thick walls and small openings – orientation and positioning won’t be determinant for aforementioned comfort, which means, they are somewhat self-sufficient in their behaviour. They will therefore behave in a similar way to the hypogeum of the earth-houses.

The stone wall bonding (the closure, which also plays the role of supporting structure) allows for deep thermal inertia, and therefore for a solid stabilization of inner temperature. Regarding wind influence, the circular shape helps with the re-cooling of the space at night – because wind finds no obstacles. Such floor plan and its conical dome serves also other purposes: it allows for the transmission of warmth from the ceiling to the floor during winter and vice-versa during summer. The natural air circulation is improved by the regular ventilation received through an opening at the top of the dome where the chimney stands – yet another similarity to earth-houses.

These logical strategies are carried out further with the light-reflection produced by water-washing their walls – that also works for hygiene matters, being the most efficient disinfectant know – or the gathering of rainwater for a cistern tank below the hose used as its own supply – which also helps with refrigeration.

In order to explain this set of climatic processes in a visual manner, we only have to think about how a ‘botijo’ – known in English as earthenware pitcher – works, and portray it into architecture. A ‘botijo’ is a traditional object coming from Mediterranean cultures –  a porous ceramic vessel used to store water. The water inside is always refrigerated, keeping itself cold even through the hottest days of summer – as the vessel’s surface absorbs heat, the water is filtered through the porous clay and evaporates at the contact of air, hence cooling itself (2.219 kilojoules per evaporated gram of water). So to speak, the botijo sweats and cools its interior through the evaporation of water.

Such effect is exactly the same that occurs inside a trullo: its limestones behave as a condensating structure that later on stores the water in the aljibe – the cistern. In summer, warm air comes into the colder environment produced by the aljibe and, through condensation, it sprouts tiny drops of water. In winter, however, the steam of water – warmer than the exterior temperature – kept inside the aljibe will condensate at its contact.

CONTEMPORARY ARCHITECTURE?

Such an architectural evolution, subsequently analyzed, come from nowhere else but from logic, observation of landscape’s possibilities and a process of experimentation carried out through millennia up to the point of reaching an efficient design from an energetic and environmental point of view in this particular region – Puglia.

But it’s also a landscape, a culture, the origin of family and neighbourhood relations and a way of life that anyone whose travels take him to Puglia will never forget. Some certain places welcome you to stay forever as soon as you arrive; homes that compel you to dwell in them. And I ask myself – isn’t that the very own dream of Architecture?

Text: Ana Asensio Rodríguez / Photography: Ana Asensio Rodríguez &  commons.wikimedia.org/ first writting for Plataforma Arquitectura / Cittion: Asensio, Ana. “Arquitectura Popular: Los Trulli Pugliese” 18 Jun 2013