OLD and new buildings can be climate responsive and able to attenuate exterior conditions.
Historic buildings, in particular, were considered to deal with climate passively, through proper design and adequate building materials.
However, the architecture of buildings is commonly altered over time and through changes in use.
As time goes by, buildings acquire new uses and original spaces and architectural details are modified to suit new needs.
In order to correct this, and instead of paying attention to the building’s original design and use, architects and conservators tend to adopt and rely entirely upon mechanical systems as ideal climate control tools for both human comfort and the conservation of museum collections.
However, for the BaTonga, their stilted huts are built traditionally and these naturally ventilated huts are made from traditional materials and techniques.
It is likely that, merely by enhancing original architectural details or controlling the ventilation regime, climate control can be achieved for both visitors’ comfort and material conservation.
The stilted huts or ngandas are the traditional dwellings of the BaTonga and bear the most obvious African influences of any Zimbabwean architecture with their closest stylic relative being the Rozvi villages of the Great Zimbabwe in Masvingo.
The stilted huts have been constantly undergoing some changes in line with the changing climatic conditions prevailing in the Zambezi Valley.
Anyone travelling to Binga would see small rondavel huts built on three-metre stilted poles.
Almost every homestead in Binga has two or three such huts, depending on the number of family members at the homestead. The huts are constantly given a new lease of life each year as the new generations of the BaTonga come to the fore with changing lifestyles.
The huts stand tall in grass or twig-fenced homesteads and they can be seen from a distance clustered among other rondavels. They are built of strong thick mopane tree poles and plastered with mud.
A nick of red and black soil or chalk mixed with baobab tree sap, completes the finishing touches to give the huts a spectacular colour of the owner’s choice.
The head of the family or the matriarch’s name is scribbled on the walls so that any visitor can tell whose homestead it is.
Sometimes, images of animals such as the hippo, elephant or crocodiles are crudely drawn on the walls to alert of one’s totem.
What prompted the switch from the ground to above the ground some hundreds of years ago is a matter for conjecture, but defence must surely have been a factor as well as the natural ventilation provided by the huts during the hot summer days in the Zambezi escarpment.
The BaTonga elders also point out that, wild animals, grain storage and flooding were among some of the reasons for the construction of the stilted huts.
These huts range in size.
Some are small, while others are big, depending on the owner’s taste.
Doors to the huts are made from strong teak and mahogany logs felled on the banks of the Zambezi River.
Today, the doors remain a treasure for most tourists because of their strength and cultural significance.
BaTonga elders say before they were displaced from the banks of the Zambezi River, they built their huts on the animal corridors (paths used by different wild animal species to the watering points on the Zambezi River). To avoid being trampled by elephants and buffaloes or eaten by lions and hyenas, they built their huts on stilts.
The BaTonga would climb into their ngandas during the night. The animals would pass or rest underneath the stilted huts and not harm them.
Another striking feature of traditional BaTonga architecture is the granary which has proven safe for grain storage.
The granary has special honey comb-like designs where different types of grains were stored for years.
Although in other tribes, all granaries are suspended on stilted poles or stones, the BaTonga uniquely stored their grain safely, in these stilted huts, from termites, insects and other vermin.
Poles used for the building of the granaries are from special trees which are thoroughly treated with oil derived from reptiles such as crocodiles and snakes.
Such oils deterred animals from coming closer to the granaries.
The ngandas also prevented the BaTonga from catching fevers associated with dampness.
During mid-March to May, the Zambezi flood plains were often immersed under flood waters from the rising water levels from the river, hence the stilted huts came in handy for the BaTonga.
The ground was often wet, making it hard for them to sleep.
It is during this period that they would quietly climb up into their huts and sleep peacefully without the fear of getting washed away should the floods get worse.
The huts near the river banks have much higher poles so that they are not submerged in case the level of water rises higher.
Again, special poles from the mahogany, teak and mukwa which are much stronger, were used to construct huts on the flood plain.
Certain traditional herbs were also rubbed onto the wood to prevent ants, termites and other insects from damaging the poles.
The most common form of modern day creosote was sap from the mopani tree.
Baobab mixed with oils from certain wild animals made the poles so strong they could last for more than 100 years.
The nganda also served as a coolant during the hot summer days.
Temperatures in the Zambezi Valley can rise up to 30 degrees Celsius.
These huts come in handy during hot days.
The adage: ‘The higher you go the cooler it becomes’ seems to have inspired the BaTonga when they constructed these stilted huts to shelter themselves from the scorching sun.
However, due to intermarriages and the changing material culture, the BaTonga have been constantly modifying these huts to suit different modern tastes.
Settlement patterns in the Zambezi Valley have also influenced the modifications.
Despite their futuristic and other worldly appearance, many of the ngandas, built some 50 years ago, have been used by colonialists and other whites who were constructing the Kariba Dam as grain stores.
Sadly, some of them have fallen into disuse over recent years, though others have been granted a new lease of life by the new generations of the BaTonga as curio storages.