Use of bamboo and earth as building materials could go a long way in making the much-needed transition to a low-energy, ecological future. That’s exactly what a group of architects are attempting to do in Nepal. At Uttara and Abari, two related architectural and engineering design firms, they have come up with some of the finest building designs with very low-energy use. The low-energy potential of bamboo and earth results from their local availability. It also results from the way these materials could work as a natural thermostat, maintaining the balance between interior and exterior temperatures. Of course, there are challenges, says Shishir Gairhe, director of Uttara Engineering, and one of the founders of the Abari Group. Procurement of bamboo and availability of skilled human resources are two major ones among them.

Buildings worldwide account for over 40 percent of the total energy consumption, and one-third of greenhouse gas emissions. Because of the ongoing modern building frenzy, this trend is going to get worse the world over — unless, of course, we make an urgent transition to a low-energy building future. In my essay last week, I wrote that modern buildings are highly energy intensive during their life-cycle — manufacturing of the building materials, their transportation to the building sites, construction of the buildings, their operations over a long period of time and finally their demolition. Transitioning towards low-energy building practices is hugely urgent to avoid runaway greenhouse gas concentration, and this transitioning has to address the use of energy and greenhouse gas emissions in every phase of a building’s life-cycle. 

Each passing year, we are seeing increasing incidences natural disasters across the world. As I write this, three major disasters are unfolding — landslides in China, floods in Pakistan and wildfires in Russia. There are ongoing disasters such as increased melting of the polar icecaps and increased melting of ice across the Himalaya and other high-mountain ranges. There have been significant changes in the monsoon cycles with increased disruptions in agricultural production. Many areas have seen prolonged droughts. There is a general consensus that these are related to the disruptions in the earth’s geo-chemical cycles wrought by the concentration of greenhouse gases. This year marked the hottest summer ever recorded across the world.

Two major sets of interventions are necessary if we are to avoid large-scale misery resulting from runaway climate change. The first set of interventions is related to significantly reducing carbon emissions and capturing back the atmospheric carbon. The second set of interventions needs to occur in the area of adapting to the inevitable changes and disruptions.

Bamboo and earth buildings address both issues. Using locally grown bamboo and locally available earth reduces the energy inputs and greenhouse gas emissions arising from the production of building materials. At present, most of the modern buildings use materials that involve the use of huge amounts of energy. Iron ore and bauxite have to be mined and processed into steel and aluminium. Lime and other stones have to be quarried and chemically processed into cement. These materials then have to be transported across long distances to the building sites.

How do earth and bamboo fare? As we all know, earth is the dirt underneath our feet. Bamboo is an incredibly versatile plant. It sequesters more carbon and produces 30 percent more oxygen than any normal tree. It grows as much as a metre a day, and is fully mature within three years. It is totally counter-intuitive, but bamboo has as much tensile strength as steel while being lighter in density than a bird, says Shishir Gairhe. Combine bamboo and earth, and you potentially have materials that are available in the place where you want to build a house. This means cutting down on energy consumption in manufacturing and transportation of modern building materials.

Well, as it is, bamboo is not available in required quantities all over, says Gairhe, who has also successfully designed a re-assemblable bamboo dome. If bamboo and the required labour are locally available, bamboo and earth buildings could cost significantly less than the currently fashionable cement-steel-concrete structures. By how much? “It could be as much as 60 percent less than cement-concrete buildings,” says Gairhe. Obviously, there are a lot of other issues involved. We have to train a new batch of builders who care about both the earth and the cost. For now, the old builders who specialised in natural building materials such as bamboo and earth are dying out, and we have not trained young ones. We also have to grow bamboo locally. The thing is that Nepal has all kinds of climatic regions that could grow varieties of bamboos.

While the combination of bamboo and earth reduces the energy intensity of the materials used in buildings, this also results in very low energy use in the operation of the buildings over their life-cycles. Buildings last a long period of time. Much of the energy consumption of buildings results from their operation across this period. In the developed world, heating and cooling of buildings require as much as 80 percent of operational energy. In Nepal, we have seen a huge growth of fans and air-conditioning. Much of that arises due to bad design and bad building materials.

Bamboo-earth buildings are warm in the winter and cool in the summer. As a result, they consume far less energy during their life-cycle than cement-concrete-steel buildings. These buildings are also very ideal for schools. Research has shown that the temperature in the classroom plays a very significant role in the learning process. At the optimum level of indoor temperature, students learn the most as they can concentrate on their studies rather than dealing with the extremes of cold and heat.

According to the Kyoto Protocol on climate change, we have to reduce the use of reinforced steel, aluminium and cement by 80, 90 and 85 percent respectively. As we face more and more climate-related catastrophes, we will be forced to transition to a low-energy future. Moving towards buildings that use less energy and local materials throughout their life-cycle is going to be more and more urgent.

We still have to keep in mind that low energy is not about low durability or ugliness. On the contrary, some of the most beautiful buildings are made of local materials. Buildings are beautiful because of their internal design and the way they merge with the landscape. In terms of durability, earth buildings have lasted for over a thousand years. With proper treatment, design and maintenance, bamboo and earth could last forever, says Gairhe, and they can withstand high-intensity earthquakes.

Besides the bamboo-earth combination, there are other low-energy building possibilities. In my next essay next week, I will explore how we can create beautiful homes from the dirt underneath our feet by using earth bag building technologies.

Anil Bhattarai: anilbhattarai@gmail.com

source: Bhattarai, A. (2010),"House of bamboo",The Kathmandu Post, 17 August 2010