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The curved roof, which features traditional 'fanyu' structural elements, maximises the efficiency of the PV panels

Putting building out to grass
Published:  03 November, 2010

An ultra renewable material could provide a global construction solution, says Professor Hongwei Tan of China’s Tongji University

Tyres, sheep wool, beer cans. We’ve seen it all in sustainable buildings, but what are the sensible alternatives to bricks and cement? How can we prepare for the future with buildings that function effectively for the modern inhabitant, are efficient and, most of all, sustainable?

With the number of households in the UK projected to grow to 27.8 million in 2031 or by 252 households per year, according to the government’s 2009 report on housing, every viable alternative needs to be considered. It doesn’t stop here: the housing problems in the UK are dwarfed by those of the 600 million urban dwellers in Africa, Asia and Latin America who live in life- and health-threatening homes.

Sustainable alternatives range from the less conventional houses being built in old whisky barrels by the Findhorn Foundation in Scotland, to the more conventional BedZED development built by the Peabody Trust in south London. These are small scale, so what is the answer to the global housing problem?

This set us thinking: sustainable housing is a global issue and what could we do at Tongji University in China to help? We’re a long way from London, Scotland and the sustainable housing projects being developed elsewhere in Europe and the US, but we do have access to an enormous supply of one particular sustainable raw material, namely bamboo.

How, I hear you ask, can the 1.2 billion stalks of bamboo grown in China each year help sustainable housing projects outside China? Isn’t bamboo’s only use in construction for the rickety scaffold often seen in Far East building projects? True, this is one use, but it is also one of the oldest materials used for construction of houses, and in Latin America bamboo bahareque and quincha houses more than 100 years old are still being lived in. One billion people already live in bamboo houses ­– in Bangladesh as much as 73% of the population do. But this is the 21st century and I am the first to admit that some of these houses do not match the standards we should expect. However, China produces 31 million tons of bamboo every year, it has an annual growth cycle and China is investing heavily in the sustainable farming of it. It is adaptable, flexible, durable and available in mass quantity – the question is how we use it in 21st century construction.

The challenge was set, surely there was something we could do. There was. We created the global bamboo housing programme along with ENN Group, a provider of integrated clean energy solutions in China. Our mission is to promote the substitution of unsustainable building materials with environmentally-friendly bamboo for construction – where appropriate – to provide solutions to the shortage of proper housing for the poor, and to develop housing-related livelihood options.

Tongii House is a collaboration between Tongii University and clean energy provider ENN Group

Bamboo house of the future

We wanted to deliver the next generation of bamboo houses. The design we developed reflects the energy-saving concept and aesthetic elements of Chinese traditional architecture, combined with modern solar PV technology. The house uses “fanyu” roof structural elements like those of Chinese traditional architecture so that the curved roof is able to maximise the electricity-generating efficiency of the PV panels and provide good ventilation, cooling and drainage capabilities.

The Tongji House, as it is affectionately known, is a one-bedroom-one-foyer configuration, made from 94m3 of bamboo, resembles the characteristics of Chinese traditional waterfront houses and can, at the same time, improve the microclimate of the outdoor residential environment. In addition, the bamboo house uses a smart control system where data regarding the house’s capacity, energy consumption and environment can be viewed directly by the home’s occupants. It is estimated that the energy capacity (kWp) of the bamboo house we created is three times its actual energy demand, which means that each house is able to become an energy plus house. Based on the measurement data, it gives back 30-40kWh to the power grid.

Our bamboo house was built for the recent European solar decathlon competition in Madrid (T&SB Summer 2010) to develop a housing concept that used only solar energy. At €250,000 build cost it sounds expensive but, for a concept house, it is not. Mass production would greatly decrease the costs involved. With the support from ENN we’re furthering our research, taking it beyond this prototype and looking at how to optimise the structure, enhance power generation and consider incorporating multi-energy resources into the house such as biomass and wind energy.

There are many benefits of bamboo housing – affordability, employment generation, availability of raw materials, adaptability, flexibility, speed of construction, durability, comfort, control of deforestation, the list goes on. Perhaps it is not such a pipe dream, and in five years’ time, people driving through the English countryside might catch a glimpse of the latest bamboo village.

Bamboo is a versatile and sustainable construction material. If you find yourself in China, our house is currently demonstrated in the Jiading Campus at Tongji University, so come and take a look.