An innovative straw-bale construction method is being used in northern China to build houses and other public buildings using waste rice straw. To date over 600 houses have been completed and the benefits of the programme include significantly reduced coal consumption and CO2 emissions, affordable warmth and less respiratory disease for residents, much greater resistance to earthquakes and savings of precious top-soils due to reduced brick production.
Aims and Objectives
- To develop safe, healthy, sustainable and energy efficient construction practices in north-eastern China.
- To use locally available materials, designers, management personnel and builders throughout the project.
- To create buildings that are healthy, comfortable, safe, affordable, durable, energy efficient and aesthetically and culturally appropriate.
There is a severe need for adequate housing in north-eastern China, exacerbated by an environmental refugee population fleeing desertification. Existing housing is frequently damaged by snow, flooding, or earthquakes and a significant proportion of the 160 million population live in substandard and dangerous housing. Often built of mud and rocks, the houses offer little protection from the severe cold of the region with temperatures as low as –40º C. These mud, stone and rubble houses collapse easily even during a minor earthquake and force families to rebuild (with meagre resources) a house that is even poorer in quality than the original. As, a result, residents are prone to suffer illness and bad health especially during the winter. Any new construction is carried out using locally made bricks, which adds to the removal of scarce topsoil, which increases the already high levels of air pollution and topsoil removal and provides poor seismic performance.
Straw-bale construction is especially well suited to the local conditions and climate in north-eastern China. It was first tested in China with a 1998 pilot project building a straw-bale school after a relatively minor earthquake had destroyed the original brick school. The new school has been very successful with much reduced heating costs and it has withstood a subsequent earthquake of 5.6 on the Richter scale while other buildings around it collapsed.
The houses built under the programme have so far withstood all earthquakes since construction without damage. This is due to the relatively lightweight straw bale walls which resist earthquake loads and absorb seismic energy through deformation. Some brick is retained in the design, mainly to convince homeowners of the strength of the construction. Overall there is a reduction by two thirds in the number of bricks used compared to a normal brick construction.
Involvement of the local communities is a key element of the project. The project only works in communities that have serious housing needs and have expressed interest in the project. Interested communities are invited to visit an existing project village to talk to straw-bale home owners and members of the local project management office. In order to participate in the project there must be local political commitment to provide matching funds, to establish and support a local project management office and to manage the project with complete transparency.
The China office of the Adventist Development and Relief Agency (ADRA) and One World Design Architecture (OWD) provides the training for local construction teams who work with the technical trainers to make sure the homes meet basic quality standards. Homeowners work with the designer and are encouraged to modify the basic designs by moving doors, windows and interior partition walls to meet their individual needs. It is important that the houses are culturally and aesthetically pleasing in order for the new technology is to be accepted. A post occupancy survey of 159 families has shown 90 per cent satisfaction with layout and design.
Technical training has empowered local designers, builders and construction foremen by giving them new design and construction skills. Members of the local Project Management Office have gained extensive management experience and new home owners have learnt how to take care of their homes and have a greater understanding of the natural environment. Participants in training programmes are now forming a Straw Building Association as a way of keeping abreast of international research and acting as a support group for each other
To date the project has trained 464 people and built 603 houses in 59 villages in five provinces of north-eastern China. In 2004 an additional two schools were completed, together with associated dormitories. The direct beneficiaries of these developments have been farming families. These include the low-income as well as the middle income groups. Those on middle income are included to avoid the stigma of the straw- bale housing being seen as being appropriate for low-income groups only.
There are very high rates of lung cancer and respiratory disease amongst the population in north eastern China, due in part to the extremely high levels of air pollution caused by the burning of highly sulphurous coal for household use. 40-50 per cent less coal needs to be burned to keep the straw-bale houses heated and health has improved, especially for the young and old. Homeowners report that there is stable, more even warmth in their homes and they have fewer respiratory ailments.
Construction costs range from $2,000 – $3,500 USD for a 50 – 80 m2 house with the higher income families choosing to have more expensive designs. The price range per m2 is $36 – $44 USD. House size depends on the needs and wishes of the owner and the local custom. The total project cost in the period 1999 – 2004 is $1.7 million USD, i.e. $2,820 USD per house. ADRA provides the funding for training, technical support and a subsidy per house. The local government pays an average of $725 USD per house either in cash, in kind (e.g. building materials) or in labour from contractors at a special negotiated rate.
The project is funded by a combination of external funding matched with internal funding from local government housing departments and a contribution from the homeowners. The external funders use a progressively diminishing subsidy system. In the first year direct subsidies equal approximately 40 per cent of the house construction cost to encourage the first families to invest in the new technology. In subsequent years, subsidies diminish to approximately 20 per cent of the house construction cost as confidence in straw-bale technology grows.
Why is it innovative?
- Use of a locally available waste product (straw) to create a building material not used in this part of China before.
- Involvement of a wide range of stakeholders, including local residents.
- Empowerment and skills development of local people.
- Use of insulation in the floor and ceiling.
- Use of passive solar design.
What is the environmental impact?
The use of straw bales has resulted in a two-thirds reduction in the number of bricks used in construction. Large amounts of energy are used to make the bricks, unlike the straw bales. Monitoring surveys have shown that on cold days 5kg less of coal is burned in a straw bale house than a brick house. The straw-bale houses are 68 per cent more energy efficient than similar size brick houses. CO2 emissions are reduced by 0.6 – 1.2 tonnes per year per house (depending on house size and severity of the winter).
There is an increase in soil conservation and drop in use of the firing fuel through a reduction in the number of bricks used for construction. Walls built from straw bales offer tremendous insulation value, thereby reducing fuel costs, CO2 emissions and air pollution and they have very low embodied energy. Straw-bale walls have a CRSI value of 5.8 compared to 0.33 for walls made from solid brick.
Is it financially sustainable?
ADRA funding has now come to an end and an extension or alternative sources are currently being arranged. There is evidence that the technology is beginning to be used without the ADRA subsidy in those villages where the project is longest established.
The project is designed to be self-supporting using Clean Development Mechanism funding defined under the Kyoto Protocol. Funding under this mechanism would be $540 – $1,080 per house (comparable to existing ADRA subsidy levels) and the project is well placed to receive it given that it has fully documented carbon savings.
The houses are simple enough to be built by local construction teams without continuing external inputs. Fuel costs are significantly lower than in brick houses, thus reducing households’ expenditure. Many of the local government parties offer low rate financing for the owner’s part of the construction cost and this is typically taken up by the poorest households in the programme. Owning good quality homes for the first time in their lives has increased the wealth and sense of well-being of the households.
What is the social impact?
Local community members are involved in areas of house design, materials acquisition and village education. The acceptance of the local community is recognised as essential for the long term benefit of the project and it is important that the technology is not seen to belong to any one income group. One World Design and ADRA China work only works where there is interest and support from the local community leadership.
- Cultural preference for brick built houses was overcome by the incorporation of brick into the building system and a long term commitment to education, financial incentives and on-going technical support.
- Aesthetic preferences of residents occasionally conflicted with the energy efficient or passive solar design. In these cases, the resident and designer would work together to find a compromise.
- Lack of an established chain of manufacture and supply for straw bales in local areas meant that assistance had to be provided with setting up local straw bale production or coordinating the sharing of balers or providing interest free loans to purchase balers when required.
- Clear, concise and strongly enforceable contracts were required to address the problem of government corruption in some areas. These contracts laid out the duties of each party and the requirements of transparency. The shared financial contributions also helped to ensure cooperation and a commitment to working through problems.
- The limited availability of cost-effective baling machinery in the area was addressed through improvements being made to the machinery of two local baler manufacturers.
- Lack of official standards and codes for larger public buildings such as schools and clinics.
- There was evidence of cracking in the render where brick and straw interface, which was overcome by using a wire meshing reinforcing and training the construction teams in proper plaster mixtures and application.
- For real environmental impact and long-term sustainable development there needs to be large-scale transfer of the technology.
- Local community interest, enthusiasm and commitment are essential elements to the success of the project. It is a waste of time and resources to train a community in which the project will not be supported.
- The involvement of all stakeholders helps to maintain motivation to successfully complete the project and keeps costs down.
- It is important to build to the best possible quality that the local materials, local skills and budget allow ensuring the highest possible standards.
- Building construction systems should be allowed to develop organically over time in relation to the local climate, building skills and materials.
- Straw-bale technology should be developed by studying and adapting existing local technologies.
- Adequate time must be given to the early phases of research, training, cooperative design and planning.
- Good technical training should be integrated with local design and local building skills.
- Post occupancy surveys carried out by ADRA in each village show high levels of satisfaction with the houses although there is limited understanding of the wider environmental benefits that are being achieved.
- Surveys have also been carried out on levels of coal consumption. These show that on cold days 5kg less of coal is burned in a straw-bale house than a brick house.
- Surveys on energy efficiency show that they are 68 per cent more efficient than similar size brick houses.
The project originally started with 21 houses in 1999 and has now spread to 59 villages and has 603 houses, due to the demand from local people. It covers five provinces of north eastern China where there are large straw surpluses.
There is evidence of transfer of straw-bale construction outside the scope of the project as five duplexes totalling 504m2 were built using straw bales in 2004 in Tangyan County, these were independent projects not funded by ADRA. More straw-bale constructions are planned in Tangyan.
Professor Kuang at Jianxi University is carrying out a research programme into the use of straw-bale technology in southern and central china and will be building demonstration straw bale-houses on the university campus.
Local building codes have been modified to include provision for straw-bale construction in some local governments. Other NGOs in China have adopted the straw bale technology and it is also being used in the Huangbaiyu Ecologically Sustainable Model Village in Benxi Liaoning. A range of other NGOs including World Vision, UNDP and ADRA have similar projects in Mongolia, Mexico, Iraq, Belarus and Argentina.
International Agency, NGO