|Sustainable Energy News - No. 20 - Newsletter for International Network for Sustainable Energy -Theme: International Development Financing - New INFORSE Action Plan (INFORSE, 1998, 32 pages)|
Building straw-bale houses became a State Program following the Byelorussian NGO initiative.
The idea of building straw houses was one of the outcomes of a seminar in the summer of 1996 at the EcoForurn in Kiev, which gathered NGOs from Byelorussia, Moldova, Ukraine, and USA.
The straw-bale technology used at the seminar allows constructing very cheap energy-saving houses using local renewable materials. (See information in the box below)
Byelorussia's first superinsulated straw-bale house was built in 1996 in the village of Druzhnaia, 150 km north of Minsk. It is 6x12 m in size and cost about $50/m2.
It was built for Chernobyl settlers with help from the German charitable organisation "Houses instead of Chernobyl".
Experimental State Program
In 1997, after the straw-bale building seminar and experience from Druzhnaia, the Government, following the initiative of the Byelorussian NGO 'BD-IAE', set up an experimental State Program to build economical dwellings of renewable natural materials. The Byelorussian design institution Gomelselstroiproekt joint this collaboration, and this led to the design of a 100 - m2 farmhouse.
Cheap, Warm and Ecologically Sound
The first farmhouse designed under the State Program was built in a few weeks in the village of Mikhedovichi in south-eastern Byelorussia. Compared with houses in the village, the straw-bale house saved considerable building costs in both labour and materials. It also uses 3-4 times less heating energy.
Compared to the brick and concrete buildings in the same village, the straw-bale building is much cheaper, warmer, and better for the environment. After being stuccoed, it is very strong, fire resistant, and durable.
More information: Evgeny Shirokov, BD-IAE, V.
Khoruyei 31a, of 523, Minsk 220002, Byelorussia.
Straw as a Building Material
From very early times straw has been used as a building material: mixed with mud and clay, or as roofing material.
The modern straw-based building technique is based on a centuries-old practice in the USA. It was started by early settlers in Nebraska, where lack of traditional building materials forced them to experiment with other materials.
The modern use of agricultural baling equipment has turned straw into building blocks.
Roughly, there are two types of building technique:
· The Nebraska method, in which stacks of straw-bales form the weight-bearing construction of the house.
· The Post-and-Beam technique with bale in-fill, where a post-and-beam structure carries the weight of the roof
The houses, covered with a finishing layer of wood or stucco, look like any other house in the area.
The straw has considerable advantages:
· Insulator - The straw has excellent insulating qualities which minimises heat losses.
· Heat accumulator - The massive structure of the straw bale and stucco absorbs large amounts of heat and, then later emits it constantly to the room providing a pleasant indoor climate.
· Easy to construct - Because the straw bales replace bricks, insulation, and facade materials, their use simplifies the building technique. The basics can be learned in a few days. This allows considerable labour costs to be saved.
· Inexpensive - As the straw is an agricultural by-product, it is cheap and available in most regions of the world, with little or no transportation cost.
These factors make it well suited self-help building method for
people with limited resources. It offers a low-cost house that meets high
By Lars Yde, Folkecenter for Renewable Energy in
Half of the energy consumption of conventional greenhouses in Denmark. Energy consumption competitive with that of producing imported open-land fruit.
Commercial greenhouse products in the northern hemisphere is highly energy-intensive. Their energy index, showing the ratio between production value and energy consumption, is 2350, while that of average industrial products have a value of 50.
One kg of tomatoes or cucumbers consumes 13 kWh, which corresponds to more than its own weight in oil. In attempt to reduce this, the Organic Agriculture Council of the Danish Ministry of Agriculture gave support to the development of a commercial low-energy greenhouse.
It seems likely that, in the long run, the practice of growing organic fruit in greenhouses with an unlimited consumption of fossil fuel will no longer be possible. Therefore, it is important to have alternative solutions ready even if they are more expensive, which is the case of the low-energy greenhouse. On the other hand, it is possible to obtain a higher price for organic products. In Denmark, it is also possible to get economic governmental support from the CO2 Fund (fund from CO2 tax revenue) for part of the construction costs of a new low-energy greenhouse. All in all, our calculations indicate that the concept is economically feasible.
Wind Instead of Oil
Energy input is required in traditional greenhouses for heating. This need is covered by fossil fuel in the form of heavy fuel oil. The low-energy greenhouse, however, uses electricity generated by a wind turbine.
Mobile insulation, Heat Pump
The two main technologies used are mobile insulation, for reduction of heat losses and for shading, and dehumidification by a heat pump.
Insulation of the glass roof during the nights reduces the loss of heat via the roof by a factor of 17 (from 4 to 0,23 W/m2 °C) and, for the whole building, by a factor of 3,7 (from 4,4 to 1,2 W/m2 °C).
The low-energy house does not use heat pipes, oil burner, boiler, or chimney. Instead, it is heated by solar radiation, artificial light, and the waste heat from the heat pump. Since the heat losses from the house are small, most of the heat derived from the artificial light and from the heat pump can be recovered and used elsewhere.
Dehumidifying via heat pump means that windows need not be opened for ventilation in the wintertime, which removes another possible avenue of heat loss. Another advantage of using heat pumps is that a certain amount of excess heat can be exported out of the green house and used to heat packing facilities, private residences, or other greenhouses, or it can be sold to a local district heating grid. See fig.1.
Fig. 2 shows wind electricity consumption in a low-energy greenhouse with 0 to 160 W/m2 installed artificial light, compared to fossil fuel used in a traditional greenhouse or in the transport of open-land fruit from Southern Europe to Denmark. Series 1 shows energy consumption and series 2 shows wind electricity consumption minus exported heat.
Folkecenter for Renewable Energy, Kammersgaardsvej 16, Sdr.
Ydby, 7760, Hurup, Thy, Denmark.