Chapter 1 S-HOUSE: sustainable building utilising renewable resources Factor 10 building with innovative solutions Robert Wimmer, Myung-Joo Kang GrAT (Centre for Appropriate Technology) TU Wien, Austria
1
Introduction
In 1999, the Austrian Federal Ministry of Transport, Innovation and Technology (bmvit) launched the research and technology program Sustainable Development, which aimed to effectively stimulate the restructuring of the economy towards a sustainable future. Various research and development projects as well as demonstration and diffusion measures have been supported by a number of subprograms in order to give new impetus to innovation in Austria’s economy. The S-House 1 project was launched and carried out within one of the subprograms, building of tomorrow, by the Centre for Appropriate Technology (GrAT, Gruppe Angepasste Technologie) at the Vienna University of Technology, and financed by the EU Life Environment Association and the State of Lower Austria. The designing and building processes of the S-House followed the idea of resource circulation and took into account the entire lifecycle of materials and energy streams used throughout all phases of the product as well as all relevant consequences. From the research and prototyping experiments carried out earlier, it was clear that efficient and innovative utilisation of renewable raw materials is a key factor for sustainable building concepts. During the project a wide range of innovations were initiated and realized and new products based on renewable raw materials were developed. Among those materials, abundant natural resources such as straw bales were used in order to contribute to the enhancement of the regional economic growth. Those building materials obtained from the region also ensure simple rebuilding and reusability.
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S-House means a Sustainable Straw bale House.
1 Proceedings: Cases in Sustainable Consumption and Production: Workshop of the Sustainable Consumption Research Exchange (SCORE!) Network, supported by the EU’s 6th Framework Program, Paris, 4-5 June 2007.
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Figure 1: North and south façade of the S-House
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Case description
2.1
Overview
In accordance with the criteria of sustainable building, the S-House project aimed to consider the following issues with regard to its concepts and components: Reduction of energy and materials consumption Promoting the use of renewable energy sources Using renewable and ecologically sound raw materials Taking into account social aspects Improving the quality of life Comparable costs to those of conventional building construction. To reach the goals, “Factor 10” 2 office buildings suitable for series production were planned and realised. Innovative design and construction elements should result in a drastic reduction of energy and resource consumption compared to conventional building technologies. This enormous resource efficiency was intended to be fulfilled through the whole life cycle of the construction, and its use. These goals have been achieved by an innovative combination of passive house technology, renewable resources and regionally available materials (e.g. straw bale insulation, wooden constructions and clay plaster) in a modular and contemporary architectural design approach. Technical performance of the demonstration results has been also constantly monitored.
2.2
Case context: landscape and regime
The building market is a business segment with particularly large volume of material flows and high energy consumption resulting from manufacturing, transportation and deconstruction processes. Most of conventional building components and structures are based on limited mineral and fossil raw materials like metals, oil, and uranium. These resources are limited in stock and cause severe environmental problems during their life cycle. Also large quantities of building waste hold high environmental impacts and corresponding high cost for disposal. 2
Factor 10: compared to conventional houses
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1,000 ton
Material consumption in business sectors 70000 60000 50000 40000 Mineral Biomass Fossil
30000 20000 10000
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Sto
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Figure 2: Material consumption in Austrian industries in 2003 (Statistik Austria, 2004) If we look at the traditional local buildings in the world they have common sustainability factors such as: - Use of renewable materials (e.g. bamboo trees, weeds, clay) - Use of regionally available materials - Unique building structure which fits the climate and the environment of the region. - Easy to build, operate, maintain and deconstruct - Provide healthy environment (e.g. indoor air, light) As a demonstration example of sustainable building, the S-House was carefully planned and constructed from the very beginning. The idea of resource circulation has been integrated along the entire lifecycle, from the selection of raw materials to the end-of-life planning. Particularly the SHouse project focused on the efficient utilisation of renewable raw materials which have a decisive influence upon the building system.
2.3
Actors and their roles/perspectives
Planning and realisation of the S-House was based on the results obtained from the research work conducted in cooperation with various partner organisations over years’ time. (Wimmer, et al. 2001a) In the course of this fundamental research studies, the technical, legislative/political and organisational scope of utilising renewable raw materials in building systems were envisaged and tangible designing solutions were developed. (Wimmer, et al. 2001b)
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2.4
Case history and development
2.4.1
Utilisation of renewable raw materials
To prove the feasibility of the S-House concept and to identify further development needs towards series production extensive prototype experiments were undertaken. According to the results obtained from the fundamental studies, the façade was built as a structure made of wooden boards and straw bales that are pressed and mounted free of thermal bridging. This straw proofing was provided with a layer of clay plaster and a wooden casing. Thus, the entire building is “packaged” with straw and it provides optimum heat insulation. The physical properties, highly effective heat insulating ability and fire resistance of the straw bale construction were tested during extensive studies. Investigations indicated that straw possesses excellent physical and constructional properties and that the tested wall construction easily achieves passive house standard due to its good heat insulating qualities. Fire resistance Flammability test (OENORM B3800, EN ISO 11925/2) Thermal conductivity Sound reduction
F90 B2, E Λ = 0,0456 W/mK 53 dB
Table 1: Technical details (Wimmer, 2001a)
Figure 3: Construction progresses 2.4.2
Intelligent building consumption
structure
and
reduction
of
resource
The building stands on a sub-ventilated building slab, which is supported by individual footings. This structure facilitated a significant reduction in the use of mineral resources as compared to a conventional foundation and does
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not allow accumulation of cold and moist air in the floor slab area. The building has adopted modular design which enables easy maintenance and long life time. Solar radiation energy is captured by the large surface glazed south façade and distributed over a mechanical ventilation and exhaust system in the building. The air is transported by specially developed wooden channels into all areas of the building. In the ground floor, a stone floor acts as a heat retainer. These stone tiles show an outstanding heat storage capacity and are the only mineral material that is used in the S-House. The stone tiles are glued using a natural adhesive substance so that recycling is ensured even here. An earth commutate takes care of temperature balancing: during winter it prevents glacial formation in the ventilation system and during summer it serves as a cooling device. Due to a centrally located (backbone) supply cable very short conduction paths are achieved in the intermediate ceiling area for the electrical power supply and illumination. A day-light controlling system ensures efficient operation of the illumination system. Not only the overall building structure but also detailed elements were designed with careful consideration. One of the examples is the Treeplast screw especially developed for the S-House (Drack, et al. 2004) Straw bales show an inhomogeneous and rough structure. Ordinary nails and screws which have been adopted for conventional building were not applicable in terms of the strength resistance as well as the sustainability philosophy behind. How to mount other building items such as shelves and façade components to the straw bale wall was questioned. To fulfil the aim of the straw bale building, not only is the shape of a device important, but also the material used for the device. The team, therefore, followed an eco-design process to come up with an environmentally sound solution for the mounting, and succeeded in developing a unique straw bale screw. The aim of the screw design was to achieve a maximum mechanical strength at minimum material consumption. The screw has been optimised during its development according to the principle of biomimicry3. As a result the screw was made of renewable resources (biopolymer), biodegradable, allowing easy dismantling of the construction and reusable.
Figure 4: Treeplast© screw made of biopolymer 2.4.3
Full utilisation of regional resources
By using raw materials (clay and straw) available on-site or in the region, environmental pollution caused by the manufacture and transportation of 3
Biomimicry is mainly concerned with the application of biological principles in technology. Many principles of design, methodology and development seen in nature can be applied in many fields and especially in the building sector.
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building materials can be minimised. Straw bales are by-products from cereal cultivation and their production lifecycle is very short. As a building material, straw bales have a good availability and cause no extra cost for production. Another innovative use of a regional resource was the collection of clay plaster for external application. The excavated material collected while preparing the individual footings and the installation shaft was stored so as to reuse it later. After the clay containing earth material was separated from the humus layer and was made free from organic substances, it was subsequently possible to process it into clay plaster for the walls of straw bales. The clay plaster applied directly on straw was an excellent alternative to the commonly used films, which mostly compound material made of fossil and synthetic substances. This “direct material recycling” indicates an important alternative to the conventional method of building where large quantities of ground excavation and building leftover materials normally occur. 2.4.4
User’s comfort
Based upon a patented system (Wimmer, 2001; 2003; 2005) a biomass stove, ‘Simplyfire’, has been developed and integrated into the heating and air distribution system in order to cover the thermal load peaks. This stove operates similar to the principle of ceramic tiled stoves, which means heat can be stored and delivered through the ventilation system at staggered timing. The unit, which is usually used as a stand-alone stove with radiation heat transfer, was adapted to the requirements of passive solar houses in two ways. Firstly the air used for burning is taken from the outside of the house, because the controlled ventilation must not be disturbed by stoves. Secondly the generated heat is distributed to the whole house. Besides the technical innovations, another important objective of the stove was also to take the users needs into account in regard to their comfort. User surveys indicate that additional heating systems used till now in passive houses are often seen as a deficiency as the fire place is absent and so also the “warm” core in the living room. This new biomass-storage oven with a visor allows direct viewing of the heat source even in the passive house. Also the indoor climate is totally free from synthetic or chemical substances. The use of two types of special wood materials for ventilation system produces the pleasant atmosphere. Figure 5: Simplyfire biomass stove
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Results
3.1
Main result: achievement of Factor 10+
By using building materials derived from renewable raw materials and the passive house technology, the consumption of resources during the
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construction of a building could be minimised by Factor 10 as compared to conventional construction methods. The comparison of a straw wall construction with a conventional wall construction has shown that the straw wall scores better by the Factor 10 in all criteria of calculations, which means, for a conventional concrete wall construction the consumption of natural resources is 10-times greater. The consumption of resources during the use of the building could be minimised through innovative solutions up to a factor of 20. These calculations were made in cooperation with the Austrian Institute for Building Biology and Ecology (IBO/Österreichisches Institut für Baubiologie und Ökologie, Austrian Institute for Ecological and Healthy Building). The construction of the S-House aimed to provide a modern, comfortable, high performance office environment and at the same time spare the resources and minimise building leftover materials during construction of the building and to reuse all building components in order to avoid environmental pollution even after the usage period of the building. Due to the special construction of the building (see 2.4.2; individual footings / subventilated building slab) even preparatory works at the building site could be done without wasting much of the building materials. The hollow spaces for individual footings were covered with film material after excavation in order to enable easy removal of the foundations. Each individual footing is prepared for easy removal and later disposal. Also the vegetation and rainwater retention on the green roof has a very low environmental impact. All performances have been appreciated by relevant authorities and the S-House has won a great number of national and international awards such as ‘Architecture and Sustainability National Award (Staatspreis für Architektur und Nachhaltigkeit)’ in Austria, ‘Rio Award’ in Germany, and ‘Global 100 Eco-Tech Award’ in Japan.
3.2
Change in sustainability performance
3.2.1
Environmental performance: passive house criteria
The design related solutions developed for the S-HOUSE meet all requirements of the passive house standard with regard to heat conductivity and wind proofing. All structural elements and designing offer a high degree of safety and user comfort because of the use of non-toxic building materials and ecologically unquestionable designing. On the whole, no metallic components or fossil synthetic materials were used in the entire building shell. Only wood was used for the static construction. Due to optimum insulation of the building and the passive house technologies used, the S-HOUSE achieves a low energy consumption (6 kWh/m2a), which is far below the standard required for a passive house (energy consumption 15 kWh/m2a). The energy supply is realised by solar radiation and biomass up to 100%. 3.2.2
Economic performance
Economic viability has been met at highest level, thus shows the potential of the S-House as a feasible sustainable building design for series production.
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The calculated building cost is equal to that of conventional buildings. The costs of maintenance are very low. Annual heating cost is approximately 50 Euro for firewood for the 400 m² office space. Multifunctional space concepts (e.g. movable interior walls) allow easy adaptation in case of future changes. Furthermore deinstallation cost will be extremely low due to the use of biodegradable untreated materials and the reusable house technology. The S-House demonstrates a successful example for sustainable innovations combining economic and ecological advantages. 3.2.3
Social performance
The use of straw bales is a new income source of the agriculture industry in the area. Farmers can sell the by-product from agriculture, which used to have very little economic value in the past, as a valuable building material. One of the most important roles of these sustainable buildings is to give people the chances to have an access to the tangible solutions and to be ensured of the feasibility. Seminars, workshops and conferences offer the possibilities to spread the knowledge among professionals, politicians, students and self builders.
3.3
Learning experiences
It is substantial that all people involved in the project (scientists, architects, practitioners, material providers and so on) play important roles in the design and implementation processes. Suggestions based on their expertise were seriously considered and reflected in a harmony with other applications. In order to monitor the environmental performances an extensive measuring system has been developed to estimate and document the important physical and climatic parameters of the building. Finally, the data obtained in the lab for the building construction are tested in practical terms. On the north side of the façade, test wall elements are built into the straw/wooden construction where additional insulating materials made from renewable raw materials are applied. This part of the façade is equipped with measuring sensors so that a comparison can be drawn between the wall elements and the rest of the building. For this purpose, insulating materials made of cork (Dämmkork/ Bucher), hemp (Thermo Hanf) and flax (Heraflax/Heraklith) were built in. Different measurements are continually evaluated and analysed. Throughout the operation and maintenance of the building a great number of forefront sustainable building techniques have been demonstrated. The S-House as an example of the combination of those techniques has drawn worldwide attentions and a great number of visitors have shown their high interest and willingness to replicate the sustainable building concept.
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Potential for diffusion and scaling up
Today the S-House is used as a centre for sustainable technology, renewable raw materials and sustainable building technologies. The
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components and designed structures are presented to visitors, and therefore, traditional know-how and recent development in the building industry become accessible to the public. Besides the exhibitions, technical events such as symposiums, workshops and advanced learning sessions are organised.
Figure 6: The S-House as an information dissemination centre Among those events, a series of workshops ‘Modern Construction and Renovation with Straw Bales’ for self builders demonstrate the straw bale building techniques. Participants learn about the quality criteria of straw bales, examination procedures, the method of designing and planning foundations, wall and roof constructions and junctions between foundations. This dissemination activity of the knowledge and experience gained from the project contributes to the growth of public awareness of the existing alternatives to the conventional building technology and give the participants chances to learn relevant skills. In addition to the hands-on activities information support has been followed up: www.s-house.at.
Figure 7: Practical workshop participants learning about clay and natural paint On the other hand the S-House forms an important part of the theme park “Sustainable Technological Development” planned in the Böheimkirchen area, where the building has been constructed. Around the S-House there is a spacious “material garden” which exhibits natural building materials that are used in the construction as well as extended structures and suitable materials for ecological garden landscaping (fences, path, facings, etc.). An international competition on sustainable architecture and design has been launched with the purpose of encouraging university students to come up with more creative utilisation of renewable materials and to develop the
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idea further with support of professional planners and architects. (www.grat.at/competition/) One of the objectives of the project is to stimulate series of sustainable buildings. In order to realise this aim industrialised production methods will be further developed.
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Overall conclusion
The power of the S-House project is to show tangible results based upon preceding research. Feedbacks from the visitors often find the experience of seeing the actual demonstration which follows the important principles of sustainable development very striking. Instead of asserting trite environmental messages the S-House shows the positive, pleasant and smart results out of different development options that really work yet hold low environmental impact. Many follow up activities from a broad range of stakeholders on an international level show that the concept has a high potential of replication.
References Drack, M. Wimmer, R., Hohensinner, H. (2004). Treeplast Screw – a device for mounting various items to straw bale constructions. The Journal of Sustainable Product Design 4:33-41, Springer Nawaro (Nachwachsende Rohstoffe). www. nawaro.at S-House. www.s-house.at / www.grat.at Statistik Austria (2004) Results of the 2004 Structural Business Statistics Manufacturing and Services. www.statistik.at Wimmer, R., Janisch, L., Hohensinner, H., Drack, M. (2001a). Wandsysteme aus Nachwachsenden Rohstoffen (Wall systems made of renewable resources), Berichte aus Energie- und Umweltforschung Band 31/2001, Bundesministerium für Verkehr Innovation und Technologie, Wien. Wimmer, R., Janisch, L., Hohensinner, H., Drack, M. (2001b). Erfolgsfaktoren für den Einsatz nachwachsender Rohstoffe im Bauwesen (Success factors for renewable resources in the building sector), Berichte aus Energie- und Umweltforschung Band 24/2001, Bundesministerium für Verkehr Innovation und Technologie, Wien. Wimmer, R., et. al., (2003). Stoffliche Nutzung Nachwachsender Rohstoffe- Beiträge zur forschungspolitischen Diskussion, Nachhaltig Wirtschaften konkret, Berichte aus Energie
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und Umweltforschung Nr. 27/2003, Bundesministerium für Verkehr Innovation und Technologie, Wien. Wimmer, R., Hohensinner, H., Petek, HP., Drack, M., Kunze, C. (2004). Infoknoten Nachwachsende Rohstoffe (Report to the information point on renewable resources www.nawaro.com), Projekt-Endbericht, Berichte aus Energie- und Umweltforschung, investigation for the Ministry of Innovation and Technology BMVIT, Vienna Wimmer, R., Hohensinner H., Drack M., Kunze C. (2005). S-HOUSE Innovative Nutzung von nachwachsenden Rohstoffen am Beispiel eines Büro- und Ausstellungsgebäudes (SHOUSE Innovative utilisation of renewable resources at an office and exhibition building), Nachhaltig Wirtschaften konkret, Berichte aus Energie und Umweltforschung Nr. 02/2005, Bundesministerium für Verkehr Innovation und Technologie, Wien. Wimmer, R. (2001). Patent Number A407438. Austria./ (2003). Patent Number DE 19859353. Germany. /(2005) Patent Number CH 694471. Switzerland.
