S-HOUSESustainable BuildingDemonstrated by a passivhouse made of renewableresourcesRobert Wimmer Dr., Hannes Hohensinner DI,Manfred Drack Dr.GrAT - Center for AppropriateTechnology at the Vienna Universityof TechnologyWiedner Hauptstrasse 8-101040 Vienna, AustriaPhone: ++43 1 58801 49523Fax: ++43 1 58801 49533E-mail: firstname.lastname@example.orgKeywords: renewable resources, straw balebuilding, passive solar housesSummarySustainable construction can be defined as follows:Not only the building concepts but also the compo-nents and materials which are used have to meetthe present needs of the users without burdeningfuture generations with waste disposal problems orprolonged use of an out-dated building design. Thussustainable architecture means: form follows ethics,i.e. the design is the result of a careful considerationof functions, materials and their life-cycle performanceincluding long term perspectives, present and futurehuman needs and social aspects. This is the basicprinciple under which the S-HOUSE, a passive solarhouse made of renewable resources, is constructed.Passive solar house technology is already well known.Building materials based on renewable resources arepresent in some areas (e.g. wood). But the combi-nation of both is quite unique. This combination is madevisible by the S-HOUSE, an office and demonstrationbuilding at the Center for Appropriate Technology inBöheimkirchen / Austria. After a care-ful planing phasethe building was put up in early 2005. In this paper theprocess of the S-HOUSE building phase is described.Details of the building are mentioned in addition toimportant background information.The challenge of the S-HOUSE-project consists incombining the high energy standard of passive solarhouse technology (less than 15 kWh/m²a) with the useof renewable resources and herewith to benefit fromthe advantages of both.Introduction to the S-HOUSEconceptOn an operative level the principles of sustainablebuilding ask for consideration of four main issues. Theseare: time, material, efficiency and appropriateness tothe given situation. Most of the buildings in Austria aremade for a very long utilization phase leading to lots ofold houses that are out of date and out of fashion.The construction domain is among the economicalsectors with the largest material flows and has anextremely high energy consumption for production andtransport of construction materials. Furthermore it hasto be dealt with quantitative and qualitative problemsof material flows which are responsible both forecological damage and rising costs for disposal.This was already mentioned by Wimmer et al. at theSB02 in Oslo, where results of preliminary studieshave shown that beneath an improved thermalinsulation mainly the amplified use of materials madeof renewable resources presents a promising solutionto these problems.With the high performance of straw bale buildingsthe “factor 10” concept – i.e. reducing the material,energy and area consumption by a factor of 10 – isimplemented in the building sector. Thereby the wholeconsumption within the live cycle is considered. Thereduced energy consumption during the utilisationphase is realised by the passive house technology.Using renewable resources like straw in the constructionreduces the material and energy consumption duringthe whole life cycle.There are of course several functional units that cannot be made of bio-based materials, for instancethe electrical installation. These applications aredesigned on a modular basis and can be dismantledeasily. The valuable materials can thus be reusedin other products and follow the technical materialcycle. After the phase of use the modular constructionelements made of renewable resources can still bereintroduced to biological cycles. Thereby they do notharm the environment with toxic substances and do notcontribute to the waste problem.Key innovationsThe combination of renewable building materialswith the concept of passive solar houses to the endsof sustainable building asks for the development ofnew techniques. Over all the S-HOUSE constructionincludes 19 innovations that cover constructiondetails within the whole house from ground work overwindows, wall construction, to the roof. Some of thekey innovations are described in the following.Construction detail strawbale wallThe wall construction of the S-House consists of thelayers shown in the figure 3. Static forces are beardby an inner wooden plate construction which alsofunctions as a vapor seal. The plates are joinedtogether and form a box. The straw bales are attachedto the plates by the use of cords for enhancedthermal bridge free heat insulation. On the outsidethe straw bales are plastered with clay to make theventilated facade less vulnerable. With the Treeplastscrews (especially developed for the S-House) thecounterlathing is mounted to the straw bales carryingthe wooden sheathing.Construction detailTreeplast screwBuilding with straw bales encounters the problem ofhow to fix various components or structural elementsto the wall. Straw bales show an inhomogeneous,comparatively rough structure. Ordinary nails orscrews as used with other building materials are notapplicable. So far there is a lack of devices that cancope with the specific requirements.The shape of the 365 mm long screw was optimizedwithabiomimetictoolfromClausMattheck.Thestressesin the material have thus be reduced considerably andfurther reduced the material consumption. As materialthe lignin based biopolymer Arboform was used. It ismade of renewable resources and is biodegradablebut water proof.
Biomass heat storage stoveAnother innovative detail is a new type of biomassstove. This stove stores the heat in an medium withhigh heat capacity. The modularly built stove – usuallyused as stand alone oven with radiative heat transfer– was adapted to the requirements of passive solarhouses. The combustion air used for burning is takenfrom the outside of the building, because the controlledventilation must not be disturbed by ovens.In passive solar houses additional heat production isneeded only with exceptionally long and cold weathercondition. But there are a whole lot of requests frompeople how want to live in a passive solar houseshowing that a small stove with visible flame will raisethe comfort of living considerably. In such cases thisstove with a power of 2.5 to 4 kW is an ideal solution.Balanced TechnologyDissemination of renew-able resources in thebuilding sectorThe exhibition on sustainable building of best practicedevelopment, which is hosted in the S-HOUSE, isopen to the public and will contribute to a broaddissemination. The high performance at considerablylow cost of bio-based materials will be demonstratedherewith, and give another impulse to sustainablebuilding in Austria and world wide.Renewable resources play an important role in theshift of our economic system towards sustainabledevelopment. Particularly in the building sector there isa multitude of functional solutions based on renewableresources on the one hand and a high disseminationpotential due to the enormous material flow on theother hand.Central aim of the exhibition in the S-HOUSE is thedissemination by offering extensive information aboutthe manifold product range of building materialsbased on renewable resources and their correctimplementation. The exhibition grants access to thedeveloped solutions to all participant groups andinterested private persons.ConclusionsThe realization of the S-HOUSE demonstration buil-ding enables the creation of an information centrefor renewable resources which opens access tosustainable technologies for a broad public anddisplays long-term measuring in a realistic userscenario. Modern architecture presents the varietyof possible applications of building materials basedon renewable resources and herewith promotes theirdissemination.The internet based platform on renewable resourceson www.nawaro.com established by GrAT is alreadyin service and provides information about productsmade of bio-based materials (mainly from the Germanand Austrian markets). It is appreciated by companiesmanufacturing products as well as by architects andprivate people building their own sustainable house.Together with the S-HOUSE this information platformcompletes the picture of new solutions.Introducing the new technology shown by thedemonstration building has a strong potential toconsiderably minimise environmental damage worldwide. Thus international co-operations already existand are intensified even more.The S-HOUSE was nominated by Austrian officials forthe Global 100 Eco-Tech Awards at the Expo 2005in Aichi, Japan.Long term monitoringAn important aspect for a successful disseminationof new building materials are tests and long termmonitoring. Although there are straw bale houses inuse that are almost 100 years old not many scientificmonitoring programs have been accomplished sofar. Thus the long term behavior with respect to heattransfer, humidity in the building material etc. is notsufficiently documented yet. An extensive monitoringconcept provides realistic and exact data about theused constructions which constitute a basis for furtheroptimization and dissemination of building materialsmade of renewable resources.In the wall sensors have been installed to measurerelevant parameters for building physics. Theparameters are divided in those with high dynamicsan those with rather static behavior. The CO2-contentor humidity within the building can be consideredto show high dynamic when for instance a group ofvisitors appears at the exhibition. Of lower dynamic oreven static behavior for instance the humidity within theinsulation material can be considered. Such data aremeasured with longer time intervals.Additionally to the straw bale construction four testboxes are filled with other insulation materials. Thesetest boxes are also equipped with measuring sensors tocompare the different behavior and to receive referencedata. All the electronically measured parameter areadequately prepared and online available via theinternet (www.s-house.at and www.nawaro.com).AcknowledgementThe S-HOUSE project is funded by: EU Life EnvironmentProgram, Building of Tomorrow - Federal Ministryfor Transport, Innovation and Technology (BMVIT),Government of Lower Austria