Renewable resources in the building sector
The increased use of renewable resources ("resources of tomorrow") is an essential strategy for sustainable development. The intelligent use of such materials, especially in the building sector, can result in the synergy between the optimal functionality of the products themselves and the reduction of environmental impact.
The central idea behind sustainable building is that the finished building and the components used in its construction should meet the present needs of the users without burdening future generations with waste disposal problems or forcing them into the prolonged use of outdated buildings. Building products and system solutions based on renewable raw materials can make an essential contribution to achieving these aims. Apart from having functional advantages, they also provide ecological benefits and can improve regional economic structures.
The investigation of factors which support or hinder the use of renewable resources in the building sector should contribute to improving their market penetration. The investigation was carried out on the technical, legal/political and organisational levels and, based on the results, measures have been derived to ensure that further technological developments meet market demands. The results of these extensive enquiries are summed up in a catalogue of building products categorised into fields of application. Essential organisational and legal aspects were highlighted and considered in a number of workshops with important protagonists from the areas of raw material generation, production, marketing and planning, and with legal and building experts.
The documentation of the technical applications of renewable resources focussed on innovative solutions with high market potential. Therefore as well as systems already available on the market, solutions still being developed were also considered.
The investigation was categorised into the following fields of application: acoustic and thermal insulation, interior textiles, surface treatment, ready made interior systems, assembly aids, wall/ceiling/roof systems, static systems, pre-manufactured systems and windows and doors. A detailed list of criteria regarding technical properties, environmentally relevant features and degree of market exploitation was used to characterise the products. Wood, as expected, is the most highly used raw material, followed by wool, linseed oil, cellulose, flax, beeswax, coconut fibres, hemp, straw and cork. It is noteworthy that only a small proportion of the products analysed consist exclusively of one basic material. More than half the products are compounds of different materials.
Numerous promising new product developments are orientated to the requirements of low energy and passive house constructions. Due to these developments, a rising demand, particularly for thermal insulation materials, is to be expected. Most of the products and technical developments fall into this field of application, followed by the category of assembly aids which has a share of approximately 17% of the new developments.
However, the majority of the building products listed have been on the market for a longer period. Only about 10% of the products had their market introduction within the last five years. A high proportion of renewable resource based building products can be regarded as being suitable for use by people constructing their own house or building from scratch.
Many products are characterised by a lack of sufficient data (regarding technical parameters) and the non-existence of test certificates.
At the legal/political level the whole legal framework for introducing renewable building materials was investigated, along with possibilities for their promotion and the role of the public sector (in the context of public procurement and the guidelines for contract awarding).
Planning and building laws in Austria are to a large extent determined by the federal governments. The result is nine different building laws which differ in their basic conception as well as in numerous details. Jurisdiction for legal questions in the building sector is also not just central but can be affected by federal laws.
Harmonisation of technical specifications has only partly been achieved, as yet. One example where this has happened though, is the "Construction Products Directive 89/106/EU", which was transposed into federal building regulations and provides, among other things, the proof of usability of building products (CE identification). Essential requirements such as "hygiene, health and environmental protection" or "energy saving and thermal protection" are also stipulated.
Lifecycle assessment for building products is not legally prescribed and there is still no generally accepted methodology of evaluation. There is also a lack of knowledge about long term toxicity, the allergy potential of building materials and other building-biological criteria. The building codes only deal directly with building materials in exceptional cases. Wood, for example, plays a special role in the building code of Styria.
Apart from the protection of health, the avoidance or minimisation of fire risk is the major protection target determined in the building codes. It is, however, not always clear which regulations are aimed at the protection of humans and which at the protection of material goods, which causes problems over the question of responsibility. Outdated protection targets lead to regulations which do not necessarily correspond to today's conditions (e.g. fire fighting capabilities, etc.)
The legal handling of innovations is of crucial importance for the introduction of renewable raw materials. Flexible interpretation of regulations in favour of innovative solutions, however, depends strongly on the commitment and status of information of the decision makers involved. Experts are discussing an 'experiment clause' for the introduction phase of innovations, which would allow buildings or building parts to be tested under determined conditions for a specified time. Such demonstration buildings can illustrate to authorities the efficiency of renewable raw materials. Visible applications of innovative building products can strongly increase their acceptance.
Technical and legal certification also plays a very substantial role in the acceptance and market penetration of products. The need for exemptions from the rules and regulations should be overcome in the long term by developing normal approval and licensing procedures for renewable building materials. This process of 'normalisation' of renewable resource based building products should be promoted actively by product manufacturers.
Existing regulations and standards discriminate in many cases against renewable raw materials. Furthermore, a lack of transparency in the specification procedure was often criticised. While the way in which laws and codes must be publicised is clearly laid down and publicly accessible, the rules for the publication of certification procedures are not sufficiently clear or concrete.
During the last few years, public funding programmes have been successfully implemented in the fields of energy efficient building technologies and the introduction of biomass heating systems, steering the public towards these ideas.
In almost all federal states an extension of existing funding guidelines to include the detailed analysis of building products is being discussed. Knowledge about the 'hidden energy' of building materials and a holistic view of the building (building shell, energy supply and ventilation as one system) have led to this emphasis on building materials. Some federal states are already considering the type of raw materials used for insulation products, and in addition there are attempts in progress to include ecological criteria in assessment for funding. A variety of codes taking into account ecotoxicology and relevant climate data are used. But reliable, easy to use assessment methods and criteria are still lacking. Appropriate assessment solutions need to be derived from existing methods, in co-operation with the funding departments of the federal states. The departments responsible are ready for co-operation and remarkably open and flexible.
Other funding assessment criteria than building materials are also being considered, and focus on functional qualities such as easy processing, indoor climatic qualities, absence of allergens and rebuild and reuse possibilities.
The role of the public sector as customer (buyer of works and services) is considered to be another significant factor at the legal/political level. Here public procurement directives are of special importance. The criteria on which public tenders are to be awarded are laid down in EU guidelines. At present it is not possible to take external (environmental) costs into account. Thus, in some states, subsequent costs for maintenance, usage and waste management are taken into account. New legislation obliges the public customer to disclose decision criteria and respective weighting. In addition to price, quality, technical value, usability and aesthetics, operating and subsequent costs, profitability, customer service and delivery time periods are also valid criteria.
It is already set out in the call for tender whether or not alternative offers are to be permitted and to what extent. In this respect Austria is considered to be more open to alternatives than most of the other EU Member States. The passage in the guidelines concerning the environmental quality of services is a striking argument for the use of renewable resources. It can be set into price relation by use-value analysis.
The stakeholders involved have different motives for their engagement in the area of renewable resource-based building products. There is an active interest on the part of the agricultural sector in increased sales in the non-food sector. Manufacturers and trade put emphasis on natural product lines, which at present only hold a small share of the market. Marketing strategies shift from stressing environmental benefits towards aspects of quality and functional advantages such as physical building characteristics.
Efficient communication channels between the main stakeholders in the production chain are still being developed. A co-ordinated entry onto the market is essential, however. Manufacturers and retailers see the necessity of common marketing, public relations and lobbying strategies, but horizontal co-operation is restricted as the market is regarded as being too small and competition still plays a large role. For this reason, vertical co-operation between the protagonists along the production chain is considered to be more promising. Independent platforms are needed to perform co-ordinating tasks. As an example of this, the study mentions the "ProHolz" initiative, set up by the wood industry to work on the improvement of technical standards and certification.
Thematic focal areas
Three particularly promising fields of application were selected for detailed study out of the variety of areas in which renewable raw materials can be used. The choice was made on grounds of market relevance, innovation potential and substitution potential for environmentally harmful substances. The following table shows the areas that are examined in detail in the study:
|Focal Area||Technical Arguments||Economical and
|Straw Bale Building||
Excellent technical qualities (thermal insulation, fire resistance)
Suitable for low energy and passive house technologies
Economic chances for agricultural by-products
Excellent supply possibilities
Low raw material price
Promising research and and development activities
Functional improvements by using new raw materials
Reduction of toxic substances
Improvement of indoor climate
|Acoustic and Thermal Insulation||
Variety of raw materials
Well developed, time-tested solutions
Energy saving function
Regional market opportunities
Straw Bale Building
In the area of straw bale building, two different fundamental technologies can be identified. For 'load-bearing' constructions, straw bale walls take the static load of the building. Another possibility is that a (wooden) framework takes the static load while the straw bales serve mainly as thermal insulation material. The load-bearing style is used internationally for houses built from scratch by the owner, but this technology has presently low distribution chances in Austria since it cannot meet legal requirements. Emphasis is therefore being placed on the development of professional solutions.
The chances for straw filled wooden frame constructions look promising, especially in the prefabricated building industry. Wooden frame constructions are well known and tested. The prefabrication of wall systems can prevent the danger of high moisture in the straw bales. It also allows for the construction of an airtight building shell without heat bridges. An additional benefit is that the combination with wood or clay increases the functional advantages of this building technology.
European and US experiences allow the following conclusions to be drawn regarding the factors influencing straw bale building quality. The properties of the bale itself (density, measure precision etc.) are much more important than the properties of the straw (type, quality). Humidity control is the main challenge to straw bale building. Fire hazard and pests play a subordinate role.
The legal situation of straw bale building was analysed according to the building regulations of Lower Austria. The relevant paragraphs deal mainly with the prevention of fire. According to §2 of the Lower Austrian building code ("NÖ Bautechnikverordnung"), deviations from the regulations are permissible in general if it can be proved that all essential requirements are fulfilled. This proof of equality can be provided with test certificates or calculations. These test certificates will form the legal basis of the market penetration of straw bale building in Austria.
The socio-economic enquiries regarding acceptance of straw bale buildings showed the following results:
Lack of acceptance and low readiness for innovations hinder the commercial use of straw as a building material. Building experts expect the application possibilities for straw bale buildings to be first and foremost in the field of low energy houses. Demonstration buildings are seen as a good chance to accumulate practical experience and to carry out long term tests.
Stakeholders express the need for more information, communication and opportunities for interaction on both the theoretical and practical levels. A well established network could meet this demand and stimulate the exchange of practical experience. The findings and reports can then be compared with the results of empirical tests from the pioneer countries in straw bale building.
In some construction details uncertainties still remain regarding the technical behaviour of straw. Further technological development of straw bale wall systems is therefore necessary if a relevant market share in the prefabricated building industry is to be achieved. In the long term, it is possible that straw could achieve a market position comparable to that of cellulose.
Surface treatment products are offered in a large variety of high functionality raw materials. Nevertheless, only 5% are well established on the market. This sector is distinguished by numerous technological innovations. Problems with dangerous solvents have been improved by using water soluble products, thus lowering allergy potential. Citrus oil could also be a possible substitute. Other technological improvements, such as the reduction of drying times through mechanical methods of microfiltation are also being developed.
The functionality of surface treatment products made from renewable raw materials is always compared to that of conventional products, as this is what concerns the user the most. The main advantages of naturally treated surfaces are health and building-biological ones. The fact that they can be maintained without loss in substance can be an essential cost advantage.
The number of customers is increasing slowly but continuously. It has been pointed out that professionals seem harder to convince than private customers to use ecological products.
An interesting industrial area of application for natural surface treatment products is the production of prefabricated parquet floors.
In the furniture industry some logistical productions are to be expected as inner surfaces need different treatment to that of external surfaces.
Offering a complete service package would provide new market opportunities. The offer of 'natural surfaces' as a complete package including maintenance and service is an attractive alternative to the sale of varnish in a can. These concepts have already been successfully applied in other economic fields.
Acoustic and Thermal Insulation
Insulation products are produced from different vegetable and animal fibres, and this sector needs well co-ordinated co-operation and trade relations between farmers and producers. Furthermore, these high quality insulation products require professional marketing.
Because of lacking sales agreements and guarantees, it is becoming harder and harder for the producer to find farmers to grow renewable raw materials, although there is enough land available. In addition there are financial barriers to the supply and processing of raw materials, caused by the costs of product tests and certification.
Manufacturers and traders try to meet the necessary test and certification requirements for their products, but they lack official support. Testing conditions are developed in accordance with conventional building materials. Therefore they often do not sufficiently consider the functional criteria of alternative products based on renewable resources.
The trend towards passive house standards is accompanied by an increasing demand for insulation materials. This development offers new chances for renewable raw materials. Price differences can be lowered by appropriate construction and efficient assembly methods (e.g. using special tools). At present, renewable raw materials hold a market share of about 3-5% of the insulation product market. Conventional insulation products are superior in price comparison due to lower raw material costs, a greater scale of industrial production and established distribution networks. Future marketing concepts should therefore stress the functional advantages, long term economy of use and easy waste management of renewable insulation products.
|Project manager:||Dipl.-Ing. Robert Wimmer
GrAT - Center for Appropriate Technology
GrAT - Center for Appropriate Technology
Dipl.-Ing. Robert Wimmer
GrAT - Center for Appropriate Technology
Vienna University of Technology
Wiedner Hauptstraße 8-10
A 1040 Wien
Tel.: +43 1 58801 - 49523
Fax: +43 1 786 42 05