Heating with wood-fuels in multi-family houses – a new trend -

Dr Christian Rakos, EVA – the Austrian Energy Agency

Dr Rakos is co-ordinator of the multi-national bio-energy collaboration, BIOHEAT. Scottish participation by NIFES Consulting Group is supported by the Cluster.

Heating with wood seems like a fairly old-fashioned practice, something reminiscent of the good old days, but not something you would expect in a modern building. Revolutionary developments in wood combustion technology and the emergence of pellets (small compressed pieces of sawdust) as a ‘high-tech’ wood fuel are changing this perception. In Austria the use of wood pellets is growing dramatically both in single-family houses and in multi-family houses. Sales of pellet boilers have almost doubled each year over the past 5 years, while the sales of oil boilers are dropping rapidly. Modern boilers that use wood-chips or pellets are highly developed devices that retrieve the wood fuel automatically from the fuel store, burn it at high temperatures and with electronically controlled air supply and can provide more than 90% of the energy contained in the wood for heating. Compare this to maybe 10% efficiency of an open fireplace or 50% efficiency of a conventional wood boiler. Modern wood boilers do not produce visible smoke, their emissions are almost as low as the emissions of natural gas boilers. State of the art models have automatic mechanical cleaning of heat exchanger surfaces and automatic ash removal. Some models even compress the ashes so it is only necessary to remove the ashes twice a year. While the use of pellet boilers for single-family houses is rapidly becoming mainstream business in Austria and in some of the Nordic countries, the use of wood-fuels in large buildings, as housing projects or public buildings, is the most recent emerging market. Figure 1 shows the number of multi-family housing projects heated with wood in Austria. In a report published by the Austrian Energy Agency in October 2001 a first systematic assessment of this new development has revealed, that a new type of sustainable housing project is emerging: more than 60% of the wood heated buildings are “low energy” buildings. More than 40% also had solar thermal collectors for hot water preparation in summer. The total heating demand of a 100m2 flat in such a building is less than 1 ton of pellets, which corresponds to heating costs of less than 200 Euro per year. Mr. Helmut Meisel, chief of technical planning at the GSWB Housing Association says: “We started with establishing solar collectors for hot water preparation in our housing projects. We were hesitant in setting up wood heating systems as these were not fully reliable in the first years and we heard of considerable start up problems. Now this technology has matured and we will equip all our new projects both with solar collectors and with wood heating systems. Our customers are aware, that wood fuels are significantly cheaper than oil or gas. In addition to that, wood fuels are a domestic resource and offer significantly higher supply security than conventional fuels, not to speak of the environmental benefits.” An important reason for implementing high insulation standards and renewable energy use in multi family buildings were special financial incentives. Franz Mair, responsible for the redesign of the housing subsidy system in the province of Salzburg: ”Until 1995 we used to give subsidies for establishing new living space without any conditions, except certain maximum cost levels. Then we started to introduce conditions by establishing a model of eco points. These points can be achieved by increasing insulation standards, by introducing the use of renewable energy, by installing controlled ventilation with heat recovery or other

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innovations that minimise both ecological impacts and operational costs of the buildings. It did not cost us an extra penny. We just put new conditions in place for receiving the subsidy.” The new system of eco-points led to a dramatic market transformation. Heating loads for newly constructed houses in Salzburg dropped within 5 years from an average of 60 W/m2 to 30 W/m2. In 2002 more than 65% of newly constructed living space was supplied with solar hot water preparation. The market share of wood heated buildings was 60% in 2002, up from less than 10% in 1995. Other provinces are coming up with similar schemes, which means that the speed of market penetration of wood heating systems will further increase in the next years. While the whole development is very encouraging, the E.V.A. analysis did reveal some weaknesses: in many cases the planners had designed the heating system for the low energy houses as if they were conventional buildings. About 50% of the boilers were more than twice as large as they needed to be. Thus it is fundamental to include a coordinated effort to educate all relevant professionals to ensure that high quality services are provided.” Such an effort to disseminate adequate information on the use of wood heating systems in large buildings is funded by the European Commission in the framework of the ALTENER programme. The ‘BIOHEAT I’ project, running from 2000 till 2002, is now followed by ‘BIOHEAT II’ running from January 2003 till the end of 2004. The total budget of the BIOHEAT projects is 1,8 Mio €. 17 countries including member states and accession countries participate in the project. BIOHEAT is dedicated to stimulate the use of modern automatic wood boilers for heating large buildings such as schools, town halls, hospitals, retirement homes or residential blocks. Why is the BIOHEAT effort focussed on large buildings? The use of wood fuels is particularly economic in this sector (Figure 2). Modern wood boilers are more expensive than oil or gas boilers, but wood fuels are significantly cheaper. If heat demand is relatively high – as in large buildings – heating with wood fuels can be considerably cheaper than heating with oil in most European countries as shown in Figure 3. The competitivity of biomass was calculated for this figure on the cost basis of a 100 kW woodchip heating system implemented in a residential block in Nestelbach (Austria). It is based on prices in 2001 for fuel oil and wood chips in the respective countries. The calculation is based on a full cost calculation according to the VDI 2067 standard, the calculation tool can be downloaded at http://www.bioheat.info/handbook/heatcost_da.html If it is cheaper – why is it not more commonly used? There are a number of significant barriers. The most obvious one is, that the use of biomass for heating today is in the same situation as wind energy 10 years ago. Efficient technology is available and used in a few selected countries, but still not commonly known and accepted as a viable option. Thus BIOHEAT makes a major effort to disseminate knowledge about the option of using wood fuels to relevant target groups as municipalities, provincial governments, housing associations, consultants, architects etc. Brochures are produced in 14 different languages and a website offering practical information has been established: www.bioheat.info. Besides disseminating basic information BIOHEAT II will aim at involving regional energy agencies and train them to develop wood heated projects. It will also include an international training course for planners and the publication of detailed technical manuals explaining the do´s and don´ts of heating large buildings with wood fuels. Finally, the national project managers will offer start-up support for pilot projects including a telephone hotline and financial support for feasibility studies.

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Christian Rakos, EVA

BIOHEAT is coordinated by Christian Rakos from E.V.A. – the Austrian Energy Agency ([email protected]). In Scotland, help and information is available from NIFES Consulting Group in Glasgow; contact Maurice Millar ( [email protected] ).

80 70 60 50 40 30 20 10 0 1992

1993

1994

1995

1996

1997

1998

1999

2000

Figure 1: Number of wood heated residential blocks in Austria

Specific investment costs of biomass heating systems EURO / kW

District heating plants

Single family houses

1400 1200 1000 800 600 400

Heating plants for large buildings

200 0 10

100

1000

10000 kW

Sources: Agricultural Chamber Styria 1998, E.V.A. 1999

Figure 2: Specific investment costs of biomass heating systems

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Comparison of total heating costs with wood chips and fuel oil

percentage of heating costs with oil

120

100

104

100 % = total heating costs with fuel oil

80

GR

66

63

61

A

F

P

49

60 39

41 E

40

20

92

91 84

I

N

DK S

NL

0

Figure 3: Competitivity of biomass, calculated on the basis of a 100 kW wodchip heating system

BIOHEAT partner in Scotland is –

BIOHEAT project manager is -

NIFES Consulting Group 8 Woodside Terrace Glasgow G3 7UY

EVA – the Austrian Energy Agency Otto-Bauer-Gasse 6, A-1060 Wien

Tel. 0141 – 332 2453 Fax 0141 – 333 0402

Tel. (+43-1) 586 15 24 Fax (+43-1) 586 15 24-40

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Christian Rakos, EVA