The pros and cons of replacing traditional materials with polymeric materials in solar thermosiphon systems were analysed by adopting a total cost accounting approach.

In terms of climatic and environmental performance, polymeric materials reveal better key figures than traditional ones like metals. In terms of present value total cost of energy, taking into account functional capability, end user investment cost, O&M cost, reliability and climatic cost, the results suggest that this may also be true when comparing a polymeric based thermosiphon system with a high efficient thermosiphon system of conventional materials for DHW production in the southern Europe regions. When present values for total energy cost are assessed for the total DHW systems including both the solar heating system and the auxiliary electric heating system, the difference in energy cost between the polymeric and the traditional systems is markedly reduced.

The main reason for the difference in results can be related to the difference in thermal performance between the two systems. It can be concluded that the choice of auxiliary heating source is of utmost importance for the economical competiveness of systems and that electric heating may not be the best choice.

To assess the suitability of solar collector systems in which polymeric materials are used versus those in which more traditional materials are used, a case study was undertaken. In this case study a solar heating system with polymeric solar collectors was compared with two equivalent but more traditional solar heating systems: one with flat plate solar collectors and one with evacuated tube solar collectors. To make the comparison, a total cost accounting approach was adopted. The life cycle assessment (LCA) results clearly indicated that the polymeric solar collector system is the best as regards climatic and environmental performance when they are expressed in terms of the IPPC 100 a indicator and the Ecoindicator99, H/A indicator, respectively. In terms of climatic and environmental costs per amount of solar heat collected, the differences between the three kinds of collector systems were small when compared with existing energy prices. With the present tax rates, it seems unlikely that the differences in environmental and climatic costs will have any significant influence on which system is the most favoured, from a total cost point of view. In the choice between a renewable heat source and a heat source based on the use of a fossil fuel, the conclusion was that for climatic performance to be an important economic factor, the tax or trade rate of carbon dioxide emissions must be increased significantly, given the initial EU carbon dioxide emission trade rate. The rate would need to be at least of the same order of magnitude as the general carbon dioxide emission tax rate used in Sweden. If environmental costs took into account not only the greenhouse effect but also other mechanisms for damaging the environment as, for example, the environmental impact factor Ecoindicator99 does, the viability of solar heating versus that of a natural gas heating system would be much higher.

Method when heating a building with solar collectors comprising also a heat pump and energy storage using phase change materials. The invention is charaterized in that the energy storage system comprises to two containers, one placed indoors, where the phase change material has a melting point between 19 and 30 degrees Celsius, and a second container located outdoors and buried in the ground, where the phase change material has a conversion temperature which corresponds to or is lower  than the mean temperature of the ground surrounding the container.

There is a need for accurate and readily available information about theoptimization, economics, and environmental impacts of combi-heating systems.Accordingly, the authors have developed TRNSYS-based software called Flexifuel thatincludes a TRNSED application for calculating the annual system performance ofcombi-heating systems involving any combination of heat pumps, flat or vacuumtube solar collectors, pellet burners, electric auxiliary heaters, and heatstorage tanks. Selection of less complex software systems and types reduces thesimulation time without significantly affecting the accuracy of the results.Annual performance data for a system can be simulated in from one to twominutes. Comparison of accumulated theoretical and measured performance dataover the time period for a full-scale test plant with heat pumps and solarcollectors showed that simulation errors were below 5%.

To assess suitability ofsolar collector systems with polymeric materials versus those with moretraditional materials such as metals a case study was undertaken within theframework of Task 39 of the IEA Solar Heating and Cooling Programme. In thisstudy one solar heating system with polymeric solar collectors were comparedwith two equivalent but more traditional solar heating systems, one with flatplate collectors and one with evacuated tube solar collectors. Life Cycle Assessment(LCA) results obtained clearly indicated that the polymeric solar collectorsystem is the most favourable as regards climatic and environmentalperformance. In terms of climatic and environmental costs per solar heat collected,the differences between the three kinds of collector systems, however, aresmall when compared with existing energy prices. In the choice between arenewable heat source and a heat source based on the use of a fossil fuel,which was also analysed in the present study, the conclusion was that forclimatic performance to be an important economic factor, the rate of carbondioxide emission must be considerably increased above the level given by thepresent EU carbon dioxide emission trade rate. The rate would be at least ofthe same order of magnitude as the general carbon dioxide emission tax rateemployed in

Sweden.An alternative to an increase in the EU carbon dioxide emission trade ratewould be to introduce a tax system based on environmental cost, making use ofe.g. Ecoindicator99, to include also other impacts on the environment not justthe greenhouse effect.

To assess climatic performance of energy producing systems, the indicator IPCC, 100a is maybe the most commonly employed in life cycle analysis, LCA. The result is expressed as the amount of green house gases that is emitted to the atmosphere during production of one energy unit as e.g. kg CO₂ equivalents per 1 MJ of energy produced or transferred by the system considered. To translate this indicator into cost the rate for green house emission trading in EU would at least in principle be applicable but has not been used for that purpose in connection with product design yet as far as we know.

The analysis of the LCA data on the two solar heating systems found in the Ecoinvent data base shows that the total cost methodology proposed by Carlsson would be a suitable tool to compare performance of different solar heating systems not only in terms of direct costs but also in terms of the indirect costs that can be attributed to the environmental negative impact the life cycles of the solar systems are causing.

The analysis has also shown that to make an adequate comparison between two solar systems with respect to environmental performance or environmental cost, the two systems have to be analysed when operating under the same external conditions with respect to outdoor climate and heat demand. The solar fraction utilized by the systems must be the same which means that only the design and the size of the two systems are different.

Den utvändiga fasaden ska ge byggnaden ett uttryck genom utformning och kulör. Fasaden ska också skydda de isolerande skikten i väggen från yttre påverkan. Dessa funktioner kan uppfyllas av i stort sett alla material. Om trä ska trä vara konkurrenskraftigt måste trämaterialet, fasadkonstruktionen och ytbehandlingssystemet väljas och samverka på ett sådant sätt att fasaden får en lång livslängd med litet och lågt underhåll. Därigenom blir träfasaden ekonomiskt och estetiskt attraktiv för brukaren i vid mening.

Denna studie belyser kunskapsfronten för utomhusanvändning av träslagen tall (Pinus sylvestris L.) och gran (Picea abies L. Karst.) ovan mark. Specifikt studeras användning i fasader utifrån aspekterna materialval, fasadkonstruktion, ytbehandling samt återvinning.

Marknaden efterfrågar träfasadsystem. De behov som marknadens aktörer, dvs. byggherrar, fastighetsförvaltare, arkitekter, konstruktörer, stomleverantörer, entreprenörer och representanter för småhusindustrin, framhäver kan sammanfattas i följande punkter:

• Behov av specificerad livslängd och givna tidsintervall för underhåll av träfasader. (Ska vara i nivå med konkurrerande material)
• Det är önskvärt att leverantören av ett fasadsystem ikläder sig ett långsiktigt ansvar för underhåll.
• Flexibilitet, leverantören ska kunna byta ut eller renovera fasaden vid behov.
• Byggkrav, träfasadmaterial måste kunna samverka med andra, speciellt brandklassade, material.
• Fasadsystem skall vara utseendemässigt attraktivt.

Den primära marknaden för nya fasadsystem bör vara flerbostadshus, men inte nödvändigtvis flerbostadshus av trä. Fokus ska ligga på fasadsystemets flexibilitet i arkitektoniskt uttryck och i relation till andra material och system. Nybyggnation är viktigt, men miljonprogrammet, renovering och tillbyggnad (ROT) samt energieffektivisering är också viktiga områden.

Den svenska marknaden är liten (idag ca. 70 000 m³ trä för fasader), men bör inledningsvis ändå prioriteras och därefter de nordiska länderna, samt Schweiz, Österrike och Tyskland.

I litteraturen beskrivs mer eller mindre välgrundade rekommendationer för att förlänga träfasaders livslängd och öka dess underhålls-intervall. Vissa av rekommendationerna är dock direkt motstridiga.

När aspekterna materialval, fasadkonstruktion och ytbehandling studeras finns det många detaljer som har betydelse för träfasadens beständighet. Det är svårt att sära ut de mest väsentliga faktorerna, men utan att ta hänsyn till aspekter som kostnader, tillgång, eller andra av praktiskt karaktär viktiga faktorer kan följande nyckelfaktorer identifieras för en miljöriktig och beständig fasad av tall eller gran:

Materialval

• Hög andel kärnved, helst uteslutande kärnved
• Virket ska ha stående årsringar
• Hanteringen ska utföras så att virket inte får mekaniska skador, får mikrobiella angrepp, eller blir uppfuktat eller nedsmutsat, dvs. snabb och rätt hantering, samt god emballering.
• Från marken – fasaden ska börja minst 30 cm ovan marken.
• Ventilation – utforma fasadbeklädnaden så att fukt snabbt kan torka ut. Ventilera utrymmet bakom fasaden vilket är ett enkelt sätt för att möjliggöra detta.
• Vattenavrinning – inga horisontella ytor.
• Flexibilitet – ska gälla både konstruktion och arkitektoniskt utförande. Fasadsystem som kan ”hängas på” befintliga byggnader efterfrågas.
• Förseglat ändträ – försegling av ändträytor för att förhindra fuktupptagning i träet är helt avgörande för trämaterialets livslängd. Spikning kan öppna nya ändträytor och bör därmed utföras omsorgsfullt och med eftertanke.
• Rundade virkeskanter – ger bättre täckförmåga hos färgen och minskar risk för mekaniska skador på fasadbrädorna.
• Val av ytbehandling – spelar en nyckelroll för fasadens prestanda. En träfasad ska levereras som en del av ett komplett underhållspaket.

Hantering från skog till fasadKonstruktionYtbehandling

För ytbehandling finns idag många tillämpningar där nanotekniken utnyttjas för att skapa mervärde hos en yta jämfört med vad dagens mer traditionella produkter kan erbjuda. Nanobaserade ytbehandlingsprodukter marknadsförs redan idag och där uppges de göra ytor smuts- och vattenavvisande, förhindra påväxt av alger, svamp och mossa, förbättra UV- och temperaturresistensen och kulörbeständigheten, förbättra rep- och nötningståligheten, samt ha antigraffiti egenskaper etc. De flesta produkterna är dock nya och för en del finns därför frågetecken vad gäller t.ex. långtidsprestanda och teknisk livslängd, underhållbarhet och därmed sammanhängande ekonomi sett ur ett livscykelperspektiv för den produkt eller system där ytbehandlingen utgör bara en del.

En kostnadsanalys som genomförts i studien gör bedömningen att nya nanoteknikbaserade ytbehandlingssystem skulle kunna ge som mest en reduktion av underhållskostnaderna med 15 %. Antagandet är då att fasadrengöring behöver göras vart femte eller sjunde år då traditionella målningssystem används.

Återvunnet trä från träfasader definieras enligt Svensk standard som trädbränsle och benämns generellt för returträ eller när materialet är i finfördelad form för returflis.

Ett stort problem med att återvinna energin från returträ är att en del av materialet är behandlat på något sätt, t.ex. impregnerat med träskyddsmedel, ytbehandlat eller innehåller andra konstruktionsdelar av t.ex. plast eller metall. Returflis är ett utmärkt bränsle för energiåtervinning förutsatt att anläggningen har tillräcklig rökgasrening och att askan hanteras på ett korrekt sätt. Ett problem idag är vad som ska ske med förorenad askan då den klassas som farligt avfall och därmed inte kan återföras till skogen. Om halterna av tungmetaller inte är för höga kan askan användas som täck- och fyllmaterial annars måste askan gå till deponi.

En bättre källsortering och översyn av regelverk skulle dessutom kunna leda till att det renare returträet skulle kunna eldas i konventionella biobränslepannor medan den förorenade andelen då skulle eldas separat.

The external façade must give expression to a building through both design and colour, and it must also protect the insulating layers in the wall from external influences. These functions can be fulfilled by almost all materials. If wood is to be competitive in this context, the wood material, the façade design and the surface treatment system must be chosen and interact in such a way that the façade is given a long life with little need for maintenance. A wooden façade will then in a broad sense be both economically and aesthetically attractive for the user.

This study illustrates the state of knowledge regarding the outdoor use of pine (Pinus sylvestris L.) and spruce (Picea abies L. Karst.) facings above ground. Specifically, it deals with the use of wooden facings with regard to the choice of material, façade design, surface treatment and recycling. The market demands wooden facing systems, and the requirements emphasized by the actors on the market, e.g. the builders, real estate administrators, architects, designers, frame suppliers, contractors and representatives for the single-family timber housing industry can be summed up as follows:

• There must be a specified life-time and given time intervals for maintenance of the wooden facings. (Shall be similar to those of competitive materials)
• The supplier of the facing system should shoulder the long-term responsibility for its maintenance.
• Flexibility, the supplier shall be able to replace or renovate the facings when necessary.
• Building requirements, the wooden facing materials must be able to interact with other, specially fire-classified, materials.
• The facing system shall have an attractive appearance.

The primary market for the new facing systems should be multi-family houses but not necessarily multi-family houses of wood. The focus shall lie in the flexibility of the facing system in architectural expression, and in relation to other materials and systems. New building is important, but the million program, renovation and additions (ROT) and greater energy efficiency are also important spheres.

The Swedish market is small (currently ca. 70 000 m³ wood for façades), but it should nevertheless be given priority before the Nordic countries, and thereafter Switzerland, Austria and Germany. The literature describes more or less well-founded recommendations for prolonging the life of wooden facing materials and extending their maintenance intervals, although some of the recommendations are directly conflicting.

Many details relating to materials choice, façade design and surface treatment are important for the durability of wooden facings. It is difficult to separate the most important factors, but without taking into consideration aspects such as costs, availability and other factors of a practical nature, the following key factors can be identified as important for an environmentally correct and durable façade of pinewood or spruce:

Choice of material

• The wood shall have a high proportion of heartwood, preferably exclusively heartwood
• The wood shall have vertical annual rings.

Handling from forest to the façade

• The wood shall be handled so that it does not suffer mechanical damage or microbial attack, or become wet or soiled, i.e. a rapid and correct handling with good packaging.

Design

• The façade shall start at least 30 cm above the ground level.
• The façade shall be ventilated so that moisture can rapidly dry out. Ventilation of the space behind the facing is an easy way of achieving this.
• Water run-off – no horizontal surfaces.
• Flexibility –both in the construction and in the architectural design. There is a demand for facing systems which can be simply “hung onto” existing buildings.

Surface treatment

• Sealed end-grain sections – sealing of the end-grain surface to prevent moisture absorption into the wood is decisive for the life-time of the wood material. Nailing can open up new end-grain surfaces and should thus be carried out carefully and only after due consideration.
• Rounded edges – increase the covering ability of paint and reduce the risk of mechanical damage to the facing boards.
• Choice of surface treatment – vital for the performance of the facings. The wooden facings shall be delivered as part of the complete maintenance package.

Nowadays there are many types of surface treatment where nano-technology is used to create an added value in a surface compared with what the more traditional products can offer. Nano-based surface-treatment products are already on the market, and they are said to make the surfaces dirt- and water-repellent, to prevent the growth of algae, fungi and moss, to improve UV- and temperature-resistance and colour permanence, to improve scratch- and abrasion-resistance, and to have anti-graffiti qualities etc. However, most of these products are new and for some of them there are still question marks with regard to their long-term performance and technical life-time, as well as their serviceability and thereto related economy seen from a life-cycle perspective for the product or system for which the surface treatment constitutes only a part.

A cost analysis carried out as a part of the study makes the assessment that the new nano-technology-based surface-treatment systems could lead at most to a reduction of 15 %. in maintenance costs. The assumption is then that the façade needs to be cleaned every fifth or seventh year when a traditional painting system is used.

According to the Swedish Standard, recovered wood from a wooden façade is defined as tree fuel and is generally designated recycled wood or, when the material is in a disintegrated form, as recycled chips,

There is a major problem in recovering energy from recycled wood when a part of the material has been treated in some way, e.g. impregnated with a wood-protection agent or surface-treated, or when it contains other design components of e.g. plastic or metal. Recycled chips are a very good fuel for energy recovery provided the plant has adequate flue-gas cleaning and the ash is handled in a correct manner. Contaminated ash constitutes a problem, since it is classified as dangerous waste and cannot therefore be returned to the forest. If the content of heavy metals is not too high, the ash can be used as a covering and filling material. Otherwise, the ash must be deposited as landfill. A better sorting of household waste and an overhaul of the regulations would mean that the cleaned recycled wood could be burned in conventional biofuel boilers and that the contaminated portion could be burned separately.

A total cost accounting approach was used to analyse the suitability of copper and aluminium as winding material for transformers, using available data from the Ecoinvent database. It could be concluded that the use of recycled metal is a necessary requisite for sustainability. Using cost data for energy and materials and reasonable assumptions about costs for labour and interest for the metal supplier and the product manufacturer, the copper alternative turns out to be the better choice, especially when the expected increase in the prices of energy, copper, and aluminium during life cycle is taken into account.

When considering environmental cost, useful indicators are those that can be expressed in cost terms. With the Ecoindicator 99 indicator as the basis for estimating environmental cost, the aluminium alternative is better than the copper alternative. However, the contribution of the environmental cost to the total cost has minor importance when compared with the effect you get from the negative cost contribution from the end-of-life phase. Therefore, the copper alternative is the better choice in terms of least total cost in the application considered.

From the study it could also be concluded that the total cost accounting approach would be a valuable design tool, when comparing two design alternatives of a product functional unit to decide which of the two is the more favourable from a sustainability point of view.