Rapport från/Report from IEA Task-14 mötet/meeting on solar heating system, Hameln Tyskland/Germany August 1992

Participation as observer at the meeting of Task 14 of IEA's Solar Heating and Cooling Projects held in Hameln, Germany has led to greater understanding of interesting developments underway in several countries. This will be of use during the development of small scale systems suitable for Swedish conditions. A summary of the work carried out by the working groups within Task 14 is given, with emphasis on the Domestic Hot Water group. Experiences of low-flow systems from several countries are related, and the conclusion is drawn that the maximum theoretical possible increase in performance of 20% has not been achieved due to poor heat exchangers and poor stratification in the storage tanks. Positive developments in connecting tubes and pumps is noted. Further participation as observer in Task 14 meetings is desired, and is looked on favourably by the members of the group. Another conclusion is that SERC should carry on with work on Swedish storage tanks, with emphasis on better stratification and heat exchangers, and possible modelling of system components. Finally a German Do-it-Vourself kit is described and judged in comparison with prefabricated models and Swedish Do-it-Yourself kits.

Monitoring results of combined pellet and solar heating system

In this study the monitoring results of prototype installation of a recently developed solar combisystem have been evaluated. The system, that uses a water jacketed pellet stove as auxiliary heater, was installed in a single family house in Borlänge/Sweden. In order to allow an evaluation under realistic conditions the system has been monitored for a time period of one year. From the measurements of the system it could be seen that it is important that the pellet stove has a sufficient buffer store volume to minimize cycling. The measurements showed also that the stove gives a lower share of the produced heat to the water loop than measured under stationary conditions. The solar system works as expected and covers the heat demand during the summer and a part of the heat demand during spring and autumn. Potential for optimization exists for the parasitic electricity demand. The system consumes 680 kWh per year for pumps, valves and controllers which is more than 4% of the total primary heating energy demand.

Testing of combined heating systems for small houses: Improved procedures for whole system test methods : Deliverable 2.3

Dynamic system test methods for heating systems were developed and applied by the institutes SERC and SP from Sweden, INES from France and SPF from Switzerland already before the MacSheep project started. These test methods followed the same principle: a complete heating system – including heat generators, storage, control etc., is installed on the test rig; the test rig software and hardware simulates and emulates the heat load for space heating and domestic hot water of a single family house, while the unit under test has to act autonomously to cover the heat demand during a representative test cycle. Within the work package 2 of the MacSheep project these similar – but different – test methods were harmonized and improved. The work undertaken includes:  • Harmonization of the physical boundaries of the unit under test. • Harmonization of the boundary conditions of climate and load. • Definition of an approach to reach identical space heat load in combination with an autonomous control of the space heat distribution by the unit under test. • Derivation and validation of new six day and a twelve day test profiles for direct extrapolation of test results.   The new harmonized test method combines the advantages of the different methods that existed before the MacSheep project. The new method is a benchmark test, which means that the load for space heating and domestic hot water preparation will be identical for all tested systems, and that the result is representative for the performance of the system over a whole year. Thus, no modelling and simulation of the tested system is needed in order to obtain the benchmark results for a yearly cycle. The method is thus also applicable to products for which simulation models are not available yet. Some of the advantages of the new whole system test method and performance rating compared to the testing and energy rating of single components are:  • Interaction between the different components of a heating system, e.g. storage, solar collector circuit, heat pump, control, etc. are included and evaluated in this test. • Dynamic effects are included and influence the result just as they influence the annual performance in the field. • Heat losses are influencing the results in a more realistic way, since they are evaluated under "real installed" and representative part-load conditions rather than under single component steady state conditions.   The described method is also suited for the development process of new systems, where it replaces time-consuming and costly field testing with the advantage of a higher accuracy of the measured data (compared to the typically used measurement equipment in field tests) and identical, thus comparable boundary conditions. Thus, the method can be used for system optimization in the test bench under realistic operative conditions, i.e. under relevant operating environment in the lab.   This report describes the physical boundaries of the tested systems, as well as the test procedures and the requirements for both the unit under test and the test facility. The new six day and twelve day test profiles are also described as are the validation results.

Equal Couples in Equal Houses : Cultural perspectives on Swedish solar and bio-pellet heating design

Knowing how to design a heating system that will work mechanically is quite different from knowling how to design a system that users perceive as responsive to their domestic practices and values. In this chapter, social anthropologist Henning argues that the challenge for designers involved in the development or marketing of green buildings with heating systems that are based on renewable sources of energy is to see things from the perspective of those who are supposed to live in these buildings. The chapter focuses on three culture-specific aspects of Swedish households and single-family houses: perceptions of house and home, of private and public space, and of male and female space. Through these three angles, some clues are given as to how design, performance and location of solar and bio-pellet heating systems could be made to resonate with predominant experiences, habits and ways of thinking among both men and women.

Heat losses and thermal performance of commercial combined solar and pellet heating systems

Various pellet heating systems are marketed in Sweden, some of them in combination with a solar heating system. Several types of pellet heating units are available and can be used for a combined system. This article compares four typical combined solar and pellet heating systems: System 1 and 2 two with a pellet stove, system 3 with a store integrated pellet burner and system 4 with a pellet boiler. The lower efficiency of pellet heaters compared to oil or gas heaters increases the primary energy demand. Consequently heat losses of the various systems have been studied. The systems have been modeled in TRNSYS and simulated with parameters identified from measurements. For almost all systems the flue gas losses are the main heat losses except for system 3 where store heat losses prevail. Relevant are also the heat losses of the burner and the boiler to the ambient. Significant leakage losses are noticed for system 3 and 4. For buildings with an open internal design system 1 is the most efficient solution. Other buildings should preferably apply system 3. The right choice of the system depends also on whether the heater is placed inside or outside of the heated are. A large potential for system optimization exist for all studied systems, which when applied could alter the relative merits of the different system types.

Variation of System Performance with Design and Climate for Combisystems in Sweden

In Sweden, 90% of the solar heating systems are solar domestic hot water and heating systems (SDHW&H), so called combisystems. These generally supply most of the domestic hot water needs during the summer and have enough capacity to supply some energy to the heating system during spring and autumn. This paper describes a standard Swedish combisystem and how the output from it varies with heating load, climate within Sweden, and how it can be increased with improved system design. A base case is defined using the standard combi- system, a modern Swedish single family house and the climate of Stockholm. Using the simulation program Trnsys, parametric studies have been performed on the base case and improved system designs. The solar fraction could be increased from 17.1% for the base case to 22.6% for the best system design, given the same system size, collector type and load. A short analysis of the costs of changed system design is given, showing that payback times for additional investment are from 5-8 years. Measurements on system components in the laboratory have been used to verify the simulation models used. More work is being carried out in order to find even better system designs, and further improvements in system performance are expected.

Simulation of Photovoltaic Panel Production as Complement to Ground Source Heat Pump System

This master thesis presents a new technological combination of two environmentally friendly sources of energy in order to provide DHW, and space heating. Solar energy is used for space heating, and DHW production using PV modules which supply direct current directly to electrical heating elements inside a water storage tank. On the other hand a GSHP system as another source of renewable energy provides heat in the water storage tank of the system in order to provide DHW and space heating. These two sources of renewable energy have been combined in this case-study in order to obtain a more efficient system, which will reduce the amount of electricity consumed by the GSHP system.The key aim of this study is to make simulations, and calculations of the amount ofelectrical energy that can be expected to be produced by a certain amount of PV modules that are already assembled on a house in Vantaa, southern Finland. This energy is then intended to be used as a complement to produce hot water in the heating system of the house beside the original GSHP system. Thus the amount of electrical energy purchased from the grid should be reduced and the compressor in the GSHP would need fewer starts which would reduce the heating cost of the GSHP system for space heating and providing hot water.The produced energy by the PV arrays in three different circuits will be charged directly to three electrical heating elements in the water storage tank of the existing system to satisfy the demand of the heating elements. The excess energy can be used to heat the water in the water storage tank to some extent which leads to a reduction of electricity consumption by the different components of the GSHP system.To increase the efficiency of the existing hybrid system, optimization of different PV configurations have been accomplished, and the results are compared. Optimization of the arrays in southern and western walls shows a DC power increase of 298 kWh/year compared with the existing PV configurations. Comparing the results from the optimization of the arrays on the western roof if the intention is to feed AC power to the components of the GSHP system shows a yearly AC power production of 1,646 kWh.This is with the consideration of no overproduction by the PV modules during the summer months. This means the optimized PV systems will be able to cover a larger part of summer demand compared with the existing system.

Annual CO-emissions of combined pellet and solar heating systems

Emissions are an important aspect of a pellet heating system. High carbon monoxide emissions are often caused by unnecessary cycling of the burner when the burner is operated below the lowest combustion power. Combining pellet heating systems with a solar heating system can significantly reduce cycling of the pellet heater and avoid the inefficient summer operation of the pellet heater. The aim of this paper was to study CO-emissions of the different types of systems and to compare the yearly CO-emissions obtained from simulations with the yearly CO-emissions calculated based on the values that are obtained by the standard test methods. The results showed that the yearly CO-emissions obtained from the simulations are significant higher than the yearly CO-emissions calculated based on the standard test methods. It is also shown that for the studied systems the average emissions under these realistic annual conditions were greater than the limit values of two Eco-labels. Furthermore it could be seen that is possible to almost halve the CO-emission if the pellet heater is combined with a solar heating system.

Emissions from realistic operation of residential wood pellets heating systems

Emissions from residential combustion appliances vary significantly depending on the firing behaviours and combustion conditions, in addition to combustion technologies and fuel quality. Although wood pellet combustion in residential heating boilers is efficient, the combustion conditions during start-up and stop phases are not optimal and produce significantly high emissions such as carbon monoxide and hydrocarbon from incomplete combustion. The emissions from the start-up and stop phases of the pellet boilers are not fully taken into account in test methods for ecolabels which primarily focus on emissions during operation on full load and part load. The objective of the thesis is to investigate the emission characteristics during realistic operation of residential wood pellet boilers in order to identify when the major part of the annual emissions occur. Emissions from four residential wood pellet boilers were measured and characterized for three operating phases (start-up, steady and stop). Emissions from realistic operation of combined solar and wood pellet heating systems was continuously measured to investigate the influence of start-up and stop phases on total annual emissions. Measured emission data from the pellet devices were used to build an emission model to predict the annual emission factors from the dynamic operation of the heating system using the simulation software TRNSYS. Start-up emissions are found to vary with ignition type, supply of air and fuel, and time to complete the phase. Stop emissions are influenced by fan operation characteristics and the cleaning routine. Start-up and stop phases under realistic operation conditions contribute 80 – 95% of annual carbon monoxide (CO) emission, 60 – 90% total hydrocarbon (TOC), 10 – 20% of nitrogen oxides (NO), and 30 – 40% particles emissions. Annual emission factors from realistic operation of tested residential heating system with a top fed wood pelt boiler can be between 190 and 400 mg/MJ for the CO emissions, between 60 and 95 mg/MJ for the NO, between 6 and 25 mg/MJ for the TOC, between 30 and 116 mg/MJ for the particulate matter and between 2x10-13 /MJ and 4x10-13 /MJ for the number of particles. If the boiler has the cleaning sequence with compressed air such as in boiler B2, annual CO emission factor can be up to 550 mg/MJ. Average CO, TOC and particles emissions under realistic annual condition were greater than the limits values of two eco labels. These results highlight the importance of start-up and stop phases in annual emission factors (especially CO and TOC). Since a large or dominating part of the annual emissions in real operation arise from the start-up and stop sequences, test methods required by the ecolabels should take these emissions into account. In this way it will encourage the boiler manufacturers to minimize annual emissions. The annual emissions of residential pellet heating system can be reduced by optimizing the number of start-ups of the pellet boiler. It is possible to reduce up to 85% of the number of start-ups by optimizing the system design and its controller such as switching of the boiler pump after it stops, using two temperature sensors for boiler ON/OFF control, optimizing of the positions of the connections to the storage tank, increasing the mixing valve temperature in the boiler circuit and decreasing the pump flow rate. For 85 % reduction of start-ups, 75 % of CO and TOC emission factors were reduced while 13% increase in NO and 15 % increase in particle emissions was observed.

In Bio-Fuel We Trust

In bio-fuel we trust. Or do we? In this chapter, ethnographic material from Sweden is used to discuss ways sin which trust may influence the choice of bio-fuel for heating purposes. The meaning and substance of trust or distrust, as well as the very conditions for trust, are elaborated on in relation to solar and bio-pellet systems, district heating with bio-fuel, and traditional fireplaces. An important conclusion of this chapter is that the degree to which people perceive others as being like themselves or not tends to be decisive for whether these others are to be trusted, and therefore worth listening to. The context and situation in which a certain heating system is being chosen does not only involve trust in individuals, however, but in companies and the authorities, as well as in the arterfacts themselves. An example is given on how distrust of district heating companies led house owners to reject an offer of district heating despite the comfort and environmental benefit this could have provided. it is shown how this distrust might be resolved by making the rhythm of households and sitrict heating companies more in step with one another. The strong emotional attachment to and deep-felt trust in the traditional fireplace is also analysed, and a question is put forward as to whether these feelings could be transferred to modern bio-pellet stoves. Finally, our great and assured trust in bio-fuel as a main solution to global climate change is shortly commented upon and partly questioned.

Decisions with Impact on Energy Reduction Opportunities : Swedish manufacturers and buyers of new single-family houses

This article discusses some of the complexities of human decision-making. It aims, in particular, at relating the nature of decision-making to the illusory dichotomies of change and stability, individual actions and cultural sharing. Serving as an illustration to the discussion of the article is ongoing fieldwork in contexts of buying, selling and constructing pre-fabricated detached houses in the central Sweden, and the very specific question of how decisions to install one kind of heating-system rather than another come about. A common reductionism is to narrow down the understanding of decisions about heating systems and energy consumption to conscious choices made by individual householders. I have asked myself whether, on the contrary, anyone actually makes such decisions at all. Perhaps some of these decisions are merely outcomes of interaction between different individuals with their respective responsibilities and focuses of interest.

Villasystem för solvärme

Del 1:Innehållsförteckning och korta sammanfattningarDEL 2:Verksamhetsberättelsen för perioden maj 1992 till april 1993 beskriver de arbeten som har gjorts av villasolvärmegruppen på SERC efter den inledande studie (SERC/UCFB-91/0039), där villasolvärmesystem kartlades. Följande arbeten beskrivs:- Utveckling av lågflödessystem och internationella kontakter- Uppbyggnad av värmelaboratorium på SERC- Praktiska test av värmelagringsenheten- Praktiska test av nya systemkomponenter i solvärmekretsen- Datasimulering inkluderande nyutvecklade systemkomponenterI verksamhetsplanen beskrivs huvudmålet för de arbeten som ska utföras under trårsperioden 93 - 96. Mera detaljerat beskrivs de arbeten som ska utföras under budgetåret 1993/94:- Beräkningsprogram för nogrannare dimensionering av finrörsvärmeväxlare- Konstruktion av maskiner för värmeväxlartillverkning- Utveckling av värmeväxlare för tappvarmvatten- Simuleringsberäkningar för hela systemet med PRESIM/TRNSYS.DEL 3:Del 3 innehåller en redovisning av mätresultat för den undersökta kombitanken. Temperaturförloppen på olika höjd i tankens har studerats vid uppvärmning genom solvärmeväxlaren och nedkylning genom tappning av varmvatten. Resultaten diskuteras kvalitativt och redovisas kvantitativt i form av diagram. Mätresultaten på två prototyper av den på SERC utvecklade finrörsvärmeväxlaren redovisas och diskuteras i jämförelse till traditionell värmeväxlare. De erhållna mätresultaten används som ingångsvärden för simuleringsberäkningar med PRESIM/TRNSYS. Problemen med de i PRESIM/TRNSYS befintliga modellerna diskuteras. De utförda modellberäkningarna tillåter en uppskattning av möjliga förbättringar i form av höjd årsverkningsgrad för ett svenskt villasolvärmesystem med kombitank. I del 3 redovisas dessutom de mätningar som har utförts på otika pumpar vilka skulle kunna användas i solfångarkretsen. Sex olika pumpar analyseras och diskuteras. Del 3 har följande rubriker:- Beskrivning av den undersökta lagringstanken- Mätningar på tappvarmvattenväxlare- Mätningar på solvärmeväxlare (kamflänsrör och finrörsvärmeväxlare)- Simuleringsberäkningar- PumpmätningarDEL 4:Del 4 innehåller publicerade rapporter under 1992 och 93 samt patentansökan för SERC?s finrörsvärmeväxlare: - NORTH SUN 1992, Solar Energy at High Latitudes, June 24-26 1992 Trondheim, Norway. Domestic solar heating system - a systematic study i progress Patentansökan på finrorsvärmeväxlare till Patent- och Registreringsverket från 93 01 23. ISES SOLAR WORLD CONGRESS, 23-27 augusti 1993, Budapest, HUNGARY Criteria for cost efficient small scale solar hot water installations.DEL 5:Del 5 hänvisar till rapporterna från IEA Task-1 4 mötena om solfångarsystem i- Hameln, Tyskland, augusti 1992 och- Rom, Italien, januari 1993.I rapporterna beskrivs aktiviteten inom den internationella arbetsgruppen speciellt med hänsyn på utveckling av villasolvärmesystem. I Rom presenterades principlösningen för den på SERC utvecklade finrörsvärmeväxlare. De har publicerats separat som nr 42 och 46 i SERCs rapportserie.

Elbesparing med pelletkaminer och solvärme i direktelvärmda småhus

The aim of this study was to investigate how electricallyheated houses can be converted to using wood pellet and solarheating. There are a large number of wood pellet stoves on themarket. Many stoves have a water jacket, which gives anopportunity to distribute the heat to domestic hot water and aradiator heating system. Three typical Swedish houses with electric resistanceheating have been studied. Fourteen different system conceptsusing wood pellet stoves and solar heating systems have beenevaluated. The systems and the houses have been simulated indetail using TRNSYS. The houses have been divided in up to 10different zones and heat transfer by air circulation throughdoorways and open doors have been simulated. The pellet stoveswere simulated using a recently developed TRNSYS component,which models the start- and stop phases, emissions and thedynamic behaviour of the stoves. The model also calculates theCO-emissions. Simulations were made with one stove without awater jacket and two stoves with different fractions of thegenerated heat distributed in the water circuit. Simulations show that the electricity savings using a pelletstove are greatly affected by the house plan, the systemchoice, if the internal doors are open or closed and thedesired level of comfort. Installing a stove with awater-jacket connected to a radiator system and a hot waterstorage has the advantage that heat can be transferred todomestic hot water and be distributed to other rooms. Suchsystems lead to greater electricity savings, especially inhouses having a traditional layout. It was found that not allrooms needed radiators and that it was more effective in mostcases t use a stove with a higher fraction of the heatdistributed by the water circuit. The economic investigation shows that installing a woodpellet stove without a water jacket gives the lowest totalenergy- and capital costs in the house with an open plan (fortoday's energy prices and the simulated comfort criteria). Inthe houses with a traditional layout a pellet stove givesslightly higher costs than the reference house having onlyelectrical resistance heating due to the fact that less heatingcan be replaced. The concepts including stoves with a waterjacket all give higher costs than the reference system, but theconcept closest to be economical is a system with a bufferstore, a stove with a high fraction of the heat distributed bythe water circuit, a new water radiator heating system and asolar collector. Losses from stoves can be divided into: flue gas lossesincluding leakage air flow when the stove is not in operation;losses during start and stop phases; and losses due to a highair factor. An increased efficiency of the stoves is importantboth from a private economical point of view, but also from theperspective that there can be a lack of bio fuel in the nearfuture also in Sweden. From this point of view it is alsoimportant to utilize as much solar heat as possible. Theutilization of solar heat is low in the simulated systems,depending on the lack of space for a large buffer store. The simulations have shown that the annual efficiency ismuch lower that the nominal efficiency at full power. Thesimulations have also shown that changing the control principlefor the stove can improve efficiency and reduce theCO-emissions. Today's most common control principle for stovesis the on/off control, which results in many starts and stopsand thereby high CO-emissions. A more advanced control varyingthe heating rate from maximum to minimum to keep a constantroom temperature reduces the number of starts and stops andthereby the emissions. Also the efficiency can be higher withsuch a control, and the room temperature will be kept at a moreconstant temperature providing a higher comfort.

Fjärrvärmedrivna vitvaror : Erfarenheter från utveckling, installationer och kostnadsberäkningar

Värmedrivna vitvaror eller HWC-maskiner som de kallas av tillverkaren värms med varmt vatten från en cirkulerande krets via en värmeväxlare inbyggd i maskinen, till skillnad från konventionella maskiner som värms med el. Denna teknik skall inte förväxlas med maskiner som är anslutna till varmvattenledningen och fylls på med varmt vatten och som därmed begränsas till disk- och tvätt. Syftet med fjärrvärmedrivna vitvaror är alltså att använda fjärrvärme, som har lägre kvalitet och pris än elenergi för uppvärmning och torkning och på så sätt spara el och utöka fjärrvärmeunderlaget. En jämförelse av koldioxidutsläpp och primärenergianvändning mellan konventionella vitvaror och fjärrvärmedrivna vitvaror visar att både koldioxidutsläpp och primärenergianvändning blir lägre för fjärrvärmedrivna vitvaror om biobränsle anses koldioxidneutralt och den el som ersätts är producerad i kolkraftverk eller gaskombikraftverk.   Denna rapport beskriver utveckling och kommersialisering av värmedrivna vitvaror (disk- och tvättmaskiner samt torktumlare och torkskåp) och hur de kan anslutas mot fjärrvärmesystem i olika systemlösningar. Dessutom har de energimässiga och ekonomiska förutsättningarna för tekniken undersökts. Erfarenheterna från fältprovning är dock mycket begränsade, eftersom de byggen där fälttesterna skulle ske försenades. Under 2013 färdigställs ett flerbostadshus med värmedrivna vitvaror i 160 lägenheter i Västerås.   De utvecklade maskinernas värmeanvändning som andel av total energianvändning vid 60 graders framledningstemperatur har uppmätts till ca 50 % för diskmaskinen, 67 % för tvättmaskinen, 80 % för torktumlaren och 93 % för torkskåpet. I det studerade flerbostadshuset av passivhusstandard uppgår lasten från värmedrivna vitvaror komfortgolvvärme och handdukstorkar till upp mot 30 % av husets totala värmeanvändning. För småhus är motsvarande siffra upp mot 20 %. Att använda fjärrvärme istället för elvärme till dessa installationer som normalt är elvärmda kan allts minska elbehovet betydligt i lågenergibebyggelse vilket också minskar både koldioxidutsläppen och primärenergianvändningen.   Ekonomiska analyser har genomförts för två olika systemkoncept (separat vitvarukrets och Västeråsmodellen) för nybyggda småhusområden och flerfamiljshus där fjärrvärme inte bara används till vitvaror utan också till handdukstorkar och komfortgolvvärme. De ekonomiska analyserna visar att Västeråsmodellen är den mest ekonomiskt intressanta systemlösningen med värmedrivna vitvaror, handdukstork och komfortgolvvärme. I flerfamiljshus kan den vara konkurrenskraftig mot de elvärmda alternativen (konventionellt system med eldrivna vitvaror, komfortgolvvärme och handdukstorkar) om prisskillnaden mellan el och fjärrvärme är större än 0,7 kr/kWh. En parameterstudie visar att kapitalkostnaden blir ganska hög jämfört med energikostnaden, vilket betyder att lång livslängd och många cykler är viktigt för att förbättra de ekonomiska förutsättningarna för värmedrivna vitvaror. För passiva småhus blir kostnaden för Västeråsmodellen med värmedrivna vitvaror, handdukstork och komfortgolvvärme likvärdig med de elvärmda alternativen vid energiprisskillnader på 0,7 kr/kWh inklusive moms, medan det krävs prisskillnader på 0,9 kr/kWh inklusive moms för normalisolerade småhusområden.   Sammanfattningsvis kan sägas att i kommuner med ett konkurrenskraftigt fjärrvärmepris finns det viss lönsamhet för hela konceptet enligt Västeråsmodellen med värmedrivna vitvaror, komfortgolvvärme, och handdukstorkar. Om man däremot ser på konkurrensen för enskilda vitvaror är det främst torktumlaren som är konkurrenskraftig i bostäder. Målpriset på 1000 kr extra för värmedrift har inte kunnat uppnås inom projektet för diskmaskiner och tvättmaskiner. Det krävs lägre priser och låga anslutningskostnader för att räkna hem diskmaskinen och tvättmaskinen som enskilda komponenter.   Värmedrivna tvättmaskiner och torktumlare är konkurrenskraftiga i flerfamiljstvättstugor. Speciellt i de fall där beläggningen är god och flera maskiner delar på anslutningskostnaden till fjärrvärmecentralen kan värmedrift bli riktigt lönsam. Torkskåpens konkurrenskraft har inte kunnat utvärderas, då priset ännu inte fastställts. Att använda VVC-systemet för värmedistribution till värmedrivna vitvaror kan vara mycket intressant, men det kräver att legionellaproblematiken kan lösas. I nuläget finns ingen lösning som uppfyller formuleringarna i boverkets byggregler. Ett annat distributionssätt som kan vara intressant, men som inte undersökts i studien är att använda VVC för varmvattendistribution och en gemensam radiator- och vitvarukrets med konstant framledningstemperatur. Den aktör som förväntas ha störst ekonomiskt intresse av att tekniken implementeras är sannolikt fjärrvärmebolagen som får sälja mer värme och det ligger därmed främst på deras ansvar att marknadsföra tekniken i mötet med sina kunder.

Making Energy Interventions more Effective : Situation, Interaction, and Precondition

A main purpose of this paper is to propose to policy makers, building professionals, and other non-social scientists a way to make energy interventions more culturally informed and, thereby, more effective. The case study on house purchasers gives an ample illustration of the richer results that can be achieved by paying attention to three aspects of energy efficiency initiatives: the contexts and situations of choice in each particular case, the interaction among relevant social actors, and the culture-specific preconditions for choice. Research on how purchasers of new pre-fabricated houses in Sweden choose their heating system show how such decisions tend to fall between two stools. Furthermore, the organizational structure of housing companies frames house purchasers' decision making. An important result is that energy saving or conversion measures must be promoted at an early stage amongst those who plan and construct buildings (rather than later amongst dwellers and energy end users).