Energy efficient and economic renovation of residential buildings with low-temperature heating and air heat recovery

With the building sector accounting for around 40% of the total energy consumption in the EU, energy efficiency in buildings is and continues to be an important issue. Great progress has been made in reducing the energy consumption in new buildings, but the large stock of existing buildings with poor energy performance is probably an even more crucial area of focus. This thesis deals with energy efficiency measures that can be suitable for renovation of existing houses, particularly low-temperature heating systems and ventilation systems with heat recovery. The energy performance, environmental impact and costs are evaluated for a range of system combinations, for small and large houses with various heating demands and for different climates in Europe. The results were derived through simulation with energy calculation tools. Low-temperature heating and air heat recovery were both found to be promising with regard to increasing energy efficiency in European houses. These solutions proved particularly effective in Northern Europe as low-temperature heating and air heat recovery have a greater impact in cold climates and on houses with high heating demands. The performance of heat pumps, both with outdoor air and exhaust air, was seen to improve with low-temperature heating. The choice between an exhaust air heat pump and a ventilation system with heat recovery is likely to depend on case specific conditions, but both choices are more cost-effective and have a lower environmental impact than systems without heat recovery. The advantage of the heat pump is that it can be used all year round, given that it produces DHW. Economic and environmental aspects of energy efficiency measures do not always harmonize. On the one hand, lower costs can sometimes mean larger environmental impact; on the other hand there can be divergence between different environmental aspects. This makes it difficult to define financial subsidies to promote energy efficiency measures.

Survery and simulation of energy use in the European building stock

the work towards increased energy efficiency. In order to plan and perform effective energy renovation of the buildings, it is necessary to have adequate information on the current status of the buildings in terms of architectural features and energy needs. Unfortunately, the official statistics do not include all of the needed information for the whole building stock.   This paper aims to fill the gaps in the statistics by gathering data from studies, projects and national energy agencies, and by calibrating TRNSYS models against the existing data to complete missing energy demand data, for countries with similar climate, through simulation. The survey was limited to residential and office buildings in the EU member states (before July 2013). This work was carried out as part of the EU FP7 project iNSPiRe.   The building stock survey revealed over 70% of the residential and office floor area is concentrated in the six most populated countries. The total energy consumption in the residential sector is 14 times that of the office sector. In the residential sector, single family houses represent 60% of the heated floor area, albeit with different share in the different countries, indicating that retrofit solutions cannot be focused only on multi-family houses.   The simulation results indicate that residential buildings in central and southern European countries are not always heated to 20 °C, but are kept at a lower temperature during at least part of the day. Improving the energy performance of these houses through renovation could allow the occupants to increase the room temperature and improve their thermal comfort, even though the potential for energy savings would then be reduced.

Advanced Building Energy Data Visualization

Advanced Building Energy Data Visualization is a way to detect performance problems in commercialbuildings. By placing sensors in a building that collects data from example, air temperature and electricalpower, then makes it possible to calculate the data in Data Visualization software. This softwaregenerates visual diagrams so the building manager or building operator can see if for example thepower consumption is to high.A first step (before sensors are installed in a building) to see how the energy consumption is in abuilding can be to use a Benchmarking Tool. There is a number of Benchmarking Tools that is availablefor free on the Internet. Each tool have a bit different approach, but they all show how much energyconsumption there is in a building compared to other similar buildings.In this study a new web design for the benchmarking tool CalARCH has been developed. CalARCHis developed at the Berkeley Lab in Berkeley, California, USA. CalARCH uses data collected only frombuildings in California, and is only for comparing buildings in California with other similar buildingsin the state.Five different versions of the web site were made. Then a web survey was done to determine whichversion would be the best for CalARCH. The results showed that Version 5 and Version 3 was the best.Then a new version was made, based on these two versions. This study was made at the LawrenceBerkeley Laboratory.

Can qualitative methods support the development of more flexible and energy saving thermal comfort?

This paper uses examples from a Swedish study to suggest some ways in which cultural variation could be included in studies of thermal comfort. It is shown how only a slight shift of focus and methodological approach could help us discover aspects of human life that add to previous knowledge within comfort research of how human beings perceive and handle warmth and cold. It is concluded that it is not enough for buildings, heating systems and thermal control devices to be energy-efficient in a mere technical sense. If these are to help to decrease, rather than to increase, energy consumption, they have to support those parts of already existing habits and modes of thought that have the potential for low energy use. This is one reason why culture-specific features and emotional cores need to be investigated and deployed into the study and development of thermal comfort.

Energy Efficiency through Thermal Energy Storage : Possibilities for the Swedish Building Stock

The need for heating and cooling in buildings constitutes a considerable part of the total energy use in a country and reducing this need is of outmost importance in order to reach national and international goals for reducing energy use and emissions. One important way of reaching these goals is to increase the proportion of renewable energy used for heating and cooling of buildings. Perhaps the largest obstacle with this is the often occurring mismatch between the availability of renewable energy and the need for heating or cooling, hindering this energy to be used directly. This is one of the problems that can be solved by using thermal energy storage (TES) in order to save the heat or cold from when it is available to when it is needed. This thesis is focusing on the combination of TES techniques and buildings to achieve increased energy efficiency for heating and cooling. Various techniques used for TES as well as the combination of TES in buildings have been investigated and summarized through an extensive literature review. A survey of the Swedish building stock was also performed in order to define building types common in Sweden. Within the scope of this thesis, the survey resulted in the selection of three building types, two single family houses and one office building, out of which the two residential buildings were used in a simulation case study of passive TES with increased thermal mass (both sensible and latent). The second case study presented in the thesis is an evaluation of an existing seasonal borehole storage of solar heat for a residential community. In this case, real measurement data was used in the evaluation and in comparisons with earlier evaluations. The literature reviews showed that using TES opens up potential for reduced energy demand and reduced peak heating and cooling loads as well as possibilities for an increased share of renewable energy to cover the energy demand. By using passive storage through increased thermal mass of a building it is also possible to reduce variations in the indoor temperature and especially reduce excess temperatures during warm periods, which could result in avoiding active cooling in a building that would otherwise need it. The analysis of the combination of TES and building types confirmed that TES has a significant potential for increased energy efficiency in buildings but also highlighted the fact that there is still much research required before some of the technologies can become commercially available. In the simulation case study it was concluded that only a small reduction in heating demand is possible with increased thermal mass, but that the time with indoor temperatures above 24 °C can be reduced by up to 20%. The case study of the borehole storage system showed that although the storage system worked as planned, heat losses in the rest of the system as well as some problems with the system operation resulted in a lower solar fraction than projected. The work presented within this thesis has shown that TES is already used successfully for many building applications (e.g. domestic hot water stores and water tanks for storing solar heat) but that there still is much potential in further use of TES. There are, however, barriers such as a need for more research for some storage technologies as well as storage materials, especially phase change material storage and thermochemical storage.

Solar Collectors for Historic Homes : Linking consumption to perceptions of space

Reduction of household energy consumption is one of the top issues in contemporary discussions on sustainable consumption. This chapter concerns one way through which consumption of purchased energy for house heating can be reduced; by having a solar thermal system added to one's house. However, the fact that one of the components - the solar collector - usually is situated on the roof or the facade of a building, is a recurrent impediment to such installations. In certain contexts, these attributes may melt into the building, while in others, they may be perceived as problematic. The latter may particularly be the case when the appearance of the building is of major imiportance, as with houses deemed worthy of preservation for coming generations. This chapter draws upon a study carried out in Visby Town, a walled Hanseatic town and a World Heritage site on the island of Gotland, Sweden.

Solar PV Powered Air Conditioner Analysis for an Office/Classroom in a Tropical Climate

This thesis focuses on using photovoltaic produced electricity to power air conditioners in a tropical climate. The study takes place in Surabaya, Indonesia at two different locations the classroom, located at the UBAYA campus and the home office, 10 km away. Indonesia has an average solar irradiation of about 4.8 kWh/m²/day (PWC Indonesia, 2013) which is for ideal conditions for these tests. At the home office, tests were conducted on different photovoltaic systems. A series of measuring devices recorded the performance of the 800 W PV system and the consumption of the 1.35 kW air conditioner (cooling capacity). To have an off grid system many of the components need to be oversized. The inverter has to be oversized to meet the startup load of the air conditioner, which can be 3 to 8 times the operating power (Rozenblat, 2013). High energy consumption of the air conditioner would require a large battery storage to provide one day of autonomy. The PV systems output must at least match the consumption of the air conditioner. A grid connect system provides a much better solution with the 800 W PV system providing 80 % of the 3.5 kWh load of the air conditioner, the other 20 % coming from the grid during periods of low irradiation. In this system the startup load is provided by the grid so the inverter does not need to be oversized. With the grid-connected system, the PV panel’s production does not need to match the consumption of the air conditioner, although a smaller PV array will mean a smaller percentage of the load will be covered by PV. Using the results from the home office tests and results from measurements made in the classroom. Two different PV systems (8 kW and 12 kW) were simulated to power both the current air conditioners (COP 2.78) and new air conditioners (COP 4.0). The payback period of the systems can vary greatly depending on if a feed in tariff is awarded or not. If the feed in tariff is awarded the best system is the 12 kW system, with a payback period of 4.3 years and a levelized cost of energy at -3,334 IDR/kWh. If the feed in tariff is not granted then the 8 kW system is the best choice with a lower payback period and lower levelized cost of energy than the 12 kW system under the same conditions.

System Integration of PV/T Collectors in Solar Cooling Systems

The demand for cooling and air-conditioning of building is increasingly ever growing. This increase is mostly due to population and economic growth in developing countries, and also desire for a higher quality of thermal comfort. Increase in the use of conventional cooling systems results in larger carbon footprint and more greenhouse gases considering their higher electricity consumption, and it occasionally creates peaks in electricity demand from power supply grid. Solar energy as a renewable energy source is an alternative to drive the cooling machines since the cooling load is generally high when solar radiation is high. This thesis examines the performance of PV/T solar collector manufactured by Solarus company in a solar cooling system for an office building in Dubai, New Delhi, Los Angeles and Cape Town. The study is carried out by analyzing climate data and the requirements for thermal comfort in office buildings. Cooling systems strongly depend on weather conditions and local climate. Cooling load of buildings depend on many parameters such as ambient temperature, indoor comfort temperature, solar gain to the building and internal gains including; number of occupant and electrical devices. The simulations were carried out by selecting a suitable thermally driven chiller and modeling it with PV/T solar collector in Polysun software. Fractional primary energy saving and solar fraction were introduced as key figures of the project to evaluate the performance of cooling system. Several parametric studies and simulations were determined according to PV/T aperture area and hot water storage tank volume. The fractional primary energy saving analysis revealed that thermally driven chillers, particularly adsorption chillers are not suitable to be utilizing in small size of solar cooling systems in hot and tropic climates such as Dubai and New Delhi. Adsorption chillers require more thermal energy to meet the cooling load in hot and dry climates. The adsorption chillers operate in their full capacity and in higher coefficient of performance when they run in a moderate climate since they can properly reject the exhaust heat. The simulation results also indicated that PV/T solar collector have higher efficiency in warmer climates, however it requires a larger size of PV/T collectors to supply the thermally driven chillers for providing cooling in hot climates. Therefore using an electrical chiller as backup gives much better results in terms of primary energy savings, since PV/T electrical production also can be used for backup electrical chiller in a net metering mechanism.

Energy performance comparison of three innovative HVAC systems for renovation through dynamic simulation

In this paper, dynamic simulation was used to compare the energy performance of three innovativeHVAC systems: (A) mechanical ventilation with heat recovery (MVHR) and micro heat pump, (B) exhaustventilation with exhaust air-to-water heat pump and ventilation radiators, and (C) exhaust ventilationwith air-to-water heat pump and ventilation radiators, to a reference system: (D) exhaust ventilation withair-to-water heat pump and panel radiators. System A was modelled in MATLAB Simulink and systems Band C in TRNSYS 17. The reference system was modelled in both tools, for comparison between the two.All systems were tested with a model of a renovated single family house for varying U-values, climates,infiltration and ventilation rates.It was found that A was the best system for lower heating demand, while for higher heating demandsystem B would be preferable. System C was better than the reference system, but not as good as A or B.The difference in energy consumption of the reference system was less than 2 kWh/(m2a) betweenSimulink and TRNSYS. This could be explained by the different ways of handling solar gains, but also bythe fact that the TRNSYS systems supplied slightly more than the ideal heating demand.

Energy Analysis within Industrial Hydraulics and Correspondent Solar PV System Design

Energy efficiency and renewable energy use are two main priorities leading to industrial sustainability nowadays according to European Steel Technology Platform (ESTP). Modernization efforts can be done by industries to improve energy consumptions of the production lines. These days, steel making industrial applications are energy and emission intensive. It was estimated that over the past years, energy consumption and corresponding CO2 generation has increased steadily reaching approximately 338.15 parts per million in august 2010 [1]. These kinds of facts and statistics have introduced a lot of room for improvement in energy efficiency for industrial applications through modernization and use of renewable energy sources such as solar Photovoltaic Systems (PV).The purpose of this thesis work is to make a preliminary design and simulation of the solar photovoltaic system which would attempt to cover the energy demand of the initial part of the pickling line hydraulic system at the SSAB steel plant. For this purpose, the energy consumptions of this hydraulic system would be studied and evaluated and a general analysis of the hydraulic and control components performance would be done which would yield a proper set of guidelines contributing towards future energy savings. The results of the energy efficiency analysis showed that the initial part of the pickling line hydraulic system worked with a low efficiency of 3.3%. Results of general analysis showed that hydraulic accumulators of 650 liter size should be used by the initial part pickling line system in combination with a one pump delivery of 100 l/min. Based on this, one PV system can deliver energy to an AC motor-pump set covering 17.6% of total energy and another PV system can supply a DC hydraulic pump substituting 26.7% of the demand. The first system used 290 m2 area of the roof and was sized as 40 kWp, the second used 109 m2 and was sized as 15.2 kWp. It was concluded that the reason for the low efficiency was the oversized design of the system. Incremental modernization efforts could help to improve the hydraulic system energy efficiency and make the design of the solar photovoltaic system realistically possible. Two types of PV systems where analyzed in the thesis work. A method was found calculating the load simulation sequence based on the energy efficiency studies to help in the PV system simulations. Hydraulic accumulators integrated into the pickling line worked as energy storage when being charged by the PV system as well.

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.

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.

Solcellsdrivet FTX-system för miljonprogramshus : Tjärna Ängar, Borlänge

Projektet omfattade undersökning och framtagande av ett solcellssystem med förmåga att försörja ett FTX-system i ett flerbostadshus från miljonprogrammet med el. För att kunna bedöma storlek och utformning av komponenter har information tagits genom: Informationssökning via databaser, kurslitteratur och intervjuer Simuleringar av solceller i datorprogrammet PVSYST Modulering av ventilationskanaler i datorprogrammet MagiCAD Syftet var främst att undersöka om det gick att få fram ett teoretiskt fungerande system med avseende på både solceller och ventilation. Beroende på vad resultatet blev skulle även ekonomin i projektet undersökas. Undersökningen visade att det teoretiskt ska gå att installera solceller för elframställning som klarar av att täcka FTX-systemets elbehov på årsbasis. Solcellerna bedöms även producera tillräckligt med el för viss övrig elkrävande utrustning under stora delar av året. Det visade sig även att det skulle gå att få solcellerna ekonomiskt lönsamma om en kalkyltid på 14 år används. Metoden som använts för dessa resultat är noga beskriven och är med små förändringar tillämpbar för ett stort antal byggnader i det svenska byggnadsbeståndet. En viktig slutsats är att om fastighetsägarna kan se 15 år fram i tiden för en investering i solenergi, skulle det innebära inte bara miljömässiga utan även ekonomiska vinster. Det finns redan idag kunnande, teknik och produkter för att utvinna en stor del av fastigheternas elbehov genom solens energi.

Energy savings potential in existing houses : Energy simulation results for Dalarna's single-family housing stock

Vägar till en halverad energianvändning i Dalarnas byggnadsbestånd