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The deployment of electric vehicles (EVs) is growing significantly in recent years. The increasing EV charging loads pose great stress on power grids in Sweden, as many existing power grids are not designed to host such large shares of new electric loads. Hence, studies investigating the impact of EV charging are needed. This study conducts a case study based on an existing Swedish residential power grid using real-life EV charging data to estimate the local grid hosting capacity (HC) for EVs. A combined time-series and stochastic HC assessment method is used with voltage deviation, cable loading and transformer loading as the performance indices. Uncertainty in EV charging locations and individual charging behaviour have been considered via Monte Carlo simulations. The power grid HC is analysed and compared under three charging strategies and four EV penetration levels. Study results show that a charging strategy based on low electricity prices gave lower HC due to simultaneous EV loads compared to the other two strategies: charging directly after plugging in the EV and an even charging load through the plug-in session. This implies the need for coordinated charging controls of EV fleets or diversified power tariffs to balance power on a large scale. © 2023 The Authors

One challenge in today’s district heating systems is the relatively high distribution heat loss. Lowering distribution temperatures is one way to reduce operational costs resulting from high heat losses, while changing the distribution system from steel pipes to plastic pipes and changing the heat distribution concept can reduce investment costs. The result is that the overall life cycle cost of the district heating system is reduced, leading to the improved cost competitiveness of district heating versus individual heating options. The main aim of this study was to determine the most cost-efficient distribution system for a theoretical solar district heating system, by comparing the marginal life cycle cost of two different distribution systems. A secondary aim was to determine the influence of the employed pipe type and insulation level on the marginal life cycle cost by comparing detailed economic calculations, including differences in pipe installation costs and construction costs, among others. A small solar-assisted district heating system has been modeled in TRNSYS based on a real system, and this “hybrid” model is used as a basis for a second model where a novel distribution system is employed and the heating network operating temperature is changed. Results indicate that a novel distribution concept with lower network temperatures and central domestic hot water preparation is most efficient both from an energy and cost perspective. The total life cycle costs vary less than 2% for a given distribution concept when using different pipe types and insulation classes, indicating that the investment costs are more significant than operational costs in reducing life cycle costs. The largest difference in life cycle cost is observed by changing the distribution concept, the novel concept having approximately 24% lower marginal life cycle cost than the “hybrid” system. © 2022 by the authors. Licensee MDPI, Basel, Switzerland.

This study inspects the effect of tapered headers on pressure drop and flow distribution in a U-type polymeric absorber with novel tapered headers and lens-shaped absorber strings using a validated thermo-hydraulic model. The model results are compared with those obtained from the literature to attain credibility in the flow distribution trend for the U-configuration. A good agreement between the developed discrete model and comparison cases is found. Moreover, in order to examine the efficacy of tapered headers in more detail, different scenarios are treated in terms of header configuration by applying cylindrical geometry in one or both inlet/outlet headers. The outcomes exemplify that even a slight cone angle of 1.73 degrees in headers can significantly reduce non-uniformity (phi(max) < 8%) with negligible influence on the total pressured drop. Yet, further reduction in maldistribution (phi(max) < 5%) can be achieved in U-type absorbers if the tapered outlet header is combined with a cylindrical inlet header in the range of AR <= 3.34 and DR <= 0.24. In this case, a compromise between additional pressure drop and flow distribution degree should be found. The present study offers a systematic approach for conducting thermo-hydraulic analysis in flat-plate solar collectors with complex absorber compositions and geometries. (c) 2022 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).

This work presents a discrete model for the thermo-hydraulic analysis of a novel polymeric solar thermal absorber with tapered headers and lens-shaped absorber strings. The numerical model developed is based on empirical correlations for laminar and turbulent flow regimes. The principal aim of this study is to ascertain if tapered headers help improve flow distribution in parallel-flow absorbers under laminar and turbulent flow conditions. In order to verify the model, the simulation results are compared to the measurement for total pressure drop and two studies from the previous literature for flow distribution. Altogether, a good agreement is found in all comparison cases, and the proposed numerical algorithm is proven to be robust and stable for complex thermo-hydraulic analysis. The results are then elaborated by comparing the tapered case to several conventional cases with cylindrical headers but with identical riser configurations to the original model. The results indicate that using tapered headers in compact absorbers with relatively large area ratios can noticeably reduce non-uniformity, especially up to middle range flows, by maintaining higher Reynolds numbers in the headers. The developed model can be used to optimize the hydraulic design of solar collectors with complex geometries and large area ratios. © 2022 The Authors

The high operating temperatures in today’s district heating networks combined with the low energy demand of new buildings lead to high relative network heat losses. New networks featuring lower operating temperatures have reduced relative heat losses while enabling an increase in the use of solar heat. The primary aim of this study was to determine if a particular district heating system can be made more effective with respect to heat losses and useful solar energy, by considering different distribution concepts and load densities. A small solar assisted district heating system with a novel hybrid distribution system has been modelled based on a real case study. This model serves as a basis for two other models where the distribution system and heating network operating temperature is changed. A secondary aim of the study was to determine the economic implications of making these changes, by using costs estimates to calculate the contribution of essential system components to total system cost. Results indicate that a novel distribution concept with lower network temperatures and central domestic hot water preparation is most energy efficient in a sparse network with a heat density of 0.2 MWh/m∙a and a performance ratio of 66%, while a conventional district heating system performs worst and has a performance ratio of less than 58% at the same heat density. In an extremely sparse network with heat density of 0.05 MWh/m∙a, the performance ratio is 41% and 30% for these systems, respectively. A simple economic analysis indicates that the novel distribution concept is also best from an economic point of view, reducing the initial investment cost by 1/3 compared to the conventional concept, which is the most costly. However, more detailed calculations are needed to conclude on this.

Hosting capacity (HC) is described as the maximum amount of new production or consumption that can be added to the grid without causing a violation. In this case study, a deterministic approach is used to investigate the HC of electric vehicle (EV) charging in a low-voltage grid, containing 13 detached single-family houses. It investigates how different parameters affect the HC, and what is causing the violation in the grid. Two different performance indices (PI) are used in the study: power cable overloading and voltage drop. The local grid is simulated for one year for four cases and the HC is derived for these. The cases are distinguished by two different violation thresholds for the voltage drop and two different implementation orders of the location of the charging. The results show that the HC of the grid is 6-11 EVs charging simultaneously. The difference in HC is primarily due to variation in the baseload through the year and location of charging. The cable between the substation and the first cable cabinet was the major contributor to the fault, and the PI causing the violation differed depending on what case was used. © Published under licence by IOP Publishing Ltd.

Existing studies have developed some advanced controls for energy storage system charging/discharging in a building cluster (enabling PV power sharing among different buildings), which can effectively improve the aggregated performances. However, in the existing controls, the flexible demand shifting ability of electric vehicles (EVs) are rarely considered, leading to limited performance improvements at building cluster level. Thus, this study proposes a coordinated control of building cluster with both energy sharing and the EV charging considered, with the purpose of improving the cluster-level performance. The simulation results show that in a typical summer week in Sweden, the developed control can increase the cluster-level daily renewable selfconsumption by 40% and meanwhile reduce the electricity bills by as much as 20% compared with conventional controls for a summer week in Ludvika, Sweden

Operational control strategies for the heating system of a single-family house with exhaust air heat pump and photovoltaic system and &ldquo;smart&rdquo; utilization of energy storage have been developed and evaluated in a simulation study. The main aim and novelty of this study is to evaluate the impact on the benefit of these advanced control strategies in terms of performance (energy use and economic) for a wide range of boundary conditions (country/climate, occupancy and appliance loads). Short-term weather data and historic price data for the same year as well as stochastic occupancy profiles that include the domestic hot water load are used as boundary for a parametric simulation study for the system modeled in detail in TRNSYS 17. Results show that the control using a forecast of dynamic electricity price leads to greater final energy savings than those due to the control using thermal storage for excess PV production in all of the examined locations except Sweden. The impact on self-consumption using thermal storage of heat produced by the heat pump using excess PV production is found to decrease linearly with increasing household electricity for all locations. A reduction in final energy of up to 842 kWh year&minus;1 can be achieved just by the use of these algorithms. The net energy cost for the end-user follows the same trend as for final energy and can result in cost savings up to 175 &euro; year&minus;1 in Germany and Spain due to the use of the advanced control.

An energy auditing tool (PHPP) was evaluated against a dynamic simulation tool (TRNSYS) and used for the assessment of energy conservation measures in a demo case study. The comprehensive comparison of useful heating and cooling demands and loads included three building types (single-, multi-family house, and office), three building energy levels (before renovation and after renovation with a heating demand of 45 and 25 kWh/(m²·a)) and seven European climates. Dynamic simulation results proved PHPP (monthly energy balance) to be able to calculate heating demand and energy savings with good precision and cooling demand with acceptable precision compared to detailed numerical models (TRNSYS). The average deviation between the tools was 8% for heating and 15% for cooling (considering climates with a relevant cooling load only). The higher the thermal envelope quality was, i.e. in case of good energy standards and in cold climates, the better was the agreement. Furthermore, it was confirmed that PHPP slightly overestimates the heating and cooling loads by intention for system design. The renovation design of a real multi-family house was executed using PHPP as energy auditing tool. Several calculation stages were performed for (a) baseline, (b) design phase, and (c) verification with monitoring in order to calculate the corresponding heating demand. The PHPP model was calibrated twice, before and after the renovation. The necessity for tool calibration, especially for the baseline, was highlighted increasing the confidence with respect to a number of boundary conditions. In this study, PHPP was tested as an energy auditing tool aiming to be a versatile and less error-prone alternative to more complex simulation tools, which require much more expert knowledge and training. 

Increasing the energy efficiency with a vast impact in the residential building stock requires retrofit solutions that can be exploited with respect to a wide range of different building typologies and climates. Several tools and methodologies are nowadays available both for the assessment of building demands and for the individuation of optimum retrofit solutions. However, they are usually either too complex to be adopted by professionals or, on the contrary, oversimplified to account for the full complexity of a deep envelope and HVAC system retrofit. In this context, this paper describes a methodology developed to generate reliable information on retrofit solutions for typical buildings in different climatic conditions. Detailed numerical models are used to simulate a number of combinations of envelope and HVAC systems retrofit measures and renewable energy integration. Energy performance results are gathered in a database that allows comparing solutions, spanning over a range of more than 250,000 combinations of building types, age of construction, climates, envelope performance levels and HVAC systems configurations. Economic feasibility is also derived for each of the combinations. In this way, the accurateness of a detailed and validated calculation is made available to assist during the decision making process, with minimum computational effort being required by professionals: the variety and density of evaluated combinations allows to easily assess the performance of a specific case by interpolating among instances previously assessed. The applicability of the results to different climates and similar building typologies is verified by a comparison of the database results with a specific case dynamic simulation.

Optimizing solar and pellet heating systems can be performed by system simulations in TRNSYS. However; this requires detailed boiler models that can properly model the thermal behaviour of the boilers, such as stratification and thermal response. This study uses a combination of existing models for modelling of the pellet burner part (TRNSYS Type 210) and the water volume (TRNSYS Type 340). This approach addresses the thermal dynamics and internal stratification more accurately than other available models. The objectives of this work are to develop a method for parameter identification for the model and to validate this method and the model itself. Sets of parameters are identified for two pellet boilers and one pellet stove with a water jacket (extended room heater) and the model is validated with a realistic dynamic operation sequence. The results show that modelling of stratification is essential in order to model the true behaviour of residential boilers. The test sequences used were adequate to parameterise the models and to provide the desired accuracy, except regarding the heat losses to room air. The model shows good accuracy for a stove and one boiler, but slightly worse performance for the other boiler regarding dynamics and modelling of the stratification.

Operational control strategies for the heating system and “smart” utilization of energy storage were developed and analyzed in a simulation based case study of a single-family house with exhaust air heat pump and photovoltaic system. Rule based control algorithms that can easily be implemented into modern heat pump controllers were developed with the aim to minimize final energy and maximize self-consumption by the use of the thermal storage of the building, the hot water tank and electrical storage. Short-term weather and electricity price forecasts are used in some of the algorithms. Heat supply from an exhaust air heat pump is limited by the ventilation flow rate fixed by building codes, and compact systems employ an electric heater as backup for both space heating and hot water. This heater plays an important role in the energy balance of the system. A typical system designed for new detached houses in Sweden was chosen for the study. This system, together with an independent photovoltaic system, was used as a base case and all results are compared to those for this base case system. TRNSYS 17 was used to model the building and system as well as the control algorithms, and special care was taken to model the use of the backup electric heater as this impacts significantly on final energy use. Results show that the developed algorithms can reduce final energy by 5–31% and the annual net cost for the end user by 3–26%, with the larger values being for systems with a battery storage. Moreover, the annual use of the backup electric heater can be decreased by 13–30% using the carefully designed algorithms.

Smart grid is triggering the transformation of traditional electricity consumers into electricity prosumers. This paper reports a case study of transforming an existing residential cluster in Sweden into electricity prosumers. The main energy concepts include (1) click-and-go photovoltaics (PV) panels for building integration, (2) centralized exhaust air heat pump, (3) thermal energy storage for storing excess PV electricity by using heat pump, and (4) PV electricity sharing within the building cluster for thermal/electrical demand (including electric vehicles load) on a direct-current micro grid. For the coupled PV-heat pump-thermal storage-electric vehicle system, a fitness function based on genetic algorithm is established to optimize the capacity and positions of PV modules at cluster level, with the purpose of maximizing the self-consumed electricity under a non-negative net present value during the economic lifetime. Different techno-economic key performance indicators, including the optimal PV capacity, self-sufficiency, self-consumption and levelized cost of electricity, are analysed under impacts of thermal storage integration, electric vehicle penetration and electricity sharing possibility. Results indicate that the coupled system can effectively improve the district-level PV electricity self-consumption rate to about 77% in the baseline case. The research results reveal how electric vehicle penetrations, thermal storage, and energy sharing affect PV system sizing/positions and the performance indicators, and thus help promote the PV deployment. This study also demonstrates the feasibility for transferring the existing Swedish building clusters into smart electricity prosumers with higher self-consumption and energy efficiency and more intelligence, which benefits achieving the ‘32% share of renewable energy source’ target in EU by 2030.

Solar heat pump systems (SHPs) have been investigated for several decades and have been proven to increase the share of renewable energy and reduce electric energy demand in residential heating applications. Many review articles have been published on the subject, however literature discussing the techno-economics of different solar technologies (thermal, photovoltaic and hybrid thermal/photovoltaic) in combination with heat pumps is lacking, and thus to directly compare the merits of different SHPs is not an easy task. The objectives of this study are: a) review the different system boundaries and the main performance indicators used for assessing energetic and economic performances; b) review techno-economic studies in the literature and identify which studies give enough information and are compatible enough for making an economic inter-comparison; c) present an economic inter-comparison based on the identified systems. The results show that there is a lack of studies including an economic assessment of solar photovoltaic and heat pump systems. Additionally, there are no consistent boundaries or approaches to the study structures, making comparisons between systems difficult. In conclusion, a standardized or broadly accepted definition of technical and economic performance for SHPs is needed. Despite this, the study has shown that there are clear trends for decreasing payback times for SHPs, both solar thermal (ST) and photovoltaic (PV), with decreasing heating degree-days and with increasing solar resource.

A large share of the buildings in Europe are old and in need of renovation, both in terms of functional repairs and energy efficiency. While many studies have addressed energy renovation of buildings, they rarely combine economic and environmental life cycle analyses, particularly for office buildings. The present paper investigates the economic feasibility and environmental impact of energy renovation packages for European office buildings. The renovation packages, including windows, envelope insulation, heating, cooling and ventilation systems and solar photovoltaics (PV), were evaluated in terms of life cycle cost (LCC) and life cycle assessment (LCA) through dynamic simulation for different European climates. Compared to a purely functional renovation, the studied renovation packages resulted in up to 77% lower energy costs, 19% lower total annualized costs, 79% lower climate change impact, 89% lower non-renewable energy use, 66% lower particulate matter formation and 76% lower freshwater eutrophication impact over a period of 30 years. The lowest total costs and environmental impact, in all of the studied climates, were seen for the buildings with the lowest heating demand. Solar PV panels covering part of the electricity demand could further reduce the environmental impact and, at least in southern Europe, even reduce the total costs. © 2017 Elsevier B.V.

Both district heating and solar collector systems have been known and imple- mented for many years. However, the combination of the two, with solar collec- tors supplying heat to the district heating network, is relatively new, and no comprehensive review of scientific publications on this topic could be found. Thus, this paper summarizes the literature available on solar district heating and presents the state of the art and real experiences in this field. Given the lack of a generally accepted convention on the classification of solar district heating systems, this paper distinguishes centralized and decentralized solar district heating as well as block heating. For the different technologies, the paper describes commonly adopted control strategies, system configurations, types of installation, and integration. Real‐world examples are also given to provide a more detailed insight into how solar thermal technology can be integrated with district heating. Solar thermal technology combined with thermally driven chillers to provide cooling for cooling networks is also included in this paper. In order for a technology to spread successfully, not only technical but also eco- nomic issues need to be tackled. Hence, the paper identifies and describes dif- ferent

A solar thermal and heat pump combisystem is one of many system alternatives on the market for supplying domestic hot water (DHW) and space heating (SH) in dwellings. In this study a reference solar thermal and air source heat pump combisystem was defined and modelled based on products available on the market. Based on the results of an extensive literature survey, several system variations were investigated to show the influence of heat pump cycle, thermal storage and system integration on the use of electricity for two houses in the climates of Zurich and Carcassonne. A singular economic cash flow analysis was carried out and the “additional investment limit” of each system variation was determined for a range of economic boundary conditions. This is the maximum extra investment cost for the system variant compared to the reference system that will give a break even result for a 10 year period. The results show that variations in electricity price affects the additional investment limit far more than the other economic parameters. Several of the variants show potential for achieving a cost benefit, but the potential varies a lot depending on load and climate boundary conditions. For all variants, the biggest difference in electricity savings was found for Zurich rather than in Carcassonne, which is explained by the larger heating load. However, in three cases the largest savings were for the SFH45 house despite the fact that the annual electricity use of the system is much lower than that for the SFH100 house, 3581 kW h/year compared to 8340 kW h/year. This was attributed to the fact that, in these cases, the operating level of the space heating circuit played a significant role, the SFH45 house being supplied with a 35/30 °C heating system while the SFH100 was supplied with a 55/45 °C heating system.

In this study a detailed model of a single-family house with an exhaust air heat pump and photovoltaic system is developed in the simulation software TRNSYS. The model is used to evaluate three control algorithms using thermal and electrical storage in terms of final energy, solar fraction, self-consumption and seasonal performance factor. The algorithms are tested and compared with respect to energetic improvement for 1) use of the heat pump plus storage tank for domestic hot water and space heating, 2) use of the electrical storage in batteries and 3) use of both electrical and thermal storage. Results show the highest increase of self-consumption to 50.5%, solar fraction to 40.6% and final energy decrease to 6923 kWh by implementing the third algorithm in a system with 9.36 kW PV capacity and battery storage of 10.8 kWh. The use of electrical energy storage has higher positive impact compared to the thermal storage with the settings and component sizes used. The combined use of thermal storage and batteries leads to final energy savings that are nearly the same as the combined savings of thermal storage and batteries separately, showing that they are mostly independent of one another for the settings of this study.

Solar thermal and heat pump combisystems are used to produce domestic hot water (DHW) and space heating (SH) in dwellings. Many systems are available on the market. For an impartial comparison, a definite level of thermal comfort should be defined and ensured in all systems. This work studied the influence of component size on electricity demand for a state of the art solar thermal and heat pump system. A systematic series of parametric studies was carried out by using TRNSYS to show the impact of climate, load and size of main components as well as heat source for the heat pump. Penalty functions were used to ensure that all variations provided the same comfort requirements. Two reference systems were defined and modelled based on products on the market, one with ambient air and the other with borehole as heat source for the heat pump. The results show that changes in collector area from 5 to 15 m² result in a decrease in system electricity of between 305 and 552 kW h/year. Changes in heat exchanger size for DHW preparation were shown to give nearly as large changes in electricity use due to the fact that the set temperature in the store was changed to give the same thermal comfort in all cases. Decrease in heat pump size was shown to give a decrease in electricity use for the ASHP in the building with larger heat demand while it increased or had only a small change for other boundary conditions. Heat pump losses were shown to be an important factor highlighting the importance of modelling this factor explicitly

The iNSPiRe project addresses the need for energy efficiency measures by focussing on making so called deep renovations using multifunctional, industrialised kits in order to speed up the on-site installation process and reduce costs. Energy renovation investment is a multi-factor decision and many of these factors are not technical, which is why this report analyses the non-technical barriers to this investment decision. The study focusses on the kits developed within the iNSPiRe project, but many of the findings are relevant for other single stage deep renovation projects. Both the planning and implementation phases are considered. The aim was to develop suggestions for overcoming these non-technical barriers so that the iNSPiRe kits can more easily be deployed in the market.

The report is based on a study of policy documents, the experiences of European umbrella organisations for architects, property owners and local governments as well as on a large number of in-depth interviews with relevant stakeholders. Many of the 60 participants were made in conjunction with stakeholder workshops that were organised for specific focus groups such as architects, private property owners, public procurers and the stakeholders of the European Housing Forum. The non-technical barriers have been split into economic, political and social barriers, with most interviewed stakeholders emphasising the economic aspects.

Subsidies are considered by most as essential for property owners to take the decision to make a deep renovation, but stability of the subsidy programs is essential to have a good impact. Low-interest loans are not as favoured. Other key economic issues are the increase in the asset value of the property after such a renovation and the green value of the resulting low energy building. These are both difficult to quantify, partly due to the fact that such renovated buildings are not as yet so common, and vary in the different property markets.

The EU has many policies on energy efficiency that are relevant for renovation of buildings, with the 2010 Energy Performance of Buildings Directive (EPBD recast) and the 2012 Energy Efficiency Directive (EED) being the most important. Many member states were late in implementing these and most have problems with forcing compliance with them. National tenancy laws can also make energy renovations difficult by restricting the possibility of raising rents for. For the iNSPiRe kits, regulations and standards are seen as a barrier in the short term as the kits combine several different functions into one product that are covered by several different regulations and/or standards.

The social barriers are mostly concerned with the tenants, while architectural considerations are also important. In buildings with owner-occupied flats, the decision process for renovation is difficult and even more so when deep renovation is to be considered. In rental properties the owners and tenants have different interests and incentives, leading to possible conflicts. All have uncertainties about the use of multifunctional kits and how well they will perform technically as well as about how much they will save economically.

The report makes a number of suggestions for overcoming these barriers. Especially important for the iNSPiRe kits is training of relevant installers and planners and use of Life Cycle Cost calculations to show the expected benefits over the lifetime of the products.

In each section of the report, in addition to the analysis of the specific barrier, there are sections with specific comments from the interviewed stakeholders.

The Solar Heat Integration NEtwork (SHINE) is a European research school in which 13 PhD students in solar thermal technologies are funded by the EU Marie-Curie program. It has five PhD course modules as well as workshops and seminars dedicated to PhD students both within the project as well as outside of it. The SHINE research activities focus on large solar heating systems and new applications: on district heating, industrial processes and new storage systems. The scope of this paper is on systems for district heating for which there are six PhD students, five at universities and one at a company. The initial work concentrated on literature studies and on setting up initial models and measurement setups to be used for validation purposes. The measurements have been used for validating simulation models, including those used for extending the capabilities of the planning tool Polysun to simulate smaller district heating systems. Some results of these studies are presented in the paper. The PhD students will complete their studies in 2017-18.

This paper presents a techno-economic analysis of a novel solar thermal and air source heat pump system. The system was designed for relatively high operating temperatures in the space heating circuit and included the use of a heat pump with vapor injection cycle and vacuum insulation on the storage tank. The system model was validated against measurements in laboratory and simulated in TRNSYS 17. Annual simulations were performed for the combination of two climates (Carcassonne and Zurich) and two house standards (SFH45 and SFH100) and the best results were achieved for the boundary conditions the system was designed for. For those conditions (Zurich and SFH100), the novel system showed potential for being cost-effective compared to state of art solar and heat pump system. The “additional investment limit”, i.e. the maximum extra investment cost for the novel system in comparison to a state of art benchmark system that gives a break even result for a period of 10 years, varied between 827 € and 2482 € depending on electricity price. The results of a sensitivity analysis showed that variations in electricity price affected the additional investment limit far more than the other economic parameters

Renovation of existing buildings is important in the work toward increased energy efficiency and reduced environmental impact. The present paper treats energy renovation measures for a Swedish district heated multi-family house, evaluated through dynamic simulation. Insulation of roof and façade, better insulating windows and flow-reducing water taps, in combination with different HVAC systems for recovery of heat from exhaust air, were assessed in terms of life cycle cost, discounted payback period, primary energy consumption, CO2 emissions and non-renewable energy consumption. The HVAC systems were based on the existing district heating substation and included mechanical ventilation with heat recovery and different configurations of exhaust air heat pump.Compared to a renovation without energy saving measures, the combination of new windows, insulation, flow-reducing taps and an exhaust air a heat pump gave up to 24% lower life cycle cost. Adding insulation on roof and façade, the primary energy consumption was reduced by up to 58%, CO2 emissions up to 65% and non-renewable energy consumption up to 56%. Ventilation with heat recovery also reduced the environmental impact but was not economically profitable in the studied cases. With a margin perspective on electricity consumption, the environmental impact of installing heat pumps or air heat recovery in district heated houses is increased. Low-temperature heating improved the seasonal performance factor of the heat pump by up to 11% and reduced the environmental impact.

An innovative small solar district heating system with one central heating plant and four solar substations has been built in Vallda Heberg, Sweden, to supply a new housing area with passive houses. The target solar fraction was 40% and the total system design, including heat distribution in the buildings, was based on previous experience and aimed to be simple and cost-effective. The main aim of this study was to determine whether the system can be designed in a more effective manner by change of distribution system and load density. TRNSYS models were calibrated against measured data and then used to predict the energy performance. Results indicate that lower distribution heat losses can be obtained by change to a distribution concept with lower operating temperatures, while potentially reducing cost. Changes in heat density cause reduced distribution losses and boiler supplied heat demand, with only minor effects on solar system yield.

Thermal Energy Storage (TES) has been a topic of research for quite some time and has proven to be a technology that can have positive effects on the energy efficiency of a building by contributing to an increased share of renewable energy and/or reduction in energy demand or peak loads for both heating and cooling. There are many TES technologies available, both commercial and emerging, and the amount of published literature on the subject is considerable. Literature discussing the combination of thermal energy storage with buildings is however lacking and it is therefore not an easy task to decide which type of TES to use in a certain building. The goal of this paper is to give a comprehensive review of a wide variety of TES technologies, with a clear focus on the combination of storage technology and building type. The results show many promising TES technologies, both for residential and commercial buildings, but also that much research still is required, especially in the fields of phase change materials and thermochemical storage.

One of the primary objectives of the iNSPiRe project was to develop a tool that predicts the energy and cost saving impacts of various systemic retrofit interventions. This tool is now available for all those involved in the renovation of older buildings (from consulting offices, moving through construction companies and to decision makers) to use as a means of selecting which retrofit package will deliver the greatest costs savings and most improved energy efficiencies.To this purpose, we have produced three databases that provide valuable information about the energy performance of a variety of buildings in different climates, based on different energy requirements. These are the results of a three stage process:1. Collection of energy use data (statistics) for the whole of EU 27, the structuring of a building stock database and the definition of reference buildings that represent the most typical buildings of the building stock. Data for six different age categories were derived, including typical construction information and insulation standards for these periods. Seven climatic regions were also defined to cover the EU 27. The structured data are available in the Building Stock Statistics database.2. Derivation of a complete and consistent database of heating and cooling demands in residential and office buildings covering the whole of the EU 27 based on the simulation of the defined reference buildings in seven climatic regions. The simulations were calibrated against the energy use statistics, and are thus consistent with these, but offer the full range of heating and cooling demands for all climates and building types for six different age categories. The results are available in the Reference Building Simulation database.3. Definition of a range of retrofit measures for the reference buildings including climatic shell, HVAC system and heating/cooling distribution. The matrix of these measures was then simulated for all building types for the seven different climatic regions to provide data for the third database, the Systemic Renovation Packages database.

One of the primary objectives of the iNSPiRe project was to develop a tool that predicts the energy and cost saving impacts of various systemic retrofit interventions. This tool is now available for all those involved in the renovation of older buildings (from consulting offices, moving through construction companies and to decision makers) to use as a means of selecting which retrofit package will deliver the greatest costs savings and most improved energy performance.The whole set of Renovation Packages in the published database includes results for a range of SFH typologies, from detached to row houses, with different external surface over building volume ratio.In order to compare the same Envelope Renovation when applied to different SFH typologies and climates, we adopted the detached constructions as the basis to define insulation, windows and mechanical ventilation measures that match the heating demand standards sought (15, 25, 40, 70 kWh/m2y). Since the solutions found are the most conservative, lower heating demands are obtained for semi-detached and row houses.The solutions elaborated in terms of window features, and walls/roof cross sections and materials, are reported in Deliverable 6.3a for the whole range of buildings and the 7 climates analysed.In this document we comment the results relative to the reference buildings built 1945-1970, renovated with four generation systems (AWHP, GWHP, gas boiler and biomass boiler) and three distribution systems (radiant ceilings, radiators and fan coils). In order to limit the number of solutions discussed, here we report results only for the detached SFHs. The full range of solutions is published on the iNSPiRe website.The generation plants are hybrid solutions designed to combine heat pumps or boilers with solar thermal and/or PV technologies. These combinations integrate multiple renewable energy sources, thus allowing to reach in the best cases the 50 kWh/m2y primary energy consumption limit that is the objective of the retrofit packages devised.

In this report, we comment the results relative to the reference buildings built within the first age (1945-1970), and renovated with 4 generation systems (air to water heat pump, ground water heat pump, gas boiler and biomass boiler) and 3 distribution systems (radiant ceilings, radiators and fan coils).According to the buildings classification (see D2.1a and D2.1c), two different Multi Family Houses typologies are identified, small Multi Family House (s-MFH) and large Multi Family House (l-MFH). In the published database, only s-MFHs are included, varying the number of floors (3, 5 and 7 floors) and, consequently, the surface over volume (S/V) ratio.As well as for the SFHs, we adopted a reference S/V ratio as the basis to define insulation, windows and mechanical ventilation measures to match the sought heating demand targets (15, 25, 45, 70 kWh/m²y), that is 5 floors and 10 apartments.

Given the environmental benefits of utilizing free thermal energy sources, such as waste heat and solar energy for cooling purposes, many developments have come about in thermally driven cooling. However, there are still some barriers to the general commercialization and market penetration of such technologies that are associated with system and installation costs, complexity, and maintenance. In efforts to overcome these limitations, a novel absorption heat pump module has been developed and tested. The module comprises a fully encapsulated sorption tube containing hygroscopic salt sorbent and water as a refrigerant, sealed under vacuum, and within which there are no moving parts. The absorption module consists of two main components, one that alternately functions as an absorber or generator and other that alternates between the roles of evaporator and condenser. The module therefore operates cyclically between a cooling delivery phase and a regeneration phase. Each module has a significant energy storage capacity with cooling delivery phases ranging from 6-10 h in length with temperature lifts between 16 degrees C and 25 degrees C. The modules are optimized for integration directly into a solar thermal collector, for roof or facade installation, for daytime regeneration and night-time cooling delivery. Collector integrated modules would be completely modular maintenance-free absorption heat pumps with similar installation requirements to standard solar thermal collectors. This article describes the test method and performance characteristics of the individual absorption modules.

The main objective of this work package was to investigate generic control strategies, generic fault-detection and on-line diagnosis algorithms that may apply to the developed prototypes of solar and heatpump systems within MacSheep. The results should lead toimproved reliability and/orincreased energy savings for the end-userthrough new controller features. The use of DHW consumption forecast was identified as a promising control strategy and a simple yet reasonably effective algorithm to get the water tapping behaviourof the userwas developed. Viessmannimplemented the ideas of this approach in an ICT solution for their controller to provide statistical tapping informationto the user who can then set the period when hot waterthatis expected to be used. The operationalstrategy based on DHW consumptionforecast for one hour was not implemented since the potential gains are small (~2%) and there is ahigh user discomfort risk in the case of an inaccurate forecastPrevious studies have shown that solar overheating of the building led to gas savings with solar gas combisystems. Using a similar strategy on the MacSheep reference system did not lead to significant savings, due to strong interactions between space and DHW heating and a higher share of HP operation time for DHW charging of the store, which has a lower efficiency.Another smart control strategy was investigated forvariable electricity pricesusing overheating of the building and/or the DHW volume of the store.The main conclusion of the study is that the combination of the two algorithms led to cost savings for the Austria (Graz) and France (Chambery) with both theSFH45 and SFH100 buildings.Since only the share related to user consumption varies during the day while the grid and transmission costs are usually constant, thecost savings were small, far below 1%.Among the proposed fault detection algorithms for solar and heat pump systems, detection of wrongly connected tubes in the solar collector loop was found interesting by Viesmmann and Regulus. It was implemented and tested in their respective prototype controller. Regulus also implemented the detection of wrong order phase connections in its heat pump prototype as well as threshold tests on abnormal temperature and pressure evolution.

This report describes the optimised solar and heat pump systems developed in the MacSheepproject as well as the simulation results for these systems. Four systems have been developed by four different development groups, each with one private company participating. The development groups have chosen different types of systems as well as different target loads for their systems, which give a wide coverage of the potential markets. The aim of the project was to achieve a 25% performance increase compared to state of the art systems, while being cost-competitive compared to the state of the art.Two reference state of the art solar and heat pump systems have been defined, modelled,and simulated to derive benchmark electricity demands and SPF values for the boundary conditions that were defined for the MacSheep project. The reference systems usedtheground (boreholes) orair as a heat source for the heat pump. The chosen boundary conditions were the climates of Zurich and Carcassone, arealistic DHW load,and two buildings, one representing a modern low energy building (SFH45) and one representing an existing building (SFH100). These reference systems and boundary conditions were defined within the first year of the project, and are used throughout the project.New components were developed for the MacSheepsolar and heat pump systems and these developments are reported in the reportsof work packages 3 –6. Component models have been programmed and validated with laboratory measurements.In this report, simulation results for the four MacSheep systems arecompared to the relevant reference system in order to quantify the expected performance increase. These simulations include the component models with their validated parameters and performance obtained from phase 3 of the project.In addition, the costs of the systemswere estimated. The key performance indicator for the final system developments was defined as a figure for electric savings (25%) compared to the state of the art at competitive (i.e. comparable) cost. Therefore, cost-savings that were achieved for some of the components that were developed were allowed to be compensated by increased cost for other components or increased collector areasin order to show the project's achievements in the light of the defined key performance indicator.At present, the updated simulations show electric savings of 17%, 24%, 26%, and 30%, respectively, for the different developments and the different target heat loads.Threeof these systems will be built and tested during 2015,using the whole system test method that was further developed within the MacSheep project (see report D2.3 for more details). The results from these tests will give benchmark energy used of these systems both for the test sequence itself but also on an annual base. In addition, the simulation models described in this report will be verified against the measurements and then used for annual simulations for otherboundary conditionsthan the once that are represented in the test sequence.