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Achieving nearly zero carbon heating continues to be identified by UK government analysis as an important feature of any lowest cost pathway to reducing greenhouse gas emissions. Heat currently accounts for 48% of UK energy consumption and approximately one third of UK's greenhouse gas emissions. Heat Networks are being promoted by UK investment policies as one means of supporting hybrid heat pump based solutions. To this effect the RISE (Renewable Integrated and Sustainable Electric) heating system project is investigating how an all-electric heating sourceshybrid configuration could play a key role in long-term decarbonisation of heat. For the purposes of this study, hybrid systems are defined as systems combining the technologies of an electric driven air source heat pump, electric powered thermal storage, a thermal vessel and micro-heat network as an integrated system. This hybrid strategy allows for the system to store up energy during periods of low electricity demand from the national grid, turning it into a dynamic supply of low cost heat which is utilized only when required. Currently a prototype of such a system is being tested in a modern house integrated with advanced controls and sensors. This paper presents the virtual performance analysis of the system and its design for a micro heat network with multiple dwelling units. The results show that the RISE system is controllable and can reduce carbon emissions whilst being competitive in running costs with a conventional gas boiler heating system.

Achieving nearly zero carbon heating continues to be identified by UK government analysis as an important feature of any lowest cost pathway to reducing greenhouse gas emissions. Heat currently accounts for 48% of UK energy consumption and approximately one third of UK's greenhouse gas emissions. Heat Networks are being promoted by UK investment policies as one means of supporting hybrid heat pump based solutions. To this effect the RISE (Renewable Integrated and Sustainable Electric) heating system project is investigating how an all-electric heating sourceshybrid configuration could play a key role in long-term decarbonisation of heat. For the purposes of this study, hybrid systems are defined as systems combining the technologies of an electric driven air source heat pump, electric powered thermal storage, a thermal vessel and micro-heat network as an integrated system. This hybrid strategy allows for the system to store up energy during periods of low electricity demand from the national grid, turning it into a dynamic supply of low cost heat which is utilized only when required. Currently a prototype of such a system is being tested in a modern house integrated with advanced controls and sensors. This paper presents the virtual performance analysis of the system and its design for a micro heat network with multiple dwelling units. The results show that the RISE system is controllable and can reduce carbon emissions whilst being competitive in running costs with a conventional gas boiler heating system.

This work attempts to answer the question: How much can we believe that the coefficient of performance provided by the manufacturer is correct, when a heat pump is required to face the real load coming from changes of temperature? The paper summarizes some basics of heat pump theory and describes the results of numerical models.

Heat pumps are increasingly gaining popularity as the world is moving towards low-carbon energy systems. Use of heat pumps for domestic heating and hot water is widely seen as a sustainable option, and a step further from conventional fuel dependence. In spite of being 'green' in terms of carbon-pollution, there is a need to move towards low GWP working fluids in heat pump systems to ensure minimal impact to the environment. Low GWP fluids and mixtures have been emerging in the light of sterner legislations being introduced to limit, if not to totally prevent, further use of high GWP fluids. Replacement fluid has to satisfy a number of criteria, primarily to perform similarly to the original fluid. We have compared high and low GWP fluids, as well as several mixtures, as working fluids in the same operational scenario. Low GWP fluids are fundamentally different from conventionally used one, but their performance has some promising features.

China has the largest construction volume in the world with about 2 billion square meters of new buildings completed annually. Currently about 80% of these are categorized as high-energy buildings and more than 90% of new buildings are considered high life-cycle energy buildings. The speed of construction in China is amazing and it's stimulated even further by the fast rates of urbanization. In order to decrease energy consumption of buildings, there is a need for strong political will and implementation of strict building regulations. China is geographically a vast country and it's impossible to design a single building code for the whole country. Energy consumption per building in China is 2-3 times higher than that of the developed countries with similar climatic conditions, and buildings are less comfortable as a result of poor thermal performance and too little insulation in most of China's buildings. Although the Chinese government has issued many standards and codes in order to improve energy efficiency of buildings, little effect has appeared and less than 6% of newly constructed buildings comply with these standards. China is a large country with a complex climate that in the national standard (GB50176-93) it's divided into five climate zones. Because of the "Qin-Huai line", for severe cold and cold zones, they have central heating system while 14 provinces and nearly half of the population of China is living in the hot summer and cold winter zones (HSCW) where they don't have central heating system. This is the first reason why in these zones heat pump systems play a very important role in heating buildings. Air source heat pump (ASHP) as an optional product has already been widely applied in families and companies. This project reports a novel application of an air source heat pump system for cooling, heating and domestic hot water production in Shanghai for a typical apartment. In winter, the system was aim to solve the central heating problem. The system was combined with a Low-H_2O heat exchanger to decrease the supply water temperature in order to save energy. The heating return water temperature was set at 30 °C, 35 °C and 40 °C for heating in winter which is lower than the conventional air source heat pump system. This system composed by the ASHP and the STDFCU has been tested, from December to February, in an apartment, aiming to the energy saving and the user's comfort. We found, for each experiment, the values of heating capacity and energy consumption and we can say that the heat pump's power is always sufficient to heat the apartment except with the temperature at 40 °C and the internal temperature at 22°C. Moreover, the internal conditions are always good for the users with an internal temperature between 19 and 21 °C. The use of computer software can be useful to simulate the model and to compare results with the experimental's data. That's why we created a model of the whole system and simulated it on EnergyPlus, an energy analysis and thermal load simulation program. Starting with a simplified model, finally we simulated the apartment finding heating capacity of the same order of magnitude that in the experiments.

The building sector accounts for approximately 40% of primary energy use within the European Union, therefore reductions in the energy use intensity of this sector are critical in decreasing total energy usage. Given that the majority of energy used within the built environment is for space conditioning and domestic hot water preparation, prudence would suggest that decreasing primary energy used for these end purposes would have the biggest overall environmental impact. A significant portion of the energy demands in buildings throughout the year could potentially be met using solar energy technology for both heating and cooling. Additionally, improving the efficiency of current heating and cooling appliances can reduce environmental impacts during the transition from non-renewable to renewable sources of energy. However, in spite of favourable energy saving prospects, major energy efficiency improvements as well as solar heating and cooling technology are still somewhat underutilised. This is typically due to higher initial costs, and lack of knowledge of system implementation and expected performance. The central premise of this thesis is that modular thermally (i.e., sorption) driven heat pumps can be integrated into heating and cooling systems to provide energy cost savings. These sorption modules, by virtue of their design, could be integrated directly into a solar thermal collector. With the resulting sorption integrated collectors, cost-effective pre-engineered solar heating and cooling system kits can be developed. Sorption modules could also be employed to improve the efficiency of natural gas driven boilers. These modules would effectively transform standard condensing boilers into high efficiency gas-driven heat pumps that, similar to electric heat pumps, make use of air or ground-source heat. Based on the studies carried, sorption modules are promising for integration into heating and cooling systems for the built environment generating appreciable energy and cost-savings. Simulations yielded an annual solar fraction of 42% and potential cost savings of €386 per annum for a sorption integrated solar heating and cooling installation versus a state-of-the-art heating and cooling system. Additionally, a sorption integrated gas-fired condensing boiler yielded annual energy savings of up to 14.4% and corresponding annual energy cost savings of up to €196 compared to a standard condensing boiler. A further evaluation method for sorption modules, saw the use of an artificial neural network (ANN) to characterise and predict the performance of the sorption module under various operating conditions. This generic, application agnostic model, could characterise sorption module performance within a ± 8% margin of error. This study thus culminates in the proposal of an overall systematic evaluation method for sorption modules that could be employed for various applications based on the analytical, experimental and simulation methods developed.

The application of heat pumps for buildings heating systems in the cold or transitional season of the year is increasingly common not only in Lithuania but also in other European Union countries. Due to the growing popularity of air to air or air to water heat pumps in the building sector, the problem of evaporator heat exchanger freezing is also increasing in importance. As the outdoor temperature drops, the heat pump's efficiency – coefficient of performance for heating (COP) decreases. At high relative humidity there is also a risk of the evaporator heat exchanger to start freezing. This increases the energy consumption of the system, has a negative effect on heat exchange. Given the need for experimental and numerical research, the aim of this work is to analyse and present the characteristics of air source heat pump (ASHP) in the presence of the risk of freezing and to qualitatively assess the COP reduction due to frost formation. This paper investigates the operation of an ASHP in the cold season, observes the freezing of the evaporator as environmental conditions change. An experimental stand was constructed for this research; the necessary measuring devices and a camera were installed for visual observation of the experiment and assessment of frost formation. The experiments were carried out during the transitional - cold season of the year. It was found that frost formation on the evaporator started when the outdoor temperature was <3.5 °C and the relative humidity reached 88%. The defrost cycle took an average of 5 minutes. The impact of evaporator freezing on the operation and efficiency of the system - COP - has been assessed.

The application of heat pumps for buildings heating systems in the cold or transitional season of the year is increasingly common not only in Lithuania but also in other European Union countries. Due to the growing popularity of air to air or air to water heat pumps in the building sector, the problem of evaporator heat exchanger freezing is also increasing in importance. As the outdoor temperature drops, the heat pump's efficiency – coefficient of performance for heating (COP) decreases. At high relative humidity there is also a risk of the evaporator heat exchanger to start freezing. This increases the energy consumption of the system, has a negative effect on heat exchange. Given the need for experimental and numerical research, the aim of this work is to analyse and present the characteristics of air source heat pump (ASHP) in the presence of the risk of freezing and to qualitatively assess the COP reduction due to frost formation. This paper investigates the operation of an ASHP in the cold season, observes the freezing of the evaporator as environmental conditions change. An experimental stand was constructed for this research; the necessary measuring devices and a camera were installed for visual observation of the experiment and assessment of frost formation. The experiments were carried out during the transitional - cold season of the year. It was found that frost formation on the evaporator started when the outdoor temperature was <3.5 °C and the relative humidity reached 88%. The defrost cycle took an average of 5 minutes. The impact of evaporator freezing on the operation and efficiency of the system - COP - has been assessed.

The present study investigates the sustainable use of a ground coupled heat pump (GCHP). In order to assess the performance of this type of installation, a computer model composed by two parts has been developed. The Borehole Heat Exchanger (BHE) model is developed in COMSOL Multiphysics, based on numerical methods. Part of the results are fed to the heat pump energy model, developed in MATLAB. A real case study has been used to validate the model: the Faculty of Engineering of La Sapienza University in Latina, undertaking a renewal project for an abandoned part of the building. After the renovation, the building will host a research center on the topic of low-enthalpy geothermal systems. The analysis have demonstrated that the modelled GCHP system can supply a significant share of the energy required from the future research center. This amount of energy can be provided keeping almost stable the thermal balance of the surrounding region in the subsoil, operating in a sustainable way. The range of variation of the ground temperature with respect to the average value is within the limit of 5°C, which is the cap set by the international legislation.