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In this study, a medium-sized residential building is analyzed when an internal combustion engine-based combined heating and power (CHP) system is applied. The multi-family building with a floor heating system is selected to represent typical Korean residential situation. Simulation models are developed for the building, prime mover, thermal storage system, and cooling and heating systems. The validated CHP model is integrated to the building, and it is operated with a thermal load following method. The CHP applied residential building model is compared to the baseline model with a grid power and a gas fired boiler system, in terms of energy, environment, and economics. When the CHP system is applied to the residential building in South Korea, total primary energy consumption is decreased by 18.4%, CO2 emissions by 11.8%, and operation cost by 9.6%, respectively. Based on the facility and operating cost, the payback year is calculated as 10.2. In addition, the building performance is further discussed in terms of weather conditions, utility fee change and energy utilization method.

The European Union’s (EU) building stock is characterised by low energy efficiency and slow growth rates. To achieve EU’s greenhouse gas (GHG) emission targets, doubling building retrofit rates is one of the focuses of the European Green Deal. In this article, a real-world retrofit study was conducted, testing the limits towards carbon neutrality. A multi-objective optimisation process was developed, aiming to minimise the operating GHG emissions and the life-cycle cost. The process was applied to a typical multi-residential building and was tested in the four Greek climate zones. It was found that the cost-optimal retrofit agrees with the observed market trends (envelope insulation, double-glazed windows, air-to-air heat pumps (HP) and solar thermal collectors), leading to more than 60% reduction in GHG emissions. A maximum of 87% to 96% reduction was achieved by applying thicker envelope insulation, low-carbon (biomass boiler) or high-efficiency (gas-condensing boiler, air-to-air or air-to-water HPs) heating and cooling systems, photovoltaic-thermal and facade-integrated photovoltaic systems. A net-zero GHG emission retrofit could not be achieved within the building premises without considering the future decarbonisation of the electricity grid and the installation of efficient electricity-driven systems.

Despite being seen as an extinguishing technology, gas-fired heating boiler units are still one of the most common sources for meeting the space heating energy demand of residential dwellings. Current energy performance assessment calculations for residential buildings are often based on insufficient details with thermodynamically ambiguous assumptions and lacking of a consistent approach. However, more detailed methodologies usually require a large set of scarcely available input data which vastly limit the (re)usability of these more refined methods. Following the limited availability of design parameters provided by manufacturers, the goal of this research is to determine the necessary level of the modelling detail to reliably predict the performance of gas-fired condensing boilers. A thermodynamically consistent model of a gas-fired condensing boiler unit is developed and discussed through its application in numerical simulations. Calibration is done by using publicly available data and standardised measurement points are used for verification of the results. The values of the exhaust gas temperature and flow rate of the formed condensate are available in the standardised experimental reports of these units. This work suggests that these values should be included in public documents given by the manufactures.

Heating tower heat pump (HTHP) technology is evolving rapidly owing to its good performance in summer and frost-free operation in winter. However, a lack of comprehensive comparisons between the HTHP and conventional methods, such as the air-source heat pump (ASHP), and the chiller and boiler, significantly limits its applications. To solve this problem, this paper analyzes the technological and economic performance of these three types of systems at 353 locations over China. The principle of energy saving and potential of the HTHP are presented, based on which a comparison of economic performance is conducted by considering the efficiency of energy conversion and cost of the three systems. The results show that the HTHP is superior to the ASHP at most locations in China, with a 10% to 20% higher annual performance factor (APF). For locations in southwest China, this improvement is less than 10% owing to the large regeneration penalty in winter, and minor differences between dry-bulb and wet-bulb temperatures in summer. The APF of the HTHP is 10% to 23% higher than the chiller and boiler system in the hot summer and cold winter zone as well as the cold zone. However, the HTHP exhibits no advantage over this system in the severe cold zone because of the low efficiency of the heat pump in winter, or in the hot summer and warm winter zone owing to the small heating load. The results are used to develop technical and economic performance maps to guide the application of the HTHP in different climatic regions.

A significant demand for building heating exists in the Tibetan area of Western Sichuan. However, there is no enough meteorological data and appropriate optimization method used for designing and operating local building heating systems. This study puts forward a building heating climate zoning method to divide the Tibetan area of Western Sichuan into four building heating climate zones. Combined with the local renewable energy resources, an optimization model that can be used to simultaneously optimize system configuration, equipment capacity, and operating parameters for a multi-source complementary heating system based on air source heat pump (MSCHS-ASHP) is proposed. Life cycle cost (LCC), seasonal coefficient of performance (SCOP), CO2 emission equivalent in operation cycle, and cumulative power consumption the during heating season (Wele) are selected as indices to evaluate the performance of MSCHS-ASHP and coal-fired boiler heating system (CBHS), which is optimized for comparison. Results show that compared to CBHS, the LCC of optimal MSCHS-ASHP can be reduced by up to 26.8%, while the SCOP can be increased by up to 398.8%. Zero CO2 emissions can be achieved during operation of MSCHS-ASHP as well. The Wele of optimal MSCHS-ASHP can reach a minimum value of 1.75 kWh/(m2·a).

Residential space heating is one of the major contributors to greenhouse gas (GHG) emissions and hence a priority sector to decarbonise in the transition to Net Zero target by 2050 in the UK. To assess environmental impacts of a current heating system and potential alternatives in the UK, this study conducted a comparative LCA of a condensing gas boiler and a hybrid heating pump for a common type of UK’s existing houses (a semi-detached house). The functional unit of this study is defined as delivering space heating for the whole lifetime (20 years) of heating system. The results suggest that the hybrid heat pump potentially saves 30% of GHG emissions as compared to the condensing gas boiler in the core scenarios (4.5E + 04 kg CO2-eq/FU vs 6.4 E + 04 kg CO2-eq/FU respectively). The hybrid heat pump also shows 13% to 48% emission reduction as compared to the condensing gas boiler in terrestrial acidification, photochemical oxidant formation, particulate matter formation and fossil depletion. However, the hybrid heat pump emits 3 to 6 times more emissions in terms of human toxicity, water depletion and metal depletion than the condensing gas boiler. The production phase contributes around 50% of the impact for metal depletion and human toxicity in both core scenarios, while the use phase dominates in other selected impact categories. The combustion of natural gas and the electricity production are the major causes for the dominance of the use phase for all selected impact categories excepting metal depletion and human toxicity. The sensitivity scenarios support the robustness of the results. Further work is needed to understand the role hybrid heat pumps can play in the residential sector decarbonisation under different scenarios of residential uptake, household behaviour and wider UK energy system decarbonisation.

The combustion of raw coal leads to severe environmental pollution; however, many people in Northern rural China still use coal as a primary heat source. How to select clean heating technologies that can replace raw coal is essential, but still unclear; therefore, it is crucial to evaluate the existing heating systems to find out the answer. Herein, we selected four possible substitution solutions, including shaped coal heating boiler, biomass pellet heating boiler, low ambient temperature air-to-water heat pump, and low ambient temperature air-to-air heat pump, to conduct field tests and compare with raw coal as the baseline. We assessed the indoor air temperature, energy conservation effect, environmental impact, and economic impact of these solutions. Results indicated that biomass pellet for heating and low ambient temperature air-to-air heat pump possess the potential for dissemination. Herein, the biomass pellet heating boiler is the best solution in rural areas with rich biomass resources, while the low ambient temperature air-to-air heat pump is deemed suitable in rural areas that lack access to biomass or have flexible heating demands. This study evaluated the possible clean heating solutions in Northern rural China, which might be useful for other countries facing similar environmental problems.

This study mainly touches on natural gas fueled combi boiler appliances having space and water heating functions. The hot water demanded in any type of building for daily activities such as personal hygiene, cleaning, and bathing is referred to as domestic hot water (DHW). Since high efficiency targets have been already reached with respect to the space heating, most of the research and development activities are now focusing on the DHW heating function. Therefore, the subject of this study is concerned with only DHW heating function and the basic objective is making a comprehensive comparison between two mathematical models via different approaches for the same DHW circuit. In the first approach, basic heat transfer equations for DHW heating function are established by means of one-dimensional and time dependent differential equations. Later on, those transient energy equations were discretized by finite-difference method implicitly and solved simultaneously in Matlab (R). The second model has been constructed with the help of commercial software, Flowmaster (R) which is one-dimensional thermo-fluid simulation tool. Then, the numerical results have been compared with the experimental data and the validity of the models has been discussed separately on the basis of the agreement between them. The advantages of both models have been evaluated as the distinctive contributions to the literature from DHW circuit modeling viewpoint. Among the intensive research and development activities of the combi boiler manufacturers to achieve high DHW comfort scores for high selling rates in the market, decreasing the time and money spent on the laboratory tests of the appliances is a challenging issue. Number of the laboratory tests is proposed to be decreased due to the preliminary results obtained from properly working numerical models for the performance analyses of completely new appliance concepts or design modifications on the regular appliances. (C) 2016 Elsevier B.V. All rights reserved.

As a renewable energy utilization system, seawater source heat pump district heating system can eliminate the local air pollution compared with the direct combustion of fuel in the conventional boiler house district heating system in northern cold climate area. A field measurement with an emphasis on the energy efficiency of an actual seawater source heat pump district heating system was conducted and analyzed. The field measurement showed that the heat pump units consumed the largest part of energy consumption of the whole system (as high as 78.9% in the project). However, the coefficient of heating performance (COP) of the seawater source heat pump unit was as low as 2.43. Then the energy efficiency enhancement potential of the heat pump unit was carefully analyzed and calculated in the light of the index of Thermodynamic Perfectibility for the heat pump unit. And the results showed that there is about an average of 24.2% energy efficiency enhancement potential of the heat pump units in the project. In the end, a verification case study indicated that the COP of the heat pump units in the project will increase 34.6% if they are substituted by the ones made by another manufacturer.

This study evaluated three-year operation of solar hot water heating system installed in multi-family housing complex with 1179 households in 14 units. At first, since the size of systems for multi-families are large, position of the building services room and collector installation becomes a significant matter. In order to resolve this, three building services rooms for three or four units of households were planned and the solar collectors were integrated directly on the roof facing South at 22° degrees to the horizontal. The accumulated heat gain from three-year operation was 52% of the design baseline (4069 GJ/year). The reason for this could be a low altitude angle of collectors from the architectural design. Moreover, hot water usage and breakdowns of the system were evaluated using detailed analyses of operation data for three years by considering seasonal factors. These results are expected to give valuable feedback for the future design and wide use of the systems, as well as update the design baseline. Lastly, compared to a conventional boiler(δ = 85%), the system produced a positive environmental effect equivalent to a reduction in oil use of 71,907 L/year, and reduced carbon emissions equivalent to 50.8 TC and 186.3 TCO2 the pay-back period for the system was expanded 5 years.

This paper uses exergoenvironmental analysis to tackle the energetic, exergetic, and environmental performance of three heating systems commonly used in the residential building sector in Turkey: a conventional coal boiler, a condensing natural gas boiler, and a ground source heat pump. This analysis presents a combination of exergy analysis and life cycle assessment (LCA). The obtained results show that the ground source heat pump is an efficient heating system for the given application from a thermodynamic perspective in terms of the coefficient of performance and exergy efficiency with values of 2.5 and 10%, respectively. On the other hand, the LCA results demonstrate that the system-related environmental impact associated with ground source heat pump is the highest among the compared systems. Based on exergoenvironmental analysis the environmental impact per kWh exergy demand for each system is found to be 4.0, 1.69, and 1.93 mPt/kWh, respectively. This demonstrates that using an efficient system from thermodynamic perspective does not offer a significant environmental advantage and Turkey must renounce the use of coal in heating applications as soon as possible in order to get rid of environmental burdens as the first step and should promote the use of natural gas at building level in order to generate heating energy.

This study puts forward to a comprehensive method to evaluate the environment impact and economic benefit of central heating systems. Three types of residential heating systems are compared about the energy use in one-year operation phase, including waste water heat pump system, coal boiler system and gas boiler system. The system, located in Tianjin City, China, is designed for residential buildings. The comparison is made with respect to cost, environment impact and integrated assessment. The results indicate that according to now power structure, if COP of the heat pump reaches 2.5 but lower than 3, heat pump system shows better environment performance but wastes more money than boiler heating systems. If the COP of the heat pump is above 3, heat pump heating system would have best integrated performance, i.e. it has lower cost and less environmental impact than the other systems.

This paper deals with exergoeconomic analysis of a dormitory heated by a conventional boiler in a central heating system. The energy and exergy flows are examined from the generation stage to the envelope of the building. The energy and exergy flows between the stages are obtained using a predesign tool for an optimized building design. Exergetic and exergoeconomic analyses of some heating equipment are comprehensively evaluated. A conventional boiler and a water heater in the central heating system are considered in the analysis. Based on the analysis results obtained, the total exergy input rate is calculated to be 1455 kW while the largest exergy loss rate is found to be 987.6 kW. Exergetic efficiencies of the conventional boiler and the water heater are also obtained to be 15.6% and 20.4%, respectively.

The electric-driven seawater source heat pump district heating system is a renewable energy utilization system, but this cannot guarantee the energy-saving effect of the system. The static energy-saving judgment between this system and the conventional boiler house district heating system was provided in a former research paper. However the static method has proved to be a very rough evaluation method and may lead to misjudgment as well. So a quasi-dynamic method, taking the total energy consumption during a whole heating season into consideration, is established in this paper. The energy-saving index turns out to be the expression of the lower limit of the average COP of the seawater source heat pump unit throughout the heating season (COPh,mc). Then a case study is presented to show how the index of COPh,mc and the actual average COP of the heat pump unit throughout the heating season (COPh,ma) are calculated. The calculation results show that the quasi-dynamic method improves the calculation accuracy dramatically, and thus provides a better solution to the quantitative energy-saving evaluation of the electric-driven seawater source heat pump district heating system.

Through investigation of the Dengfeng heating network in the city of Daqing, China, for the 2007–2008 heating season, we found serious problems of excessive heat supply in the primary heating network. Therefore, we propose the application of gas-fired boilers in underperforming heating substations as peak-load heat sources to effectively adapt to the regulation demands of seasonal heat-load fluctuations and reduce the excessive heat supply. First, we calculated the excessive heat supply rates (EHSRs) of five substations using detailed investigative data. We then discussed the feasibility of the proposed scheme providing energy savings from both energetic and exergetic points of view. The results showed that the average EHSR of the five substations between January and March was 20.57% of the gross heat production but consequently reduced to 6.24% with the installation of the gas-fired boilers. Therefore, the combined heating scheme with coal as the basic heat-source and gas-fired boilers as peak-load heat sources is energy-efficient to some extent, although requires the use of natural gas. Meanwhile, the exergy decreased by 10.97%, which indicates that the combined heating scheme effectively reduces the primary energy consumption and pollutant emission of the heating systems.

Heating and cooling systems consume the most energy and are the largest source of emissions in the entire life cycle of a house. This study compares the life cycle impacts of three residential heating and cooling systems—warm-air furnace and air-conditioner, hot water boiler and air-conditioner, and air–air heat pump over a 35-year study period. Simulation and life cycle assessment studies of the systems at four locations in the United States, namely Minnesota, Oregon, Pennsylvania and Texas determine the effect of regional variations in climate, energy mix, and the standard building characteristics on the systems’ environmental impacts. In Minnesota, Pennsylvania, and Texas, the heat pump has the highest impacts whereas in Oregon the heat pump has the lowest impacts. A second scenario shows that substitution by high-efficiency equipment reduces the impacts of all systems but does not affect the order of relative performance by region. Another scenario examined the replacement of coal-generated electricity by renewable generation in regional grids. In order to reduce the impacts of the heat pump system to the lowest of the three systems, renewable sources would have to replace 42% of electricity generation in Minnesota, 15% in Pennsylvania, and 38% in Texas.

The introduction of natural gas in the Greek energy market broadened the options in the field of space heating. Residents in five major Greek cities can choose from a variety of different fuels and systems for heating their houses or working spaces; 12 more cities will be connected to the gas network within the next 5 years. Considering that space heating is the major energy consuming activity in the Greek building sector and that the environmental constrains imposed by the Kyoto protocol will be met only with difficulty, if at all, a strategy concerning the developments in space heating seems to be necessary. This however presupposes an elaborate analysis of the overall performance of the alternative systems, taking into consideration the particular conditions of the Greek energy system and the ‘established’ way of designing residential and mixed-use buildings. The present paper aims to present the empirical comparative results related to the three most popular heating systems operated in Greek multi-apartment and mixed-use buildings, which use three different fuels, respectively: a central oil-fired boiler, a unitary gas-fired boiler and unitary heat pumps.

Izmir Institute of Technology campus is in use since 2000 and still under development. At present, heating is provided by individual fuel boilers. On the other hand, the campus has a geothermal resource in its borders with a temperature of 33 °C. Because of this low geothermal fluid temperature; heat pump district heating system is considered for the campus. As an alternative, fuel boiler district heating system is studied. Each heating system is simulated using hourly outdoor temperature data. For the simulations, a control system with constant flow rate and variable return water temperature is used and the main control parameter is the indoor temperature. Various heating regime alternatives have been studied for heat pump district heating system for the various condenser outlet temperature and geothermal fluid flow rate, and two of these alternatives are given in this study. Furthermore, economic analysis has also been done for each heating system alternative based on investment and operational costs. Results indicate that heat pump district heating system has the highest investment but lowest operational cost. The alternatives are evaluated according to internal rate of return method, which shows the profit of the investment and resulted that, the heat pump district heating system has minimum 3.02% profit comparing with the fuel boiler district heating system at the end of the 20-year period.

An experiment was carried out over two heating seasons to test the performance of an inferential control scheme (ICS), which was designed to optimise the control of boilers in multi-zone heating systems [Building Services Engineering Research and Technology 4 (2003) 245], in a real installation. This paper presents the development of the prototype controller, method and result of the experimental testing. The experimental results show that the ICS can significantly improve the long-term performance, i.e. energy efficiency and thermal comfort, of the multi-zone heating system compared with conventional control schemes. It also demonstrates that the ICS can be implemented in a microprocessor-based controller and be commissioned using short-term monitoring data, which makes it a practical control technique.

An existing dynamic model of a dwelling has been extended with a model of a central heating system. Results of research regarding static and dynamic properties of boilers, radiators, convectors and thermostats have been used for this. With this mathematical model several design and operation strategies and their influence on the energy consumption and temperature in the living room have been studied. Application of a high-efficiency boiler instead of a conventional boiler in this example resulted in an energy saving of about 15%. Also, heating of only three rooms (living room, kitchen and bathroom), placing the boiler in the kitchen instead of the attic and reduction of the return-water temperature to 50 °C resulted in energy savings varying from 6% to 15%. In the last case, the temperature in the living room is about 1 °C lower because the dimensioning of the radiators was based on the usual water temperatures so that their capacity became too low. Improper distribution of the water over the radiators causes an increase of 10% in the energy consumption. Application of convectors and improper adjustment of the anticipator of the room thermostat both cause a 6% higher energy consumption. In the case of the convectors this is explained by the increased water flows and the reduced temperature drop over the convectors as compared with radiators.