An Adaptive Underfloor Heating Control with External Temperature Compensation

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Assessing the potential of heat pumps to reduce energy-related carbon emissions from UK housing in a changing climate

This thesis describes three connected stages of development and analysis of residential heat pump energy use: firstly, the analysis of heat pump performance data from a monitoring study of ground source heat pumps; secondly, the definition and development of a generalised residential heat pump energy model embedded within an enhanced dwelling energy model; finally, the analysis of the effects of possible residential heat pump installation scenarios on the UK energy supply and carbon emissions. The monitoring study involved three ground source heat pump installations. The data collected consisted of heat output, electric power input, system temperatures and system status indicators. Analysis indicated that these systems showed reductions in carbon emissions from homes ranging from 18% to 37% compared with their counterfactual fuel-burning systems. The monitoring study provided empirical values to parameterise the heat pump model which was built around a linear regression relationship of heat pump COP to source / sink temperature differential based on heat pump performance data from standard laboratory test results. This model was added in a new module to enhance the BRE domestic energy model, BREDEM-8, which provides monthly estimates. Estimating rules were included for energy use from bivalent alternate, bivalent parallel operation and space cooling. The enhanced BREDEM-8 model was used to analyse the effects of possible residential heat pump installations within a housing stock energy model developed using the English Housing Survey datasets as a data source. Baseline estimates for the current stock were created using data reduction techniques to provide parameters (u-values, glazing details) for the enhanced BREDEM-8 model. Scenarios for heat pump deployments were created for the periods up to 2020 and 2050, selecting dwellings for heat pump application according to scenarios reflecting the perceived needs of the period, ie. the likely reduction in UK generating capacity up to 2020 and CO2 emissions reduction targets to 2050. Results showed that up to 2020, a policy of targeting dwellings with the highest overall emissions for replacement would reduce carbon emissions by 7.6%, at the expense of a 12% increase in electricity consumption. Targeting dwellings with the highest emitting existing systems caused a smaller increase in electricity consumption of about 6.5% with carbon emissions reduced by about 6.8%. The scenarios for the period to 2050, including 80% replacement of gas systems with heat pumps, gave an estimated 80% reduction in carbon emissions, when accompanied by an similar reduction in the carbon intensity of electricity generation and bringing about an increase in electricity consumption of somewhat over 40%. The effect of the more extreme scenario is to replace all but a small proportion of the energy used for heating and hot water with standard rate electricity, in 84.6% of the dwellings, and retaining gas in the remainder, 15.2%, bringing about a radical shift to electric heating throughout the housing stock

Do domestic heating controls save energy? A review of the evidence

© 2018 The Authors Claims about the benefits of heating controls are often biased, unsubstantiated, misleading, or incorrect. This paper presents a systematic and critical international review of the evidence for the energy saving, cost effectiveness and usability of heating controls. The focus is domestic, low-pressure hot water heating systems in temperate climates. Eleven different types of standard, advanced and smart controls are assessed plus five components and features that add smart functionality. The review retrieved over 2400 documents from on-line databases and other sources. Screening criteria and quality assurance scoring identified just 67 items, mainly from the UK and USA, which appeared to contain relevant evidence. This evidence was derived from computer modelling, field trials and full-scale experiments, and for usability, from expert evaluations and controlled assessments. The evidence was synthesised and its quality classified as very low, low, moderate or high using the GRADE system which is more commonly applied in evidence-based medicine. The energy savings of most heating controls depends strongly on whether the heating system is operated with a continuous or periodic heating pattern, as well as on the energy efficiency of the dwelling and the severity of the climate. For most control types, the quality of the evidence for energy savings was low, very low or non-existent. However, there was moderate quality evidence that, when appropriately commissioned, zonal controllers, which heat individual spaces to different temperatures at different times, could save energy compared to whole-house controllers, and that low-cost systems of this type could be cost-effective. There was moderate quality evidence that smart thermostats do not save energy compared to standard thermostats and programmers and may, in fact, increase energy demand. The usability studies focussed on general heating controls and programmable thermostats and provided high quality evidence that heating controls are difficult to use, especially by older people. However, no studies were uncovered that quantified the consequent energy penalty. There was no high quality evidence about the impact on energy demand of any of the heating controls studied, mainly because there have been no well-founded, large-scale, multi-disciplinary, multi-year field trials

Optimization approaches for exploiting the load flexibility of electric heating devices in smart grids

Energy systems all over the world are undergoing a fundamental transition to tackle climate change and other environmental challenges. The share of electricity generated by renewable energy sources has been steadily increasing. In order to cope with the intermittent nature of renewable energy sources, like photovoltaic systems and wind turbines, the electrical demand has to be adjusted to their power generation. To this end, flexible electrical loads are necessary. Moreover, optimization approaches and advanced information and communication technology can help to transform the traditional electricity grid into a smart grid. To shift the electricity consumption in time, electric heating devices, such as heat pumps or electric water heaters, provide significant flexibility. In order to exploit this flexibility, optimization approaches for controlling flexible devices are essential. Most studies in the literature use centralized optimization or uncoordinated decentralized optimization. Centralized optimization has crucial drawbacks regarding computational complexity, privacy, and robustness, but uncoordinated decentralized optimization leads to suboptimal results. In this thesis, coordinated decentralized and hybrid optimization approaches with low computational requirements are developed for exploiting the flexibility of electric heating devices. An essential feature of all developed methods is that they preserve the privacy of the residents. This cumulative thesis comprises four papers that introduce different types of optimization approaches. In Paper A, rule-based heuristic control algorithms for modulating electric heating devices are developed that minimize the heating costs of a residential area. Moreover, control algorithms for minimizing surplus energy that otherwise could be curtailed are introduced. They increase the self-consumption rate of locally generated electricity from photovoltaics. The heuristic control algorithms use a privacy-preserving control and communication architecture that combines centralized and decentralized control approaches. Compared to a conventional control strategy, the results of simulations show cost reductions of between 4.1% and 13.3% and reductions of between 38.3% and 52.6% regarding the surplus energy. Paper B introduces two novel coordinating decentralized optimization approaches for scheduling-based optimization. A comparison with different decentralized optimization approaches from the literature shows that the developed methods, on average, lead to 10% less surplus energy. Further, an optimization procedure is defined that generates a diverse solution pool for the problem of maximizing the self-consumption rate of locally generated renewable energy. This solution pool is needed for the coordination mechanisms of several decentralized optimization approaches. Combining the decentralized optimization approaches with the defined procedure to generate diverse solution pools, on average, leads to 100 kWh (16.5%) less surplus energy per day for a simulated residential area with 90 buildings. In Paper C, another decentralized optimization approach that aims to minimize surplus energy and reduce the peak load in a local grid is developed. Moreover, two methods that distribute a central wind power profile to the different buildings of a residential area are introduced. Compared to the approaches from the literature, the novel decentralized optimization approach leads to improvements of between 0.8% and 13.3% regarding the surplus energy and the peak load. Paper D introduces uncertainty handling control algorithms for modulating electricheating devices. The algorithms can help centralized and decentralized scheduling-based optimization approaches to react to erroneous predictions of demand and generation. The analysis shows that the developed methods avoid violations of the residents\u27 comfort limits and increase the self-consumption rate of electricity generated by photovoltaic systems. All introduced optimization approaches yield a good trade-off between runtime and the quality of the results. Further, they respect the privacy of residents, lead to better utilization of renewable energy, and stabilize the grid. Hence, the developed optimization approaches can help future energy systems to cope with the high share of intermittent renewable energy sources

Evaluating the influence of building fabric, services and occupant related factors on the actual performance of low energy social housing dwellings in UK

This paper empirically investigates the influence of building fabric, services and occupant related factors on actual energy use of six case study dwellings, located in three new low energy social housing developments in UK, covering a variety of built forms and construction systems (timber frame, hempcrete, steel-frame). Physical monitoring of indoor environment and window-opening is cross-related with building fabric and systems’ performance, and qualitative data gathered through occupant surveys, review of control interfaces and handover guidance, to understand the causes of the gap between modelled and measured energy use. Actual energy use is found to exceed design expectations by a factor of three, questioning the need for whole-house mechanical ventilation heat recovery (MVHR) systems at measured air permeability rates of 6m³/(h.m²) against the design target of 3m³/(h.m²). Lack of proper commissioning of MVHR and heating systems, combined with inadequate user comprehension about their operation and control leads to occupant ‘misuse’ wherein systems are de-activated, thereby negatively affecting indoor air quality. This is confounded by occupant factors related to higher demand temperatures, unexpected opening of windows during winters due to under-performance of MVHR combined with habitual behaviours, and over-use of heating systems to compensate for higher than expected air permeability

Strategies for low carbon buildings : Assessment of design options and the translation of design intent into performance in practice

To deliver low carbon buildings requires: a) Performance assessment and option appraisal; b) Industry process to translate selected options into low carbon performance in practice. This thesis aims to make some contribution in each of these two areas. Legislation such as the European Performance of Buildings Directive (EPBD) is stimulating the market to put forward many technical options for design or retrofit of low carbon buildings. The need is identified here for a low cost, EPBD compatible, simulation based, real time method for performance assessment and upgrade option appraisal to inform decisions for a range of users with various levels of technical knowledge. The hypothesis is advanced that such a method can be developed. An EPBD compatible, dynamic simulation based, real time, performance assessment and option appraisal method is then proposed and evaluated. A range of test applications and user groups are considered. Test applications include the generation of energy performance ratings based on a simple questionnaire. Other applications cover a range of individual building, policy or strategy contexts. A critical analysis is carried out of the applicability, scope and limitations of the method. The proposed method proved useful in a range of applications. For other applications some limitations were identified. How these can be addressed is discussed. The development and deployment examples are for a specific building stock but provide insights to enable replication for other situations. The research provides a foundation for further research and development. There is much evidence that selection of appropriate options is not sufficient to achieve low carbon performance. Many issues can lead to gaps between intended and actual performance. Problems are identified in the design and implementation of low carbon systems and controls. Problems include poor understanding, errors in implementation, and poor visibility of actual performance. The need for a method to address these problems is identified. The hypothesis is advanced that such a method can be developed. A Modular Control Mapping and Failure Mode Effect Analysis (FMEA) method is then proposed and evaluated for a range of test applications to buildings intended to be low carbon. The insights from the test applications are reviewed and the scope and limitations of the proposed method discussed. Overall the applications were successful and the useful application demonstrated. The method was deployed post-occupancy, then applicability at various stages of the design process was demonstrated by using concept and detailed design information. The modular control mapping and FMEA process proposed leverages in part the approach taken in industrial sectors identified as benchmarks by proponents of the Building Information Modelling (BIM) initiative. The potential application of further processes from BIM benchmark industry is discussed in the context of current buildings industry initiatives. The performance assessment and option appraisal method, the modular control mapping and FMEA method, and the outcomes from their evaluations are intended to contribute to the realisation of low carbon buildings in practice. The future integration of both methods within a BIM framework is proposed

Strategies for low carbon buildings, assessment of design options and the translation of design intent into performance in practice

To deliver low carbon buildings requires: a) Performance assessment and option appraisal; b) Industry process to translate selected options into low carbon performance in practice. This thesis aims to make some contribution in each of these two areas. Legislation such as the European Performance of Buildings Directive (EPBD) is stimulating the market to put forward many technical options for design or retrofit of low carbon buildings. The need is identified here for a low cost, EPBD compatible, simulation based, real time method for performance assessment and upgrade option appraisal to inform decisions for a range of users with various levels of technical knowledge. The hypothesis is advanced that such a method can be developed. An EPBD compatible, dynamic simulation based, real time, performance assessment and option appraisal method is then proposed and evaluated. A range of test applications and user groups are considered. Test applications include the generation of energy performance ratings based on a simple questionnaire. Other applications cover a range of individual building, policy or strategy contexts. A critical analysis is carried out of the applicability, scope and limitations of the method. The proposed method proved useful in a range of applications. For other applications some limitations were identified. How these can be addressed is discussed. The development and deployment examples are for a specific building stock but provide insights to enable replication for other situations. The research provides a foundation for further research and development. There is much evidence that selection of appropriate options is not sufficient to achieve low carbon performance. Many issues can lead to gaps between intended and actual performance. Problems are identified in the design and implementation of low carbon systems and controls. Problems include poor understanding, errors in implementation, and poor visibility of actual performance. The need for a method to address these problems is identified. The hypothesis is advanced that such a method can be developed.;A Modular Control Mapping and Failure Mode Effect Analysis (FMEA) method is then proposed and evaluated for a range of test applications to buildings intended to be low carbon. The insights from the test applications are reviewed and the scope and limitations of the proposed method discussed. Overall the applications were successful and the useful application demonstrated. The method was deployed post-occupancy, then applicability at various stages of the design process was demonstrated by using concept and detailed design information. The modular control mapping and FMEA process proposed leverages in part the approach taken in industrial sectors identified as benchmarks by proponents of the Building Information Modelling (BIM) initiative. The potential application of further processes from BIM benchmark industry is discussed in the context of current buildings industry initiatives. The performance assessment and option appraisal method, the modular control mapping and FMEA method, and the outcomes from their evaluations are intended to contribute to the realisation of low carbon buildings in practice. The future integration of both methods within a BIM framework is proposed.To deliver low carbon buildings requires: a) Performance assessment and option appraisal; b) Industry process to translate selected options into low carbon performance in practice. This thesis aims to make some contribution in each of these two areas. Legislation such as the European Performance of Buildings Directive (EPBD) is stimulating the market to put forward many technical options for design or retrofit of low carbon buildings. The need is identified here for a low cost, EPBD compatible, simulation based, real time method for performance assessment and upgrade option appraisal to inform decisions for a range of users with various levels of technical knowledge. The hypothesis is advanced that such a method can be developed. An EPBD compatible, dynamic simulation based, real time, performance assessment and option appraisal method is then proposed and evaluated. A range of test applications and user groups are considered. Test applications include the generation of energy performance ratings based on a simple questionnaire. Other applications cover a range of individual building, policy or strategy contexts. A critical analysis is carried out of the applicability, scope and limitations of the method. The proposed method proved useful in a range of applications. For other applications some limitations were identified. How these can be addressed is discussed. The development and deployment examples are for a specific building stock but provide insights to enable replication for other situations. The research provides a foundation for further research and development. There is much evidence that selection of appropriate options is not sufficient to achieve low carbon performance. Many issues can lead to gaps between intended and actual performance. Problems are identified in the design and implementation of low carbon systems and controls. Problems include poor understanding, errors in implementation, and poor visibility of actual performance. The need for a method to address these problems is identified. The hypothesis is advanced that such a method can be developed.;A Modular Control Mapping and Failure Mode Effect Analysis (FMEA) method is then proposed and evaluated for a range of test applications to buildings intended to be low carbon. The insights from the test applications are reviewed and the scope and limitations of the proposed method discussed. Overall the applications were successful and the useful application demonstrated. The method was deployed post-occupancy, then applicability at various stages of the design process was demonstrated by using concept and detailed design information. The modular control mapping and FMEA process proposed leverages in part the approach taken in industrial sectors identified as benchmarks by proponents of the Building Information Modelling (BIM) initiative. The potential application of further processes from BIM benchmark industry is discussed in the context of current buildings industry initiatives. The performance assessment and option appraisal method, the modular control mapping and FMEA method, and the outcomes from their evaluations are intended to contribute to the realisation of low carbon buildings in practice. The future integration of both methods within a BIM framework is proposed