Search

Published UK 2050 energy scenarios specify a range of decarbonised supply side technologies combined with electrification of transportation and heating. These scenarios are designed to meet CO 2 reduction targets whilst maintaining reliability of supply. Current models of the UK energy system either make significant assumptions about the role of demand side management or do not carry out the analysis at sufficient resolution and hence determining the impact of heat electrification on the reliability of supply of the scenarios is not possible. This paper presents a new model that estimates national supply and demand, hour-by-hour. Calculations are based on 11 years of weather data which allows a probabilistic assessment of deficit frequency throughout the day. It is found that achieving demand reduction targets are far more important than meeting electrification targets and that significant adoption of CHP is most likely to deliver a viable energy future for the UK. [ABSTRACT FROM AUTHOR]

Since the inception of 3D concrete printing (3DCP) in the early to mid-2000's, the commercial landscape for this technology has expanded rapidly in parallel with developments of relevant materials, production technologies and knowhow. To benchmark the state-of-the-art of 3DCP technology in the construction field, this study presents a systematic review and analysis of 3DCP's development and applications based on information from articles, patents and publicly available data. An estimation of Technology Readiness Level (TRL) for 3DCP has been formulated through expert review, and the evidence suggests this is in the region of TRL6-7 similar to that reported for polymer-based fused deposition modelling processes. A new schema for the TRL assessment process is suggested and applied to two case studies: 1) the production of decorative works; 2) the fabrication of dwellings. Finally, we have identified four frontiers for research and development that should be exploited to raise the TRL of 3DCP. [ABSTRACT FROM AUTHOR]

The need for quality control and assurance in 3D Concrete Printing (3DCP) is widely recognised. Achieving geometric accuracy to a specified tolerance is a cornerstone of component-based production and assembly. Although published work within the field recognises such issues, these fall short of proposing systematic methods to evaluate, diagnose, improve, monitor and compare system performance. This work takes inspiration from the test geometry approach readily deployed in Additive Manufacturing and develops a full-scale test part to establish a reproducible benchmark for evaluating and assuring part geometric quality of 3DCP systems. The approach is used to evaluate the benefits of a new fabrication approach that combines subtractive milling on green cement mortar in combination with 3DCP. It was demonstrated to yield useful information for direct comparison of different processes and diagnosing problems for performance improvement. The test part and measurement approach offer the 3DCP community a means of cross-platform benchmarking of 3DCP system performance. [ABSTRACT FROM AUTHOR]

A key benefit of 3D concrete printing is the removal of the need for a mould enabling one-off and low volume production with greater variability in part geometry. The staircase effect generated by the layering is used as a feature of many applications, however for smooth surfaces and at interfaces between components, this may not always be desirable. In addition, global deformation of the part during printing may influence the accuracy of the final element. In order to compete with cast equivalents in this regard, secondary treatments such as subtractive milling and trowelling can be applied post printing. These are relatively new developments in the field of digital fabrication with concrete and there is little published work on methods and in particular, none that examine the effect of milling on the surface condition of 3D printing mortar. This paper explores these issues based on a manufacturing tooling perspective and finds that high quality surfaces can be formed, the roughness of which is affected by the size of the aggregates in the mix and the set-state of the material, which needs to be close to the solid state. In practice, this results in a 'milling window' which has implications for process timing and the robotic systems typically deployed for 3D concrete printing applications. [ABSTRACT FROM AUTHOR]

Highlights: [•] Season appears to have influence on the end-of-day window position. [•] Being located on the ground floor may influence the end-of-day window position. [•] Males and females appear to have different behaviour on end-of-day window positions. [•] Personal preference plays a role in determining end-of-day window position. [•] The distribution of types of window users is dependent on gender and floor level. [Copyright &y& Elsevier]

Domestic Hot Water (DHW) production accounts on average between 14 14% and 30% of the residential energy consumption worldwide. In UK dewllings, a quarter of the energy is consumed to produce hot water and this proportion is likely to increase as the energy required for space heating reduces over time in order to achieve demand reduction targets. As the margins for improving the performance of heating system technologies increase, the need for improving modelling accuracy and precision increases also. Although studies have considered DHW use in buildings, there is a lack of reflection on the energy loss and performance of systems in contemporary dwellings. Current simulation tools with simplified assumptions, limited variables and algorithm detail, might lead to unreliable results in terms of the estimated heat losses. In this research, an analytical dynamic model has been developed to estimate heat loss from a domestic hot water system based on high resolution monitored data for a set of dwellings in the UK. The model estimated heat losses during flowing and non-flowing (cooling down) conditions in the distribution system as well as heat losses from the storage tank. It was found that apart from the significant heat loss from the storage tank, short draw-offs are particularly influential in determining the amount of heat wasted. Considerable savings might be achieved 'avoiding' short draw-offs through a better control of the system and/or changes in the user behaviour. Insulating and reducing the effective length of the distribution pipe network through better design of the system similarly predict significant reductions in heat losses. [ABSTRACT FROM AUTHOR]

This article offers a comprehensive, systematic overview of the existing solutions for integrating reinforcement in digital concrete technologies with particular emphasis on Additive Manufacturing (AM) with concrete, also called 3D concrete printing (3DCP). While the functionalities of various types of reinforcement are briefly addressed, the major focus is on the integration process as such, i.e., on its technological aspects. On this basis a generic classification and process description outline has been developed for reinforcement integration, which is regarded as an extension of the RILEM process classification framework for Digital Fabrication with Concrete (DFC). In many instances, the integration occurs in a separate process step prior to or after concrete shaping. This holds true for all formative digital concrete shaping processes and for many 3DCP solutions. 3DCP approaches enable, however, integration of the reinforcement during concrete shaping as part of a single-step AM process in a simultaneous or contiguous manner, while placement of reinforcement is considered to be a sub-process. [ABSTRACT FROM AUTHOR]

The additive manufacture of parts using extrusion-based techniques such as 3D Concrete Printing (3DCP) offers an alternative to traditional moulding processes. The precision to which the desired shape can be produced, however, is limited by the extrusion process and layer thickness, exacerbated by the deformation that occurs in the wet material during manufacture. Quantifying manufacturing precision is a critical part of defining process capability and quality control procedures, but this has yet to be explored for these technologies. To address this, this paper presents the problem of evaluating the geometrical precision of manufactured parts and then proposes an approach based on geometric dimensioning and tolerancing (GD&T), commonly used in manufacturing. This is then applied in a case study in order to demonstrate the application of the technique for understanding and defining process capability, to enable more effective design rules that lead to greater confidence in the viability of part designs, and to provide the reliable performance metrics necessary for process improvement and control. The work concludes that the outlook for such techniques is positive and that the application will be beneficial in the future development of quality control procedures for 3DCP. • A GD&T framework is developed to inspect the manufacturing precision of 3D printed concrete parts for process calibration. • Methods for the evaluation of the reproduction precision of features are presented through a test case study. • Sensitivity to process, material and design parameters was demonstrated, thus enabling process calibration and monitoring. • It is argued that methods based on GD&T are likely to underpin future quality control standards for 3D Concrete Printing. [ABSTRACT FROM AUTHOR]

• Changes in appliance driven by life events in a residential building are observed for the first time. • Quality control charts are demonstrated to be effective at detecting changes in consumption patterns. • A shift awards increased consumption due to a life event is identified. • A potential method to provide constant feedback on the impact of domestic routines is demonstrated. • A data processing framework has been developed to select data features for change detection. Energy consumption in the home is heavily influenced by the occupants and the routines they adopt. Although these routines tend to be regarded as somewhat static in nature, more recent evidence from the social sciences suggests that patterns of consumption are actually more fluid and constantly evolve to accommodate the contingencies of everyday living. This makes detecting changes in patterns of activity and their impact on energy consumption difficult, particularly when these patterns are often invisible to the householder to begin with. Being able to identify when a change occurs, therefore, could be a powerful tool to establish the context of change and so to determine more appropriate corrective action to curb waste and create opportunities for greater flexibility in consumption. The growing adoption of smart meters and home energy monitoring provide a platform for numerical approaches, yet there is little work reported in the literature and none that have attempted to evaluate effectiveness of such methods applied to detect changes in behaviour using field monitoring data from family homes. This paper reports on the application of a Change Point Detection method based on statistical quality control charts applied to identify changes in activities a family home using typical monitoring data. The approach was found to be very effective, identifying 78% of the changes that occurred over a two-year period and hence the outlook for such methods is promising. The findings suggest that such techniques could significantly improve the quality of information provided in energy feedback and so could play a significant role in the pursuit of more efficient energy use in the home by adding value to monitoring systems and services. [ABSTRACT FROM AUTHOR]

• Whole system modelling of air source heat pump and thermal energy storage systems. • Introduces a new 'service' measure to evaluate heating and hot water performance. • The impact of user demand and system size on delivered service is significant. • Impact of electricity demand load shifting on service provision is demonstrated. The demand for local heat storage to help manage energy demand in dwellings is likely to increase as the electrification of heat through heat pumps becomes more widespread. Sizing thermal energy storage systems has been an important topic in contemporary literature, but the effect of the electrical load shifting tariff and the service the householder receives in terms of space-heating and hot water delivered, however, has not and this is particularly important when households transition from conventional gas fired to low carbon technologies. This paper takes a whole system modelling approach to understand the impact of user demand patterns and load shifting scenarios on the volume of energy storage required for a heat-pump installation. The work uses monitoring data from several family homes to drive the simulation and finds that the level of service the householder receives is sensitive to their patterns of consumption, thermal energy storage volume and the electricity tariff, with some households being far more sensitive to tariff choice than others. The paper introduces a novel, quantifiable measure of service for space-heating and hot water systems that can be incorporated into thermal energy storage sizing procedures. [ABSTRACT FROM AUTHOR]

This investigation constitutes the fourth phase of a conceptual framework designed to produce circular concrete upon the main principals of circular economy reduce, reuse and recycle. Comparative life cycle assessment is carried out for conventional and circular concrete mixtures to identify biases in the results of common life cycle assessments. Ten midpoint and four endpoint indicators are assessed using the impact 2002+ method. In baseline scenarios, environmental performances of conventional and circular concrete mixtures are compared over identical service lifes, considering cradle-to-grave and cradle-to-cradle (closed-loop) system boundaries, respectively. Results reveal that by using optimal amounts of two industrial wastes i.e. Silica fume and ground granulated blast furnace slag, as binder materials, and recycled concrete aggregate, the environmental performance of concrete is significantly enhanced. Such condition is obtained by remarkable reduction of environmental indicators (up to 44%) at both midpoint and endpoint levels. Also, circular concrete embraces a considerable amount of Non-Renewable Energy saving (40%). Investigating the impact of different end-of-life scenarios indicates that limiting boundary conditions in the cradle-to-gate approach (lack of considering end-of-life stage) has offset the results. Furthermore, the comparison trends were completely reversed in some environmental indicators upon considering the impact of service life. [Display omitted] • Circular concrete has lower environmental impacts than conventional concrete. • GGBFS and SF increase service life and reduce environmental impacts. • Ignoring different end-of-life scenarios offset the results of comparative LCA. • Ignoring the impact of service life reverses the results of comparative LCA. • A new functional unit is proposed to consider service life in environmental impact. [ABSTRACT FROM AUTHOR]

Developing sensitivity analysis (SA) that reliably and consistently identify sensitive variables can improve building performance design. In global SA, a linear regression model is normally applied to sampled-based solutions by stepwise manners, and the relative importance of variables is examined by sensitivity indexes. However, the robustness of stepwise regression is related to the choice of procedure options, and therefore influence the indication of variables’ sensitivities. This paper investigates the extent to which the procedure options of a stepwise regression for design objectives or constraints can affect variables global sensitivities, determined by three sensitivity indexes. Given that SA and optimization are often conducted in parallel, desiring for a combined method, the paper also investigates SA using both randomly generated samples and the biased solutions obtained from an optimization run. Main contribution is that, for each design objective or constraint, it is better to conclude the categories of variables importance, rather than ordering their sensitivities by a particular index. Importantly, the overall stepwise approach (with the use of bidirectional elimination, BIC, rank transformation and 100 sample size) is robust for global SA: the most important variables are always ranked on the top irrespective of the procedure options. [ABSTRACT FROM AUTHOR]

The UK is currently suffering great overheating issues in summer, especially in residential buildings where no air-conditioning has been installed. This overheating will seriously affect people's comfort and even health, especially for elderly people. Phase change materials (PCMs) have been considered as a useful passive method, which absorb excessive heat when the room is hot and release the stored heat when the room is cool. This research has adopted a simulation method in DesignBuilder to evaluate the effectiveness of using PCMs to reduce the overheating issues in UK residential applications and has analyzed potential factors that will influence the effectiveness of overheating. The factors include environment-related (location of the building, global warming/climate change) and construction-related (location of the PCM, insulation, heavyweight/lightweight construction). This research provides useful evidence about using PCMs in UK residential applications and the results are helpful for architects and engineers to decide when and where to use PCMs in buildings to maintain a low carbon lifestyle. [ABSTRACT FROM AUTHOR]

Abstract: With the increasing demand for more energy efficient buildings, the construction industry is faced with the challenge to ensure that the energy performance predicted during the design stage is achieved once a building is in use. There is, however, significant evidence to suggest that buildings are not performing as well as expected and initiatives such as PROBE and CarbonBuzz aim to illustrate the extent of this so called ‘performance gap’. This paper discusses the underlying causes of discrepancies between energy modelling predictions and in-use performance of occupied buildings (after the twelve month liability period). Many of the causal factors relate to the use of unrealistic input parameters regarding occupancy behaviour and facilities management in building energy models. In turn, this is associated with the lack of feedback to designers once a building has been constructed and occupied. The paper aims to demonstrate how knowledge acquired from Post-Occupancy Evaluation (POE) can be used to produce more accurate energy performance models. A case study focused specifically on lighting, small power and catering equipment in a high density office building is analysed and presented. Results show that by combining monitoring data with predictive energy modelling, it was possible to increase the accuracy of the model to within 3% of actual electricity consumption values. Future work will seek to use detailed POE data to develop a set of evidence based benchmarks for energy consumption in office buildings. It is envisioned that these benchmarks will inform designers on the impact of occupancy and management on the actual energy consumption of buildings. Moreover, it should enable the use of more realistic input parameters in energy models, bringing the predicted figures closer to reality. [Copyright &y& Elsevier]

Abstract: A transition to a decentralised, decarbonised energy system for the domestic sector is constrained by the difficulty of obtaining energy balance between fluctuating demand and the intermittent, non-dispatchable power supply delivered by most renewables. A microgrid system including a mix of renewable generation technologies, energy storage and demand response (DR) systems has been modelled using a linear programming approach, based on real world data of residential energy consumption and weather variables. This model allows the exploration of the effects of fluctuations in demand and supply, microgrid scale and configuration, energy management options and alternative optimisation criteria. The model demonstrates quantitatively that a mixed-renewables microgrid system can reduce demand fluctuations and improve energy balance. Peak demand hour fluctuations were reduced by up to 19% for a simulated microgrid containing 144 households with one renewable unit and four batteries per household, with a renewables mix of 83% photovoltaic (PV) panels and 17% wind turbines. With this system, the demand on macrogrid energy supply was reduced by 16%, CO2 emissions associated with energy use were reduced by 10% for all hours of operation, and by 74% during the hours of renewable supply. These findings suggest that microgrids using contemporary technologies can contribute significantly to CO2 mitigation targets. [Copyright &y& Elsevier]

3D concrete printing has tremendous potential for construction manufacturing; however, weak interface bonding between adjacent layers remains a well-known issue that affects the mechanical properties of printed structures. The layers introduce anisotropy and reduce the capacity to resist tensile and shear loads. Reinforcements, inserted perpendicular to the printed layers to traverse the interfaces, can improve these limitations, but the insertion of reinforcements is difficult to achieve in practice, and there are few published studies exploring appropriate methods. This study presents a promising approach using U-shaped nails inserted into concrete during the printing process. The bridging effect and dowel action of the applied U-nails are visualised and analysed to elucidate the toughness improvement. The ultimate tensile strength and shear strength of 3D printed concrete are significantly increased by 145.0% and 220.0%, respectively. U-nails with a filament thickness of 2–2.5 mm are recommended to yield optimal improvement in the interlayer strength. • An in-process interlayer reinforcement approach for 3D concrete printing was proposed through the concurrent deposition of U-nails. • Significant strength and toughness improvement was achieved for U-nail reinforced 3D-printed concrete. • The bridge linking effect and dowel action of U-nails were analysed. • Response surface method were utilised to quantify the effects of U-nails on the interlayer bonding behaviour. [ABSTRACT FROM AUTHOR]

In this paper, the building energy performance modelling tools TRNSYS (TRaNsient SYstem Simulation program) and TRNFlow (TRaNsient Flow) have been used to obtain the energy demand of a domestic building that includes the air infiltration rate and the effect of natural ventilation by using window operation data. An initial model has been fitted to monitoring data from the case study, building over a period when there were no heat gains in the building in order to obtain the building infiltration air change rate. After this calibration, a constant air-change rate model was established alongside two further models developed in the calibration process. Air change rate has been explored in order to determine air infiltrations caused by natural ventilation due to windows being opened. These results were compared to estimates gained through a previously published method and were found to be in good agreement. The main conclusion from the work was that the modelling ventilation rate in naturally ventilated residential buildings using TRNSYS and TRNSFlow can improve the simulation-based energy assessment. [ABSTRACT FROM AUTHOR]