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Overheating of premises is a typical thermal discomfort issue in naturally ventilated primary schools in Ho Chi Minh City, Vietnam. Several design parameters were shown to affect the indoor thermal environment. A parametric study was conducted and based on several building performance simulations to investigate the influences of the individual design parameters on indoor air temperatures and the prevalence of overheating in primary schools. The sensitivity analysis indicated that the material of building envelopes, the openings, and the solar controls, in descending order, affected overheating occurrence. The findings could assist the architect in choosing which parameters should be prioritised in the design stage, which is particularly useful in renovation and retrofit projects.

In the last few years, the renovation and refurbishment of existing buildings have been recognized as one of the main strategies to achieve energy efficiency and sustainability goals. However, the current studies have mainly focused on the retrofit, life cycle assessment (LCA), and Life Cycle Cost (LCC) of buildings in isolation without envisaging the impact of microclimate and the surrounding buildings on the outcome of energy simulation. Specifically, many energy simulation software needs to include the environmental responses when buildings are treated with outdoor conditions based on weather data from the nearest metrological site. Therefore, this study aims to investigate the impact of microclimate on retrofit and LCC of a community of buildings rather than a single isolated building. For this purpose, a coupling method is developed to integrate building energy simulation (BES) and computational fluid dynamics (CFD), which exchange parameters on a dynamic time step basis using Envi-met to create weather files from microclimate parameters and use it on energy simulation through DesignBuilder software. Furthermore, this study interlinks the life cycle cost assessment and retrofit strategies on a community scale. A case study of Amman – Jordan, is selected in this paper by one a residential building with two floors and an area of 450. At the same time, the retrofit strategy is considered as implementing green roofs for community areas, which are implemented in the context around the buildings. In addition, this study calculates the net present value and the pack period regarding the life cycle cost study. The initial result shows that there is an impact for microclimate parameters on the temperatures gained on the building's envelope as a result of the effect of airflow through context parameters, which in turn affect the value of energy consumption used for cooling inside the buildings. Moreover, this paper demonstrates that using green roofs on one of the neighbourhood buildings will decrease energy consumption by 28% in the simulated time while the payback period is 9.5 years.

Global warming, pollution, and increasing energy demand have compelled electrification of the transport sector. Electric vehicles are not only an attractive and cleaner mode of transport, but they also possess the capacity to offer flexible storage alternative based on bidirectional vehicle-to-grid schemes. Vehicle-to-grid or V2G technology permits electric vehicles' batteries to store energy and discharge it back to the power grid during peak-load periods. However, the feasibility and economic viability of V2G is still a matter of concern and needs investigation. In this paper, the authors delved into the feasibility of V2G technology by analysing the real time-charging data of a V2G demonstration project named EV-elocity, located at the University of Nottingham campus in the UK. The authors analysed the charging data and trip-status data of two charging sites and put forward some insights regarding the feasibility of V2G and the behavioural traits of the vehicles. This paper will enlighten the research community regarding the feasibility and benefits of V2G in a real-world environment by analysing the charging/discharging and vehicle behaviour and reporting the opportunities and benefits of vehicle-to-grid technology. [ABSTRACT FROM AUTHOR]

Vehicle-to-grid (V2G) has been identified as a key technology to help reduce carbon emissions from the transport and energy sectors. However, the benefits of this technology are best achieved when multiple variables are considered in the process of charging and discharging an electric vehicle. These variables include vehicle behaviour, building energy demand, renewable energy generation, and grid carbon intensity. It is expected that the transition to electric mobility will add pressure to the energy grid. Using the batteries of electric vehicles as energy storage to send energy back to the grid during high-demand, carbon-intensive periods will help to reduce the impact of introducing electric vehicles and minimise carbon emissions of the system. In this paper, the authors present a method and propose a V2G control scheme integrating one year of historical vehicle and energy datasets, aiming towards carbon emissions reduction through increased local consumption of renewable energy, offset of vehicle charging demand to low carbon intensity periods, and offset of local building demand from peak and carbon-intensive periods through storage in the vehicle battery. The study included assessment of strategic location and the number of chargers to support a fleet of five vehicles to make the transition to electric mobility and integrate vehicle-to-grid without impacting current service provision. The authors found that the proposed V2G scheme helped to reduce the average carbon intensity per kilowatt (gCO2/kWh) in simulation scenarios, despite the increased energy demand from electric vehicles charging. For instance, in one of the tested scenarios V2G reduced the average carbon intensity per kilowatt from 223.8 gCO2/kWh with unmanaged charging to 218.9 gCO2/kWh using V2G. [ABSTRACT FROM AUTHOR]

Airtightness refers to the amount of air leakage through a building's envelope. This uncontrolled exchange of air between inside and outside, either infiltration or exfiltration, may lead to thermal discomfort. Nevertheless, little or no attention has been given to airtightness in some countries including Brazil. In Brazil, a range of different strategies are suitable to achieve thermal comfort depending on the several climatic regions. In those regions where winter conditions are noticeable, such as in São Paulo, airtightness is a key parameter, but it has been historically overlooked. In this work, the authors deployed the innovative Pulse test methodology to determine airtightness levels for the first time in Brazil, in the city of São Paulo. Three representative multifamily residential buildings dating from the 1970s, 1980s and 2000s were measured, and the results' values widely ranged from 1 to 5.7 h−1, at 4 Pa. Next, dynamic building simulations were conducted using measured and representative airtightness values (converted to infiltration) to understand the contribution of this variable on the thermal comfort. The results suggested that up to 9% improvement in the thermal comfort levels could be achieved by adopting 1 h−1 as maximum infiltration, and up to 14% by adopting 0.5 h−1. [ABSTRACT FROM AUTHOR]

Summary A numerical parametric study is presented of a domestic thermal storage heat exchanger to explore the effect of highly localized positive temperature coefficient cylindrical heating elements in a phase change material (PCM) with conductive enhancement by open‐pore metal foam. By using 90 L of commercially available Rubitherm RT70HC wax, 5.7 kWh of thermal energy is captured by the unit. The discharge is via a central convective air channel. The constant low‐temperature heating elements are inherently safe for combustible PCM. The heat distribution by Fourier's law and the creeping flow is investigated using the local thermal equilibrium assumption between the PCM and metal foam. Heating element position, diameter, and temperature are varied to optimize charge time and exit air temperature. Two heating elements of 1 cm diameter and constant temperature of 90°C produce a suitable performance for overnight store charging of 7.23 hours. Discharge via the air channel provides an average temperature of the output air over 30°C. The results indicated that the PCM inside metal foam almost follows Fourier's law. The creeping flow of molten PCM inside the pores of the porous medium (free convection heat effect) has an inconsiderable influence on heat transfer in the domain. [ABSTRACT FROM AUTHOR]

Summary: The effect of various arrangements of airflow channel in a proposed storage heater based on copper foam soaked in a phase change material (PCM) is investigated. Different configurations of the air channel using a serpentine channel, as well as numbers of the air channels, are examined in a representative three‐dimensional computer‐based model (Ansys Fluent). Evaluation is performed by PCM discharging rate and output air temperature of the unit. The goal is to improve both uniformity and value of air temperature. Changing the airflow arrangement using serpentine configuration to increase heat exchange surface area reduces solidification time and increases output maximum air temperature as well as pressure drop; conversely, exit air achieves lower temperature uniformity. In the case of the shortest solidification time using one air‐channel with the length of 51 cm, the solidification time reduces to almost 6 hours, compared with 13.6 hours for the straight channel with 37 cm length, with the average output temperature of 56°C compared to 41°C for the straight channel; however, the achieved temperature difference from the initial to the end of solidification time is 13.7°C compared to 4.5°C for the straight tube. [ABSTRACT FROM AUTHOR]

The aim of this paper is to study the influence of enclosure size in latent heat thermal energy storage systems embedded in a porous medium for domestic usage of latent heat thermal energy storage heat exchangers. A 2-D rectangular enclosure is considered as the computational domain to study the heat transfer improvement for a phase change material embedded in a copper foam considering a constant heat flux from the bottom surface. Different dimensions of the composite system are examined compared with a system without a porous medium. The thermal non-equilibrium model with enthalpy-porosity method is employed for the effects of porous medium and phase change in the governing equations, respectively. The phase change material liquid fraction, temperature, velocity, stream lines and the rate of heat transfer are studied. The presence of a porous medium increases the heat transfer significantly, but the improvement in melting performance is strongly related to the system's dimensions. For the dimensions of 200 × 100 mm (W × H), the melting time of porous-phase change material with the porosity of 95% is reduced by 17% compared with phase change material-only system. For the same storage volume and total amount of thermal energy added, the melting time is lower for the system with a lower height, especially for the phase change material-only system due to a higher area of the input heat. The non-dimensional analysis results in curve-fitting correlations between the liquid fraction and Fo.Ste.Ra −0.02 for rectangular latent heat thermal energy storage systems for both phase change material-only and composite-phase change material systems within the parameter range of 1.16 < Ste < 37.13, 0 < Fo < 1.5, 2.9 × 104 < Ra < 9.5 × 108, 0 < L f < 1 and 0 < Fo.Ste.Ra −0.02 < 0.57. Over a range of system's volume, heat flux and surface area of the input heat flux, the benefit of composite phase change material is variable and, in some cases, is negligible compared with the phase change material-only system. [ABSTRACT FROM AUTHOR]

A pulse pressurisation technique is developed and utilised for determining building leakage at low pressure, based on a "quasi-steady pulse" concept. The underlying principle of the technique is to subject the building envelope to a known volume change in a short period of time (typically 1.5 s). The resulting pressure pulse is recorded, from which the leakage characteristic at low pressure is determined. The technique minimizes the effects of wind and buoyancy forces and has proven to be repeatable. It can use a compact and portable test rig and does not need to penetrate the building envelope. Therefore, it can obtain the leakage of a building very quickly and efficiently. Throughout the various stages of research and development of the pulse technique, experimental investigations have been carried out under different configurations and scenarios in order to validate the changes that have been made for the purpose of system development and optimisation. This paper provides an overview of experimental investigations in the validation process by covering comparison between blower door and pulse unit, comparison between piston-based pulse unit and nozzle-based pulse unit, testing with multiple pulse units in a large building, testing with a known opening, and testing in different building types with a range of volumes and airtightness levels. It enables us to understand the strengths and the limits of the pulse technique, from the experimental and practical perspectives. A good repeatability level (within ±5%) has been maintained throughout the various developmental stages and the average value of Q50/Q4 reported herein was in close agreement (<1%) with that reported in a study based on a large database obtained across a number of countries. It was also proven feasible to measure the airtightness of large buildings using the pulse technique. [ABSTRACT FROM AUTHOR]

This paper describes a technology platform for monitoring homes within a community energy scheme. A range of sensors was deployed to measure in-home environmental conditions, occupancy, electrical power, electrical energy, thermal energy, heating behaviour and boiler performance to better understand and predict energy consumption in individual homes and across the community. The community assets include solar photovoltaic panels that are deployed in an urban solar farm and on rooftops to generate energy that is used to charge a central battery. This community scale storage supports participation in grid services to help balance the national grid and in future phases to power a community heat network, electric vehicle charging and self-consumption within individual properties. The monitoring data helps develop insights to optimise this multifaceted system and to provide feedback to residents to visualise and control their energy consumption and encourage reductions in demand. It was found that a diverse range of Internet of Things technologies was required to generate this data and make it available for subsequent access and analysis. This diversity was consolidated in the cloud to provide a common data structure for consumption by other services via industry standard interfaces. The cloud infrastructure utilised scalable and easily deployable services that are readily available from Internet of Things platforms from the major technology companies. The paper concludes by highlighting promising areas of focus for community-level monitoring in related projects. [ABSTRACT FROM AUTHOR]

Project SCENIC (Smart Controlled Energy Networks Integrated in Communities) involves connecting properties at the University of Nottingham's Creative Energy Homes site in a community scale, integrated heat and power network. The system will use distributed generation to develop the prosumer concept, where consumers are both buyers and sellers of energy in both heat and power systems. The first of its kind, the system consisting of a network flow loop to supply heat to homes, and a generation loop to collect energy from residential heating systems and supply it to a thermal store. To achieve the design, steady state heat load and dynamic building modelling have been used. A pre-insulated pipe was sized using flow rate calculations. The diameter ranges from 40 to 25 mm, with a heat loss as low as 7.0 W/m. In addition, flow rates will fluctuate below a maximum of 1.99 l/s. A standard heat interface units (HIU) has been selected as the network-building link, to satisfy a calculated peak design heating loads of between 36.74 and 44.06 kW. Furthermore, to enable the prosumer concept and associated business models an adapted HIU was selected to interface the distributed heat sources with the network. This paper gives details of the concept, energy flows, calculated and modelled results for the heat network. A premise is given to maintaining low temperatures in the network to ensure system efficiency in line with the latest research thinking. [ABSTRACT FROM AUTHOR]