Search

Due to the serious problems with energy efficiency, carbon emissions, and thermal comfort of rural residences in northern China, an optimization of active and passive heating technologies for rural residences is necessary. In this paper, an optimization for rural residences in northern China is conducted with four objectives: the whole life cycle carbon emission; the annual energy consumption through heating, ventilation, and air conditioning systems; the annual cost; and thermal comfort. In addition, the optimization model with active–passive heating technology synergy is resolved by NSGA-II genetic algorithm. The active and passive design variables, including the type of air source heat pump, orientation, the type and thickness of envelope insulation, the layer of window glass, the window-to-wall area ratio, as well as sunspace parameters are preferred to obtain the optimal solution. The results indicate that the optimal solution obtained by the ideal point method gives the most outstanding performance. Compared with the prototype, the optimized carbon emissions in severe cold and cold regions decreased by 56.1% and 54.6%, respectively. The annual energy consumption decreased by 59.7% and 62.2%. Finally, the roof insulation thickness is the most sensitive design variable in Pareto-optimal solution sets. This paper offers significant guidance in the application of the optimization method of active–passive technology synergy to the energy-saving design of buildings. [ABSTRACT FROM AUTHOR]

The UK government has announced its ten-point plan to annually install 600,000 low-carbon heat pumps by 2028. However, there is a lack of evidence showing potential overheating risk in dwellings retrofitted with heat pumps. This paper examines the prevalence and magnitude of summertime overheating across 24 naturally ventilated social housing dwellings retrofitted with ground source heat pumps (GSHPs). The dwellings are located in a socially deprived area in Oxford (UK). The empirical study included longitudinal monitoring of indoor temperatures in the living rooms and bedrooms during the non-heating seasons of 2021 and 2022 (May–September), which included a record-breaking heatwave in July 2022. Indoor temperature and CO2 levels in bedrooms were monitored across a subset of six dwellings alongside the monitoring of window opening state in three bedrooms to understand the effect of natural ventilation in removing excess heat. About 136 thermal comfort surveys were conducted to ascertain the subjective responses of residents. Overheating risk assessment was carried out using CIBSE static and adaptive methods, which revealed that summertime overheating was prevalent across half of the dwellings in the non-heating season of 2022, as compared to 17% overheated dwellings in 2021. Bungalows with upgraded cavity wall insulation and top floor flats facing south and south-west had a propensity to overheat. The variation in indoor temperature and CO2 levels across a small sample also indicated the relationship between overheating and residents' behaviour. Given that the majority of the dwellings were occupied by retired elderly people with low incomes who are vulnerable to heat and cannot afford active forms of cooling, it is vital to deploy passive design measures, such as appropriate shading devices that are suitable for a heating-dominated climate and enhanced ventilation, as part of home energy retrofits. Implementing reversible heat pumps coupled with solar PVs can provide cooling during heatwaves while delivering low-carbon heat in the winter. [ABSTRACT FROM AUTHOR]

While heat pumps have been acknowledged as a key enabling technology to achieve Net Zero goals, their uptake is limited by their performance and cost. In this paper, a simulation-based study is conducted to analyse the performance of ground source heat pumps (GSHPs) utilising high thermal conductivity materials for the borehole heat exchanger (BHE) pipe (1 W/mK) and grouting (3 W/mK) developed in the GEOCOND project. Exergy analysis is conducted to account for energy quantity and quality with a focus on BHE performance. An annual hourly simulation was performed using DesignBuilder V5.4 and Earth Energy Designer (EED4) for representative cool and hot locations in Europe—Stockholm and Valencia, respectively. For a constant BHE length, the results for Stockholm show that the high conductivity materials result in an increase of about 13% BHE exergy extraction compared to the standard grout and pipe, but no such improvement was observed for Valencia. The difference between outdoor temperature and its dynamic variation from the indoor setpoint is identified as a key factor in the overall GSHP exergetic performance. In future research, we propose a thorough life cycle analysis across diverse locations and varying indoor comfort criteria to pinpoint areas where the high thermal conductivity material can enable cost-effective, sustainable heating and cooling. [ABSTRACT FROM AUTHOR]

The collaboration project UNICARagil aiming to develop new autonomous battery electric vehicle concepts has progressed and the four vehicle prototypes have been built up. All seven universities and six industrial partners have worked towards this milestone. At the time of writing the four vehicles are operational and can be driven by a safety driver using a sidestick. The automated driving functions are being applied on the test track and first demonstrations are carried out. This paper gives an overview of the results, which have been achieved within the work package of the thermal onboard network. The thermal management system including the heating, ventilation and air conditioning system and its development process is explained in detail. Furthermore, climate chamber measurements with prototype hardware of a sensor data processing computer and the integration of the air conditioning control unit into the vehicle's automotive service-oriented architecture framework are described. A coupled simulation approach to predict occupant thermal comfort in one vehicle variant is presented. Simulation results using environmental conditions typical for a European summer show a comfortable environment for all six occupants. In addition, the simulation and development process of a thermoelectric heat pump is shown. First measurement results with the heat pump on a test bench are highlighted which show an achievable coefficient of performance greater than two. [ABSTRACT FROM AUTHOR]

The penetration of renewable energies is increasing in energy systems worldwide. Consequently, the intermittency of the energy sources raises technical challenges for sustainable energy supply. Demand-side flexibility is an effective solution to counterbalance renewable power fluctuations. In the residential sector, electrical heat pumps exhibit great flexibility potential. In this paper, a novel approach is proposed to generate FlexOffers for individual heat pumps considering the uncertain nature of weather conditions. To achieve the aim, firstly, the thermal dynamic model of residential buildings is presented mathematically. The model addresses different temperature zones. The constant coefficients of the thermal dynamics are estimated using Continuous-Time Stochastic Model (CTSM) in R software. Afterward, the building model is integrated with a success function to generate FlexOffers. The success function is comprised of two objective functions including minimization and maximization of the energy consumption of heat pumps. The FlexOffers are generated considering the existing gap between the minimum and maximum energy consumption. The patterns of energy consumption are defined based on occupants' thermal comfort temperature setpoint. The FlexOffers are programmed in UPPAAL-STRATEGO software. Finally, a high-fidelity building model with four rooms is used to examine the proficiency of the suggested approaches. The simulation results confirm that the proposed method generates flexibility potentials for the upstream network in both optimistic and pessimistic states of energy consumption patterns. [ABSTRACT FROM AUTHOR]

The electrification of heating and transportation systems is one of the objectives of developed countries to minimize CO2 emissions. This objective pushes distribution systems' (DBs) operators to incorporate numerous high-power loads into low-voltage networks that were not designed for such loads. DBs' reconfiguration and the loads' flexible characteristics are two remedies exploited to overcome this issue. Heat pumps (HPs), as the most prevalent loads, can be managed by demand response programs (DRPs) to postpone the costly reconfiguration of distribution systems. HPs' DRP participation affects indoor air temperature. If this is not accomplished reasonably, the occupants' thermal comfort (OTC) will be compromised, and it will be impossible to convince them to continue contributing to DRPs. Based on the ASHRAE55 standard and an experimental building electrothermal model, this article presents a novel framework for determining the HPs' DRPs participation. This framework ensures the OTC and optimizes the HPs' DRP participation. The modified IEEE 33-bus network is employed as the test system to evaluate the proposed method. The simulation results confirm the usefulness of the proposed strategy to improve the technical and economic aspects of the network. [ABSTRACT FROM AUTHOR]

Back-up heaters are essential for sustainable retrofit heat pump systems to achieve low capital costs and high system temperatures. Despite its importance, current literature focuses primarily on single aspects of the interaction between the back-up heater and the heat pump system. Furthermore, influences of varying scenarios are typically not considered. This paper simultaneously investigates the impact of 18 different scenarios on the optimal answer to the questions: Which back-up heater to choose, where to place it, and how to control it? A scenario consists of boundary conditions for weather, building envelope, radiator sizing, operational envelope, and the electricity-to-gas price/emission ratio, respectively. Using annual dynamic Modelica simulations, we evaluate and assess all interdependencies based on a full factorial design. We analyze final energy consumption, thermal comfort, and back-up heater as objectives. For gas-fired back-up heaters, the optimal placement and control align with current state-of-the-art recommendations. However, for electric back-up heaters, current guideline recommendations yield up to 30% higher operational costs and emissions compared to our findings. Consequently, future studies should develop optimal design rules for sustainable retrofit heat pump systems. [ABSTRACT FROM AUTHOR]

Energy management plays a crucial role in cabin comfort as well as enormously affects the driving range. In this paper energy balances contemplating the implementation of a heat pump and an expansion device in battery electric vehicles are elaborated, by comparing the performances of refrigerants R1234yf and R744, from -20°C to 20°C. This work calculates the coefficient of performance, energy requirements for ventilation (from 1 to 5 people in the cabin) and energy required with the implementation of a heat pump, with the employment of a code in Python with the aid of Cool- Prop library. The work ratio is also estimated if the work recovery device recuperates the work during the expansion. Comments on the feasibility of the implementation are as well explicated. The results of the analysis show that the implementation of an expansion device in an heat pump may cover the energy requirement of the compressor from 27% to more than 35% at 20°C in cycles operating with R744, and from 15% to more than 20% with refrigerant R1234yf, considering different compressor efficiencies. At -20°C, it would be possible to recuperate between around 30 and 24%. However, the risk of suction when operating with R1234yf at ambient temperatures below -10°C shows that the heat pump can only operate with R744. Thus, it is the only refrigerant that achieves the reduction of energy consumption at these temperatures. [ABSTRACT FROM AUTHOR]

• Households change their heating patterns when they switch to a heat pump. • Typically, a setback temperature 2–5 °C lower than the desired thermostat setting. • We calculate the increase in heat demand with varied parameters. • The increase in heat demand is determined by heat loss and thermal mass. • This would be a useful metric for 'heat pump readiness'. Heating with air source heat pumps is an important step in the transition to Net Zero Carbon for many households. When predicting the resulting energy consumption it is frequently assumed that heating demand is unchanged from before the switch from gas heating. However, heating patterns usually change, with a net increase in heating demand to achieve the same level of thermal comfort. This paper discusses the change in pattern and uses modelling to determine the resulting increase in energy demand. It shows that the increase can be predicted with information about dwelling heat loss and thermal mass as well as weather and the pre and post switch heating pattern. The increase can be 20% or more for homes with high heat loss. It proposes that the metric for heating demand increase would be a useful measure of heat pump readiness, and that the parameters required to assess this should be provided on energy performance certificates. [ABSTRACT FROM AUTHOR]

Residential demand response using low carbon technologies can potentially offer energy flexibility to the electricity network along with integration of renewable generation. This paper seeks to empirically evaluate the effectiveness of residential demand response trials on a low voltage feeder of a secondary substation in Barnsley (UK). The study used a sample of 14 well-insulated dwellings equipped with home batteries, heat pumps and solar photovoltaic systems coordinated using automated control. Statistical analysis was undertaken using time-series monitoring data obtained at the individual dwelling level, dwelling sample and at the feeder level of the local low voltage network. Resident experience of the trials was assessed through qualitative data obtained from household telephone surveys. Over three weeks of trials, daily demand response interventions of 2 h duration were applied to the sample of 14 dwellings. For evening peak times, the mean reduction in grid electricity import was found to be 1.3 kWh (67%) per dwelling for turn-down interventions which aimed to minimise import. For turn-up interventions between 1 and 3 pm, the mean increase in grid electricity import was found to be 5.8 kWh (645%) per dwelling. The effect of interventions was measured at the low voltage network level for two single-phase feeders, where penetration of trial homes was approximately one-third. A reduction in mean real power up to 21% was observed for turn-down interventions as well as an increase in real mean power up to 307% for turn-up interventions. In general, the trials had little effect on residents in terms of thermal comfort, hot water availability, noise disturbance or disruption to routines, and where such effects were noticed, they were broadly acceptable. The widespread implementation of residential demand response schemes will require increased roll-out of time-of-use tariffs, enhanced resident support and extensive monitoring of low voltage feeders in electricity substations. [ABSTRACT FROM AUTHOR]

Decarbonisation in moderate and cold climates is reliant on the replacement of existing heating technologies with electric heat pumps. Heat pumps work differently from incumbent technologies, including in how they are controlled, their distribution of heat around the home and their space requirements. Despite evidence that domestic practices and interests associated with women played an important role in previous heating transitions, policy and research have not yet considered how heat pumps might interact with traditionally gendered needs and concerns. This could have significant implications for the success of the heat pump transition. This synthesis uses a framework of evidenced heating needs, incorporating wellbeing, resources, ease of use and relational dynamics, to structure a narrative literature review on how experiences of heat pumps may be gendered. Indicative evidence suggests that heat pumps have the potential to improve female thermal comfort, but that other possibly gendered heating needs such as minimising perceived waste and easy controllability are not always addressed. Amidst a lack of empirical studies exploring women's needs, and whether they are met by heat pumps, a series of recommendations is provided for multidisciplinary research on the topic and to enhance consideration of gendered needs and experiences in policy development. [ABSTRACT FROM AUTHOR]

The present work proposes a simulation and control framework for home and building automation, focusing on heating, ventilating, and air conditioning processes. Control systems based on different advanced control architectures and different control policies are simulated and compared, highlighting control performances, and energy-saving results in terms of CO2 emissions reduction. Heat, lighting, and natural ventilation phenomena were modelized through first-principles and empirical equations, obtaining a reliable and flexible simulation framework. Energy-consuming and green energy-supplying renewable sources were integrated into the framework, e.g., heat pumps, artificial lights, fresh air flow, and natural illuminance. Different control schemes are proposed, based on proportional–integral–derivative advanced control architectures and discrete event dynamic systems-based supervisors; different control specifications are included, resulting in a multi-mode control system. The specifications refer to energy savings and comfort management, while minimizing overall costs. Comfort specifications include thermal comfort, lighting comfort, and a good level of indoor air quality. Simulations on different scenarios considering various control schemes and specifications show the reliability and soundness of the simulation and control framework. The simulated control and energy performances show the potential of the proposed approach, which can provide energy-saving results greater or equal to 6 [%] (in each season) and 19 [%] (in one year) with respect to more standard approaches. [ABSTRACT FROM AUTHOR]

Based on the simulation results of the typical rural ultra-low energy building (ULEB) in five different climatic regions of China, three indicative technical parameters for paralleled-loop exhaust air heat pump (PEAHP) R&D which are nominal heating-cooling capacity, maximum required fresh air to return air ratio (MFRR) and system energy efficiency grades were calculated and summarized according to the demand of indoor thermal comforts by using statistic method. The nominal heating-cooling capacities were determined according to the peak loads, which are 6.84-2.01 kW, 5-2.96 kW, 3.9-4.6 kW, 3.08-5.02 kW, and 3.4-0.46 kW in the ULEB of Harbin, Beijing, Shanghai, Guangzhou, and Kunming, respectively. To ensure both thermal comforts and energy conservation, during the heating season, full fresh air supply is suggested in Beijing and the 1:0.5 MFRR is suggested in Harbin, Shanghai, Guangzhou, and Kunming. During the cooling season, the 1:5 MFRR is suggested in Shanghai and Guangzhou, the 1:3, 1:1.5, and 1:0.5 MFRR are suggested in Harbin, Beijing and Kunming, respectively. The PEAHP energy efficiency grades 1~5 are 7.92~11.7, 7.58~11.5, 7.5~11.35, 6.12~9.27, and 4.64~7.03 during the heating season of Harbin, Beijing, Shanghai, Guangzhou, and Kunming, respectively, and are 2.33~3.54, 3.93~5.96, 4.61~6.98, 4.62~6.99, and 2.04~3.1 for the cooling season, respectively. [ABSTRACT FROM AUTHOR]

In order to supply the thermal load of a building, a huge amount of energy is consumed. Therefore, it is necessary to use renewable energy sources in today's architecture. As a matter of fact, this issue has begun to be the focus of many studies worldwide making the topic even more interesting. In this regard, the wind has always been known as an outstanding renewable source of energy used in Iran for thousands of years. Windcatchers, known as Badgirs in Iran, are notably used in warm-humid and hot-dry climates to make the best use of wind energy in these areas. However, Badgirs are neglected in today's life due to the limitation associated with their use in modern buildings. Accordingly, the current study aims to take into account some advantages of the windcatchers (Badgirs) in addition to highlighting their effect in both reducing energy consumption and providing thermal comfort. In previous research, humidification and similar solutions have been used to provide cooling and heating by a windcatcher, however, in none of them the Ground source heat pump system has not been used for this purpose. This study proposes a system consisting of a windcatcher and a Ground Source Heat Pump system for a building in Yazd, Iran. For this purpose, the study is conducted in three steps. First, current literature is studied. Second, the proposed system is simulated using Transys software. Finally, a mathematical calculation is performed. The simulation model consists of a room located in Yazd with width, length, and height of 4m, 6m and 3.5m, respectively. The findings show the positive effect of the proposed system in improving thermal comfort and energy by about 37.6% in summer and 7% in winter. [ABSTRACT FROM AUTHOR]

The use of fuzzy logic controllers in refrigeration and air conditioning systems, RACs, has as main objective to maintain certain thermal and comfort conditions. In this sense, fuzzy controllers have proven to be a viable option for use in RACs due to their ease of implementation and their ability to integrate with other control systems and control improvements, as well as their ability to achieve potential energy savings. In this document, we present a review of the application of fuzzy controls in RACs based on vapor compression technology. Application information is discussed for each type of controller, according to its application in chillers, air conditioning systems, refrigerators, and heat pumps. In addition, this review provides detailed information on controller design, focusing on the potential to achieve energy savings; this design discusses input and output variables, number and type of membership functions, and inference rules. The future perspectives on the use of fuzzy control systems applied to RACs are shown as well. In other words, the information in this document is intended to serve as a guide for the creation of controller designs to be applied to RACs. [ABSTRACT FROM AUTHOR]