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Daytime subambient radiative cooling is a most promising alternative to electricity-free building cooling. However, optical performance degradation arising from surface contamination and inevitable parasitic heat gain still pose unprecedented challenges to cool building at subambient temperatures. This paper proposed a superhydrophobic cellulose aerogel cooler (SHB-CAC) as building envelope by integrating self-cleaning capacity, passive daytime radiative cooling and thermal insulation to reduce environmental heat gain. The SHB-CAC demonstrates high solar reflectance (93%) and long-wave infrared emittance (91%), accomplishing a temperature drop of 8.5 °C lower than the ambient under sunlight of 800 W/m2 in the outdoor experiment. Notably, the SHB-CAC possesses low thermal conductivity (28 mW/(m∙K)) that suppresses parasitic heat gain from warmer surrounding and reduces cooling energy consumption. The self-cleaning property resulting from superhydrophobicity protects SHB-CAC from water wetting and dust contamination but also maintains its good surface radiation capacities under different humidity environment. A building energy simulation was conducted and results showed that 43.4% of cooling energy on average could be saved compared to the building baseline consumption, if SHB-CAC was widely used in China, indicating that the strategy of optical and thermal conductivity management of cooler has the potential to reduce the energy consumption of buildings. [Display omitted] • Waste paper is converted into aerogel cooler for building cooling. • High R solar and ε IR , thermal insulation, and self-clean are achieved in one design. • The aerogel achieves a high sub-ambient temperature drop of ∼8.5 °C on daytime. • The aerogel shows that 43.4% of cooling energy could be saved. [ABSTRACT FROM AUTHOR]

[Display omitted] • Aerogel sandwich construction building insulation offers higher energy savings ratio. • Functional silane modification reduces shrinkage of Z-direction from 57.5% to 2.3%. • Sandwich aerogel created super-efficient thermal insulation and sound absorption performances. • SA@UGFW demonstrates ultra-light, high-strength and efficient self-cleaning capability. In the context of "carbon neutrality and emission peak", aerogel that can meet national energy saving and emission reduction requirements while achieving efficient noise reduction has become a hot research topic. However, the development of multifunctional applications is greatly limited by the fact that pure aerogel usually exhibits relatively homogeneous properties. In this paper, SA@UGFW sandwich aerogel composites with functional silanes for structural strengthening were developed. SA@UGFW not only demonstrates ultra-lightweight (58 kg/m3) and high-strength properties (0.1 MPa) but also highly efficient self-cleaning capability (water contact angle ≈ 152.4°). The sandwich aerogel created super-efficient thermal insulation (0.015–0.017 W/(m·K)) and sound absorption performances (α max = 0.93, NRC = 0.51, 9.77 mm). SA@UGFW exhibited a cold surface temperature of 54.2 ℃ and a ΔT of 145.8 ℃ when the heat source temperature was 200 ℃, despite the sample thickness of only 9.77 mm. At this point, ΔT was higher than 70 % of the heat source temperature. The thermal conductivity of SA@UGFW was as low as 0.00975 W/(m·K), even in −40 ℃ environment. In addition, the sandwich aerogel also showed 0.0204 W/(m·K) of low thermal conductivity following ultra-low temperature (-196 ℃) treatment for 168 h. Simulation results show that aerogel building insulation reduces heating energy savings by 31.00 % and cooling energy savings by 27.34 % compared to traditional insulation. Therefore, the sandwich aerogel with multiple functions reported in this paper achieved the enhancement of indoor comfort and was expected to be widely applied in the construction field. [ABSTRACT FROM AUTHOR]

The necessity to improve the energy saving potential of buildings is now a duty. European and national policies are being implemented to address the important decisions being made on this subject. For these reasons, several studies focus on this relevant topic. This paper review not only focusses on it but studies it in-depth. A commercial 3D simulation software was used to design a building sited in Palermo estimating the thermal losses before and after external envelope insulation. In particular, all the thermal bridges (TBs) were analysed with the finite element method (FEM) and mitigated with rock wool insulation. The paper shows the linear thermal transmittance difference and heat flux loss before and after TB mitigation. The results confirm the importance of installing an external insulation layer in the old building envelope. The linear thermal transmittance of TBs and the associated heat flux loss often decrease by more than 50%. [ABSTRACT FROM AUTHOR]

Energy issues have always been one of the most concerned issues in the world. To solve the problem of building energy consumption, the future development of building energy-saving projects is more meaningful. This article aims to study the application of the parameter tester based on ferroelectric ceramics in building energy-saving projects. This paper proposes to use the orthogonal test method to elaborate and accurately calculate the energy-saving projects of green buildings and calculate the annual energy-saving rate and load rate of green buildings, to achieve real building energy conservation and reduce energy consumption. The comparative analysis method is used to conduct strict calculation and analysis of the four specific energy-saving systems in the enclosure structure, such as doors and windows, external wall insulation, roof, and sunshading, to more clarify the advantages and disadvantages of each component in the enclosure structure place. According to the experimental data of this article, under the premise that the energy saving rate of this article fully meets the national requirements exceeds 50%, in this model, in terms of the full life cycle cost, the cost of using the worst solution can be reduced by 614,900 yuan compared with the cost of the best solution. [ABSTRACT FROM AUTHOR]

The photovoltaic double skin façade (PV-DSF) is a cutting-edge building envelope renowned for its dynamic nature and power generation capabilities, which attracts substantial scientific attention. However, the current lack of experimental support makes it challenging to draw definitive conclusions about the influence of façade material. This study aims to address this gap by investigating the energy performance of PV-DSF with different façade materials, thereby establishing an empirical foundation for its optimization. In this regard, the full-size comparison experiments on PV-DSF with 20/40% photovoltaic (PV) glass as external façade and laminated/double glass as internal glass were conducted in Harbin, China. The EnergyPlus software is adopted for the simulation of lighting energy consumption. The results indicate that PV-DSF with 40% PV outperforms that with 20% PV, leading to significant reductions in total energy consumption in both summer (22.73%) and winter (16.84%). The double glass can prevent 0.49 MJ of total heat gain in summer, which is accompanied by a marginal 0.03 MJ increase in winter energy consumption. In total, for optimal annual performance, 40% PV and double glass are recommended as the façades of PV-DSF. The results of this investigation can provide an experimental foundation for PV-DSF optimization in sustainable building design. • This paper presents the semi-experimental study on photovoltaic double skin façade. • The impact of façade material on the net energy-saving performance is studied. • The 40% photovoltaic (PV) glass outperforms 20% PV glass in both summer and winter. • The double glass possesses great advantage in summer, with a tiny short in winter. • From the view of year-round operation, 40% PV and double glass are recommended. [ABSTRACT FROM AUTHOR]

In this paper, a CdTe photovoltaic double-skin ventilated window integrated with vacuum glazing (VPV-DSV) is proposed. The mathematical model of VPV-DSV was developed and validated through tests in Hefei, China. Annual energy performance and the economic analysis of the VPV-DSV was evaluated and compared with the other two PV-DSVs and an insulating glazed window (IG) under climate conditions of five selected cities, including Changchun, Hefei, Kunming, Shenzhen, and Shijiazhuang. Moreover, effects of window design factors, including the window-to-wall ratio, PV coverage, and pillar spacing of the VG, were explored. Results indicated that: (1) the VPV-DSV produced the best energy saving results and the least energy consumption. (2) NECs of the VPV-DSV in the five cities above was 955.05 kW•h, 464.31 kW•h, 110.66 kW•h, 53.71 kW•h, and 443.14 kW•h, respectively. (3) Due to high cost of the VG, the VPV-DSV only had the best economic performance in Shenzhen and the NPV was 3931.47 CNY. (4) The WWR and PV coverage had obvious impacts on the overall performance of the VPV-DSV, while the pillar spacing only had a more significant impact on the air conditioning energy consumption. [ABSTRACT FROM AUTHOR]

The optimal control of the heating, ventilation, and air-conditioning (HVAC) system in buildings has a significant energy saving potential and therefore is of a great practical interest. An event-based HVAC control adjusts control actions when certain events occur, which may be faster and more scalable than state-based or time-driven control methods. However, events may capture either local or global changes in the rooms. The choice of events is a tradeoff between the computational efficiency and the control performance. This challenging problem remains open. We consider this as an important problem in this paper and make three major contributions. First, we define local and global events for the HVAC control problem. The complexity of these event-based control policies is defined. Second, based on hypothesis testing, we develop a method to select events that capture a sufficient state information and with a relatively small event space. Third, we demonstrate the performance of this method on two groups of examples, including one group of small-scale problems for the proof of concept and the other group of large-scale problems in the HVAC control. It is shown that our method outperforms the Levin search, which is a traditional complexity-based search method and finds event-based HVAC control policies with a good performance. Note to Practitioners—When there are multiple rooms in a building, the HVAC control may achieve a significant energy saving and an indoor comfort satisfaction in the same time through exploring the coupling among the rooms. By appropriately defining the events, the size of the event space is usually much smaller than the state space. Therefore, an event-based control is more scalable and preferred in practice. Local events capture the state changes of rooms in a small neighborhood, which leads to a small event space but limited information. Global events capture the state changes of rooms in a large neighborhood, which leads to more information but a large event space. It remains open how to select events in large-scale HVAC control problems, especially when the computing budget is limited. In this paper, we define the complexity of an event-based control policy by the number of neighboring rooms considered. We develop a method based on hypothesis testing to select events with a proper complexity in order to achieve a good system performance. The performance of this method is demonstrated on an HVAC control problem. [ABSTRACT FROM AUTHOR]

A cheap, simple, and scalable method for producing transparent radiative coolers (TRC) is introduced in this paper. A prototype of the TRC is fabricated that transmits the visible band of sunlight, highly reflects the near infrared spectrum, and selectively emit/absorb mid-IR in the atmospheric transparency window (AW). An outdoor experimental test for comparison is conducted. The experimental setup consists of two boxes with an illuminometer and a thermometer. One of the boxes has conventional soda lime, and the other has modified glass. The results show that the fabricated structure can reduce temperature as much as 21. 97 ° C and also control the visible intensity of the sunlight by a factor of 4 to prevent glaring in daylighting of buildings, especially in hot climate regions. In the end, a comparison of the present work and similar experiments is provided. [Display omitted] • Tollens' reaction was used for coating glass to produce effective reflector for Mid-IR. • Polymethyl methacrylate thin layer was used to protect silver layer. • Polydimethylsiloxane layer was used as a selective Mid-IR absorber/emitter. • A prototype of the structure was fabricated and measured. • A comparison between fabricated structure and similar ones were provided. [ABSTRACT FROM AUTHOR]

PV windows are considered to be a promising building-integrated PV technology due to their excellent electrical, daylighting and thermal performance. However, the shading of the PV cells increases the heating load in winter and the high temperature of PV cells exacerbates the cooling load in summer. Moreover, a significant portion of the heat absorbed by the PV modules is usually wasted. To address these issues, this paper proposed a multi-functional PV/T window. This system could recover the heat on PV cells for producing warm air in winter and hot water in other seasons. As a result, the proposed system can realize the combined PV/T utilization of solar energy and reduce the seasonal thermal needs of the building. First, the mathematical model of the proposed window was developed and validated. Next, the developed model was integrated into building energy software to evaluate the overall energy performance of the proposed window in four different cities of Yangtze River region: Shanghai, Nanjing, Wuhan, and Chongqing in China. These cities experience the subtropical humid climate (Cfa in the Köppen-Geiger classification) and belong to the zones with medium global horizontal irradiation. The sensitivity analysis revealed that the optimal slat angles are between 0o and 40o, while the optimal orientation angles range from 30o to 60o. Selecting low-iron glass as the inner glass resulted in the lowest overall energy consumption. By adopting the MFPV/T window, the annual operation cost of the studied case could be reduced by 34% (6.4 $/m2), 36% (7.0 $/m2), 28% (5.7 $/m2), and 16% (2.9 $/m2) in these four cites, respectively. Additionally, the annual CO 2 emissions could be curtailed by 53.5, 58.5, 47, and 22.3 kg/m2, respectively. • A novel PV/T window was proposed for addressing the common issues of PV windows. • The mathematical model of proposed window was developed and validated. • The parameter sensitivity was analyzed. • The overall energy performance was predicted in Yangtze River region. [ABSTRACT FROM AUTHOR]

Thermal insulations have begun to play an increasing important role in realizing building energy saving in the past years. Thermal insulations made of biomasses like agro-residues, forest residues, etc., are developing very fast recently, although their research and development history is relatively short. In order to help researchers to achieve a global viewpoint of the research on this topic and to improve the research and application progress, a systematic review is presented in this study. After review and screening, 144 original research journal papers were selected as samples and analyzed to investigate the following topics: Historical development of bio-insulations from 1974 up to April 2016, from viewpoint of number of papers published and corresponding journals; Geo-graphical distribution of researchers, according to country and continent categories; Kinds of biomasses under research including agro-residues, forestry residues, economic plants, etc.; Analysis methodologies and research scale of bio-insulations; Common types, manufacturing methods and properties of bio-insulation; Experimental equipment, software, and corresponding standards. Moreover, the shortcomings of the current research are discussed in details. Finally, some suggestions are presented, including: a scientific plan on bio-insulation research; selection of suitable types; traditional and innovative treatments for improving specific properties; the required properties testing order; scientific presentation of research results. This study can help to achieve a more precise comprehension about bio-insulations research status, find suitable experimental equipment for effectively testing various properties, adopt innovative ways to improve specific properties, avoid making mistakes during the research and provide a better expression of the research results. Furthermore, this study can stimulate the research and application of bio-insulations to get a great-leap-forward development in the near future, especially in the fabricated building field. [ABSTRACT FROM AUTHOR]

Occupant behavior in buildings might result into gap between predicted and actual energy use and cause indoor thermal comfort fluctuations, due to its uncertainty and unpredictability. Previous studies mainly focus on the investigations of occupant behavior impact and modeling methods, whereas few concludes strategic solutions. It is hard to narrow the negative impact of occupant behavior without a clear Impact-Modeling-Solution clue. Thus, the major objective of this research is to review and analyze the impact of occupant behavior and then to summarize modeling methods and strategic solutions by connecting specific techniques and approaches. This paper first investigates the characteristics of occupant behavior and then discusses the impact. It indicates that thermal comfort (environmental condition) triggers occupant actions with corresponding building systems, resulting in energy load changes. The occupant behavior in turn causes thermal comfort fluctuations. The strategic approaches of traditional methods such as surveys, experiments/tests and simulations, and artificial intelligence (AI)-based techniques are analyzed respectively. It is found that the intelligent approach shows high robustness in addressing the uncertain and unpredictable characteristics of occupant behavior in buildings, compared with traditional methods. The AI-based methods and data-driven approaches can enhance the prediction of building energy consumption and the recognition of occupant's thermal comfort. Typical modeling methods and flowchart for occupant behavior are presented with comparisons. The novel physics-based and data-driven model which performs strong adaptability, high decision-making efficiency and fast response of the controller is especially introduced. The corresponding improvements and future directions are also proposed to reach optimal effects. • The research clue of Impact-Modeling-Solution for occupant behavior in buildings is proposed. • Traditional methods and AI-based techniques and data-driven approach are compared. • Typical modeling methods for occupant behavior are presented with comparisons. • Typical strategic solutions are presented upon connections with modeling scopes and methods. • AI-based approaches to address building energy prediction and thermal comfort are summarized. [ABSTRACT FROM AUTHOR]

Abstract In this paper, a novel micro combined cooling, heating, and power (MCCHP) system based on Proton Exchange (PEM) fuel cell and single-effect lithium LiBr H 2 O absorption machine, was designed and studied. PEMFC exhaust gas is used for heating the building and combustor exhaust gas energy is provided to absorption chiller for house cooling. A developed mathematical model is used to predict the MCCHP unit annual energy performance and saving. The study is focused on the MCCHP unit integrated on a single-family house located into eight different French climatic cities (Trappes, Rennes, Nantes, Strasbourg, Clermont-Ferrand, Bordeaux, Orange, and Marseille). Three operational strategies: following electric load (FEL), following thermal load (FTL) and following thermal and cold loads (FTCL) are investigated. The advantage of each strategy is analysed basing on different operational parameters such as electrical, thermal and total efficiencies of the combined PEMFC-absorption chiller, hydrogen consumption, and self-consumption ratios. The proposed MCCHP has been compared with the conventional separated energy systems using the fuel energy saving ratio as a performance index. The results show that the MCCHP unit saves energy during the whole year respecting the French climatic constraints and the house energy need. The best operational strategy is for MCCHP respecting electricity demand where the yearly average fuel energy saving ratio is about 35%. Furthermore, the analyses show that the maximum Fuel Energy Saving Ratio is about 35%, obtained for a single-family house located at Marseille, while the minimum Fuel Energy Saving Ratio, about 32%, is reached for a house situated at Rennes. Highlights • A small scale MCCHP unit based on PEMFC with LiBr–H2O absorption chiller, is studied. • The MCCHP energy saving and performance is analysed for the different climatic French regions. • Three MCCHP operational energy strategies are investigated. [ABSTRACT FROM AUTHOR]

Refurbishment of energy inefficient buildings is an effective way of reducing energy consumption in urban areas. This can be done by taking advantage of the renewable energy sources available, mainly, solar energy. Desiccant evaporative cooling combined with unglazed transpired collectors, UTC's, allows covering the heating demand in the cold season and cooling demand in the hot season. UTC's can be installed on the facades of buildings, meeting a double goal: refurbishing the building exterior and providing heating and cooling to indoor spaces. In this paper, a model of this system was implemented using TRNSYS and the energy savings obtained were evaluated in different climatic conditions, different façade orientations and different building shapes. The objective was to find the best conditions to install this system and estimating the energy savings that can be reached, and its costs. The results showed that the reduction of heating demand was possible in all climatic conditions, weakly depending on the shape and orientation of the UTC façade installed. Cooling was also possible, but it depended more on the shape of the building. The higher energy savings were found for the linear shape buildings. Therefore, refurbishment using a UTC façade could be an interesting alternative for energy saving throughout the year in these cases. [ABSTRACT FROM AUTHOR]

Space heating accounts for a large proportion of a building's energy consumption, and improving heating efficiency is a significant approach to reduce heating energy consumption and carbon emissions. To improve heating efficiency and meet the demand for thermal comfort, this paper proposes an adaptive model predictive control (AMPC) based heating control strategy to regulate the heating parameters of heat exchange stations in residential communities. A multi-input non-linear model combined with subspace identification algorithms is constructed using the heating data from the heat exchange stations and meteorological data. An AMPC control system, a model predictive control (MPC) and a proportional-integral-derivative (PID) control system, are then built to compare their control performances such as room temperature control accuracy, energy saving capacity, response speed, and robustness under extreme weather. The results show that the AMPC strategy outperforms the other two, with a 67.5% reduction in room temperature control deviation and a 20.3% reduction in energy consumption compared to the actual operation of the heating plant. Under extreme weather conditions, the AMPC strategy has 44% less deviation in indoor temperature control and a shorter response time than the least effective PID control strategy of the three. The AMPC system has broad application prospects in the heating field. • Field data collected from 23 representative residential rooms in winter. • Data-driven model was constructed and applied in AMPC to control heating. • Update the AMPC model with historical data from the past week to improve robustness. • Performance evaluation of the three control systems under extreme weather. [ABSTRACT FROM AUTHOR]

Sizing of air-conditioning water pump systems in buildings is a critical issue in design practice concerning the pump energy consumption in operation and risk of being undersized. As a result, significant energy is often wasted in operation due to oversizing to avoid the risk of being undersized. In current practice, throttling of commissioning valves are commonly adopted to push water flowrate (and pressure head) back to the design point no matter how much oversizing exists in a system. That partly mitigates the oversizing problem. This paper presents a novel approach consisting of probabilistic optimal design concerning uncertainties and on-site adaptive commissioning to further maximize energy savings of constant water flow pump systems. Minimized throttling is achieved by on-site adaptive commissioning, which reduces unnecessary pressure head and significant energy consumption. Pumps selected by the probabilistic optimal design can operate under both conventional design conditions and the projected possible off-design (oversized) conditions. The projection is based on the probability distribution of actual pressure head, which is estimated using Monte Carlo simulation by quantifying uncertainties in pressure loss calculation and system construction. Three case studies are conducted to test and validate this new design and commissioning approach. Results show that about 20% energy saving could be achieved, when the system is oversized by 20%, compared to conventional design and commissioning methods. The proposed approach also offers better energy performance in general compared to the designs all using variable speed pumps. [ABSTRACT FROM AUTHOR]

[Display omitted] • Dynamic evaluation of economic and energy benefits due to thermostatic valve installation. • Dynamic evaluation of economic and energy benefits due to heat metering installation. • The adoption of both thermostatic valves and heat metering least to a payback period lower than 2 years. • Analysis carried out considering several shapes of typical building. The aim of this paper is to propose a novel approach in order to accurately calculate the energy and economic savings due to the use of heat metering and thermostatic valves in residential buildings. The paper aims at proving that the present simplified approaches used in European Legislation may lead to significantly underestimate the profitability of this technology. The study is developed for four different typologies of buildings located in the city of Naples (South of Italy), including their geometrical and thermophysical properties. The buildings are first modelled in Google Sketchup and subsequently linked to the TRNSYS environment, which also includes a detailed model of the piping systems. The models allow one to evaluate, for every period of the year, energy demand, energy supplied by radiators, heat gains, transmission, etc. The developed models are used to calculate energy demands for three scenarios for each type of building: centralized heating systems not equipped with heat metering; thermostatic valves without heat metering; heat metering and thermostatic valves. The possible savings related to thermostatic valves and heat metering are estimated using the developed model. The results are compared with the ones provided by the Italian Standards. Results show that the thermostatic valves adoption leads to a significant reduction, up to 50%, of the thermal energy demand of the residential buildings and that all the proposed systems exhibit a remarkable economic profitability, with a payback period lower than 1.7 years. [ABSTRACT FROM AUTHOR]

Accurate cooling load prediction has continually attracted interest due to its important role in building energy saving. Much attention to existing methods has been paid to the temporal information of the features that affect the load prediction. However, facing the time-varying interactions between various types of features, existing approaches have limited ability to extract the implicit information of the complex associations among them. This limitation leads to underutilization of features, especially those that indirectly affect the load prediction through such interactions, and further constrain prediction accuracy. To this end, this paper proposed a graph neural network-based cooling load prediction method to integrate the associations and temporal information of the features. Using the weighted mask mechanism, a knowledge embedded dynamic association graph is constructed to handle the time-varying feature associations rationally. By introducing empirical knowledge and adjusting the graph structure automatically according to the real-time data, the proposed method can provide accurate cooling load prediction. Comprehensive experiments are carried out on the onsite data, and the experimental results show the practicability and effectiveness of the proposed method for cooling load prediction. [ABSTRACT FROM AUTHOR]

Zonal occupant level is of great practical interest for building energy saving under normal operations and for fast evacuation under emergency. Though there are many existing sensing systems to estimate this information, the problem is still challenging due to the privacy concerns, the random human movement, and the accumulative error. In this paper, we consider this important problem and focus on infrared beam systems that monitor the zonal arrival and departure events. We make the following contributions. First, a rule (i.e., Rule 1) based on the stay time is developed to reduce the accumulated estimation error in each zone. Second, a rule (i.e., Rule 2) is designed to coordinate the estimation among neighboring zones. A decentralized estimation method is then developed using these two rules. Third, the advantage of this method is demonstrated through simulation results and field tests. We hope this work brings insight to zonal occupant level estimation in buildings in more general situations. [ABSTRACT FROM AUTHOR]

Due to the large amount of energy consumed in buildings, building energy savings has attracted more and more attention recently. The total energy consumed during building operations is determined by the building energy efficiency and the total demand. On the one hand, though most existing studies focus on improving building energy efficiency, there are limits. On the other hand, the demand grows fast and without limit. Therefore it is important to coordinate the supply and demand in buildings. We consider this important problem in this paper and make the following major contributions. First, the concept of average price of electricity (APE) is defined to measure the average generation cost of electricity using multiple devices. Second, a comfort model of occupant is developed to capture the tradeoff between thermal comfort and cost. Human building interaction allows the user to adjust their temperature set ranges according to the APE in real time. Third, an iterative solution method is developed to solve the supply demand coordination optimization problem. Numerical examples show that significant energy saving is possible through exploring the soft comfort requirement of the occupants, and the iterative method achieves a solution which is close to that of the centralized method, but in a much faster way. We hope this work brings insight to building energy saving in general. [ABSTRACT FROM PUBLISHER]

Integrated control by controlling both natural ventilation and HVAC systems based on human thermal comfort requirement can result in significant energy savings. The concept of this paper differs from conventional methods of energy saving in HVAC systems by integrating the control of both these HVAC systems and the available natural ventilation that is based on the temperature difference between the indoor and the outdoor air. This difference affects the rate of change of indoor air enthalpy or indoor air potential energy storage. However, this is not efficient enough as there are other factors affecting the rate of change of indoor air enthalpy that should be considered to achieve maximum energy saving. One way of improvement can be through the use of model guide for comparison (MGFC) that uses physical-empirical hybrid modelling to predict the rate of change of indoor air potential energy storage considering building fabric and its fixture. Three methods (normal, conventional and proposed) are tested on an identical residential building model using predicted mean vote (PMV) sensor as a criterion test for thermal comfort standard. The results indicate that the proposed method achieved significant energy savings compared with the other methods while still achieving thermal comfort. [ABSTRACT FROM AUTHOR]

Abstract: A temperature and humidity independent control (THIC) system is a way to regulate indoor temperature and humidity separately through different approaches. Because of this distinction, THIC air-conditioning systems can satisfy the adjustment requirements of indoor temperature and humidity better than conventional systems can, and they show significant potential for energy conservation. In the past ten years, rapid improvements have been achieved in both theoretical research and the development of equipment related to THIC systems, and more and more applications are being put into use in non-residential buildings in China. This paper focuses on the development of THIC systems in China and reviews recent achievements and progress related to the main devices used for temperature and humidity control, including outdoor air handling dehumidification processors, sensible heat terminals, and high-temperature cooling sources. The energy performance of THIC systems is examined based on an analysis of established applications. Both the performance of key components and the energy consumption of entire systems indicate that THIC systems result in significant improvements in energy performance compared to conventional systems. Developmental trends and recommendations about design methodology, ways to improve the performance of handling devices, and feedback from applications of THIC systems are also discussed. [Copyright &y& Elsevier]

Highlights: [•] The optimal control gains were obtained from the linear matrix inequalities with mixed H 2 and H ∞ control algorithm. [•] The proposed method guaranteed convergence, stability, and provided a way for disturbance rejection and energy savings. [•] The coupling effects occurred among the compressor speed, opening degrees, evaporator temperatures and superheats. [•] The system identification and thermal dynamics equations could obtain the inner and outer loop transfer functions. [•] All simulations in this paper were in discrete time domain. [ABSTRACT FROM AUTHOR]

Abstract: The control of the use of fossil fuels, major cause of greenhouse gas emissions and climate changes, in present days represents one of Governments' main challenges; particularly, a significant energy consumption is observed in buildings and might be significantly reduced through sustainable design, increased energy efficiency and use of renewable sources. At the moment, the widespread use of renewable energy in buildings is limited by its intrinsic discontinuity: consequently integration of plants with energy storage systems could represent an efficient solution to the problem. Within this frame, hydrogen has shown to be particularly fit in order to be used as an energetic carrier. In this aim, in the paper an energetic, economic and environmental analysis of two different configurations of a self-sufficient system for energy production from renewable sources in buildings is presented. In particular, in the first configuration energy production is carried out by means of photovoltaic systems, whereas in the second one a combination of photovoltaic panels and wind generators is used. In both configurations, hydrogen is used as an energy carrier, in order to store energy, and fuel cells guarantee its energetic reconversion. The analysis carried out shows that, although dimensioned as a stand-alone configuration, the system can today be realized only taking advantage from the incentivizing fares applied to grid-connected systems, that are likely to be suspended in the next future. In such case, it represents an interesting investment, with capital returns in about 15 years. As concerns economic sustainability, in fact, the analysis shows that the cost of the energy unit stored in hydrogen volumes, due to the not very high efficiency of the process, presently results greater than that of directly used one. Moreover, also the starting fund of the system proves to be very high, showing an additional cost with respect to systems lacking of energy storage equal to about 50%. From the above, it can be deduced that, in the aim to obtain a quick, effective penetration of hydrogen into the market, it is at the moment indispensable to enact incentivizing policies, attributing to hydrogen production fares able to cover the additional costs due to its production, storage and reconversion. [Copyright &y& Elsevier]

Abstract: In consideration of the climatic characteristics of different climatic zones, the annual energy consumption of existing buildings before and after reconstruction in hot summer and warm winter regions of South China and cold regions of North China is analyzed in this paper using DOE-2 dynamic cold and heat load simulation software. For cold regions of North China, the annual comprehensive energy saving benefits of existing buildings reconstruction in summer and winter should be analyzed, and the cost savings in the initial investment for heat resource and electricity construction should also be included at the same time. While for hot summer and warm winter regions of South China, the building energy saving should focus on new buildings. The building energy saving reconstruction and the feasibility in the two regions is also compared and analyzed. [Copyright &y& Elsevier]

Abstract: Heat transfer through window surfaces is one of the most important contributions to energy losses in buildings. Therefore, great efforts are made to design new window frames and glass assemblies with low thermal conductance. At the same time, it is also necessary to develop accurate measurement techniques in thermal characterisation of the above-mentioned building components. In this paper the authors show an innovative measurement method mainly based on radiative heat transfer (instead of the traditional convective one) which allows window thermal conductance measurements with corresponding uncertainty budget evaluation. The authors used the 3D finite volume software FLUENT® to design the experimental apparatus. The numerical results have been employed for the system optimisation and metrological characterisation. [Copyright &y& Elsevier]

Abstract: The paper clarified the effect of humidity adjustment of Trombe wall on indoor environment by the experimental comparison between a passive solar cell and a reference cell. Theoretical analysis on indoor humidity adjustment of Trombe wall in the passive solar cell is also performed based on steady moisture transfer theory. Simultaneously, the experiment proved that the passive solar cell could provide a relatively comfortable indoor environment. [Copyright &y& Elsevier]

The number of airtight buildings equipped with air-conditioning units along with levels of energy consumption from residential and commercial buildings has both increased markedly in China since 1990 due to rapid economic growth and urbanization. During this same period, home refurbishment/decoration/remodeling activities in newly constructed or existing apartments have become very popular and brought attention to a wide range of health concerns. This paper reviews building energy-saving and indoor-air-quality (IAQ) related standards in China. In summary, the two systems of building energy-saving and IAQ-related standards have been already established separately, although Chinese IAQ standards contain some indices related to building ventilation and energy (e.g. fresh air volume, relative humidity, and temperature). Building energy-saving systems are applicable to buildings existing in a wide range of climatic conditions. Formaldehyde was selected as a pollution index in “Chinese Evaluation Handbook of Ecological Residence Technology” (promulgated in 2001) for buildings mainly contaminated with harmful compounds emitted from interior decorating materials. As part of its IAQ control strategy, China promulgated a series of IAQ-related standards and compulsory national standards for limits of harmful substances contained in interior decorative materials (LHSCIDM), which placed strong emphasis on source control. When enacting the IAQ-related standards, China adopted some of the standards used in developed countries and related international standards for reference. [Copyright &y& Elsevier]

• TT PS-TIM smart window provides dynamic regulation of solar admission. • Impacts of design factors of TT PS-TIM window on building performance are presented. • Evaluated an office performance with TT PS-TIM window using an inclusive approach. • Applying TT PS-TIM window results in energy saving of up to 27.1%. • The TT PS-TIM window offers significant improvement in daylight performance. With the increasing awareness of building energy efficiency, indoor environment quality for human wellbeing and working efficiency, efforts have intensified in to inventing intelligent building components. This paper provides a first step in developing a novel multi-effect smart window system, which achieves enhanced energy efficiency and an improved indoor luminous environment by integrating a Transparent Insulation Material (TIM) structure incorporating a Thermotropic material. This system automatically regulates the admittance of solar heat and natural light into the building by responding to a changing environment while taking advantage of the increased thermal resistance and scattered daylight of window integrated TIM. A comprehensive workflow via EnergyPlus and RADIANCE was used to accurately predict the luminous and energy performance of applying the smart window system on a typical south-facing office under selected climates (London, Stockholm, Rome and Singapore). The effect of the optical properties and transition temperature of thermotropic material on building performance was explored in detail. Annual simulation results predict that, with a careful selection of the Thermotropic material properties, installing the TT PS-TIM window system is able to yield up to a 27.1% energy saving when compared with a conventional double glazed window, under the modelled Rome climate. TT PS-TIM windows also provide dynamic daylight control, resulting in increased daylight availability with the percentage of working hours that fall into the UDI 500–2000 lx range increasing to 62.3%. The results of this research provide guidance for the next step of the material design and development that seek to balance energy efficiency and solar and daylight control through the use of thermotropic materials. [ABSTRACT FROM AUTHOR]

Passive photonic radiative cooling is used to make sky exposed surfaces sub-ambient with recent development in metamaterials throughout the day and night cycle. Daytime radiative cooling depends on the intensity of solar radiation, and both daytime and nighttime radiative coolings have a function of environmental factors like ambient temperature, humidity, wind velocity, cloud fraction, etc. Hence, the passive radiative coolers have location-specific performance and need analysis individually for a location before implementation. In this paper, the potential of passive radiative cooling for Indian cities of various climatic conditions covering maximum climate diversity is evaluated for different (ideal, broadband and selective) emissive radiative cooler surfaces. The effects of various environmental parameters on the cooler performance are studied. The cooling energy-saving potentials of various photonic radiative coolers as roof envelope integrated with the conventional air conditioning system are evaluated as well. Results reveal that the selective radiative cooler performs better in low humidity locations, namely Jaisalmer and Delhi, with maximum temperature drops of 20.6 °C and 17.3 °C, respectively. However, it is less likely to recommend for monsoon season and high humid cities. The cooling load reduction of 36% observed for low humidity locations with an integrated system. • Potential of photonic radiative cooling for various Indian climates is evaluated. • Effects of various solar-environmental parameters on cooler performance are studied. • Energy saving potentials of various radiative coolers as roof envelope are evaluated. • Selective cooler is suitable for low humidity and broadband one is for high humidity. • Cooling load reduction of 36% is observed for low humidity location with integration. [ABSTRACT FROM AUTHOR]

• The same building geometries and the same thermal properties of building envelope for different seven climatic cities were assumed. • Energy conservation effect including saving amount and saving ratio were discussed annually and monthly among seven cities. • The inner mechanism of the difference was revealed from the hourly and daily perspectives through two extremely contrast climatic cities. • Guidance and reference were provided for both standard determination and behavioral energy saving for air conditioning systems. Indoor setting temperature is a key controllable parameter by users, highly impacting the total cooling energy usage. In this paper, the hourly cooling load of residential buildings is simulated for seven cities respectively when the cooling setting temperature (CST) increases by 1°C, and the dissimilarity and internal mechanism of the energy saving effect are discussed and revealed from the hourly and daily perspectives through two extremely contrast climatic cities. The results show that although the higher yearly energy saving amount (ESA) can appear in a hotter city, energy saving effect is all significant in different cities. The ESA in hotter months of hotter cities may not be higher than that in the corresponding months of cooler cities, and the hotter cities have more obvious platform features while the cooler cities have single peak features, and the peak value is much higher than the plateau value. The yearly cooling saving ratio (CSR) is higher in cooler cities because CSR depends on both the hourly CSR and its weightiness, and the proportion of the higher ratio hours in cool cities is larger. This study can provide references for both standard determination and behavioral energy saving for air conditioning systems. [ABSTRACT FROM AUTHOR]