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Increasing use of volatile renewable energy sources causes challenges in balancing supply and demand. Therefore, demand-side flexibility has rising importance for system operators and balancing authorities. Flexibility management methods are needed to integrate loads like ventilation systems of different buildings (e.g., residential and commercial) into flexibility service. However, the available methods described in research papers require further development for implementation in practice. Heating and cooling systems have received much attention from researchers, but the potential of ventilation systems has been left out of focus. Therefore, this paper provides a complete set of novel flexibility management methods for ventilation systems created from an aggregator's viewpoint. The flexibility is quantified through capacity (e.i. the amount of power consumption that can be altered), forced ventilation rate duration, and the tendered price for the service. The proposed methods were tested on a building model constructed and simulated in IDA ICE. The data processing and flexibility management methods were applied in MATLAB. Two types of ventilation systems with different sensor configurations were considered: constant and variable air volume. Forced ventilation rate duration is calculated using energy and mass balance analysis where the root means squared error was 10 to 33 min, depending on the system type, measured parameter, and sensor location. The flexibility service pricing model was tested on the 2022 years' manual frequency restoration reserve (mFRR) activation and balance energy market data. [ABSTRACT FROM AUTHOR]

Retrofitting the design of a ductwork system is often a critical aspect when renovating a centralized air distribution system. However, the existing approaches rely on the rules of thumb due to the absence of a standardized guideline for the design retrofitting process. Consequently, design engineers face costly and time-consuming challenges in generating retrofitted designs, particularly when dealing with the complexities of reusing the existing ductwork system. Although their design output may achieve functionality, it is not necessarily optimal in terms of cost and performance. To overcome these challenges, this paper proposes a simulation-based ductwork design strategy that utilizes metaheuristic optimization techniques to generate optimized ductwork designs for retrofits. The proposed method offers an automated solution for generating optimized ductwork configurations (i.e., layout and sizes). It strategically maximizes the reuse of existing ductwork components while simultaneously fulfilling the design performance criteria desired by the system and minimizing its life cycle cost. A case study was conducted to present the effectiveness of the developed method in retrofitting the ductwork design for a multi-story school building. This study involved a comparison between the design solution generated by the proposed method and the design solution generated through a conventional retrofitting design approach. The results from the proposed design retrofitting method showed a 17 % lower LCC and an approximately equally well-balanced design. These findings indicate the method's promising potential to contribute to the HVAC industry by providing an effective simulation-based method for automatically optimizing ductwork designs for retrofits. [ABSTRACT FROM AUTHOR]

The Passive House (PH) Standard is a voluntary building energy performance standard focused upon reducing space heating demand to a very low level and therefore considered a viable climate change mitigation technology. Besides comfort and energy requirements, the PH standard also defines criteria with respect to ventilation. However, the question remains, how well do PH dwellings perform when they are occupied? Does the PH approach provide good indoor air quality (IAQ) for its occupants and how does IAQ compare to non-PH homes, in particular, naturally ventilated homes? Additionally, can PH certification improve the quality of installed ventilation systems? This paper summarizes indoor air quality relevant aspects of the PH standard and presents results from measurements examining in-use IAQ in more than 600 PH or PH-like, newly built or retrofitted dwellings. The results reveal that pollutant and carbon dioxide concentration are generally lower compared to naturally ventilated homes, presumably due to the requirement to install a balanced Mechanical Ventilation with Heat Recovery (MVHR) system. Results also suggest that the quality assurance measures of PH certification are capable of improving ventilation and IAQ performance. However, the lack of cooking fume capture requirements in the PH standard, in combination with efforts to avoid energy losses associated with a possible extraction kitchen hood, may lead to elevated particulate matter concentration in PHs. Future research on cooking induced IAQ impairment is encouraged to assess the effectiveness of recently published PH-specific recommendations. Future efforts in empirical IAQ research should also address the lack of high quality IAQ measurement data and the standardisation of IAQ assessment methods and protocols. [ABSTRACT FROM AUTHOR]

• Climate change and urban setting impact energy use of buildings. • Energy use is higher due to overlapping effect of climate change and microclimate. • A method is proposed to account for future and urban environment in thermal simulation. • The results can assist in sizing passive ventilation systems. Urban settings and climate change both impact on energy use and thermal comfort inside buildings. This paper first presents a study of changes in energy demand in residential buildings considering the overlapping effect of climate change and urban heat island intensity in two European locations; Cadiz (Spain) and London (United Kingdom), representing temperate and hot European climates and moderate and dense urban settings. Future-urban weather files were generated and simulations were run considering energy demand and indoor thermal comfort. In hot climate regions such as the one of Cadiz, future climate will increase the cooling demand and the additional impact of the UHI leads to a further increase of up to +28% of total energy demand compared to the current climate without considering urban effects. Future-urban weather conditions will be detrimental also for buildings in London, where the annual energy demand is predicted to increase by up to the 16% if future climate and urban effects are included. This is due to a higher increase in cooling demand compared to the reduction for the heating need. The paper also presents a method to take into account microclimatic conditions in naturally ventilated buildings, especially the effect of wind variations around the building which impacts natural ventilation rates. Air and surface temperature and wind speeds were studied using ENVImet and the resulting microclimatic conditions were used as inputs to the EnergyPlus Airflow Network model for the calculation of the building ventilation rates. It was found that ventilation rates are reduced (in comparison to meteorological weather files) and this reduction impacts negatively on internal operative temperatures. A thermal comfort analysis was carried out indicating that the selection of a suitable weather file and microclimatic conditions is essential for more accurate predictions of internal thermal comfort and will assist in the sizing of passive and active systems to avoid overheating. [ABSTRACT FROM AUTHOR]

• This paper presents a comprehensive review of cross ventilation research in buildings. • The advantages and disadvantages of different research methods are compared. • The ventilation models of cross ventilation are reviewed. • The influencing parameters of cross ventilation are summarized. • The future perspectives of cross ventilation research and practical applications are proposed. There is a growing body of literature that recognizes that natural ventilation plays a vital role in indoor air quality, thermal comfort and building energy consumption. This paper systematically reviews the previously published research of the most efficient and typical natural ventilation type - cross ventilation, aiming to present the main research topics in contemporary research and provide an agenda for future studies. The methodologies, airflow pattern, ventilation models and influencing parameters of cross ventilation were comprehensively summarized and discussed. The chained analysis and data-driven methods are the potential approaches to study cross ventilation more efficiently. The comparisons of different ventilation models of cross ventilation help to better understand the basic mechanisms that drive the cross ventilation airflow. [ABSTRACT FROM AUTHOR]

Highlights • Development of a heat exchanger semi-empirical model accounting for frost formation. • Experimental validation of the HX model in partially frost regime. • Frost control strategies numerically implemented and compared. • Strategies lead to trade-offs between ventilation quality and energy consumption. Abstract This paper tackles the issue of frost formation in air-to-air heat recovery devices dedicated to single room ventilation by means of both numerical simulations and experimental approaches. In such heat exchangers, it is commonly known that the formation of a frost layer on the surface generates an additional thermal resistance and a flow section reduction, which leads to an overall degradation of the overall unit performance. This paper proposes a three-zone model, considering a dry, a wet and a frost zone, by determining the location of moving boundaries. Each zone is handled independently and the relative proportion of each zone is determined by means of the exchanger wall temperature. Besides this frost model, a defrost model is also envisaged. Once validated with experimental data collected on a U-flow-type heat exchanger, the developed model is used to implement different strategies to reduce or prevent frost formation in the exchanger. Based on three different criteria, these strategies are compared with each other to evaluate their benefits and drawbacks. The criteria give information on the energy efficiency of the ventilation, on the air renewal quality and on the pressure balance between the inside and the outside of the building. [ABSTRACT FROM AUTHOR]

Highlight • New on/off controller for residential applications validated using minute-level field data. • On/off controller improves the HVAC accuracy around 19% in terms of NMBE. • On/off cycling makes the operation and associated energy use more realistic. Abstract Heating, ventilation, and air-conditioning (HVAC) systems are sized using design conditions, conditions that occur only a small percentage of time each year. As a result, HVAC systems frequently operate at part-load conditions since their capacity is larger than necessary except in the most extreme weather conditions. Most HVAC systems for residential and small commercial buildings in the U.S. use on/off controls, however, most energy modeling software tools do not simulate the on/off nature of this type of HVAC controls. This paper presents the development and validation of an on/off controller for residential applications in EnergyPlus using a custom EMS (energy management system). This controller is validated using minute-level field data collected for a house located in Sacramento, California with simulated occupancy and internal loads. The results obtained from EnergyPlus with and without the use of the developed on/off controller are also compared. The application of the developed on/off controller improves the HVAC energy use results accuracy around 19% in terms of the Normalized Mean Bias Error (NMBE) at the one-minute level compared to the results without the application of the on/off controller. It also makes the nature of operation and associated energy use signal of the HVAC system more realistic in terms of the on/off nature of the residential direct expansion coils. Furthermore, in this paper, the accuracy improvement of the results dominated by the internal loads is investigated by applying the one-minute schedule compared to the usual hourly schedules for the internal thermal loads. [ABSTRACT FROM AUTHOR]

Highlights • This paper uses building structural attributes such as shapes of buildings, relative compactness(RC), glazing area(GA), roof area(RA), surface area(SA), wall area(WA), orientation(OR), overall height(OH) and glazing area distribution(GAD) for prediction of heating and cooling load. • The paper explores the data set and features to get insights with feature correlation, mutual information their association strengths etc and their relation with heating and cooling load. • The paper proposes novel group of methods based on emerging machine learning method extreme learning machine(ELM) which has shallows architecture. • The paper proposes novel method based on ELM variant online sequential extreme learning machine(OSELM) for heating and cooling load prediction in online and adaptive environment. This model also helps when data is trained in chunk by chunk fashion. • The paper demonstrates several models based on combination of learning mode, activation function and features sets and compare their results with existing work extensively. Abstract In the present day environment, smart buildings require optimization of energy consumption through monitoring, consumption prediction and making policy decisions accordingly. Attributes related to building design and structure play a vital role in heating load(HL) and cooling load(CL) of the building which directly affects the energy performance of the buildings. For prediction of HL and CL, emerging machine learning approaches can help in improving accuracy and efficiency in real time. This paper provides improvements in energy load assessment of the buildings. It is the first is the in-depth study and analysis of design and structural attributes and their correlation with HL and CL, the novel methods based on ELM and its variants online sequential ELM(OSELM) to predict HL and CL. This study also proposes OSELM based online/real-time prediction when data is coming in stream The total 24 models have been developed including 12 models based on ELM and 12 models based on OSELM with different feature sets and activation functions. Models have been compared on the basis of accuracy, computational performance and efficiency with few existing models. The experimental results show that the proposed models learn better and outperform other popular machine learning approaches such as the artificial neural network(ANNs), support vector machine(SVM), radial basis function network(RBFN), random forest(RF) and existing work in the energy and building domain. [ABSTRACT FROM AUTHOR]

This paper examines the provision of demand-side ancillary services using building thermodynamics and heating ventilation and air-conditioning (HVAC) systems. In particular, we consider the secondary frequency control service where the load has to declare a power capacity and a nominal power at the beginning of the regulation period and then in real-time track the received regulation signal around its declared nominal power. A hierarchical control scheme is proposed in this paper. The local building controllers at the lowest level track the temperature setpoints received from the thermal flexibility controller which maximizes the flexibility of building’s thermal consumption. At the highest level, the electrical flexibility controller controls the HVAC system while maximizing the flexibility provided to the grid. The two flexibility control layers are based on robust optimization methods. A control oriented model of a typical HVAC system is developed, and simulations are carried out to demonstrate the efficacy of the proposed approach. Results show that extra flexibility may be attained by exploiting the coefficient of performance (COP) of the chiller. Furthermore, occupant comfort increases as a consequence of providing ancillary services. [ABSTRACT FROM AUTHOR]

In order to obtain satisfactory effect of air conditioning and ventilation, the floor–supply displacement ventilation has widely applied in many civil buildings. Swirl diffusers mounted on the floor are widely used to provide fresh air into the occupied zone in the floor–supply displacement ventilation system. This paper studied the air distribution performance of swirl diffuser by 2D-PIV (particle image velocimetry). The experiment was implemented in a full-scale room to achieve reliable data of swirl diffusers. Flow visualizations have been carried out to determine the shape of the swirl jet. The whole velocity field was measured by 2D-PIV system, which is very useful to analyze air distribution above the swirl diffuser. With the aid of the flow visualizations and PIV test technology, the macro and micro structure of the air flow above the swirl diffuser is specified in more detail. Moreover, the centerline velocity decay coefficient (K value) and entrainment ratio were obtained. The research work of this paper provides detailed experimental data of air flow above the swirl diffuser, which provide the reference for selection of air terminal devices and a basis for follow-up numerical simulation study. [ABSTRACT FROM AUTHOR]

Improved ventilation in an urban residential neighborhood is a determinant for better energy efficiency and air quality of the neighborhood. This is particularly important for the real estimates recently developed in many cities in China, as these neighborhoods are built with high density. In this paper, we consider in an idealized neighborhood with two categories of packaging building densities ( λ p ) of 0.25 and 0.44, which respectively represent medium and compact urban development. For each packaging density, the frontal area density of arrays is varied from 0.125 to 0.5 through adding building blocks and reducing building size simultaneously. Computational fluid dynamics simulations are carried out to predict the wind flow through the building arrays by the use of renormalization group (RNG) k - ε turbulence model. Our predictions are validated by comparing with experimental data. Numerical results reveal that ventilation rate could be greatly enhanced when a low level of packaging building density is maintained. The momentum exchange rate at the canopy roof level is effectively strengthened when the frontal area density decreases, together with a reduction of ventilation in the urban canopy layer (UCL). Additionally, a linear relationship is found between the UCL ventilation rate and the momentum exchange rate at the urban canopy roof level. For a constant packaging density, reducing frontal area density improves the city block ventilation by enhancing the air exchange rate at the roof level rather than increasing horizontal drag. This paper also illustrates a practical strategy in optimum neighborhood building layout design to minimize the pollutant level. [ABSTRACT FROM AUTHOR]

This paper investigates the theoretical capacity of the Swiss peri-urban dwelling stock to meet energy efficiency requirements through incremental scenarios. The notion of “typical dwelling” allows the assessment of housing energy efficiency at the country scale. The “2000-W society” concept and federal policies provide the assessment framework of the daily-mobility and housing operational energy demand along with embodied energies of the dwelling stock. The typical dwellings’ current performance for several territorial entities highlight the extent of the challenge the peri-urban housing stock is facing today. Therefore, the paper investigates which conditions would allow the peri-urban typical dwelling to meet “2000-W society” intermediary targets. Eight incremental scenarios present theoretical improvements of mobility and housing. They assume an evolution of social practices and individual behaviours, as well as the development of improved technologies. Results show a drastic reduction of primary non-renewable energy (PNRE) demand and greenhouse gas (GHG) emissions for both mobility and dwelling-related consumption. The main findings are that the current MINERGIE-A label is sufficient to build energy efficient buildings, but the current mobility practices remain very far from targets. An optimization of trips and a broader recourse to low carbon conveyances are required to reduce the overall environmental footprint. [ABSTRACT FROM AUTHOR]

Concerning the building environment HVAC facilities, even if a great effort has been made in developing components and systems with high nominal efficiencies, less attention has been paid to the problem of system maintenance. The main objective of the thermoeconomic diagnosis is to detect possible anomalies and their location inside a component of the energy system. The second objective, and indeed the one to be achieved in this paper, is indicated as inverse problem. It is associated with the quantification of the effects of anomalies in terms of thermoeconomic quantities. Its rigorous application in building thermal installations has some difficulties relating to the strong interrelation between the different components and the fact that energy supply facilities are continuously changing with time. The way to deal with dynamic circumstances is thoroughly explored in this article. Likewise, this paper’s main goal is to demonstrate an application of two thermoeconomic diagnosis methodologies in the building sector, one based on the malfunction and dysfunction analysis and the other one based on the characteristic curves of the components. The results obtained allow us to point out the advantages and limitations of both methodologies as well as to combine them and then develop a more reliable diagnosis. [ABSTRACT FROM AUTHOR]

Numerous cost-optimal studies have been undertaken by EU member states to define minimum energy performance requirements for buildings within that member state in accordance with the Energy Performance of Buildings Directive. As few of these studies have examined the effect of heating and ventilation system parameters on life cycle cost (LCC) and energy use in detail, this paper analysed 84 HVAC solution-sets, including parameters for the heating supply system, heating distribution system and ventilation system, for a case study in Norway. The choice of heating supply system was the dominant parameter, with ground source heat pump solutions offering the lowest purchased energy use and LCC. Electric water heating and district heating systems had low capital costs which make these options more attractive to property developers looking for a good return on investment. Using an exhaust ventilation system with an exhaust air heat pump lowered LCC and capital costs for ground source heat pump and district heating systems but does not meet current Norwegian energy regulations. Despite using more energy, a constant setpoint schedule resulted in a lower LCC than a variable setpoint system due to the variation in hourly energy pricing and the dominant role of monthly pricing based on peak load. The choice of yearly heating strategy and heat emitter had a relatively small impact on energy use, capital cost and LCC. With all the parameters combined, there was variation within each heating system of up to 21 kWh/(m2∙year) in energy use, 78 Euro/m2 in capital cost and 236 Euro/m2 in LCC. Therefore, it is important that such system parameters are considered in cost-optimal assessments to give a fair comparison of HVAC systems. [ABSTRACT FROM AUTHOR]

• Ventilation rate and arrangement are crucial to prevent airborne disease in healthcare facilities. • Local ventilation is practical for supply fresh air and diluting contaminants in high-risk areas. • Microplastics emerged as potential virus carriers in indoor environments, warrant further investigations. The prevalence and transmission of airborne infections pose significant challenges to public health, leading to consequential negative impacts. Ventilation strategies are crucial in mitigating airborne infections in healthcare settings, preventing the spread of infectious diseases, thus protecting patients and healthcare workers. While individual studies have explored various aspects of ventilation in healthcare settings, a synthesized overview of the current state of knowledge is lacking. Therefore, this study attempts to bridge the gap by conducting a review and bibliometric analysis based on 198 papers published within the recent decades (1993–2022). The findings will provide a holistic understanding on the innovative interventions and identify areas for future research, thereby contributing to the development of effective guidelines for controlling airborne infections. The co-authorship analysis revealed that China emerged as the main contributor in the current research field due to the keen interest of researchers and the substantial financial support provided by funding agencies. The keyword co-occurrence analysis identified three primary research hotspots within the field, (i) the optimized ventilation strategies for combating airborne infection, (ii) the transition towards the application of computational fluid dynamics (CFD) in analyzing airflow patterns, and, (iii) the characteristics of airborne particles and their impact on infection transmission. The present review highlights the significance of local ventilation as an additional measure to the main ventilation system for enhanced dilution of contaminants in high-risk areas. The transition towards dynamic airflow analysis considered human movement's effect, allowing for more precise assessments and tailored ventilation strategies optimization. The review also underscores the emerging concern of microplastic as an indoor contaminant with potential implications as a virus carrier, emphasizing further research on its behavior and impact on airborne infection transmission. [ABSTRACT FROM AUTHOR]

Assessment methods to assess smart ventilation, in most countries focus only on comfort as criteria for the indoor air quality (IAQ) (Guyot et al., 2019). This is an issue as in doing so, pollutants that are known to cause harm to the human health are not taken into consideration while the exposure to VOCs will be elevated if the smart ventilation system lowers the ventilation flowrates to save energy (De Jonge & Laverge, 2021). This research addresses the question of what the impact of changing family sizes would be on the individual exposure to unhealthy pollutants for a smart ventilation system that only uses comfort related parameters to control the ventilation system. By introducing sources of Volatile Organic Compounds (VOCs) into a Modelica building energy and IAQ model of a typical Belgian apartment the occupant-dependent (CO 2 and RH) smart ventilation can be assessed for non-occupant dependent pollutants (VOCs). For three given smart ventilation systems, ten different households, with varying sizes and occupants are simulated. The results show that the presence of other family members influences the exposure to VOCs of an individual. One of the three smart ventilation systems is analyzed in detail, for this system, the minimum DALY count is 14.75 yr and maximum is 17.72 yr. They also show that the energy use of the building can be quite different although the only changing parameter in the simulation are the occupants. For the different simulated households, the minimum yearly energy use is 731kwh and maximum yearly energy use is 1319kwh. Similar results are obtained for the other two cases. Overall, the three smart ventilation systems show significant energy savings compared to the continuous nominal reference system but the expected impact on health increases. When designing a simulation-based assessment framework for residential ventilation, the occupant's behavior will always be an unknown factor to consider. The results indicate that in developing a simulations-based assessment framework, it is recommended to not assume just one household as in doing so, the system performance is not properly checked with regards to health and energy use during the lifetime of the system and the related expected variation in household types and sizes. The results in this paper confirm that a stochastic approach for assessing residential smart ventilation systems based on health-related pollutants (VOCs) should be investigated further. [ABSTRACT FROM AUTHOR]

HVAC systems in buildings are composed of many subcomponents which consume energy in huge amounts. In recent years, energy consumption becomes very important aspect due to the lack of energy resources and environmental reasons. In terms of energy consumption, the components of HVAC systems account for large portion of total energy used in buildings. Therefore optimization of energy consumption in HVAC applications is an essential requirement in terms of thermodynamic and economic point of views. Besides, the efforts for decreasing energy consumption turn into economic recovery. It also provides benefits for human health and cleaner environment. In this paper, as originality, thermodynamic and economic analyses of an existing social and cultural building which has a heating and cooling area of 8852 m 2 are presented by comparing of a conventional HVAC and a VRF system. A novel contribution is given to the open literature by comparing two systems with actual data measured from the existing system. The other originality is to apply and test a VRF system to a complex-structured building. This study is a rare one which contains insulation, heating and cooling accounts of a building together. In this paper, VRF system is modelled to the existing building for the comparison of the conventional HVAC system. Both systems have been compared in terms of heating and cooling capacity, initial, operation and maintenance costs. It is found that the VRF system is more economic and efficient such that the VRF system is found to have 44% cost profit when compared with the conventional HVAC system. [ABSTRACT FROM AUTHOR]

A sleeping person is naturally immobile in a relatively small space. Hence, task\ambient air conditioning (TAC) can be best applied to a sleeping environment because of its proven performances in energy saving. However, when using previously developed the TAC systems for sleeping environment applications, cold draft was a serious issue and could hardly be avoided due to a high air velocity and a low air temperature inside an occupied zone. Therefore, in the experimental study reported in this paper, a radiation-based TAC (R-TAC) system has been developed, and its performances experimentally evaluated. In this paper, firstly, an experimental setup for a prototype R-TAC system, and experimental conditions and methods are reported. This is followed by presenting experimental results on the thermal comfort and ventilation performance. Finally, the issues of condensation risk when using the proposed R-TAC system are discussed. The study results presented in this paper have shown that the use of the R-TAC system could not only result in better thermal comfort and ventilation performances, but also effectively resolve the cold draft problem. In addition, the potential problem of potential condensation on a surface may be resolved by raising the panel surface temperature, or using a lower fresh air supply humidity. [ABSTRACT FROM AUTHOR]

This paper investigates the potential for incorporation of human commercial building design modelling into the pig production industry. During the last decades pig building design has relied heavily on building manufacturers compared to human commercial buildings that regulate standards to improve the sustainability of the building. Thus, the aim of this paper was to gain a greater understanding of the design requirements for sustainable forms of pig housing, which could potentially improve the welfare of the pig and promote greater resource use efficiency. Part of an existing mechanically ventilated UK pig production building, which represents three adjacent fully-slatted units each capable of holding approximately 292 pigs and measuring approximately 18 m x 14m, was used as a basis to create a dynamic thermal model of the building. The model takes into account the possibility of future rises in environmental temperature and the effect of this climate change on building performance and pig growth, feed efficiency and welfare. The results of the model showed that as the finishing pigs increased in size they have the potential to be subject to increasingly poor indoor air quality, during the winter months. The model also shows that improving the thermal properties of the building not only helps with reducing the amount of time that the pigs could potentially spend at extreme low temperatures, by approximately 1115 h (46 days), but can also help with reducing the number of hours the pigs spend above 26 °C during the summer months, by approximately 8 h. [ABSTRACT FROM AUTHOR]

This paper presents validation of the neural network model for predicting airtightness of residential and non-residential units. Proposed model developed in previous research utilizes a neural network in prediction of airtightness and it is obtained based on in situ measurements at 58 units in Croatia. Model applicability earlier was tested by independent validation through 20 additional measurements in Croatia and on 5 measurements in Serbia. This paper presents validation of neural network model for predicting airtightness of residential and non-residential units on database formed beyond the regional area. Database used for model validation in this paper consists of 20 residential and non-residential units from Poland with building construction technology similar to Croatian ones. Comparison of the results obtained by measurements and prediction model indicates that the model gives consistent results on the validation data set with similar building construction technology and demonstrates that model is not locally conditioned. [ABSTRACT FROM AUTHOR]

Envelope systems are the main contributors to the energy consumption associated to cooling or heating buildings. There have been significant research efforts to improve the performance of building envelope systems by integrating passive cooling strategies to reduce cooling loads and maintain acceptable indoor thermal comfort. The ventilated wall cavity system is one of these passive-cooling strategies that have received considerable attention recently due to the significant benefits of reducing thermal loads of buildings. In particular, evaporative cooling inside ventilated wall cavities is an attractive passive cooling technique especially in hot and dry climates. This paper presents the initial findings of a current research study focusing on improving the ventilated wall cavity with spray evaporative cooling system that produce fine water droplets. Specifically, this paper describes a numerical modeling approach to evaluate the performance of the proposed passive cooling system to cool buildings in hot and dry climates. The simulation results suggest that a significant reduction in cooling loads can be achieved since the wall cavity can absorb heat from the indoor and outdoor while inducing acceptable supply air temperature capable of maintaining indoor thermal comfort within buildings. [ABSTRACT FROM AUTHOR]

Computer simulation for buildings has become affordable and possible in both research and industry during the last decades with rapid progress of computer industry as well as fundamental advancement of computational techniques. This paper provides an overview of such advancements achieved between 1987 and 2014, during which Professor Branko Todorovich served as Editor in Chief of Energy and Buildings Journal. The review, however, was not restricted to this journal only, in order to provide a fair snapshot on overall technique advances. Simulation and computational techniques cover a variety of aspects of building. This paper focuses specifically on six different topics including ventilation performance prediction, whole building energy and thermal load simulation, lighting and daylighting modeling, building information modeling, indoor acoustic simulation, and life cycle analysis of buildings. Major advances in each area are highlighted, as well as the trends for development and application. [ABSTRACT FROM AUTHOR]

This paper investigates experimentally the cooling performance of a concept, where the radiant ceiling is suspended from the hollow-core concrete slab and by ventilation supply in the plenum and the perforations of the ceiling tiles, ventilation air is distributed without ducts and air terminals to the occupied zone. Literature has proven that this concept allows for more streamlined installation procedures and excellent performance in terms of thermal comfort and draught. The paper reports experimental results from a climate chamber, where the concept was tested under both steady-state and quasi-steady conditions. The steady-state conditions were chosen to map the cooling performance with different air change rates, and different ventilation and water supply temperatures. The results showed that for air change rates of 3 h−1 in the occupied zone and water supply temperature of 17 °C, the cooling output from the ceiling increased by 10 %. The concept was also tested under quasi-steady conditions in a 48 h cycle to quantify the thermal buffering effect of the exposed upper concrete slab when subjected to ventilation supply air. The effect amounted to 11–12 % increased cooling capacity at the end of the working day when the driving temperatures between air, water and thermal zones were at their maximum. [ABSTRACT FROM AUTHOR]

Abstract This paper presents a feasibility study on the use of multilayer neural networks to determine airflow infiltration from thermographs, thus the related energy leak. The developed method, aimed at accurate evaluation of intake airflow through an opening in the building's envelope, uses as input data infrared images of the temperature changes in a rendering surface near an opening in the building's envelope. Data collection of these measurements can be achieved with relative simplicity, and therefore could lead to an alternative or complementary method to the standardised ways of measuring infiltration based on Blower Door test, increasing the possibilities of monitoring, supervision and continuous management of building's ventilation and airtightness. Laboratory results show over 93% average accuracy for instant samples, and over 98% global accuracy for sequences. The generalization capability of this method has also been explored, and several neural network topologies analysed. [ABSTRACT FROM AUTHOR]

Abstract The integration of Phase Change Materials (PCMs) in buildings as a potential method to improve indoor thermal comfort can be achieved via free cooling/heating approach. This paper presents the results of a study on indoor thermal comfort and energy efficiency regarding the PCM's positive role when applied to the new constructive solutions, inside a building with a ceiling fan-assisted ventilation system. The scope was driven to investigate the potential of the solution for overheating/overcooling mitigation. The thermal performance of the proposed system was experimentally evaluated by comparing the behaviour of a prototype test room (including PCM panel), with the behaviour of a similar prototype test room, in which no PCM was added. First the experiments are conducted in an artificial climate inside a laboratory environment chamber which was controlled by harmonic and linearly rising/falling temperature changing processes. Experiments were performed based on 5 level RSM CCD method to quantify the potential effects of using PCM panels and to determine individual/interactive effect of parameters on thermal discomfort index, PPD. Results indicate that minimum discomfort level can be achieved when inlet air temperature and humidity, fan rotating speed and PCM slab height and thickness were set to 29, 48%, 115 rpm, 31 cm and 2.6 cm, respectively. PPD was obtained 4.1% in the optimized condition. Then optimised tests rooms were subjected to realistic daily temperature profiles during winter and summer. In summer case, the experiments proved that the PCM application in one of the rooms lead to an overheating reduction of 13.83% representing a PCM efficiency of 56%. Under the winter condition during two months, the experiments showed proposed hybrid system can averagely reduce discomfort level around 2.61% corresponding a PCM efficiency of about 35.49%. Based on the results, proposed system have the potential to shift cooling/heating energy demand away from peak hours. [ABSTRACT FROM AUTHOR]

Abstract In this paper, a combined solar chimney and water wall is proposed to provide ventilation as well as moderate heating to an attached room. A transient heat balance model (THBM) is established to predict the thermal performance of the combined system under mild winter conditions in Sydney, Australia. The effects of the glass panel thickness, air gap width, water column thickness, surface tinting and the relative position of solar chimney and water wall are studied respectively. The results show that the combined solar chimney and water wall is capable of providing ventilation throughout the day and night while maintaining the warmth level of the room even though it continuously draws fresh air from the ambient into the room. It is found that increasing the glass panel thickness or reducing the water column thickness enhances the thermal performance of the combined system by increasing both the room temperature and the ventilation rate. On the other hand, increasing the air gap width helps to increase the ventilation rate, but will cause the room temperature to decrease. In addition, between the two configurations, one with the water wall in front of the solar chimney (referred to as the WW-SC configuration) and the other with the solar chimney in front of the water wall (referred to as the SC-WW configuration), the ventilation rate and room temperature obtained with the SC-WW configuration are higher, and thus the latter configuration is more favorable. Furthermore, it is found that surface tinting generally degrades the thermal performance of the proposed system. [ABSTRACT FROM AUTHOR]

Highlight • A method is proposed to determine the potential limitations of free cooling. • The method links heat related health risks and thermal comfort. • A gap exists between thermal comfort and heat stress ergonomic standard indices. • A same temperature scale from thermal comfort to heat stress thresholds is proposed. • Thermal stress thresholds should be adjusted to heat acclimatisation of people. Abstract Heatwaves are responsible for many deaths due to hot weather. Natural ventilation is promoted as a cooling solution to reduce the impacts of climate change because of its energy-saving potential. This paper addresses the prediction of heat-related health risk situations in naturally ventilated dwellings, where indoor thermal conditions depend on external climate and occupant behaviour. Thus, the operating limits of a dwelling vary according to its dynamic thermal response to indoor and outdoor stresses. To secure a building design, a method to improve the prediction of heat-related health risks is proposed that links predicted percentage dissatisfied (PPD) and wet-bulb globe temperature (WBGT) indicators to distinguish a moderately warm situation from a heat stress situation (WBGT > 29 °C). Simulations are performed for a dwelling during the 2015 heatwave in Paris (France) to test the method. In the example, natural ventilation was found to reduce the indoor temperature, but there remains ambiguity regarding the ability of natural ventilation to provide moderate conditions. According to the scope of the ergonomic standards, "moderate thermal environment" and "heat stress" temperature ranges are not contiguous. Bridging of this gap requires establishing thermal comfort ranges and heat stress thresholds adapted to people according to their acclimatisation level and their sensitivity to heat. [ABSTRACT FROM AUTHOR]

Highlights • The Passive House (PH) Standard is shown to facilitate nZEB implementation. • nZEB houses can be constructed at no extra cost over traditionally built dwellings. • The IEQ of the monitored PH outperform current building regulations dwellings. • The nZEB/PH exhibits low heating costs and high occupant satisfaction. • Overheating needs to be addressed through design and operation. Abstract Across Europe dwellings will be constructed to comply with nearly Zero Energy Buildings (nZEB) standards by 2020. This requires highly performing dwellings, an arena previously the preserve of the Passive House (PH) Standard. This study examines the operational performance and cost of a set of nZEB dwellings built as PH dwellings and thereby investigates the potential of the PH typology as a solution to nZEB. This investigation is undertaken with particular focus on the context of social housing, given that this will account for a considerable portion (c.40%) of housebuilding in the next 10 years within some EU jurisdictions. Detailed construction cost comparisons are presented for an nZEB compliant PH dwelling (which is part of a scheme of 12 such dwellings) and compared to a similar dwelling which is constructed to comply with the current building regulations in the Republic of Ireland. The Indoor Environmental (IEQ) conditions, energy consumption and monitored cost of heating and ventilation are also presented. In addition, the paper presents the results of a comprehensive occupant satisfaction survey and extensive post occupancy monitoring and analysis for the scheme of PH dwellings. Finally it compares the monitored performance with that of 20 "standard" and PH dwellings, a number of which are nZEB compliant. While the study uses data across the UK and Ireland it has relevance to a much wider context for the deployment of nZEB in Europe and housing globally, and in particular the provision of social housing. [ABSTRACT FROM AUTHOR]

Abstract The aim of this paper is to determine the comfort temperature for men and women in two office buildings, one operating under mixed-mode strategy (naturally ventilated and/or air-conditioned) and one fully air-conditioned. Thus, 116 field studies were performed from March 2014 to March 2016 involving 584 participants in two office buildings. In order to collect temperature, relative humidity and air velocity data, microclimate stations were installed in the offices. Data collected were submitted to statistical analysis: they were initially separated according to the type of building (mixed-mode or fully air-conditioned) and operating system, and then they were distributed according to gender. The comfort temperatures were estimated by means of linear regression and by using the Griffiths method. Results show that the Griffiths method is more suitable to express the comfort temperature for men and women. Overall, the comfort temperature was 24.0°C for females, and 23.2°C for males. In the mixed-mode building, comfort temperature was statistically higher for females than that for males (23.7°C and 23.0°C, respectively). In the fully air-conditioned building, significant differences were found for comfort temperature for females and males (24.2°C and 23.4°C, respectively). Furthermore, when the mixed-mode building operated under natural ventilation the comfort temperatures tended to be lower for both men and women when compared to the comfort temperature found in the same building during air-conditioning operation. [ABSTRACT FROM AUTHOR]

Highlights • The accuracy of current CIBSE TM benchmark for University Campus (UC) was assessed. • A new revised benchmark called UCrb was presented which is more accurate than the current benchmark. • There is a difference of 110 kWh/m2/yr between UC and UCrb which is a significant improvement. • A new methodology for thermal energy estimation at the monthly scale was developed. Abstract According to Chartered Institution of Building Services Engineers, CIBSE TM46 benchmarks, a typical college building needs 240 kWh/m2 thermal energy annually. This paper firstly analysed the accuracy of the CIBSE TM46 ‘University Campus’ benchmark against the thermal consumption values displaying on Display Energy Certificates (DECs). The DECs of 52 typical college buildings in Dublin were assessed and based on the 46% discrepancy between the median of samples and the CIBSE benchmark a new benchmark of 130 kWh/m2/yr was recommended. Secondly, monthly thermal energy models (MTEMs) which take into account the variations of heat demand during a year were generated. MTEMs were created using five key factors, including the mixed use method, CIBSE UC recommended benchmark, activities area, heating degree days, and typical operational hours of heating systems. The high level of accuracy of MTEMs was assessed against the actual consumption. The developed methodology predicts an accurate and detailed estimation of monthly thermal energy consumption in typical college buildings. In addition, a new definition for typical college buildings which is a mixed use building including seven major activities is presented. [ABSTRACT FROM AUTHOR]

Highlights • A full-scale physical model of No. 8 Subway from Jiaodong International Airport, Qingdao, China, under shield tunneling was established. • Both numerical simulation and field measurement results reveal that dust particles in the tunnel cannot be effectively controlled under original ventilation condition. • The distance between the pressure outlet-2 in a secondary pressure ventilation system and the cutter, denoted as L p , was optimized. Abstract In order to gain a more in-depth knowledge of a shield machine's dust-suppression ventilation system, this paper uses the shield region on the south side of the No. 8 Subway from Jiaodong International Airport, Qingdao, China, as a case study, and conducts field measurements and numerical simulations for examining dust concentration distributions in a tunnel when the ventilation system is not in operation (i.e., under single-pressure conditions) and when the air pressure cylinder is in operation (specifically, the distance between the pressure outlet-2 and the cutter, denoted as L p , was set at different values within a range of 30∼75 m). The results reveal that under single-pressure conditions, dust was diffused throughout the entire tunnel and caused serious pollution. After the ventilation system was opened: when L p < 50 m, the use of a ventilation system could not control the diffusion of dust effectively, and its dust-suppression performance was enhanced with the increase of L p ; when 50 m ≤ L p ≤ 55 m, its dust suppression performance was relatively optimal, but some dust still spread to the operating region; when L p > 70 m, a low-velocity airflow belt was formed in the operating range of 25∼30 m, i.e., the ventilation requirements could not be satisfied; and when 60 m ≤ L p ≤ 70 m, both the ventilation and optimal dust suppression performance could be achieved simultaneously. Graphical abstract Image, graphical abstract [ABSTRACT FROM AUTHOR]

Abstract Understanding occupants’ thermal sensation and comfort is essential to defining the operational settings for Heating, Ventilation and Air Conditioning (HVAC) systems in buildings. Due to the continuous impact of human and environmental factors, occupants’ thermal sensation and comfort level can change over time. Thus, to dynamically control the environment, thermal comfort should be monitored in real time. This paper presents a novel non-intrusive infrared thermography framework to estimate an occupant's thermal comfort level by measuring skin temperature collected from different facial regions using low-cost thermal cameras. Unlike existing methods that rely on placing sensors directly on humans for skin temperature measurement, the proposed framework is able to detect the presence of occupants, extract facial regions, measure skin temperature features, and interpret thermal comfort conditions with minimal interruption of the building occupants. The method is validated by collecting thermal comfort data from a total of twelve subjects under cooling, heating and steady-state experiments. The results demonstrate that ears, nose and cheeks are most indicative of thermal comfort and the proposed framework can be used to assess occupants’ thermal comfort with an average accuracy of 85%. [ABSTRACT FROM AUTHOR]

Highlights • A methodology to assess fan energy savings when improving ductwork. • The methodology is based on EN 16798-5-1. • Simulations are compared with measured results on an experimental ventilation system. Abstract This paper proposes a methodology to assess fan energy savings when improving ductwork airtightness. This methodology builds on standard EN 16798-5-1:2017. Unlike the classical ``cube law'', it considers pressure drops at air terminal devices separately from the pressure drops in the rest of the system. The calculation tool based on this methodology: (a) gives the fan energy use before and after airtightness improvements with various inputs depending on the initial state; (b) indicates whether or not the required airflow rates are met at the air terminal devices; (c) gives a range of energy savings assuming, on the one hand, perfect fan adjustment, no errors in input data and constant fan efficiency, and on the other hand, safe-side estimates of deviations from these assumptions. Using experimental data from an earlier study on a full scale ductwork built in a laboratory, the tool gives results in good agreement with measured energy savings (within 7 percentage points). With ideal pressure adjustment and when required airflow rates were met before tightening, the maximum fan energy savings by tightening the ductwork from 1.5 times Class A to Class C reaches 51% according to the tool versus 46% according to measurement data. [ABSTRACT FROM AUTHOR]

Cooling demands of commercial buildings present a relevant challenge for a sustainable future. They account for over half of the overall energy needs for the operation of an average office building in warm climates, and this situation is expected to become more pressing due to increasing temperatures in cities worldwide. To tackle this issue, it is widely agreed that the application of passive strategies should be the first step in the design of energy efficient buildings, only using active equipment if it is truly necessary. Nonetheless, there is still further need for information regarding the potential limits derived from their application. This paper explores the effectiveness of selected passive cooling strategies in commercial buildings from warm climates, defining performance ranges based on the assessment of multiple scenarios and climate contexts. This task was conducted through the statistical analysis of results from documented research experiences, to define overall ranges and boundary conditions; and through software simulation of selected parameters to isolate their impact under a controlled experimental setup. General findings showed that the mere application of passive strategies is not enough to guarantee relevant savings. Their effectiveness was conditioned to both the harshness of a given climate and different building parameters. Specific recommendations were also discussed for the selected passive strategies considered in the evaluation. [ABSTRACT FROM AUTHOR]

In this paper we propose a novel and easily implementable model-based air balancing method for a ventilation system. The proposed method provides a well-defined form of balancing for a ventilation system, which can be effectively solved. The method follows three procedures: (i) mathematical modeling for duct system which is based on steady-state pressure balance; (ii) model parameters identification by supervised machine learning; (iii) determination of damper positions based on the model. The performance of this method is validated through testing in a duct testbed with five terminals. The results show that the final flow rates in all terminals match with the desired values with no more than 6.8% relative error. [ABSTRACT FROM AUTHOR]

Buildings consume a significant amount of energy worldwide in maintaining comfort for occupants. Building energy management systems (BEMS) are employed to ensure that the energy consumed is used efficiently. However these systems often do not adequately perform in minimising energy use. This is due to a number of reasons, including poor configuration or a lack of information such as being able to anticipate changes in weather conditions. We are now at the stage that building behaviour can be simulated, whereby computer programs can be used to predict building conditions, and therefore enable buildings to use energy more efficiently, when integrated with BEMS (i.e. simulation assisted control [1]). In this paper we demonstrate a low cost BEMS that uses building simulation to predict optimised electrical heating startup control points. Those that use electricity for heating in Scotland, where this study was based, tend to be fuel-poor, hence there is a strong case for optimisation, particularly when electricity costs nearly three times as much as the equivalent unit of gas for heating applications. The proposed system demonstrated a 50% energy saving in the reduced heating time compared to scheduling when retrospectively evaluated. [ABSTRACT FROM AUTHOR]

Occupant behaviour has a direct impact on building energy consumption. A better understanding of human-building interactions enables to describe with higher accuracy the occupant behaviour. This paper addresses occupant behaviour in residential buildings, providing a review of current methods in (1) monitoring occupant behaviour, (2) developing occupant behaviour models, and (3) applying occupant behaviour models in building performance simulations. Occupant behaviour studies with focus on residential buildings are presented including both challenges and potential for improving building energy performance. [ABSTRACT FROM AUTHOR]

A critical element of assessing a building's suitability for Demand Side Response (DSR) is understanding its turndown potential to ensure that DSR participation will be financially viable. While research has been undertaken on site level DSR estimation methods, there is currently no research that compares the outcomes of these methods. This paper compares four non-domestic energy estimation methods used for understanding the DSR potential of electrical appliances in a building to provide insights about uncertainty levels based on input requirements. Each method is deployed to estimate the DSR potential of HVAC chiller assets at two UK hotels over two years. The results show the methods have a range of error levels from the highest Mean Average Percentage Error (MAPE) of 159% to the lowest MAPE of 39%. The input requirements followed a general trend of more complex informational inputs resulting in lower error values. The outcomes of this research enable users to make informed decisions in selecting DSR estimation methods based on information availability and acceptable estimation error levels. [ABSTRACT FROM AUTHOR]

The rising costs of energy usage in the building sector have intensified research interest in passive energy saving strategies such as night ventilation (NV). Night ventilation has been shown to reduce the energy demand for cooling buildings as well as significantly ameliorate thermal comfort. A large number of studies have been undertaken to model and assess the effectiveness of NV across a wide variety of climates and building types. This paper reviews the key research on night ventilation strategies and identifies the main themes and directions present in contemporary research. It also classifies NV performance into three broad groups, namely climate, building and technical parameters. The literature provides evidence that night ventilation strategies are effective across most climate types, but as with most passive design strategies, optimization is required. Approaches to research within the reviewed literature include computer simulations and empirical studies; testing with full-scale physical prototypes; and monitoring of real world case studies. The effectiveness of different strategies in different climates is examined, as are NV control systems, and the coupling of NV with other systems. [ABSTRACT FROM AUTHOR]

In this paper our objectives are to perform a numerical and experimental study of the velocity field in the area affected by a circular exhaust duct, to define the outline of flow separation area at its inlet, to come up with a reliable mathematical simulation of the separated flow at exhaust duct inlet, and to determine the effect of the duct inclination angle its serviced area. The stationary discrete vortex method has enabled development of an adequate and reliable technique for computation of separated flows at inlet of a local exhaust hood. We have studied airflow patterns around the exhaust duct using the discrete vortex method, CFD and natural experiment. Characteristic dimensions of the flow separation area at exhaust hood inlet have been determined with relation to the length and inclination angle of the hood. Shaping the exhaust duct to fit the resulting separation zone outline will enable savings of energy that would otherwise be wasted on overcoming local drag forces; furthermore, this will prevent escape of contaminants circulating in the separation area to the environment. Determining airflow velocity distribution patterns will facilitate the choice of the most efficient exhaust duct design to minimize the cost of contaminant removal. [ABSTRACT FROM AUTHOR]

Supermarkets are energy intensive buildings and present a unique space conditioning challenge because of the interaction between the HVAC system and the refrigerated display cabinets. HVAC system is the largest consumer of energy after refrigeration depending on system design, geographical location and controls. Night ventilation is used extensively as a low energy strategy to cool buildings in climates where night temperatures are suitable. This paper presents a study of cooling benefits of night ventilation for supermarkets with high cooling demand. Energy and environmental data from two stores with high percentage of frozen and chilled goods and with different HVAC systems are presented. Validated models in EnergyPlus are developed for the two stores and their systems. A parametric study of the coupled operation of night ventilation and active cooling for the climatic conditions of south east England is carried out and optimisation strategies are modelled. Results indicate that effective night ventilation can reduce the duration of active cooling during trading times and achieve 17% reduction in cooling annual energy use, 3.3% in total annual energy use while refrigeration energy use is not affected. [ABSTRACT FROM AUTHOR]

Providing a comfortable and pleasant indoor environment for the occupants is the primary objective of an efficient ventilation process. Therefore, it is important to gain a proper understanding between the interaction of airflow and the occupants which determines the ultimate ventilation strategy and as one of the final outcomes, the architecture layout itself. The CFD (Computational Fluid Dynamics) methods provide an accurate and robust tool to simulate the complex airflow structure in enclosed spaces. Among the CFD simulation approaches, the large eddy simulation (LES) and its hybrid variants such as detached eddy simulation (DES) provides the information on the flow behavior by modeling the small turbulent structures of the airflow encountered in an indoor environment. These methods are highly sensitive to the boundary conditions which are the pivotal factors in an indoor airflow modeling and its accuracy. The main objectives of this paper are: (a) to assess the performance of different LES and DES models in capturing velocity and thermal fields (b) to investigate the effect of manikin’s shape on the accuracy of predictions. Three LES SGS (sub-grid scale) and one DES models are applied in this study considering the cases with and without the radiation from the manikin. Moreover, the effect of simplifying the manikins’ geometry on velocity and thermal distribution is investigated. Results showed that a detailed manikin shape can provide more accurate predictions (4–10%) at some locations, especially those close to the manikin’s body. As for performance of the applied models, Comparisons showed that ZEM and WALE models provide a better predictions of velocity and temperature fields by 3–10% at different locations. [ABSTRACT FROM AUTHOR]

Whole-house ventilation, which is defined as systems that supply and exhaust or relieve ventilation air for a residence, has been a mandatory provision since the announcement of IECC 2012. As a result, an increasing numbers of publications and standards are now addressing residential ventilation in terms of performance and efficiency. In addition, loudness is increasingly addressed in standards and guidelines, especially in the last decade as it is now considered to be a significant factor for certified performance ratings of ventilation fans. Because of the above interest in fan performance, this paper provides statistics of bathroom ventilation fan tests and their results for an almost decade-long period from 2005 to 2013. Also, the paper interprets these statistics with regards to the recent development of residential ventilation standards and guidelines. In order to investigate year-to-year changes, this paper first evaluates changes in loudness ratings for the test period 2005–2013, and its relevance to applicable standards, including ASHRAE 62.2. Then, noticeable transitions in loudness and efficacy in specific time frames are investigated. The test results of DC-motor high-efficiency bathroom fans are also compared to AC-motor fans. Relationships between performance variables and loudness are investigated, and formulated by developing regression models. [ABSTRACT FROM AUTHOR]

Smart building systems are opening up new markets, nevertheless the implementation of these novel technologies still lacks suitable and proven whole engineering solutions in complex buildings. This paper presents a detailed approach for the ventilation control of an underground space, as an example of application of the developed solution to a very harsh environment but also highly demanding in terms of energy consumption. The underground spaces are characterized by a particular thermal behavior, because of the continuous and huge thermal exchange they have with the outside, via the openings and the ground surrounding the majority of the building. The main objective of the developed methodology is to reduce energy consumption of ventilation control while maintaining acceptable comfort levels: succeeding in achieving this twofold goal in a real station and the generalization of the approach are the most relevant contributions of the paper. The developed solution is based on a Model-based Predictive Control algorithm used together with a proper monitoring platform. The model predictive control is based on a Bayesian environmental prediction model, which works in cooperation with a weather forecast web service, schedule-based predictions about trains and external fans and an occupancy detection system to appraise the real amount of people. The prediction model develops scenarios useful to allow the controller acting in advance in order to adapt the system to the current and future conditions of use, taking profit of the knowledge of the real ventilation demand. Finally, the proposed control architecture is applied to the Passeig de Gràcia metro station in Barcelona as a case study, validating the usefulness of the proposed approach and obtaining more than 30% of energy savings in the ventilation system, while maintaining the pre-existing comfort levels. The saving percentage values estimated by simulation are confirmed by the direct measures continuously taken on site through energy-meters. [ABSTRACT FROM AUTHOR]

This paper focuses on a full-scale experiment to assess and model the airflow rate in a naturally ventilated room using different approaches. The building studied is located in a coastal area of Corsica and mostly affected by thermal breezes phenomena which lead to high airflow rate during day (between 8 and 30 ACH ) and lower during night (between 2 and 8 ACH ). The first aim of this work is to set up a method in order to measure continuously the airflow rate in cross ventilation configuration using a minimal number of sensors. Our methodology involves direct measurements of velocity on a mesh and use of statistical methods. The second objective is to develop and evaluate different airflow modeling approach in cross natural ventilation configuration. Various levels of complexity are tested and compared: empirical modeling, model calibration and behavioral modeling based on artificial neural networks. In terms of error, the artificial neural network appears to be the best compromise to model the airflow rate and allow to reach a MAE of 1.75 ACH with a one minute time step. Suggested model in this paper can be coupled with a thermal model and is suitable for model based natural ventilation control. [ABSTRACT FROM AUTHOR]

In this paper, a phase change material (PCM) to air rectangular heat exchanger is studied for an objective of electricity peak shaving. First, a set of dimensionless numbers are derived from physical equations to understand the storage device behaviour: 1/ BiFo , Bi / St and Ste . Second, these numbers are used to select the PCM based on the thermophysical properties of the material. Finally, the storage device is pre-designed by a proper analysis of the remaining dimensionless numbers. With the methodology developed in this paper, it is possible to efficiently design solutions from the specification requirements of the storage system. [ABSTRACT FROM AUTHOR]

Industry is stuck in reactive mode regarding the maintenance of their heating, ventilation and air conditioning (HVAC) systems, which leads to inefficient operation. To avoid wasteful use of natural resources a proactive approach is needed. To enable this transition combined knowledge-based and data-driven approaches such as the Industrial Data Analysis Improvement Cycle (IDAIC) framework have been proposed, but there is a lack of practical implementation in the literature. In this paper, we implement the IDAIC framework on an Air Handling Unit (AHU) in a real industrial facility to address the lack of practical and reproducible real world analysis. The lack of domain knowledge-driven data mining solutions is addressed primarily in two parts. Firstly, data and control issues are addressed to enable the application of knowledge-based techniques to detect faults that are easily identifiable. Secondly, data-mining based techniques are applied which focus on the detection of more subtle faults which are indicative of component degradation. This approach enabled the development of data-driven analysis that visualises the effect of the different modes of operation on the energy consumption of the AHU, which allow the onsite facilities team to make more informed decisions regarding the maintenance of this AHU. [ABSTRACT FROM AUTHOR]

One major obstacle encountered in building energy conservation and retrofit is the lack of detailed energy submetering data. Direct submetering is expensive and sometime very difficult to be installed in real practice. For example, the HVAC terminal end-use electricity consumption is extremely difficult to measure, because its data is always mixed together with lighting-plug or power submeter. This paper presents a new approach to solve this problem, which is based on a Fourier series model (FSM) for calculating the lighting-plug and power submeters in commercial buildings, and then disaggregate the HVAC terminal end-use hourly electricity consumption from them. Compared with black-box models, such as ANN, SVM and so on, FSM as a grey-box model has two key advantages (1) the application is convenient because of its simple model structure and (2) once a model is developed, it can be used in other same type commercial buildings directly. Measured data from two office buildings and two shopping malls located in Shanghai are analyzed in this paper. The disaggregation results demonstrate that the method is accuracy within a reasonable degree. The calculated hourly HVAC terminal end-use electricial consumption is close to the real measured data. The MRE (mean relative error) and CV (coefficient of variability) both can be controlled within 10%, and in some special cases they are almost within 1%. [ABSTRACT FROM AUTHOR]

This paper proposes a ventilated window with a phase change material (PCM) heat exchanger as a new window application. In summer, night ventilation mode is operated to discharge energy stored in PCM by the ambient cold air, which can be reloaded again, when ventilation pre-cooled air is provided. Numerical model is built and verified by full-scale experiment to evaluate the PCM ventilation system. The nonlinear properties and hysteresis of PCM are set in the model. The conclusion is that the configuration optimization should be based on different climates. In the case study in Copenhagen, the heat exchanger with 10 mm plate thickness is optimized. It can cool down the ventilated air 6.5 °C on average in 3.9 h pre-cooling effective time with 3.19 MJ/day energy saving. The material cost saving is 16.87% compared to 20 mm plate thickness which has similar discharged heat amount. Nevertheless, the heat exchanger with 5 mm plate thickness has a faster thermal response and a higher cost saving ability, which is good for the climate when the period of outdoor air temperature suitable for night ventilation in a day is short. [ABSTRACT FROM AUTHOR]

Conventional applications of earth-air heat exchanger (EAHE) inevitably have high initial cost to have better performance, or issues about insufficient installation space. To improve the feasibility of EAHE in high-density housing, this paper presents an integrated system consisting of air pipes immersed in the water-filled raft foundation, taking advantage of immense amount of water and relatively stable temperature in raft foundation of building. The aim of the study is to perform a field monitoring and performance analysis of EAHE integrated with water-filled raft foundation of residential building. The foundation-integrated EAHE was applied to a residential building located in Yilan, Taiwan, and its thermal performance was measured in the field experiment. The results indicated that the cooling potential of integrated system was close to the potential of soil-based EAHE at 2 m depth or deeper. An analytical model based on thermal resistance method was validated by measurement results, and was used to carry out the dimensioning of foundation-integrated EAHE. In addition, the return-on-investment with regard to thermal performance and economics of the application was evaluated. Because the installation for air pipes is scheduled in the building foundation construction, the utilization of integrated system spends less construction cost compare to the conventional EAHEs. [ABSTRACT FROM AUTHOR]