Search

• 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 • 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]

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]

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]

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]

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]

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]

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]

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]

Natural ventilation is a green building strategy that improves building energy efficiency, indoor thermal environment, and air quality. However, in practice, it is not always clear when and how to utilize the natural ventilation and coordinate its operation with the HVAC system. This paper introduces a reinforcement learning control strategy, specifically through model-free Q-learning, that makes optimal control decisions for HVAC and window systems to minimize both energy consumption and thermal discomfort. This control system evaluates the outdoor and indoor environments (temperature, humidity, solar radiation, and wind speed) at each time step, and responds with the best control decision that targets both immediate and long-term goals. The reinforcement learning control is evaluated through numerical simulation on a building thermal model and compared with a rule-based heuristic control strategy. Case studies in hot-and-humid Miami and warm-and-mild Los Angeles demonstrated the superior performance of reinforcement learning control, which led to 13% and 23% lower HVAC system energy consumption, 62% and 80% lower discomfort degree hours, and 63% and 77% fewer high humidity hours compared to heuristic control. Unlike heuristic control that requires specific knowledge of individual buildings and the creation of exhaustive decision-making scenarios to improve performance, reinforcement learning control guarantees optimality through self-advancement on given goals and cost functions and is able to adapt to stochastic occupancy and occupant behaviors, which is difficult to accommodate by heuristic control. [ABSTRACT FROM AUTHOR]

The requirements concerning energy performance of buildings and their internal installations, particularly HVAC systems, have been growing continuously in Poland and all over the world. The existing, traditional calculation methods following from the static heat exchange model are frequently not sufficient for a reasonable heating design of a building. Both in Poland and elsewhere in the world, methods and software are employed which allow a detailed simulation of the heating and moisture conditions in a building, and also an analysis of the performance of HVAC systems within a building. However, these systems are usually difficult in use and complex. In addition, the development of a simulation model that is sufficiently adequate to the real building requires considerable time involvement of a designer, is time-consuming and laborious (Menberg et al., 2019) [1]. A simplification of the simulation model of a building renders it possible to reduce the costs of computer simulations. The paper analyses in detail the effect of introducing a number of different variants of the simulation model developed in DesignBuilder on the quality of final results obtained. The objective of this analysis is to find simplifications which allow obtaining simulation results which have an acceptable level of deviations from the detailed model, thus facilitating a quick energy performance analysis of a given building. [ABSTRACT FROM AUTHOR]

A major challenge facing the buildings sector is the absence of continuous commissioning and the lack of performance monitoring and evaluation leading to buildings energy performance gaps between predicted and actual measured performance. Aiming to better characterize, evaluate and bridge these gaps, the paper proposes an online building energy performance monitoring and evaluation tool ObepME, serving as a basis for fault detection and diagnostics and forming a backbone for continuous commissioning. A calibrated building dynamic energy model is developed and employed to automatically run on a daily basis and simulate the building transient performance for the previous day. The simulated energy consumption results form a baseline to which the actual collected data are compared to evaluate the dynamic energy performance gap. The OU44 University building in Denmark is considered as a case study to implement the proposed framework. A holistic energy model was developed in EnergyPlus and calibrated employing data from various building meters, collected weather conditions, generated occupancy schedules and systems operational parameters and set-points. The calibrated model was employed in the ObepME tool to automatically and continuously monitor and evaluate the OU44 building energy performance, on the level of the whole building and individual energy systems consumption, throughout the period from February to mid-March 2017. The reported dynamic energy performance gap was around −2.85%, −3.47% and 5.48% for heating, total electricity and ventilation system electricity consumption. In addition, specific observations were made on a daily basis in terms of the overall electricity, heating, lighting and ventilation energy consumption as highlighted by the ObepME tool. The ObepME tool is currently running automatically as a part of the OU44 building continuous commissioning and performance evaluation aiming to identify possible discrepancies and deviations paving the way for a methodical preventive fault detection and diagnostics process on various levels in the building. [ABSTRACT FROM AUTHOR]

This paper presents the development of a symbolic transformation based strategy with interpretability and visualisation for building energy performance assessment. The strategy was developed using shape definition language based symbolic transformation and hierarchical clustering. Advanced visualisation techniques including dendrogram, heatmap and calendar view were used to assist in understanding building energy usage behaviours. A comparison of this proposed strategy with a Symbolic Aggregate approXimation (SAX) based strategy was also performed. The performance of the proposed strategy was tested and evaluated using the three-year hourly heating energy and electricity usage data of a higher education building. The result demonstrated that the proposed strategy can identify distinct building energy usage behaviours. The visualisation techniques used also assisted the information discovery process. The discovered information helped to understand building energy usage patterns. The comparison of the proposed strategy with the SAX based strategy showed that the proposed strategy outperformed the SAX based strategy for the case building tested in terms of the variations in building energy usage. This proposed strategy can also be potentially used to evaluate the operational performance of building heating, ventilation and air-conditioning (HVAC) systems. [ABSTRACT FROM AUTHOR]

The paper investigates whether air-water heat exchanger with longitudinal fins along the air flow direction are an appropriate means to reduce pressure loss in mechanical ventilation systems, compared to conventional heating coils. To answer this question, theoretical calculations regarding pressure loss and heat transfer are performed and the results are checked by measurements. It is found that a longitudinal fin heat exchanger with 30 radially arranged fins and an overall length of 830 mm transfers the same heat flow as a conventional heating coil (∅ 125). The pressure loss only adds up to about 60% to 70%, so a reduction of 30% to 40% can be achieved. Additionally it is expected, that the longitudinal fin heat exchanger is more suitable for efficient low temperature heating systems, because of the counter-current heat transfer. The disadvantage of its increased length can be compensated by integrating the longitudinal fin heat exchanger in a duct silencer, which is required anyway. Hence, the energy efficiency of mechanical ventilation system can be increased. [ABSTRACT FROM AUTHOR]

Facade integrated ventilation systems have the potential to improve local air quality and occupant comfort, reduce building energy consumption and provide economic retrofit opportunities. However, existing modelling and evaluation methods are not able to sufficiently address the technology's potential capabilities. In this paper, a new model is developed specifically adapted to facade-integrated air handling units interacting with ventilated fenestration systems. The new modelling approach is based on the co-simulation of two different models through a Functional Mock-Up Unit (FMU) Interface. An airflow network model of the air handling unit is developed in Modelica and exported as an FMU based on this specification. The FMU is then simulated within an updated version of the building simulation program Fener that includes a physical model that calculates the window heat fluxes and temperatures, as well as the window gap air outlet temperature in case of ventilated facades. The different sub-models are first validated versus experimental data from a test chamber in Villafranca di Verona, Italy. Then, the full co-simulation approach is applied to a case study in which different control strategies for the fenestration system are investigated. [ABSTRACT FROM AUTHOR]

There are approx. 5.5 million residential buildings in Poland including 5 million single-family houses, 90% of which were built before 2002. Most of the existing single-family houses are not energy-efficient and a large amount of energy is wasted. It is therefore essential to develop, experimentally validate and then disseminate strategies for thermal modernization of the existing single-family houses, including strategies for ventilation systems renovation. In two-storey single-family houses with sloping roofs it is possible to locate a ventilation heat recovery (VHR) unit and ventilation ducts in the unheated roof space. The paper presents the results of tests of combined ventilation systems: mechanical ventilation with heat recovery in rooms on the second floor and stack ventilation in the rooms on the first floor. On-site measurement of the efficiency of ventilation heat recovery was performed, the airtightness of the house was measured twice before and after its improvement. The results of the experimental tests of the hybrid system were used to estimate the ventilation airflow in the house and the energy demand for ventilation. The ventilation airflow was calculated using the software CONTAM. The estimated heat demand for the tested ventilation system was 37.4 kWh/m 2 /season; though it seems possible to reduce it below 20 kWh/m 2 /season. [ABSTRACT FROM AUTHOR]

Abstract: The present paper focuses on the development and experimental validation of a model of air-to-air heat exchanger dedicated to domestic mechanical heat recovery ventilation. The proposed model describes dry and partially wet regimes. The first part of the paper presents a semi-empirical model based on the physical characteristics of the heat recovery device and relying on empirical correlations available in the literature for the convective heat transfer coefficients. In the case of partially wet regime, a moving boundary model is applied in order to predict sensible and latent heat transfer rates. A model developed with friction factor coefficients estimated by correlations from the literature is also presented in order to predict the hydraulic performance in dry conditions. The second part of the paper describes the experimental investigation conducted on an off-the-shelf heat exchanger. Experimental data are used to tune correlations for the determination of the convective heat transfer coefficient and validate the proposed simulation model of the ventilation heat recovery exchanger in partially wet conditions. The model developed to determine the hydraulic performance with existing correlations for the friction factor coefficient does not require a calibration. Finally, examples of use of the developed model are presented, which includes coupling the model with a building simulation model, a study of the influence of the humidity on the evolution of the latent and sensible heat transfer rates and strategies to avoid freezing in the heat exchanger. [Copyright &y& Elsevier]

Air temperature and speed play a critical role in the thermal sensation of comfort felt by occupants, especially in the tropics. It is of great practical interest to coordinate air conditioning and mechanical ventilation (ACMV) system and personal fans so as to enhance building demand response (DR) capability while minimizing energy cost in response to a specific electricity price signal and maintaining a thermal comfort level. In this paper, an optimization problem of coordinating ACMV and personal fans is addressed, which captures the coupling between ACMV and fans. A Lagrangian relaxation-based algorithm is developed to solve the problem by individually solving the subproblems of ACMV and personal fans with Lagrangian multipliers as the coordinated signals. This algorithm can separate the calculation of the cooling effect from the optimization procedure, so we do not have to solve the problem using a non-analytical model for evaluating the cooling effect provided by the fans. The performance of the proposed method is evaluated and validated using experimental and simulation results. Both the results show that coordinating ACMV and fans can substantially enhance building DR capability, save energy cost, and also improve customized thermal comfort microenvironment. [ABSTRACT FROM AUTHOR]

This paper introduces a low-cost, high-quality Decision Making Mechanism for supporting the tasks of temperature regulation of existing HVAC installations in a smart building environment. It incorporates Artificial Neural Networks and Fuzzy Logic in order to improve the occupants’ thermal comfort while maintaining the total energy consumption. Contrary to existing approaches, it focuses in achieving significantly low computational complexity, which in turn enables its hardware implementation onto low-cost embedded platforms, such the ones used in smart thermostats. Both the software components and hardware implantation are described in detail. To demonstrate its effectiveness, the proposed method was compared to ruled-based controllers, as well as state-of-the-art control techniques. A simulation model was developed using the EnergyPlus building simulation suite, a detailed modeled micro-grid environment of buildings located in Chania Greece and historic weather and energy pricing data. Simulation results validate the effectiveness of our approach. [ABSTRACT FROM AUTHOR]

The hollow block ventilated wall is a new kind of ventilated wall, the exhaust air of HVAC system is used as the supply air to flow through the cavity of this wall in this paper. The heat or cool storage in the wall is reduced by using the heat recovery technology; the temperature of internal surface is lowered in summer and increased in winter, and the human thermal comfort is enhanced. A semi-dynamic heat transfer model of the ventilated wall is presented for thermal performance prediction. The dynamic optimized resistance-capacitance (ORC) model and the number of transfer units (NTU) model are joined together to develop the semi-dynamic heat transfer model of this ventilated wall. The experimental study is carried out for validating the semi-dynamic heat transfer model. The maximum relative error is 4.3% for mean internal and external surface temperatures, and it is 2.6% for the outlet air temperature of the cavity. The heat transfer model established for hollow block ventilated wall is fairly reasonable and possesses high accuracy. This model can be used to predict the surface temperature of the hollow block ventilated wall and the heat flux removed by the airflow in the cavity for performance evaluation. [ABSTRACT FROM AUTHOR]

Abstract: This paper summarizes a study undertaken to reveal potential challenges and opportunities for integrating optimization tools in net zero energy buildings (NZEB) design. The paper reviews current trends in simulation-based building performance optimization (BPO) and outlines major criteria for optimization tools selection and evaluation. This is based on analyzing user''s needs for tools capabilities and requirement specifications. The review is carried out by means of a literature review of 165 publications and interviews with 28 optimization experts. The findings are based on an inter-group comparison between experts. The aim is to assess the gaps and needs for integrating BPO tools in NZEB design. The findings indicate a breakthrough in using evolutionary algorithms in solving highly constrained envelope, HVAC and renewable optimization problems. Simple genetic algorithm solved many design and operation problems and allowed measuring the improvement in the optimality of a solution against a base case. Evolutionary algorithms are also easily adapted to enable them to solve a particular optimization problem more effectively. However, existing limitations including model uncertainty, computation time, difficulty of use and steep learning curve. Some future directions anticipated or needed for improvement of current tools are presented. [Copyright &y& Elsevier]

To date, religious facilities have received little attention in the published literature regarding energy use and efficiency. With unique operating and building characteristics, these buildings have distinct opportunities for analysis in regards to building energy use and occupant comfort. With overall lower average energy intensity, religious facilities rarely receive energy assessments or are operated by experienced personnel. Therefore, identifying common issues is critical for training church owners in energy efficiency. This paper presents an in-depth analysis of heating, ventilation and air conditioning (HVAC) systems and occupant comfort in two religious facilities. The analysis reveals that the largest opportunities for reduction in energy use come from proper maintenance and operation of HVAC equipment and schedules. Temperature setbacks are shown to be an important operational setting to reduce energy usage. An accompanying analysis on thermal comfort reveals that temperature setbacks must be coupled with sufficient preconditioning of the space to ensure occupant comfort during intermittent building occupancy. An analysis of CO 2 levels in the building during occupancy reveals the need for sufficient outside air to meet ventilation standards. [ABSTRACT FROM AUTHOR]

Inter-building effect is responsible for affecting buildings’ primary energy requirement for heating, cooling, and lighting. Nevertheless, the impact of natural ventilation should also be considered while predicting building energy demand, since it is documented to substantially affect indoor environmental quality and thermal comfort. This paper investigates the impact of natural ventilation on building primary energy requirement prediction. The Inter-Building Effect (IBE) approach is applied in a typical residential block in Italy. A sensitivity analysis is performed to determine the key input parameter among (i) climate boundary, (ii) infiltration rate, (iii) opening percentage, and (iv) wind strength. Two scenarios, i.e. the stand-alone building and the same building surrounded by its neighborhood, are compared. The thermal-energy dynamic simulation of the different scenarios is carried out to investigate the impact of outdoor airflows on building primary energy requirement for heating and cooling and on indoor thermal comfort, investigated by means of the Thermal Deviation Index method. Inaccuracies in energy need prediction imputable to natural ventilation without taking into account the IBE are detected. The findings show that IBE is much more affected by buildings’ opening percentage, infiltration rate, and local wind compared to the weather context since IBE is a local microscale phenomenon. [ABSTRACT FROM AUTHOR]

Abstract: With cities accounting for approximately two thirds of the global demand for energy, there is significant scope to optimize energy usage of cities, in particular by improving the use of the built form. Large non-domestic buildings are increasingly the focus of attention, due to their substantial demands and associated environmental impacts such as CO2 emissions. Various approaches have been adopted to address building energy efficiency, with more recent studies relating consumption patterns to human occupancy. This paper proposes a new method to measure activity, using WiFi connections as a proxy for human occupancy. Data on the number of WiFi connections and energy consumption (electricity, steam and chilled water) were compared for two buildings within the Massachusetts Institute of Technology''s campus. The results of the study demonstrate: the operation of the heating, ventilation and air conditioning (HVAC) systems adhered more closely to factors other than occupancy i.e. external temperature, whilst a small part of the electricity levels did correlate with the occupancy. In order to present possible solutions to address the disconnect between the HVAC system and occupancy levels, this paper identifies future steps that could begin to improve energy usage. [Copyright &y& Elsevier]

Most of the state-of-the-art building simulation programs implement models in imperative programming languages. This complicates modeling and excludes the use of certain efficient methods for simulation and optimization. In contrast, equation-based modeling languages declare relations among variables, thereby allowing the use of computer algebra to enable much simpler schematic modeling and to generate efficient code for simulation and optimization. We contrast the two approaches in this paper. We explain how such manipulations support new use cases. In the first of two examples, we couple models of the electrical grid, multiple buildings, HVAC systems and controllers to test a controller that adjusts building room temperatures and PV inverter reactive power to maintain power quality. In the second example, we contrast the computing time for solving an optimal control problem for a room-level model predictive controller with and without symbolic manipulations. Exploiting the equation-based language led to 2200 times faster solution. [ABSTRACT FROM AUTHOR]

Model predictive control (MPC) has been studied in the building science realm for about three decades. However, the following two aspects of the building control have not been studied thoroughly in MPC research. One is the impact of the mixed-mode cooling system on the active heating ventilation and air conditioning (HVAC) energy consumption, and the other is the differences of individual thermal comfort preference and its impact on energy. This paper proposes an occupant-oriented mixed-mode EnergyPlus predictive control system to optimize HVAC energy consumption while meeting the individual thermal comfort preference. A web-based dashboard is implemented in the test-bed building for three months to collect individual thermal comfort preference data. The data analysis results suggest that occupants have various tolerances and preferences about thermal comfort. The simulation results show that, during one week of a typical swing season, the mixed-mode system further reduces the active HVAC energy consumption, and the diversified occupant thermal comfort preference has significant impact on HVAC energy consumption. [ABSTRACT FROM AUTHOR]

Combined air heating and ventilation systems are often used in low energy buildings. However, operating these systems in the heating mode increases vertical air temperature gradient in rooms and can have negative effect on indoor air quality. The effectiveness of ventilation and personal exposure of the occupants to airborne pollutants generated at the floor level in rooms with the combined air heating and mixing ventilation was analyzed in this paper. The dispersion of pollutants was evaluated under three air distribution methods (in-ceiling four-way and one-way air supply, and high level wall grille air supply) and under three air change rates (1, 2, and 3 ach). Each of these cases were tested at the supply air temperature of +20 °C and +25 °C by performing CFD simulations and experiments in the full-scale test chamber. The results of the experiments showed higher inhaled concentration of the contaminants under the heating mode. The inhaled-to-ambient pollutant concentration ratio varied in the range of 1.05–1.41 under the ventilation mode and it rose up to 1.14–1.78 under combined air heating and ventilation mode. CFD predictions confirmed that pollutants generated at the floor level are entrained into convective boundary layer of the occupant in cases when vertical air temperature gradient was present. The personal exposure to pollutants released at the floor level can increase significantly when a HVAC system runs in the combined air heating and ventilation mode; this effect will not necessarily dissolve with the increase of the air change rate. [ABSTRACT FROM AUTHOR]

In buildings, HVAC systems consume a high amount of energy to provide thermal comfort for occupants. A methodology is presented in this paper to control thermostat operation of the buildings considering the effects of indoor and outdoor boundary conditions and phase change material (PCM) characteristics. EnergyPlus v8.1 building energy simulation software was used to analyze the energy performance of the PCM incorporated building models and to implement Fanger model to control HVAC thermostat operation according to BS EN 15251:2007 thermal comfort categories. Three types of building HVAC schedule, PCM with different melting points and layer thicknesses were studied for Madrid climate zone. Moreover, the impact of occupants clothing on the energy consumption was investigated. Furthermore, payback analysis was conducted to find out the economic benefits of PCM integration into the building envelopes. Application of PCM improved the cooling and heating energy performances except for the office model in winter (heating period). Additionally, higher energy savings and lower payback periods were observed when PCM with higher melting point was applied to the buildings. Eventually, energy savings in PCM incorporated models were found to improve further when occupants changed their clothing behavior in winter. [ABSTRACT FROM AUTHOR]

Mechanical ventilation systems have a significant influence on the energy demand of buildings. The Government's aim is to reduce the energy demand for mechanical ventilation by 2020. Therefore, energy efficient mechanical ventilation systems are required. Using dampers to balance the ventilation system, the centralised fan must provide sufficient static pressure to overcome the maximum pressure drop in the system. This means that there will be excess pressure in parts of the duct system. Using decentralised fans instead of dampers, the excess pressure can be eliminated as each fan provides the pressure needed for that particular part of the duct system. In duct systems in conventional supply ventilation systems, there is a positive static pressure compared with the pressure inside the building. Using decentralised fans, parts of the duct system will have a negative pressure and room air may enter the duct system and spread to other parts of the building. In this paper, the possibility of reversed airflow was investigated. An evaluation of reversed airflow was implemented both theoretically and experimentally. With the objective of simulating a malfunctioning, one integrated fan did not operate during the investigations while the others did. When a manifold was used to distribute the pressure, the reversed airflow was eliminated. This was due to the positive pressure in the manifold that was maintained by the main fan. When the ventilation system was a regular supply duct system with a main fan and a main duct with branches, then there was a possibility of reversed airflow if a fan malfunctioned. [ABSTRACT FROM AUTHOR]

In order to reduce energy consumption in buildings, a solution using phase change materials (PCMs) as thermal energy storage (TES) is presented. During summer nights, cold is stored and delivered during the day to reduce cooling load, whereas in winter, heat from solar air collector is stored for heating during morning and evening hours. Proposed is a stand-alone unit suitable for offices, which consists of plates filled with paraffin RT22HC. The objective of the paper is to examine the functioning of the suggested TES system on an annual basis and to explore the feasibility of using it for both, cooling and heating. First numerical model is set up, which assumes 2D geometry and evaluates thermal response, calculations are carried out in Fluent. Then validation of simulations with experimental results is established. Finally the feasibility of storage unit on an annual basis is demonstrated. [ABSTRACT FROM AUTHOR]

Artificial intelligence techniques have been successfully applied to control dynamic systems looking for an optimal control. Among those techniques, reinforcement learning has been shown as particularly effective at reducing the dimensionality of some real problems and solving control problems by learning from experience. The use of thermal energy storage active systems in the building sector is identified as suitable option to reduce their energy demand for heating and cooling. However, these systems might be expensive and require appropriate control strategies in order to improve the performance of the building. In this paper a ventilated facade with PCM is controlled using a reinforcement learning algorithm. The ventilated facade uses mechanical ventilation during nighttime to solidify the PCM and releases this cold stored to the inner environment during the peak demand period. It is crucial to decide correctly the schedule of charge and discharge process of the PCM according to the weather and indoor conditions. An experimentally validated numerical model is used to test the performance of the control algorithm under different weather conditions. Important improvements on the energy savings due to the use of control strategies were found and supported by the data under the different tested climatic conditions. [ABSTRACT FROM AUTHOR]

The damper used for the control of airflow in heating, ventilation and air conditioning systems can constructively be adapted to measure the air velocity with its moment characteristic. It is a device that indirectly determines the air velocity by measuring the position of the blades and the air stream moment acting on it. The subject of this paper is energy consumption of the air torque position damper depending on its structure. The aim is to compare the energy consumption of four possible types of dampers with non-cascading blades: with one blade, with two cross-guided blades, with two parallels-guided blades and with two blades, one of which is a measuring blade and the other remains fixed in horizontal position. The case when there is a straight section of a duct both in front of and behind the damper was considered. Adequacy of the existing mathematical model and energy consumption for all four types of dampers was determined experimentally. It was found that the damper with two blades of which one is a measuring blade and other remains fixed in horizontal position had minimal energy consumption. [ABSTRACT FROM AUTHOR]

The paper presents the results of the analysis of the impact of various ventilation systems on the energy consumption performed for one Polish museum building that was built in 1929–1930. Simulations were carried out with the use of two computer codes: CONTAM and ESP-r. Multi-zone models including the exhibition rooms and the staircase were prepared. The simulations were made of synthetic weather data for one of the Polish towns for two months of the heating season. Twenty-four hour variability of internal heat gains was taken into account. The results show clearly that the natural ventilation system (which is currently used in the building) enables the air exchange with fresh air on the first floor only. The air infiltration on the upper levels is close to zero. Rebuilding the ventilation system generates changes in the energy demand of the building. It is presented how the heat demand increases with the increase of the ventilation air flow and what is the impact of the air infiltration on the heat demand for different variants of ventilation. [ABSTRACT FROM AUTHOR]

The paper focuses on the assessment of the windows’ contribution to the energy performance of buildings in the warmer regions of Europe. This is derived by calculating the cooling energy index q c and the area weighted energy needs for different window configurations installed on a reference room for two different building uses, office and residential. The examined window types differed with regard to their thermophysical and optical properties ( U - and g -value), geometry (frame and window fractions) and orientations. The energy parameters used for the performance assessment were calculated with the help of a dynamic simulation tool for a location with a representative Mediterranean climate. The extensive multi-parametric analysis exhibited interesting results. It was found that for the cooling mode the energy performance of windows in warm climates is influenced significantly by their thermophysical properties. More specifically, the impact of solar transmittance is significant and its optimal selection can contribute in minimizing the energy consumption, especially in environments with controlled ventilation, such as offices. On the contrary, advanced fenestration products with low thermal transmittance seem to behave unfavorably, since their extremely low thermal transmittance prohibits the dissipation of heat toward the ambient environment and results ultimately in higher cooling energy loads. [ABSTRACT FROM AUTHOR]

This paper discusses the performance of CO 2 adsorption device and its utilization to save energy in buildings. This new device adsorbs CO 2 and a small amount of moisture in the CO 2 capture process, and it evaporates pure CO 2 by thermal energy in the desorption process. This study shows the possibility of implementing a CO 2 capture device in the operation of an air ventilation system for high performance air cooling and heating of buildings. This innovative strategy provides a means to recirculate indoor air to save energy for a certain period of time and the potential for an energy-efficient operation of buildings. This study presents the analysis of CO 2 adsorption performance measurements and evaluates the application of the device by numerical calculations. The results of simulations for the tropical summer and Central European winter season show that 30–60% of air ventilation energy for cooling and heating can be saved competed to conventional systems. Based on these results, this study describes the possibility of using this system to recirculate indoor air using the CO 2 capture device to save energy and minimize air cooling and heating loads. This novel strategy introduces a new paradigm of air ventilation and can replace conventional air ventilation systems for certain period of time. [ABSTRACT FROM AUTHOR]

This paper presents the results of a study relating to thermal comfort in 28 buildings and schools, in the coastal and central areas of Cameroon. This research was conducted during the dry and rainy seasons, employing the adaptive approach, in naturally ventilated buildings, in accordance with ASHRAE 55/2004, ISO 7730 and ISO 10551. Wind speed, air temperature, relative humidity and CO 2 levels were measured, and 2650 questionnaires were distributed simultaneously. The results revealed that 76.7% of the voters in Douala found the results environmentally acceptable, as against 82.6% in Yaoundé. On average, 74.6% of the respondents found that these were within the comfort range, while 25.3% were neutral. When the local thermal comfort factor was analysed, it was found that the percentage of dissatisfied persons exceeded 40% in both cities, Yaoundé in particular, due to its higher average temperature. [ABSTRACT FROM AUTHOR]

Underfloor air distribution (UFAD) system, which is a relative new method of providing conditioned air and ventilation to the commercial buildings and data centers, is focused by researchers and designers for its potential advantages of better indoor thermal comfort (ITC) and indoor air quality (IAQ), layout flexibility, reduced life cycle costs, and energy saving. However, the application of UFAD system are still obstructed by the gap in the fundamental understanding of some new elements, such as the cooling load calculation, control of the thermal stratification, and evaluation of energy consumption. This paper reviews the current situation of UFAD technology, and the existing problems in recent researches are summarized. To improve the performance of UFAD system, several possible directions for the further studies are suggested. [ABSTRACT FROM AUTHOR]

Naturally ventilated dairy cattle buildings are one of the major sources for ammonia and greenhouse gas emissions to the atmosphere. Generally it is difficult to clean the air from naturally ventilated buildings. In order to reduce the emissions, a hybrid ventilation system, which is natural ventilation combining with mechanical partial pit ventilation, has been developed. By full-scale measurement, this study was to quantify ammonia and methane emissions and to investigate the impacts of climate parameters on gaseous emissions, air exchange rate (ACH) and concentrations at sampling locations in a dairy cattle building with hybrid ventilation. The results revealed that 64–83% of ammonia emissions were collected by partial pit ventilation while 10–50% of methane emission was collected. The results showed that ammonia emission through natural ventilation was around 60% lower than the value found in literatures. ACH was significantly influenced by wind speed and wind direction (wind angle in the range of 135–270°) in summer. The ACH increased generally with wind speed in winter while it hardly changed with wind speed when the windows opening ratio was 6% and even lower. The paper further investigated the impact of wind speed and outdoor temperature on ammonia emissions. [ABSTRACT FROM AUTHOR]

This paper investigates, by simulation study, the potential of five different ventilation and cooling strategies with regard to energy efficiency and thermal comfort in different climates. A 5-zones building simulation model is set-up considering a typical office building. The results demonstrate a high potential for night ventilation strategies in cool climates with low ambient air temperatures. In temperate climates, water based low-energy cooling technologies based on radiant cooling make use of the cool ground in summer. Active cooling provides good thermal comfort in warm and hot climates with high and fluctuating cooling loads. The results also point out that the use of different comfort models has a significant influence on the comfort rating. [ABSTRACT FROM AUTHOR]

An approach, able to easily and effectively integrate field measured data in whole building energy simulation (BES) models is crucial to increase simulation accuracy for existing buildings. In this paper, the robustness of a linear regression method for extracting transmission losses above ground (including air leakage) and ground heat loss parameters are analyzed. The regression method is evaluated on two documented and monitored multifamily buildings with mechanical supply and exhaust ventilation systems, with and without heat recovery. The obtained results are found to be robust, with variations less than 2% in the extracted estimates of transmission losses above ground (including air leakage) and with a high goodness of fit ( R 2 > 0.96) against measured data from two years. In addition, the estimations of the buildings ground heat loss were in good agreement with calculations in accordance with EN ISO 13370:2007. The high quality output from the used regression method serves as good prerequisites for the method to be used in conjunction with BES models to aid the analyst in a BES calibration process. [ABSTRACT FROM AUTHOR]

Night ventilation may improve the indoor air temperature and reduce the cooling load. However, the effects of different night ventilation rates on the indoor air relative humidity, wall inner surface temperature, inner surface moisture flux, sensible heat load, latent heat load and total load are rarely studied in terms of the inner surface moisture transfer. The present paper aims to investigate the effect of different night ventilation rates on the above items in a hot-humid climate in China. The results show the following: when the moisture absorption–desorption process at the wall inner surface is not considered, the air-conditioning load of the night ventilation at 15ACH is approximately 5% lower than that at 5ACH. When the moisture absorption–desorption process is considered, the night ventilation rate has a smaller impact on the indoor air temperature and has a larger impact on the indoor air relative humidity during the night. The night ventilation rate negatively correlates with the sensible heat load and positively correlates with the latent heat load due to the increased amount of moisture that is absorbed or desorbed at the interior wall surface. The total air-conditioning load of Case B.1, which featured a 15ACH night ventilation rate, was approximately 8% higher than that of Case A.1, which featured a 5ACH night ventilation rate. [ABSTRACT FROM AUTHOR]

Abstract: Energy efficiency and energy saving are important concepts bearing in mind by governments and population during the last years. There exist a widespread concern about fossil fuel depletions and the consequent sharp rise in their value. In particular, building is an area highly influenced by those issues. Studies indicate that 40% of the energy generated worldwide is consumed inside buildings, and then, measures to reduce energy consumption are required. In this work, an optimal controller for distributing the energy consumption rate inside a building and preserving, at the same time, the user welfare is proposed. More precisely, the paper presents a predictive control approach that obtains a high thermal comfort level optimizing the use of an HVAC (Heating, Ventilation and Air Conditioning) system by means of a cost function. The optimization procedure is based on the Lagrangian dual method, which allows the use of parallel programming paradigms in an easy way. This may reduce the computational effort proportionally to the number of processing elements when the problem to solve is large. [Copyright &y& Elsevier]

Abstract: The possibility of storing thermal energy within the building structure to reduce building energy consumption has been studied. Hollow core panels used for a building structure are able to pass air through core cavities and be utilized as thermal storage. Previously, thermal storage models for ventilated slab system using the panels have been developed but it has typically focused on the system development and performance evaluation under particular conditions. As a result, it has been difficult to understand the effect of the system on whole building energy performance. This study develops a computational model for a ventilated slab system and investigates its implementation in a whole building energy simulation program, EnergyPlus. The system has two major components: an auxiliary air handling unit (AHU) and a radiant slab with hollow core panels. The auxiliary AHU includes an outside air mixer, coils, and a fan to produce either conditioned or unconditioned air depending on the user''s input. The air is then controlled by a defined delivery method, after passing through the cavity of the panel. This paper illustrates the new model development for the building energy simulation program and provides some evaluation with an existing model from another study. [Copyright &y& Elsevier]

Abstract: Manual ventilation of dwellings in winter consumes excess heating energy, as cold outdoor air replaces warm indoor air. The German government promotes ‘shock-ventilation’ (Stoßlüften), where all windows are opened simultaneously, fully and briefly, to minimise energy wastage. However, the predominant design of windows in Germany''s housing stock mitigates against this strategy, as these windows open inwards while their indoor ledges provide ideal storage for pot-plants and other objects, blocking normal opening. An alternative window setting, long periods of trickle-ventilation, can consume up to 20 times as much energy as shock-ventilation. This paper reports a pilot study of household ventilation capabilities and practices in the German municipality of Aachen. A statistical analysis indicates 29% of dwellings have sufficiently unimpeded windows to facilitate shock-ventilation, while householder interviews reveal reasons for reliance on trickle-ventilation, including convenience and underestimation of its energy consumption. Analysis of results using ‘social practice theory’ suggests three possible policy interventions to improve energy-efficiency of ventilation. The results suggest the need for a nationwide study to quantify energy wastage through mismanaged ventilation, not least because of its possible cost to the country, of several billion Euros annually, and the millions of tonnes of CO2 emissions it most likely causes. [Copyright &y& Elsevier]

Abstract: The purpose of the research described in this paper was to demonstrate that an old Danish multi-family building built in 1896 could be retrofitted to a “nearly-zero” energy building. Three types of retrofit measures were implemented in a “test” apartment to obtain practical experiences. The first measure was the installation of two different types of interior insulation, specifically, an insulation component consisting of an aerogel–stone wool mixture or vacuum insulation panels. The second measure related to the retrofit of windows in which five measures were completed that consisted of applying a secondary frame, a sash mounted on the frame or to coupled frames. The third measure consisted of installing a decentralised mechanical ventilation system with heat recovery. The results showed that following the retrofit the building''s theoretical energy use diminished from 162.5kWh/(m2 year) to 51.5kWh/(m2 year), corresponding to a reduction in energy use of 68%. The theoretical energy use after retrofitting fulfilled the requirements for new buildings in Denmark. The practical experiences that were retained following the retrofit were that the ventilation system ought to be installed with low noise components, insulation materials must be sized and cut to fit on site, and that new windows were selected. [Copyright &y& Elsevier]

Abstract: Indoor air pollution has a negative impact on human health, comfort and productivity. Emissions, however, are often related to essential functions of the indoor environment and cannot be eliminated with source control. Ventilation is then used to dilute these pollutants to acceptable concentrations. Due to recent crises in the energy markets and the subsequent quest for higher efficiency in energy use, heat recovery ventilation has gained capstone status in sustainable building concepts. However, along with a reduction of ventilation heat loss, operating a heat recovery unit increases the pressure drop and fan power consumption in the system. These aspects are rarely traded off against each other and even more scarcely for a broad range of operating conditions. This paper addresses this trade-off based on primary energy, carbon dioxide emission, household consumer energy price and exergy frameworks for the different climates in Europe. The results presented here demonstrate that, for the moderate climate region of middle Europe, natural ventilation, simple exhaust mechanical ventilation and heat recovery ventilation have no clear advantage over each other as far as operating energy is concerned. Realistically low specific fan power will make heat recovery ventilation advantageous in virtually all tested conditions. [Copyright &y& Elsevier]

Abstract: The European Directive 2002/91/EC about the energy performance of buildings aims to achieve minimum standards on the energy performance both of new and existing buildings that are subject to major renovation. The improvement of “building performance requirements” and the development of new strategies for “very low energy buildings” represent one of the European Directive priority. In fact, an effective saving potential may be obtained reducing the energy consumptions due to the heat flux transmitted through the envelope of residential and commercial buildings. In regions with high level of solar radiation, ventilation of building structures reduces the cooling load during summer period and contributes to the reduction of the energy needs of buildings. During summer period, one of the advantages provided by the ventilation is the reduction of the heat fluxes transmitted by the structures exposed to the solar radiation, thanks to the combined effect of the surfaces shading and of the heat removed by the air flow rate within the ventilated air gap. The objective of this paper has been the analysis of thermal behavior of ventilated roofs characterized by a different placement of thermal layer insulation respect to the air gap. The “Fluent” software has been used with the aim of acquiring a better knowledge of the thermo-fluid dynamic behavior of the air within the ventilated roof and the heat fluxes through ventilated roofs have been calculated. The results of the study show that the ventilation of roofs can reduce significantly the heat fluxes (up to 50%) during summer season. [Copyright &y& Elsevier]

Abstract: Integrating passive systems such as cross and stack ventilation, a solar chimney, a wind tower or an earth-air tunnel into a building envelope has the potential to significantly reduce the ventilation and air-conditioning demand on buildings. However the application of combination of these features in low rise contemporary buildings is limited. Among the major reasons, is the lack of simple building modelling techniques preventing effective integrated passive systems. Existing coupled multi-zone airflow and thermal modelling software such as COMIS-TRNSYS, CONTAM-TRNSYS or TRNFLOW do not include the passive airflow components which require simultaneous prediction of temperature and airflow rate in the components such as solar chimneys and wind-induced earth-air tunnels. This paper develops an integrated model incorporating these passive airflow components into a coupled multi-zone ventilation and building thermal model. The model is validated against COMIS-TRNSYS software for a lightweight building with large openings. The prediction of each passive airflow component is validated with available published analytical and experimental findings. The solar chimney model is able to predict reverse flow and accurately predicts the air temperature in the chimney. The earth air tunnel (EAT) considers the transient heating up effect of the soil during operation and predicts the outlet air temperature. [Copyright &y& Elsevier]