The free-piston engine generator (FPEG) is regarded as the next generation of energy conversion system which may replace traditional engines in the future. The effect of key operational parameters like excess air ratio of input mixture and ignition position on the engine performance of a dual-cylinder FPEG was investigated, and their sensitivity was analyzed in this paper. The operating compression ratio of the system is susceptible to changes in excess air ratio and ignition position. At the same time, it decreases from 15.8 to 6.6 when excess air ratio increases from 0.85 to 1.15, but it increases from 6.1 to 13.3 as ignition position increases from 15 mm to 20 mm. The operating frequency and indicated power are more sensitive to changes in excess air ratio than ignition position. But it is the opposite for the indicated thermal efficiency and friction loss. Excess air ratio and ignition position have a quite similar influence on heat transfer. Therefore, from the perspective of system operation and performance, it is preferable to keep excess air coefficient slightly below 1.0. In contrast, when selecting ignition position, it is of great importance to comprehensively consider the risk of structural damage caused by the increase in the compression ratio and in-cylinder gas pressure.

The relationship between engine mechanics and thermo-dynamics has been investigated by means of numerical simulation. The inherent mismatching between the mechanical behaviors and the thermodynamic process in internal combustion engine is identified, which is believed to be one of the important limiting factors of energy efficiency for conventional engines available in the current market. An approach for engine efficiency improvement through optimal matching between mechanics and thermodynamics (OMBMT) is proposed. An ideal matching model is defined and the conflicts due to the constraints among the mapping strokes in a 4-stroke engine are analyzed. A novel mechanical model is built for approaching optimal matching among all 4 individual strokes in a 4-stroke spark-ignition engine, which is composed of non-circular gears (NCG) and integrated with conventional slider crank engine mechanism. By means of digital mechanical model and numerical simulation, the matching gains among all 4 strokes are defined and calculated for quantifying the NCG engine efficiency improvement by comparing with a baseline engine. The potentials with the OMBMT implemented and the enhancements made by NCG mechanism for engines in terms of overall engine efficiency are reported. Based on the results achieved, it is recommended that the feasibility studies and the experimental validations should be conducted to verify the engine matching concept and effectiveness of the NCG mechanism engine model proposed, and the engine performance and NCG design parameters should be further optimized.

Diesel engines meeting the latest emission regulations must be equipped with exhaust gas aftertreatment system, including diesel oxidation catalysts (DOC), diesel particulate filters (DPF), and selective catalytic reduction (SCR). However, before the final integration of the aftertreatment system (DOC+DPF+SCR) and the diesel engine, a reasonable structural optimization of the catalytic converters and a large number of bench calibration tests must be completed, involving large costs and long development cycles. The design and optimization of the exhaust gas aftertreatment system for a heavy-duty diesel engine was proposed in this paper. Firstly, one-dimensional (1D) and three-dimensional (3D) computational models of the exhaust gas aftertreatment system accounting for the structural parameters of the catalytic converters were established. Then based on the calibrated models, the effects of the converter’s structural parameters on their main performance indicators, including the conversion of various exhaust pollutants and the temperatures and pressure drops of the converters, were studied. Finally, the optimal design scheme was obtained. The temperature distribution of the solid substrates and pressure distributions of the catalytic converters were studied based on the 3D model. The method proposed in this paper has guiding significance for the optimization of diesel engine aftertreatment systems.

To meet increasingly stringent emission standards and lower the brake-specific fuel consumption (BSFC) of marine engines, a collaborative optimization study of exhaust gas recirculation (EGR) and a Miller cycle coupled turbocharging system was carried out. In this study, a one-dimensional numerical model of the EGR, Miller cycle, and adjustable two-stage turbocharged engine based on WeiChai 6170 marine diesel engine was established. The particle swarm optimization algorithm was used to achieve multi-input and multi-objective comprehensive optimization, and the effects of EGR-coupled Miller regulation and high-pressure turbine bypass regulation on NO_x and BSFC were investigated. The results showed that a medium EGR rate-coupled medium Miller degree was better for the comprehensive optimization of NO_x and BSFC. At medium EGR rate and low turbine bypass rates, NO_x and BSFC were relatively balanced and acceptable. Finally, an optimal steady-state control strategy under full loads was proposed. With an increase in loads, the optimized turbine bypass rate and Miller degree gradually increased. Compared with the EGR-only system, the optimal system of EGR and Miller cycle coupled turbine bypass reduced NO_x by 0.87 g/(kW·h) and BSFC by 17.19 g/(kW·h) at 100% load. Therefore, the EGR and Miller cycle coupled adjustable two-stage turbocharging achieves NO_x and BSFC optimization under full loads.

The performance of microwave-assisted spark ignition (MAI) under exhaust gas recirculation conditions was explored with CO₂-diluted CH₄-air premixed spherical flames in a constant volume combustion chamber. The flame kernel radius at 5 ms after spark started was selected to evaluate the property of MAI for CO₂ dilution ratio of 0–20% and equivalence ratio of 0.6–1.4 with 1 kHz microwave pulse repetition frequency under 0.2 MPa ambient pressure. The results showed that the addition of microwave induced some wrinkles on the flame surface and strongly deformed the flame. MAI expanded the limit of CO₂ dilution ratio to 16% with an equivalence ratio of 0.75, in which case the spark only (SI) failed to ignite the mixture. With the CO₂ dilution ratio increasing, the wrinkles induced by microwave pulses decreased apparently, and the enhancement value of MAI peaked at 4% CO₂ dilution ratio. The effect of microwave was considered in two aspects, namely, reaction kinetics and thermal effect, which shows a “trade-off” as CO₂ dilution ratio rose. With 8% volume of CO₂ added, the flammable interval (equivalence ratio 0.6–1.2) of mixture in SI mode shrunk, and MAI can maintain a flammable interval consistency with the case that no CO₂ was added.

One of the proposed concepts for spark ignition engines is advanced port fuel injection (APFI), which suggests using two port injectors for each cylinder. In this research, we numerically examine the capabilities of this concept in reducing fuel consumption and increasing engine performance. The results demonstrated that the use of this concept is very effective due to the use of two injectors and the possibility of reducing the spraying time and bringing the injection start time closer to the air inlet valve opening time. The maximum amount of fuel film formed on the walls is reduced by about 75%, naturally, which leads to better and more homogeneous fuel distribution inside the combustion chamber and increases combustion efficiency. The results showed that under the same boundary conditions and engine operating point, the use of two port injectors for each cylinder leads to an increase of more than 20% of the maximum combustion chamber pressure and about 4% combustion efficiency. On the other hand, fuel film formation becomes worse in cold conditions. So in this study, the capabilities of this concept in cold conditions were investigated too. Investigations have shown that the advanced port fuel injection, unlike conventional engines, is almost insensitive to inlet temperature changes.

RP-3 jet fuel could be an alternative fuel for diesel engines. In this study, the injection characteristics of RP-3 jet fuel under single and split injection strategies were investigated and compared with diesel fuel. The experimental results indicate that RP-3 jet fuel has slightly shorter injection delay time than diesel fuel, but this difference is negligible in actual engine operations. Further, although the lower density and viscosity of RP-3 jet fuel lead to higher volumetric injection rates and cycle-based injection quantities, the cycle-based injection mass and the mass injection rates at the stable injection stage of RP-3 jet fuel are close to or slightly lower than those of diesel fuel. Based on these experimental observations, it could be concluded that fuel physical properties are the secondary factor influencing the injection characteristics in both single and split injection strategies, as RP-3 jet fuel and diesel fuel are taken for comparison.

Oxygen fuels have broad application prospects and great potential for realizing efficient and clean combustion, and hence this study applies diesel/n-butanol blends to explore the influence of split-injection strategy on combustion and emission characteristics. Simultaneously, changing the way of exhaust gas recirculation (EGR) gas introduction forms uneven in-cylinder components distribution, and utilizing EGR stratification optimizes the combustion process and allows better emission results. The results show that the split-injection strategy can reduce the NO_x emissions and keep smoke opacity low compared with the single injection, but the rise in accumulation mode particles is noticeable. NO_x emissions show an upward trend as the injection interval expands, while soot emissions are significantly reduced. The increase in pre-injection proportion causes the apparent low-temperature heat release, and the two-stage heat release can be observed during the process of main combustion heat release. More pre-injection mass makes NO_x gradually increase, but smoke opacity reaches the lowest point at 15% pre-injection proportion. EGR stratification can optimize the emission results under the split injection strategy, especially the considerable suppression of accumulation mode particulate emissions. Above all, fuel stratification coupled with EGR stratification is beneficial for further realizing the in-cylinder purification of pollutants.

A three-dimensional diesel particulate filter (DPF) simulation model was developed by using AVL software FIRE to study the effects of four factors on soot particle distributions along the axial and radial directions in the DPF after the model accuracy was validated. An orthogonal test method was used to determine the importance and weights of the design of experiments (DoE) factors such as the expanding angle, the number of channels per square inch, and the exhaust mass flow rate. The effects of these factors on the uniformity of the soot particle distributions were also analyzed. The results show that when the soot loading time was 400 s, the soot particles inside the DPF along the axial direction exhibited a bowl shape, which was high on the both ends and low in the middle. The uniformity of the axial distribution of soot particles reduces significantly with an increase in the number of channels per square inch. The uniformity of the radial distribution reduced with an increase in the expanding angle of the divergent tube. Based on the impacts on the axial uniformity, the three most influencing factors in a descending order are the number of channels per square inch, the exhaust mass flow rate, and the expanding angle of the divergent tube.

Research on dual-fuel (DF) engines has become increasingly important as engine manufacturers seek to reduce carbon dioxide emissions. There are significant advantages of using diesel pilot-ignited natural gas engines as DF engines. However, different combustion modes exist due to variations in the formation of the mixture. This research used a simulation model and numerical simulations to explore the combustion characteristics of high-pressure direct injection (HPDI), partially premixed compression ignition (PPCI), and double pilot injection premixed compression ignition (DPPCI) combustion modes under a low-medium load. The results revealed that the DPPCI combustion mode provides higher gross indicated thermal efficiency and more acceptable total hydrocarbon (THC) emission levels than the other modes. Due to its relatively good performance, an experimental study was conducted on the DPPCI mode engine to evaluate the impact of the diesel dual-injection strategy on the combustion process. In the DPPCI mode, a delay in the second pilot ignition injection time increased THC emissions (a maximum value of 4.27g/(kW·h)), decreased the emission of nitrogen oxides (a maximum value of 7.64 g/(kW·h)), increased and then subsequently decreased the gross indicated thermal efficiency values, which reached 50.4% under low-medium loads.

In the global background of “Carbon Peak” and “Carbon Neutral”, natural gas engines show great advantages in energy-saving and pollution reduction. However, natural gas engines suffer from the issues of combustion instabilities when operating under lean burning conditions. In this paper, the role of turbulence enhancement in improving the lean combustion of natural gas was investigated in an optical SI engine with high compression ratios. Variable swirl control valves (SCV) were designed and intake tumble and swirl were combined to regulate turbulent motion and turbulent intensity. Particle image velocimetry was employed to measure in-cylinder turbulence, and transient pressure acquisition and high-speed photography were synchronously performed to quantify combustion evolutions. The results show that in-cylinder turbulent intensity is enhanced significantly through reducing SCV closing angles. Such that flame propagation speed and thermal efficiency are significantly improved with an increment of turbulent intensity, which indicated that mean effective pressures are not sensitive to spark timing. The analysis of flame images shows that the combined turbulence increases in the radial orientation from the spark plug to the cylinder wall, leading to an earlier flame kernel formation and a faster burning rate. Therefore, the combined turbulence has the potential in reducing the cyclic variations of lean combustion in natural gas engines.

Fe-ZSM-5 catalysts modified by Cu and Ce by aqueous solution ion-exchange and incipient wetness impregnation methods were tested in the selective catalytic reduction of NO_x with NH₃. A variety of characterization techniques (NH₃-SCO, BET, XRD, XPS, UV-Vis, NH₃-TPD, H₂-TPR) were used to explore the changes of the active sites, acid sites and pore structure of the catalyst. It was found that the dispersion of active Cu species and Fe species had great influences on the catalytic activity in the whole catalytic process. The Cu doping into the Fe-ZSM-5 catalyst produced new active species, isolated Cu ions and CuO particles, resulting in the improved low-temperature catalytic activity. However, the NH₃ oxidation was enhanced, and part of the Fe³⁺ active sites and more Brønsted acidic sites in the catalyst were occupied by Cu species, which causes the decrease of the high-temperature activity. The recovery of high-temperature activity could be attributed to the recovery of active Cu species and Fe species promoted by Ce and the promotion of active species dispersion. The results provide theoretical support for adjusting the active window of Fe-based SCR catalyst by multi-metal doping.

A series of transition metal Mn, Cu, Ce and Fe were loaded on TiO₂ by sol-gel method with noble metal Pd as promotor for the application of passive NO_x absorber. Experiments on adsorption and desorption of NO_x were conducted and characterization methods such as X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM) and in situ Fourier transform infrared spectroscopy (in situ DRIFTS) were involved. The experimental results show that Mn-contained catalysts, Mn-Ti and Pd-Mn-Ti, performed excellent NO_x adsorbing ability and appropriate desorption temperature window. On the other hand, Ce- and Cu-contained samples were not suitable for the purpose of PNA. In addition to the low adsorption capacity, these two series of catalysts released massive amount of NO below 150 °C. Characterization results indicated that Pd was highly dispersed on all catalysts. The loading of Pd lowered not only the valence states of transition metals but surface oxygen percentage as well. From in situ DRIFTS tests, the Pd had little influence on the types of adsorbed substances for Mn, Ce and Cu series. However, the storage forms of NO_x were obviously different on Pd-Fe-Ti and Fe-Ti.

This paper studied a supervisory control system for a hybrid off-highway electric vehicle under the charge-sustaining (CS) condition. A new predictive double Q-learning with backup models (PDQL) scheme is proposed to optimize the engine fuel in real-world driving and improve energy efficiency with a faster and more robust learning process. Unlike the existing “model-free” methods, which solely follow on-policy and off-policy to update knowledge bases (Q-tables), the PDQL is developed with the capability to merge both on-policy and off-policy learning by introducing a backup model (Q-table). Experimental evaluations are conducted based on software-in-the-loop (SiL) and hardware-in-the-loop (HiL) test platforms based on real-time modelling of the studied vehicle. Compared to the standard double Q-learning (SDQL), the PDQL only needs half of the learning iterations to achieve better energy efficiency than the SDQL at the end learning process. In the SiL under 35 rounds of learning, the results show that the PDQL can improve the vehicle energy efficiency by 1.75% higher than SDQL. By implementing the PDQL in HiL under four predefined real-world conditions, the PDQL can robustly save more than 5.03% energy than the SDQL scheme.

Personal conditioning system (PCS) is receiving considerable attention due to its energy-saving potential and the ability to satisfy individual comfort requirements. As a part of PCS, personal heating systems can maintain human thermal comfort in cold environments, which leads to their potential role of important heating mode in cold winter, especially in the Hot Summer and Cold Winter regions of China. In order to better promote the development and application of personal heating systems, this paper reviews the published studies. Personal heating systems can be divided into four types based on the mode of heat transfer: conductive, convective, radiative and combinative type. Characteristics of each category and respective devices are introduced. Furthermore, identifying the effects of personal heating on thermal comfort and the models for predicting or evaluating thermal comfort during local heating. This paper would provide users with a guideline for choosing suitable heating equipment during winter.

Accurate basic data are necessary to support performance-based design for achieving carbon peak and carbon neutral targets in the building sector. Meteorological parameters are the prerequisites of building thermal engineering design, heating ventilation and air conditioning design, and energy consumption simulations. Focusing on the key issues such as low spatial coverage and the lack of daily or higher time resolution data, daily and hourly models of the surface meteorological data and solar radiation were established and evaluated. Surface meteorological data and solar radiation data were generated for 1019 cities and towns in China from 1988 to 2017. The data were carefully compared, and the accuracy was proved to be high. All the meteorological parameters can be assessed in the building sector via a sharing platform. Then, country-level meteorological parameters were developed for energy-efficient building assessment in China, based on actual meteorological data in the present study. This set of meteorological parameters may facilitate engineering applications as well as allowing the updating and expansion of relevant building energy efficiency standards. The study was supported by the National Science and Technology Major Project of China during the 13th Five-Year Plan Period, named Fundamental parameters on building energy efficiency in China, comprising of 15 top-ranking universities and institutions in China.

Passive house has been constructed in China on a large-scale over the past couple years for its great energy saving potential. However, research indicates that there is a significant discrepancy in energy performance for heating and cooling between passive houses in different climate zones. Therefore, this research develops a comparative analysis on the energy saving potential of passive houses with the conventional around China. A sensitivity analysis of thermal characteristics of building envelope (insulation of exterior walls and windows, and airtightness) on energy consumption is further carried out to improve the climate adaptability of passive house. Moreover, the variation of energy consumption under different heat gain intensity is also compared, to evaluate the effects of envelope thermal characteristics comprehensively. Results suggest that the decrease of exterior wall insulation leads to the greatest increase in energy consumption, especially in severe cold zone in China. However, the optimal insulation may change with the internal heat gain intensity, for instance, the decrease of insulation (from 0.4 to 1.0 W/(m²·K)) could reduce the energy consumption by 4.65 kW·h/(m²·a) when the heat gain increases to 20 W/m² for buildings in Hot Summer and Cold Winter zone in China.

For the carbon-neutral, a multi-carrier renewable energy system (MRES), driven by the wind, solar and geothermal, was considered as an effective solution to mitigate CO₂ emissions and reduce energy usage in the building sector. A proper sizing method was essential for achieving the desired 100% renewable energy system of resources. This paper presented a bi-objective optimization formulation for sizing the MRES using a constrained genetic algorithm (GA) coupled with the loss of power supply probability (LPSP) method to achieve the minimal cost of the system and the reliability of the system to the load real time requirement. An optimization App has been developed in MATLAB environment to offer a user-friendly interface and output the optimized design parameters when given the load demand. A case study of a swimming pool building was used to demonstrate the process of the proposed design method. Compared to the conventional distributed energy system, the MRES is feasible with a lower annual total cost (ATC). Additionally, the ATC decreases as the power supply reliability of the renewable system decreases. There is a decrease of 24% of the annual total cost when the power supply probability is equal to 8% compared to the baseline case with 0% power supply probability.

To study the effects of perceived control on human thermal sensation and thermal comfort in heated environments, a psychological experiment was conducted. In total, 24 subjects participated in an experiment. The experiment consisted of two cases in which the indoor temperature was set at 18 °C with different cold radiation temperatures. The experiment lasted for 120 min and was divided into three phases, adaptation, without perceived control and perceived control. In the second phase, the subjects were told in advance that the indoor temperature could not be adjusted. In the third phase, subjects were told that they could adjust the indoor temperature to meet their own thermal expectations, but the indoor temperature could not actually be changed. The results showed that the effect of perceived control on thermal sensation was related to the thermal expectation. For people with strong expectations for a neutral environment, perceived control improved their thermal sensation by satisfying their thermal expectations. For people with low thermal expectations, perceived control reduced their thermal tolerance to the environment, eventually leading to thermal discomfort. These new findings provide more supports for the importance of psychological effects and a reference for the personal control of heating temperatures.

The distributed energy system has achieved significant attention in respect of its application for single-building cooling and heating. Researching on the life cycle environmental impact of distributed energy systems (DES) is of great significance to encourage and guide the development of DES in China. However, the environmental performance of distributed energy systems in a building cooling and heating has not yet been carefully analyzed. In this study, based on the standards of ISO14040-2006 and ISO14044-2006, a life-cycle assessment (LCA) of a DES was conducted to quantify its environmental impact and a conventional energy system (CES) was used as the benchmark. GaBi 8 software was used for the LCA. And the Centre of Environmental Science (CML) method and Eco-indicator 99 (EI 99) method were used for environmental impact assessment of midpoint and endpoint levels respectively. The results indicated that the DES showed a better life-cycle performance in the usage phase compared to the CES. The life-cycle performance of the DES was better than that of the CES both at the midpoint and endpoint levels in view of the whole lifespan. It is because the CES to DES indicator ratios for acidification potential, eutrophication potential, and global warming potential are 1.5, 1.5, and 1.6, respectively at the midpoint level. And about the two types of impact indicators of ecosystem quality and human health at the endpoint level, the CES and DES ratios of the other indicators are greater than 1 excepting the carcinogenicity and ozone depletion indicators. The human health threat for the DES was mainly caused by energy consumption during the usage phase. A sensitivity analysis showed that the climate change and inhalable inorganic matter varied by 1.3% and 6.1% as the electricity increased by 10%. When the natural gas increased by 10%, the climate change and inhalable inorganic matter increased by 6.3% and 3.4%, respectively. The human health threat and environmental damage caused by the DES could be significantly reduced by the optimization of natural gas and electricity consumption.

Kunming, a city in southwest China, has a climate that is different from most of the other places in the world because of its unique geographical characteristics. Due to its temperate climate, most of the residential buildings in this region are naturally ventilated. Accordingly, a winter thermal comfort study was conducted in Kunming to reveal the thermal response of residents. Indoor and outdoor environmental parameters were measured, and participants were investigated about their clothing, thermal sensations, thermal preferences, and thermal acceptance using online questionnaires. Data from 162 valid questionnaires were collected in the survey. Although the climate is referred to as “mild”, the survey showed that the indoor temperature during winter was lower than the typical comfort range. Nevertheless, the participants responded that most of them felt neutral and comfortable. The neutral temperature of participants living in Kunming was determined to be 16.96 °C. The acceptable thermal sensation vote (TSV) range of the residents is −0.72 to 1.52. The acceptable indoor air temperature range is 15.03 °C to 19.55 °C, and the optimum indoor air temperature is 17.2 °C. According to this study, the existing thermal comfort evaluation models can hardly predict residents’ thermal responses in Kunming well.

Hypobaric hypoxia is the main environmental feature of the Tibetan plateau which would influence the efficiency of human metabolic heat production and the ability of thermal regulation. In order to understand the influence of the hypoxic environment on the plateau on the thermal comfort of short-term sojourners in Tibet, China, oxygen generators were used to create oxygen-enriched environments, and physiological and psychological reactions of subjects were compared under different oxygen partial pressures (

) and air temperatures (t_a). The results showed that subjects’ thermal sensation, thermal comfort and mean skin temperature decreased with a decrease in the oxygen partial pressure. When t_a=17 °C, the influence of oxygen partial pressure was more pronounced, compared to

p_{{\text{O}}_2}=16.4\text{kPa}

\documentclass[12pt]{minimal}\usepackage{amsmath}\usepackage{wasysym}\usepackage{amsfonts}\usepackage{amssymb}\usepackage{amsbsy}\usepackage{mathrsfs}\usepackage{upgreek}\setlength{\oddsidemargin}{-69pt}\begin{document}$${p_{{{\rm{O}}_2}}} = 16.4\,\,{\rm{kPa}}$$\end{document}

, the thermal sensation of subjects under

p_{{\text{O}}_2}=13.7\text{kPa}

\documentclass[12pt]{minimal}\usepackage{amsmath}\usepackage{wasysym}\usepackage{amsfonts}\usepackage{amssymb}\usepackage{amsbsy}\usepackage{mathrsfs}\usepackage{upgreek}\setlength{\oddsidemargin}{-69pt}\begin{document}$${p_{{{\rm{O}}_2}}} = 13.7\,\,{\rm{kPa}}$$\end{document}

decreased by 33%. The rate of subjects feeling comfortable decreased by 25%, and the mean skin temperature decreased by 0.7 °C. The hypoxic environment of the plateau exacerbates human discomfort. Therefore, it is necessary to fully understand the actual thermal requirements of sojourners in Tibet, China. The results of this study would have implications for a better understanding of thermal comfort characteristics in the hypoxia environment in plateau.

The study aims to investigate the thermal comfort requirements in residential buildings and to establish an adaptive thermal comfort model in the cold zone of China. A year-long field study was conducted in residential buildings in Xi’an, China. A total of 2069 valid questionnaires, along with indoor environmental parameters were obtained. The results indicated occupants’ thermal comfort requirements varied with seasons. The neutral temperatures were 17.9, 26.1 (highest), 25.2, and 17.4 °C (lowest), and preferred temperatures were 23.2, 25.6 (highest), 24.8, and 22.4 °C (lowest), respectively for spring, summer, autumn, and winter. The neutral temperature and preferred temperature in autumn are close to the neutral temperature in summer, while the neutral temperature and preferred temperature in spring are close to that in winter. Besides, the 80% and 90% acceptable temperature ranges, adaptive thermal comfort models, and thermal comfort zones for each season were established. Human’s adaptability is related to his/her thermal experience of the current season and the previous season. Therefore, compared with the traditional year-round adaptive thermal comfort model, seasonal models can better reflect seasonal variations of human adaptation. This study provides fundamental knowledge of the thermal comfort demand for people in this region.

Ventilation is an effective solution for improving indoor air quality and reducing airborne transmission. Buildings need sufficient ventilation to maintain a low infection risk but also need to avoid an excessive ventilation rate, which may lead to high energy consumption. The Wells-Riley (WR) model is widely used to predict infection risk and control the ventilation rate. However, few studies compared the non-steady-state (NSS) and steady-state (SS) WR models that are used for ventilation control. To fill in this research gap, this study investigates the effects of the mechanical ventilation control strategies based on NSS/SS WR models on the required ventilation rates to prevent airborne transmission and related energy consumption. The modified NSS/SS WR models were proposed by considering many parameters that were ignored before, such as the initial quantum concentration. Based on the NSS/SS WR models, two new ventilation control strategies were proposed. A real building in Canada is used as the case study. The results indicate that under a high initial quantum concentration (e.g., 0.3 q/m³) and no protective measures, SS WR control underestimates the required ventilation rate. The ventilation energy consumption of NSS control is up to 2.5 times as high as that of the SS control.