American Society Of Heating , Refrigerating And Air-Conditioning Engineers Research Articles

Impact of Diffuser Location on Thermal Comfort Inside a Hospital Isolation Room

Thermal comfort is increasingly recognized as vital in healthcare facilities, where patients spend 80–90% of their time indoors. Sensing, controlling, and predicting indoor air quality should be monitored for thermal comfort. This study examines the effects of ventilation design on thermal comfort in hospital rooms, proposing four distinct ventilation configurations, each with three airflow rates of 9, 12, and 15 Air Changes per Hour (ACH). The study conducted various ventilation simulation scenarios for a hospital room. The objective is to determine the effect of airflow and the diffuser location distribution on thermal comfort. The Reynolds-Averaged Navier–Stokes (RANS) equations, along with the k–ε turbulence model, were used as the underlying mathematical representation for the airflow. The boundary conditions for the simulations were derived from the ventilation standards set by the American Society of Heating, Refrigerating, and Air-Conditioning Engineers (ASHRAE) and insights from previous studies. Thermal comfort and temperature distribution were assessed using indices like Predicted Percentage Dissatisfaction (PPD), Predicted Mean Vote (PMV), and Air Diffusion Performance Index (ADPI). Although most of the twelve scenarios failed to attain thermal comfort, two of those instances were optimal in this simulation. Those instances involved the return diffuser behind the patient and airflow of 9 ACH, the minimum recommended by previous studies. It should be noted that the ADPI remained unmet in these cases, revealing complexities in achieving ideal thermal conditions in healthcare environments. This study extends the insights from our prior research, advancing our understanding of ventilation impacts on thermal comfort in healthcare facilities. It underscores the need for comprehensive approaches to environmental control, setting the stage for future research to refine these findings further.

Thermal Comfort and Cognitive Performance under Glass Facade Buildings

Glass is one of the most adaptable modern materials. However, the use of glass can have unfavorable effects such as glare, heat, and discomfort. This study focuses on the issue of designing contemporary glass buildings and facades in humid tropical environments to evaluate the thermal comfort of building occupants and assess its effects on the completion of cognitive tasks. The Wet-Bulb Globe Temperature (WBGT) parameter was used to measure thermal comfort, and the ASHRAE (American Society of Heating, Refrigerating, and Air-Conditioning Engineers) scale was used to assess thermal comfort perception. The Montreal Cognitive Assessment was used to assess eight female respondents’ cognitive abilities, and the cut-off point was 26. The WBGT has a temperature range of 25, 54°–28, 83°C, in terms of thermal sensation, 54% of respondents feel hot and 62% are uncomfortable. In the completion of cognitive tasks, 75% received a score of less than 26. The results show that there is an effect of thermal comfort on cognitive performance. Due to respondents feeling uncomfortable in high-rise buildings with glass facades, as well as with cognitive outcomes that are below the cut-off point, recommendations for improvement are needed to increase thermal comfort, such as double glass facades.

Correlation analysis of building parameters according to ASHRAE Standard 90.1

Building energy codes promote efficient energy management in both conventional and eco-friendly buildings. These codes are periodically updated to reduce energy consumption and carbon emissions. However, these updates can induce correlations among building parameters, which could lead to incorrect results when creating or analyzing data sets based on them. This study aims to investigate the impact of correlations in building parameters caused by the trend of updates in building energy codes. The most widely used building energy standard, namely Standard 90.1 of the American Society of Heating, Refrigerating, and Air-Conditioning Engineers (ASHRAE), is utilized to understand the trends of energy codes. We confirm that periodic updates to ASHRAE Standard 90.1, representative of numerous energy standards and codes, induce correlations in the input parameters. Moreover, we analyze the problems caused by these correlations through sensitivity analysis and Principal Component Analysis (PCA). Consequently, the sensitivity index of parameters with correlations increases while the importance of parameters without correlations decreases. In the PCA, the number of parameters required to explain more than 95 % of the variance in the raw data changed. This study's findings highlight the need to carefully consider correlations when analyzing building energy code-impacted data and provide insight that enhances the accuracy of the interpreting parameter relation in such data analysis.

Indoor air quality control at national-level regulations: A special case in Indonesia

Introduction: While many national-level governments have worked to tighten atmospheric air quality standard, the Authors observe, Indoor Air Quality (IAQ) control as part of building-codes have remained understudied and not yet enforced in many national-level regulations. The COVID-19 pandemic seemed to trigger an immediate response worldwide for IAQ control. Indoor air pollutants need to be tightly regulated. International agencies have produced recommendations to cope with the pandemic, however, national- level IAQ standards and building codes have been slow to adapt.
 Materials and methods: IAQ regulations from various nations worldwide were studied along with the international standards: The American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE), and World Health Organization (WHO). A comprehensive review was conducted comparing the national-level building codes and regulations as legal implementation instruments. Focus group discussions were also conducted to complement preliminary findings and further analysis.
 Results: Except for Indonesia, bacteria and fungi have been categorized as infectious aerosols in many national-level regulations that fare up to the international standards as indoor air pollutants with their acceptable levels. However, while they set thresholds for pollutants, their effectiveness regulating IAQ in public buildings remain unknown. It also found that there is a significant lack of national building codes in Indonesia.
 Conclusion: The COVID-19 epidemic raises awareness of IAQ. The health aspect is currently being prioritized, particularly in Indonesia, where the majority of related regulations are still fragmented and prioritize energy conservation over health. This study can inform policymakers with evidence of IAQ control and practices worldwide for applicable regulatory building and implementation, as well as for health emergency and disaster risk management.

Experimental investigation of desiccant dehumidification with four different combinations of silica gel desiccant wheel on indoor air quality

Indoor air quality (IAQ) describes the air quality within buildings and other structures, particularly concerning how it affects the health and comfort of building inhabitants. Your likelihood of experiencing indoor health issues can be decreased by being aware of and controlling common indoor contaminants. In addition to maintaining indoor relative humidity at or below 65%, The American Society of Heating, Refrigerating, and Air-Conditioning Engineers (ASHRAE) recommends temperatures between 21 and 26 °C in the summer and 20–24 °C in the winter. The EPA advises using humidity levels between 30 and 60% to stop mold from growing. Silica gel, lithium chloride, and molecular sieves 5A are excellent for dehumidification due to their strong moisture adsorption capability and potential for regeneration. Choosing the right desiccant depends on factors like adsorption capacity, pore size, and chemical compatibility, which are crucial for dehumidification applications and environments. This study compares the performance of silica gel desiccant wheels with three additional composite materials for air dehumidification, which is unusual in this work because very few studies of these combinations have been provided. For all desiccant wheels, the various operating parameters of the needed dehumidification process have been investigated and compared. For adsorption and regeneration rate, the performance of three different composite desiccant wheels was examined and compared experimentally. This experimental evaluation reveals that the composite desiccant wheel (silica gel-lithium chloride-molecular sieve 5A) has a higher adsorption and regeneration rate than others. When a composite desiccant wheel made from silica gel-lithium chloride, silica gel-molecular sieve 5A, and silica gel-lithium chloride-molecular sieve 5A was compared to the performance of a silica gel desiccant wheel, the percentage improvements in adsorption rate were 34.99%, 43.58%, and 85.5%, and the percentage increases in regeneration rate were 5.65%, 7.08%, and 14%.

Temporal and spatial heterogeneity of indoor and outdoor temperatures and their relationship with thermal sensation from a global perspective

People spend most of their time indoors. However, indoor temperature and individual thermal exposure are generally not considered in epidemiological studies of temperature and health. Based on the American Society of Heating, Refrigerating, and Air-Conditioning Engineers (ASHRAE) RP-884 Database, the ASHRAE Global Thermal Comfort Database II and the Chinese Thermal Comfort Database, this study first explored the relationship between outdoor temperature, indoor temperature and thermal sensation from a global perspective. Moreover, the potential influence of spatiotemporal heterogeneity on health studies was explored. A breakpoint was found at approximately 11.5 °C in the segmented regression of indoor and outdoor temperature, and the slope of the curve was greater when outdoor temperature was above the breakpoint (n = 67,896). Based on multi-group propensity score matching (PSM) and generalizedadditivemodels (GAM), spatiotemporal heterogeneity was found in the relationship between indoor and outdoor temperatures after adjusting for building type and year. Furthermore, the relationship between indoor temperature and thermal sensation was influenced by the outdoor temperature. This study highlights the importance of considering indoor temperature or individual thermal exposure in temperature-related health studies.

Experimental investigation of thermophysical properties of ethylene glycol based secondary fluids

Aqueous solutions of ethylene glycol are commonly used as secondary fluids in different indirect refrigeration systems and heat pumps as well as nanofluids. A very extensive literature review has been done, including more than 90 references published from 1905 to 2023. Despite the wide application and importance, especially in the energy sector, ethylene glycol solutions seem to be less investigated in low temperature ranges and more research is required to improve the quality and quantity of available data. The novelty of this paper is to investigate the most important thermophysical properties of ethylene glycol solutions in low temperatures. In this study a different approach was made and solutions having a specific freezing point temperature (between -5 and -50 ºC) rather than specific concentration were investigates in temperature ranges applicable for different cooling applications. The concentrations giving a certain freezing point temperature seemed to deviate in some cases with 1–2 wt-% between different sources. Nevertheless, the density results were in rather good agreement with all reference data. The viscosity results were lower by up to ±10% compared to reference values. Additionally, the obtained experimental results for thermal conductivity were higher by up to 12% compared to ASHRAE (American Society of Heating, Refrigerating and Air-Conditioning Engineers) data. The specific heat capacity results were higher by up to 14.6% and 5.4% than current reference data. There is a high probability that the current ASHRAE data for specific heat are actually indirectly calculated values from thermal conductivity data and not validated using differential scanning calorimetry techniques.

Optimalisasi Ventilasi Ruang Kelas untuk Mencegah Penularan Covid-19 dengan Setting Experiment

The spread of the SARS-CoV-2 virus has forced many schools to implement health protocols such as wearing masks, social distancing, and limiting the number of students in classrooms when face-to-face learning resumes as it did before the pandemic. This is due to the World Health Organization (WHO) and the Centers for Disease Control and Prevention (CDC) stating that Covid-19 can spread through the air (airborne). In addition to implementing health protocols, another important thing is to maintain classroom ventilation. By increasing the ventilation of outside air into the classroom, the risk of virus transmission can be reduced, and the indoor air quality can be improved. Introducing as much outside air as possible into the room is one important way to prevent the spread of Covid-19 because it can reduce the concentration of the virus in the room. ASHRAE (American Society of Heating, Refrigerating, and Air Conditioning Engineers) recommends a minimum of 6 ACH (Air Change per Hour) for classrooms. Research conducted on one middle school classroom in Tangerang Selatan, equipped with 2 AC units and 1 window, showed that the ASHRAE standard can be met by opening the window at least 50% during learning activities and turning on 1 AC unit with the fan setting at full speed to achieve an ACH greater than 6. If besides wanting to prevent the transmission of Covid-19, you also want to create comfort during the learning process, you can turn on both AC units with the fan setting at low to full speed. Keywords: Airborne, ASHRAE, Social distancing, US-CDC, WHO

Occupancy and Thermal Preference-Based HVAC Control Strategy Using Multisensor Network

Human-in-the-loop Heating, Ventilation and Air Conditioning (HVAC) control-based methodologies have gained much attention due to continual discomfort compliance of occupants in residential and commercial buildings; spawning thermal comfort research interest in leveraging emerging advanced technologies to address the prolonged problem of discomfort and energy efficiency. In the past, thermal comfort studies have been conducted to determine the thermal sensation, preference and comfort based on the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) Global Thermal Comfort Database II and customized dataset through machine learning. The ASHRAE Database II is an open-source database that includes sets of objective indoor climatic observations with corresponding subjective evaluations by the building occupants who were used as subjects in experiments. Environmental parameters and occupants’ skin temperature have been used to develop machine learning algorithms to predict thermal comfort indices in both indoor and outdoor settings. However, none of these studies have investigated merging environmental parameters and thermal images to predict thermal comfort indices of occupants. In this study, the holistic understanding of individuals thermal comfort environment was considered by fusing analog environmental sensors and thermal images captured at the time of the subjective measurement. Wavelet scattering features were obtained from the occupants’ thermal image surroundings and joined to the environmental parameters. This research developed different machine learning models, processing methods and evaluated the results based on the fused dataset. The results show the possibility of real time prediction of occupancy and thermal preference through classical machine learning, and stacked models with high accuracy. The proposed framework achieved an estimated 45% mean energy savings during a ten-day energy analysis.

Evaluation of thermal environment and human thermal comfort in 8 types of public places from 2019 to 2021

Objective: To evaluate the thermal environment of different types of public places and the thermal comfort of employees, so as to provide scientific basis for the establishment of microclimate standards and health supervision requirements. Methods: From June 2019 to December 2021, 50 public places (178 times) of 8 categories in Wuxi were selected, including hotels, swimming pools (gymnasiums), bathing places, shopping malls (supermarkets), barber shops, beauty shops, waiting rooms (bus station) and gyms. In summer and winter, microclimate indicators such as temperature and wind speed were measured in all kinds of places, combined with the work attire and physical activity of employees in the places. Fanger thermal comfort equation and center for the built environment (CBE) thermal comfort calculation tool were used to evaluate the predicted mean vote (PMV), predicted percent dissatisfied (PPD) and standard effective temperature (SET) according to the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) 55-2020. The modification effects of seasonal and temperature control conditions on thermal comfort were analyzed. The consistency of GB 37488-2019 "Hygienic Indicators and Limits in Public Places" and ASHRAE 55-2020 evaluation results on thermal environment was compared. Results: The thermal sensation of hotel, barber shop staff and the gym front-desk staff were moderate, while the thermal sensation of swimming place lifeguard, bathing place cleaning staff and gym trainer were slightly warm in summer and winter. Waiting room (bus station) cleaning and working staff, shopping mall staff felt slightly warm in summer and moderate in winter. Service staff in bathing places felt slightly warm in winter, while staff in beauty salons felt slightly cool in winter. The thermal comfort compliance of hotel cleaning staff and shopping mall staff in summer was lower than that in winter (χ(2)=7.01, 7.22, P=0.008, 0.007). The thermal comfort compliance of shopping mall staff in the condition of air conditioning off was higher than that in the condition of air conditioning on (χ(2)=7.01, P=0.008). The SET values of front-desk staff in hotels with different health supervision levels were significantly different (F=3.30, P=0.024). The PPD value and SET value of the front-desk staff, and the PPD value of cleaning staff of hotels above three stars were lower than those of hotels below three stars (P<0.05). The thermal comfort compliance of front-desk staff and cleaning staff in hotels above three stars was higher than that in hotels below three stars (χ(2)=8.33, 8.09, P=0.016, 0.018). The consistency of the two criteria was highest among waiting room (bus station) staff (100.0%, 1/1) and lowest among gym front-desk staff (0%, 0/2) and waiting room (bus station) cleaning staff (0%, 0/1) . Conclusion: There are different degrees of thermal discomfort in different seasons, under the condition of air conditioning and health supervision, and the microclimate indicators can not fully reflect the thermal comfort of human body. The health supervision of microclimate should be strengthened, the applicability of health standard limit value should be evaluated in many aspects, and the thermal comfort of occupational group should be improved.

Uncertainty method and sensitivity analysis for assessment of energy consumption of underground metro station

An accurate calculation of energy consumption is a precondition for energy underground metro station design, which determines the amount of energy geostructure. This study develops a simplified deterministic method for the underground metro station energy performance that accounts for weather and interior heat gain uncertainty. A Monte Carlo technique with Latin hypercube sampling is then employed to confirm the probability distributions of the peak load, average yearly load and annual energy demand, and compared to deterministic method to improve the design robustness. The sensitivities of 14 input variables with respect to the underground metro station energy performance are discussed through three sensitivity methods. The simplified deterministic method is more accurate than the DeST and American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) in describing the fluctuation of the underground metro station energy performance. The uncertainty distribution of energy performance is advantageous to the system design, considering both safety and economy. Moreover, a comparison with the deterministic method is performed to determine the reasonability of the safety factor 1.2, which is usually used in practical programs. The peak load is dominated by outdoor parameters, while there are no control parameters for the average yearly load or annual energy demand.

Modelling an air handling unit, building and occupant variation regarding energy, moisture and frost protection based on measurements of an air handling unit and occupants’ moisture supply

Objectives of this paper are to propose a reasonable simulation model that can handle condensation and frost formation in heat exchangers dependent on moisture concentration and outdoor climate conditions, and to analyze risk of frost formation and discuss different frost protection strategies. Using psychometrics, American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) heat exchanger calculation, condensation and frost calculation methods, simulations models for heat recovery ventilation and energy recovery ventilation are developed. It is concluded that the risk of frost in heat exchangers is higher in northern Sweden than in southern Sweden and Denmark due to low outdoor air temperatures during the winter, however heat recovery systems in Copenhagen and Gothenburg still has a risk of frost formation even though these cities has relatively warm weather conditions. Out of several simulation models that are created during the study, the detailed model that takes condensation effect into consideration, is proven to be worthy to be used in further investigations, due to results that more accurately represent real word conditions. Risk of frost formation becomes significantly lower in every city when heat recovery ventilation is changed into energy recovery ventilation. Even though heat recovery ventilation is simulated only with the simplified model, it is safe to assume that it will still be effective in reality. Although bypass strategies were effective at eliminating the risk of frost in heat recovery units, they are not as efficient from an energy perspective. The more air is by-passed through the cross-flow plate heat exchanger, the fewer opportunities there are to recover energy from exhaust air, which leads to lower supply air temperatures and higher energy need for heating a living space.

Quantifying Energy Reduction and Thermal Comfort for a Residential Building Ventilated with a Window-Windcatcher: A Case Study

Previous studies on window-windcatchers have shown their effectiveness in capturing the prevailing wind and redirecting it into a building, increasing the actual-to-required ventilation ratio by 9%, above what is required by the American Society of Heating, Refrigerating, and Air-Conditioning Engineers (ASHRAE). However, the effect of implementing the proposed system on energy performance, energy costs, and thermal comfort has not been studied. Therefore, here, we investigate and test the implementation of the window-windcatcher on a typical residential building, using a validated DesignBuilder model. Compared to the base case (no window-windcatcher), the total annual energy consumption of the entire building (Etot,b), and consequently the cost, is reduced by approximately 23.3% (i.e., from 18,143 kWh/year to 13,911 kWh/year) when using the window-windcatcher. The total annual reduction in thermal discomfort hours is estimated to be 290 h, which corresponds to an average monthly reduction of approximately 24 h.

Application of a Model Based on Rough Set Theory (RST) to Estimate the Energy Efficiency of Public Buildings

The study was carried out on a group of 85 public buildings, which differed in type of use, construction technology and heating systems. From the collected data, a set of qualitative and quantitative variables characterizing them in terms of heat demand was extracted. In this paper, the authors undertook to test the suitability of a model based on rough set theory (RST), which allows the analysis of imprecise, general and uncertain data. To obtain input data for the RST model in quantitative form, the authors used an alternative approach, which is a method based on the thermal properties of buildings. The quality of the predictive model was evaluated based on the following indicators, such as the coefficient of determination (R2), the mean bias error (MBE), the coefficient of variance of the root mean square error (CV RMSE) and the mean absolute percentage error (MAPE), which are accepted as statistical calibration standards by ASHRAE (American Society of Heating, Refrigerating and Air-Conditioning Engineers). A quality-acceptable predictive model must meet the calibration conditions: MBE ±5%, CV RMSE &lt; 15% and R2 &gt; 0.75. For the analyzed RST model, the following values of evaluation indicators were obtained: MBE = −1.1%, CV RMSE = 11.8% and R2 = 0.91. The evaluation results obtained gave rise to the conclusion that the method used, which is based on a limited amount of data describing buildings, gives good results in estimating the unit rate of energy demand for heating.

Assessment of solar load models for bifacial PV panels

Solar load is one of the key inputs in thermal analysis of all solar based applications using ray tracing. Commercial and academic Computational Fluid Dynamics (CFD) codes incorporate different solar load models for ray tracing, i.e., Solar Position and Intensity (SOPLOS) theoretical maximum function, American Society of Heating, Refrigeration, and Airconditioning Engineers (ASHRAE) fair weather and constant solar load models. However, solar load depends largely on weather conditions of the site whereas the solar load models in CFD software do not accommodate changing weather patterns and hence the CFD simulation results obtained are not representative of an extended period of time. This paper studies the effect of changing weather patterns on solar load assessment, using bifacial solar panels as a case study. In this study, on-site data of a humid sub-tropical region for monsoon season, mid-June to mid-August, has been used as an input for solar ray tracing due to large temperature variations and cloud cover for longer duration. Comparative study of SOPLOS and ASHRAE models with in situ model shows that they over predict front side solar load, with only 0.5% and 13% matching in situ data respectively, while both models under predict rear side solar load in the studied time period, with 2% and 24% solar load estimation agreeing with in situ data respectively.

Assessing Indoor Environmental Quality in a Crowded Low-Quality Built Environment: A Case Study

Home heating, cooling and ventilation are a major concern for those living in low-quality built environments, particularly those with high occupancy rates (crowded houses). In New Zealand, both owner-occupiers and tenants can experience problems associated with poor Indoor Environmental Quality (IEQ), such as poor thermal comfort and dampness, when Heating Ventilation and Air-Conditioning (HVAC) systems are not installed, improperly installed or too expensive to run. Occupants of poorer households are the most affected by high installation or running costs of HVAC systems, and are also more likely to live in households with a higher level of crowding. Poor IEQ in housing is associated with adverse health outcomes, particularly respiratory illness. This paper outlines the IEQ problems experienced by households living in an area of New Zealand with higher levels deprivation and shows how an HVAC system could be employed to remedy poor IEQ. This report presents a case study of a house with poor IEQ that was selected from a survey conducted across 24 homes in the Manukau, Auckland region of New Zealand. The IEQ results are presented for this house, which performs poorly in terms of relative humidity, temperature and thermal comfort. This house is then analysed using the computational fluid dynamics (CFD) approach in ANSYS CFX 2021R1 based on the American Society of Heating, Refrigeration and Airconditioning Engineers (ASHRAE) standard 55-2017 and a model of temperature and air flow is created in the software, which can identify ways to improve these parameters in the house. These results are compared with the New Zealand Healthy Homes Standards 2019. The simulation showed the system was capable of lifting the indoor temperature to above 21 ℃, eliminating cold spots and improving thermal comfort, and reduced relative humidity to below 50%.

Optimization of the Construction System of Relief Tents Used in Emergency Accommodation

INTRODUCTION: The frequency of natural disasters is high in Iran due to its special climatic and geophysical conditions. However, the provision of better services to trauma victims requires further research. Decisions on emergency accommodation and meeting the needs of the victims are often made in conditions of uncertainty, and the lack of appropriate studies leads to the provision of low-quality and intermittent services. METHODS: This applied and descriptive-analytical study was conducted to determine the advantages and disadvantages of relief tents using documentary and library resources, observation, and interviews with officials and experts, and the effective standards for the construction system of emergency accommodation. The thermal comfort of the victims was then investigated using the guidelines of the American Society of Heating, Refrigerating, and Air-Conditioning Engineers (ASHRAE), interviews with the victims, and field tests. Moreover, solutions are introduced for the improvement and optimization of relief tents, and a new building system is introduced for the emergency accommodation of victims in incidents by removing the disadvantages of the systems previously used in emergency accommodation. FINDINGS: According to the observations and investigations, the previously used emergency shelters do not meet the needs of the accident survivors properly and their design does not correspond to the users’ culture and needs. The problems with the current accommodating methods include lack of privacy, lack of protection against disturbing cold and heat, and inappropriate and non-standard dimensions of the existing tents. Solutions have been presented to solve the existing problems and a new system for emergency accommodation has been introduced based on field observations and interviews with experts. CONCLUSION: It is noteworthy that the votes of 22 percent of people are in the range of slightly warm to slightly cold; which shows that these people are satisfied with their accommodation regarding thermal comfort. 78 percent of the people's votes were outside the satisfaction range. Due to the chambered structure of the tent, direct sunlight in the summer, the lack of proper air exchange, the weakness of the structural components of the tent and the lack of heat retention in the winter, proper mechanical systems should be used to provide thermal comfort, which is not feasible in practice due to the extent of the incidents and large amounts of equipment and resources needed which bolds the importance of the proposed construction system.

CFD SIMULATION FOR AIRSPEED AND TURBULENCE VALIDATION IN MAIN DUCTING OF OFFICE BUILDING

This paper focuses on the calculation of sizing ducting based on cooling load requirements the main ducting of office building following regulation airspeed requirements using American Society of Heating, Refrigerating and Air Conditioning Engineers (ASHRAE) and Computational Fluid Dynamics (CFD) simulations. The purpose of this research is to validate the airspeed and turbulence that occurs in the main ducting between manual calculations and CFD simulations. From the calculation, the cooling load requirement is 58.22 kW, for the cooling process an air flowrate of 7117 L/s is needed which is designed to pass through the main ducting in rectangular shape. The main ducting size uses 1200 mm x 500 mm at a speed of 12.7 m/s according to ASHRAE. Autodesk Inventor software is used for ducting modeling and Autodesk CFD is used for airflow simulation. CFD simulations are performed by applying boundary conditions and input parameters. The results showed that the velocity of the ducting design was suitable at 12.7 m/s with laminar flow. The ducting geometry must be designed aerodynamically to reduce the pressure drop which can cause the speed to increase so that it is outside the required limits. Thus, the CFD simulation results have verified the validity of manual calculations.

Preliminary evaluation on specific energy consumption of refrigerated trucks in Thailand’s cold chain used for national energy policy planning

The objective of this study was to evaluate the suggested specific energy consumption (SEC) of refrigerated trucks in the cold chain in Thailand. Types of refrigerated trucks were classified following the regulations of the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE), the Ministry of Public Health, Thailand and the Department of Land Transport, the Ministry of Transport, Thailand. The fuel consumption, weight, distance traveled, and other data were recorded on 50 refrigerated trucks operating in practice. The SEC was calculated following the European Standard EN 16212:2012. The relationship between the SEC and the ratio between good weight and maximum allowance load weight or called as the weight ratio for each truck type was established in a power function. The suggested SEC for each truck type at a certain weight ratio could be determined from this relationship. The lowest SEC or the target for the best energy saving practice was determined at the weight ratio of 1.0. In addition, the comparison found that the international small-sized truck had lower SEC than the 4-wheeler truck in Thailand. Therefore, the domestic 4-wheeler refrigerated trucks should be the primary target for the government to enforce the cold chain energy saving plan.

Air Handling Unit Shutdowns During Scheduled Unoccupied Hours: US Commercial Building Stock Prevalence and Energy Impact

Abstract Commercial buildings account for 18% of U.S. energy consumption, with 44% used for heating, ventilation, and air conditioning (HVAC). American Society of Heating, Refrigerating and Air Conditioning Engineers (ASHRAE) 90.1 requires HVAC systems to shutdown fans and outdoor air ventilation during unoccupied times, only allowing fans to cycle on, without outdoor air, to maintain thermostat setpoints. However, it is minimally understood how often existing building operations align with energy code requirements and the energy implications of not doing so. This study used building automation system data from 843 buildings containing 5706 air handling units (AHUs) to determine three unoccupied AHU shutdown control schemes ranging in efficiency and then estimated their prevalence in the U.S. commercial building stock, segmented by building type. ComStock was then used to analyze the energy savings potential of implementing the most energy efficient unoccupied shutdown control scheme in non-participating buildings across the U.S commercial building stock. Results show that only 23% of AHUs align completely with the ASHRAE 90.1 requirement. ComStock modeling results show 4% annual stock energy savings by switching all non-participating buildings to the most efficient scheme, with 19% annual energy savings demonstrated for the median building switching from the least efficient scheme to the most efficient. Findings also show 114.5 TBtu electricity and 75.8 TBtu natural gas fuel savings when converting to the most efficient scheme. These findings help stakeholders understand the high prevalence of buildings not aligning with the ASHRAE-90.1 requirements for unoccupied AHU shutdowns and the energy savings potential of utilizing the most efficient unoccupied AHU shutdown scheme.