Indoor Air Conditions Research Articles

Research on air conditioning energy use and indoor thermal environment with Private Finance Initiative data monitoring of junior high schools before and during the COVID-19 pandemic in Japan

The COVID-19 pandemic began to spread at the beginning of 2020 in the world and in Japan, which is expected to impact the air conditioning (AC) energy use (EU) in educational buildings when AC and natural ventilation are used together as a new regulation to decrease infectious disease transmission. Furthermore, this regulation of natural ventilation is expected to impact the AC EU when the outside temperature affects indoor comfort causing changes in the regular AC setting temperature and AC operating times. This study aims to evaluate the AC EU, and the indoor thermal environment changes with Private Finance Initiative (PFI) data monitoring in junior high schools in Oita City before and during the COVID-19 pandemic during summer and winter through a sensitivity analysis method. The result found that AC EU significantly increased during the pandemic, 2 times escalation in summer and 1.9 times in winter. Besides, during the pandemic, indoor air temperature comfort was achieved with longer AC operation time, lower AC setting temperature in summer, and higher AC setting temperature in winter. The result of this research can be expected to be beneficial for future studies regarding AC energy saving and indoor thermal comfort-related investigation and valuable for new regulations related to air conditioner settings and operations for the new normal during the pandemic.

Sustainable Thermal Insulation Derived from Recycled Textile Waste

The textile industry is one of the oldest industries and the third most important industry branch in Macedonia. It has had a steady increase in production over the years. Growing production line proportionally generates textile waste. Although it is terminologically categorized as waste, textile waste can be a valuable resource and is one of the textile industry’s main challenges. Textile waste, appropriately treated with the possibilities offered by the recycling process or used as a clean waste, can find multi-faced application in different construction areas. This paper covers research that examines the possibilities of applying textile waste in the field of thermal insulations in buildings. The focus is on developing thermal insulation solutions applied in sustainable and ecologic buildings. Applied thermal insulation has a primary impact on reducing electricity consumption and greenhouse gas emissions associated with indoor air conditioning. That would mean that buildings incorporating appropriate thermal insulation offer greater comfort, directly increasing the quality of life. This is an additional economic-environmental dimension. According to the experimental testing, the thermal conductivity coefficient of the textile waste is obtained at 0.039 W/m·K. Its value defines a thermal insulation material suitable for the purpose and has approximate values to the other materials usually used for thermal insulation in buildings. Implementing a product made of textile waste with appropriate performance would bring economic benefits to the industry and open new job opportunities.

Система обеспечения параметров воздуха в помещении для содержания крупного рогатого скота

Creating comfortable conditions for animals ensures their longevity and high productivity. Artificial ventilation, which includes supply and exhaust systems and a control system, minimizes the influence of the human factor on maintaining the indoor air parameters. The proposed system of indoor air-conditioning for the loose cattle housing layout was developed based on the analysis of ventilation systems of livestock premises and studies proving the effectiveness of dehumidification in winter using a regenerative heat exchanger. The system for providing indoor air parameters was developed using the computer-aided design program “Compass” (CAD) of the “Askon” company. The developed system for providing indoor air parameters for keeping cattle includes an electrofilter and a coarse filter, fans, a plate heat exchanger, a turbodefector; temperature, humidity, and air flow velocity sensors, dust collectors, a pump, a tank with a disinfectant, and a mechanism for shutting down supply air and recirculated air. The use of a recuperative dehumidification system at low outdoor temperatures helps maintain the relative indoor humidity within the regulatory limits (75…40%) and reduce the concentration of carbon dioxide by 20…45%. To ensure these indoor air parameters without dehumidification, 200 kW of thermal power is needed to heat the supply air. The proposed combined energy-saving all-season climate control system provides monitoring of indoor air parameters and energy saving through the use of a turbo deflector, disinfects the ventilation air, dehumidifies the air in the cowshed in winter and cools in summer, and also partially removes dust from the air with an electromagnetic filter.

Investigating natural ventilation performance on apartment units in Jakarta based on field test measurements

The COVID-19 pandemic has changed the way of living of many people across the planet. In the beginning of the pandemic, when the strict lockdown was implemented, numbers of individual were encouraged to work from home. In the city living, high rise living were apparent and became a global phenomenon. This paper evaluates natural ventilation performances of existing apartment units in Jakarta, Indonesia by measuring the indoor temperature, indoor airflow and relative humidity. This research studied three different apartment units in Jakarta in the form of single-sided ventilation or cross ventilation. This study conducted by field test measurement on three different apartment units across Jakarta with various natural ventilation strategy and room volume. Statistical analysis was carried out to investigate the relationship and influence between the results of field test measurement and external weather data collected from ERA5. The results of the analysis suggested that external weather influence the indoor air condition, especially indoor temperature where significant influence was apparent. Furthermore, the field test data measurement in this paper contributed to validation study in predicting indoor airflow.

Ten questions concerning the impact of environmental stress on office workers

We regularly face stress during our everyday activities, to the extent that stress is recognized by the World Health Organization as the epidemic of the 21st century. Stress is how humans respond physically and psychologically to adjustments, experiences, conditions, and circumstances in their lives. While there are many reasons for stress, work and job pressure remain the main cause. Thus, companies are increasingly interested in creating healthier, more comfortable, and stress-free offices for their workers. The indoor environment can induce environmental stress when it cannot satisfy the individual needs for health and comfort. In fact, office environmental conditions (e.g., thermal, and indoor air conditions, lighting, and noise) and interior design parameters (e.g., office layout, colors, furniture, access to views, distance to window, personal control and biophilic design) have been found to affect office workers' stress levels. A line of research based on the stress recovery theory offers new insights for establishing offices that limit environmental stress and help with work stress recovery. To that end, this paper answers ten questions that explore the relation between the indoor office-built environment and stress levels among workers. The answers to the ten questions are based on an extensive literature review to draw conclusions from what has been achieved to date. Thus, this study presents a foundation for future environmental stress related research in offices.

Uptake and reactivity of formaldehyde on lime-cement-plaster under typical indoor air conditions

Inorganic construction materials are chiefly envisaged as structural materials. However, they provide unexplored interfaces with characteristic surface chemistry to interact with indoor gases. This work proposes for the first time an insight on uptake abilities of lime-cement-plaster toward indoor pollutant. Because of toxicity and regulation policies, formaldehyde is selected as representative indoor pollutant. This work explores gas-material interaction to elucidate fate of formaldehyde onto lime-cement-plaster and addresses air quality impact. Uptake and fate of formaldehyde onto plaster is addressed using Field and Laboratory Emission Cell coupled with SIFT Mass Spectrometer. The experimental sequence is continuously deployed on 90 days to address realistic and long-term behaviour of formaldehyde uptake. Experimental approach evidences that from 65 to 77% of formaldehyde inlet concentration is continuously taken up on plaster samples throughout experimental sequence. Concomitantly, methanol is observed showing the reactivity of formaldehyde uptake on this material-class. Diffuse Reflectance Infrared Spectroscopy evidences that formaldehyde undergoes heterogeneous Cannizzaro reaction on the plaster surface. This surface reaction proceeds with adsorbed formaldehyde, even in the absence of gaseous pollutant supply. The quantitative balance of the disproportionation process is proposed along the experimental sequence to clarify the fate of formaldehyde encompassing gaseous and adsorbed-phase. The evidenced surface process can impact formaldehyde budget in indoor air, thus relevant parameters are determined to allow further implementation of this reactive contribution to indoor air quality models. This work settles perspectives for passive mitigation of indoor formaldehyde, and points at the need to address reaction products for their indoor air quality impact.

Semi-Supervised Random Forest Methodology for Fault Diagnosis in Air-Handling Units

Air-handling units have been widely used in indoor air conditioning and circulation in modern buildings. The data-driven FDD method has been widely used in the field of industrial roads, and has been widely welcomed because of its extensiveness and flexibility in practical applications. Under the condition of sufficient labeled data, previous studies have verified the utility and value of various supervised learning algorithms in FDD tasks. However, in practice, obtaining sufficient labeled data can be very challenging, expensive, and will consume a lot of time and manpower, making it difficult or even impractical to fully explore the potential of supervised learning algorithms. To solve this problem, this study proposes a semi-supervised FDD method based on random forest. This method adopts a self-training strategy for semi-supervised learning and has been verified in two practical applications: fault diagnosis and fault detection. Through a large number of data experiments, the influence of key learning parameters is statistically represented, including the availability of marked data, the number of iterations of maximum half-supervised learning, and the threshold of utilization of pseudo-label data. The results show that the proposed method can effectively utilize a large number of unlabeled data, improve the generalization performance of the model, and improve the diagnostic accuracy of different column categories by about 10%. The results are helpful for the development of advanced data-driven fault detection and diagnosis tools for intelligent building systems.

Analisis Kualitas Udara Pada Rumah Warga Terhadap Parameter Bakteri dan Jamur

The final processing and disposal the waste occurs at the Final Disposal Facility (TPA). Because the rubbish heaps include a variety of contaminants and produce air pollution, landfills can have an impact on the environment's quality. This study intends to identify and contrast the outcomes of the analysis of the air quality in residents' homes near the Piyungan TPA location, which is 50 m, 350 m, 650 m, and 1000 m from the TPA, with quality standards according to the Decision of the Minister of Health No. 1077 of 2011 based on bacterial and fungal parameters. The ideal distance between residential areas and the TPA location is another goal of this study. Air sampling at each location used the air sampling method directly with NA media and PDA media in petri dishes. The results showed that the number of bacterial colonies at a distance of 50 m was 4,485.6 CFU m-3 and the fungal colonies were 2,306.4 CFU m-3. At a distance of 350 m, the number of bacterial colonies was 3,355.4 CFU m-3 and fungal colonies were 2,130.9 CFU m-3. The number of bacterial colonies at a distance of 650 m was 2,919.7 CFU m-3 and the number of fungal colonies was 2,001.3 CFU m-3. The number of bacterial colonies at a distance of 1000 m was 1,353.2 CFU m-3 and the number of fungal colonies was 765.2 CFU m-3. Air quality in residents' homes with a distance of 50 m to 1000 m does not meet the healthy air quality requirements based on Minister of Health Regulation No. 1077 of 2011 concerning Indoor Air Conditioning at Home with maximum levels of airborne microbes <700 CFU m-3.

Feasibility of Harris Hawks Optimization in Combination with Fuzzy Inference System Predicting Heating Load Energy Inside Buildings

Heating and cooling systems account for a considerable portion of the energy consumed for domestic reasons in Europe. Burning fossil fuels is the main way to produce this energy, which has a detrimental effect on the environment. It is essential to consider a building’s characteristics when determining how much heating and cooling is necessary. As a result, a study of the related buildings’ characteristics, such as the type of cooling and heating systems required for maintaining appropriate indoor air conditions, can help in the design and construction of energy-efficient buildings. Numerous studies have used machine learning to predict cooling and heating systems based on variables that include relative compactness, orientation, overall height, roof area, wall area, surface area, glazing area, and glazing area distribution. Fuzzy logic, however, is not used in any of these methods. In this article, we study a fuzzy logic approach, i.e., HHO−ANFIS (combination of Harris hawks optimization and adaptive neuro-fuzzy interface system), to predict the heating load in residential buildings and investigate the feasibility of this technique in predicting the heating load. Fuzzy techniques obtain perfect results. The analysis results show that the HHO−ANFIS with a population size of 400, the highest value of R2 (0.98709 and 0.98794), and the lowest value of RMSE (0.08769 and 0.08281) in the training and testing dataset, respectively, can predict the heating load with high accuracy. According to the high value of R2 (98%) and low value of RMSE, HHO−ANFIS can be used in predicting the heating load of residential buildings.

Simulation of interaction between high-temperature process and heat emission from electricity system in summer

During the hot summer season, using electricity systems increases the local anthropogenic heat emission, further increasing the temperature. Regarding anthropogenic heat sources, electric energy consumption, heat generation, indoor and outdoor heat transfer, and exchange in buildings play a critical role in the change in the urban thermal environment. Therefore, the Weather Research and Forecasting (WRF) Model was applied in this study to investigate the heat generation from an indoor electricity system and its influence on the outdoor thermal environment. Through the building effect parameterization (BEP) of a multistorey urban canopy scheme, a building energy model (BEM) to increase the influence of indoor air conditioning on the electricity consumption system was proposed. In other words, the BEP+BEM urban canopy parameterization scheme was set. High temperatures and a summer heat wave were simulated as the background weather. The results show that using the BEP+BEM parameterization scheme of indoor and outdoor energy exchange in the WRF model can better simulate the air temperature near the surface layer on a sunny summer. During the day, the turning on the air conditioning and other electrical systems have no obvious effect on the air temperature near the surface layer in the city, whereas at night, the air temperature generally increases by 0.6 ℃, especially in densely populated areas, with a maximum temperature rise of approximately 1.2 ℃ from 22:00 to 23:00. When the indoor air conditioning target temperature is adjusted to 25–27 ℃, the total energy release of the air conditioning system is reduced by 12.66%, and the temperature drops the most from 13:00 to 16:00, with an average of approximately 1 ℃. Further, the denser the building is, the greater the temperature drop.

Model predictive control of a thermal chimney and dynamic solar shades for an all-glass facades building

Controlling the operation of HVAC (Heating, Ventilation, and Air-Conditioning) systems is arguably the most effective way to reach desired indoor conditions in buildings. Nevertheless, such control may involve complex dynamics when dealing with passive energy technologies. In this paper, we focus on maximizing the passive operation of HVAC in a novel low-energy building design by means of Model Predictive Control (MPC). The low-energy building design, located in The Green Village, consists of a thermal chimney and solar shades over all-glass facades to provide the required indoor air conditioning as passively as possible. The MPC controller is based on a transient grey box model and a hierarchical control architecture to satisfy thermal comfort while minimizing the active energy requirements. Using sensor data collected from the actual building in April and May 2021, the grey box model shows a good agreement with the measurements, since the variance accounted for is 90% in most cases. Moreover, via a comparative study among different MPC architectures we show that managing the distinct transient response of each component (shades and chimney) is the best for successful overall performance – e.g. considering linear agents for shading and nonlinear agents for ventilation. The hierarchical MPC architecture established outperforms the standard ones by 22.7% in terms of control performance. We also compare the proposed MPC approach against the rule-based control method currently implemented in the actual building, which indicates that MPC demands about 78% less active energy, highlighting the proposed optimization-based control approach.

Integrated Design and Assessment for Indoor Heating, Ventilation and Air-Conditioning in Hot Summer and Cold Winter Area: A Case Study in China

Integrated design of the heating, ventilation and air-conditioning (HVAC) is indispensable to green design because the increasing demand for HVAC systems has led to the diversification of indoor terminals for residential buildings, either focusing on energy efficiency or specializing in creating comfortable indoor environments, and they have different impacts on architectural and engineering design. The paper discussed the assessment-based integration design of the HVAC system, and by introducing case experiences, the whole process of the collaboration between architects and engineers was explored. Various methods were used in the research. The analytic hierarchy process (AHP) was employed to develop the assessment structure and calculate weightings; employing fuzzy comprehensive evaluation (FCE), the social performances of HVAC systems were subjectively evaluated; simulation technology was used to calculate the energy performances; the final results were ranked by the order of preference by similarity to ideal solution (TOPSIS). The research perspective of the collaboration between architects and engineers contributed to the existing literature. Besides, different indoor terminals were analyzed from the two disciplines; an assessment tool (ATI) was conducted and could be referred to; the current green building rating tools were analyzed, and suggestions were proposed to promote the integrated design.

Numerical Investigation on The Effect of Grille Blockage Ratio on Air Flow Characteristics of Air Vents

Vents with louvers are an important component in the indoor heating, ventilation, and air conditioning (HVAC) system in providing a degree of freedom to the occupants to direct the air flow and prevent foreign objects from entering or exiting the air ducts. As a result, whether designing air ventilation or any duct design that involves louvers, the influence of louver design cannot be ignored. For vent design, aside from louver angle, blockage ratio is an important factor in air distribution due to its effect on pressure drop and flow distribution to indoor space. The blockage ratio is often described as the ratio of the projected area of the structure in flow direction to the cross sectional area of the domain around the structure. The purpose of this study is to investigate the effect of varying blockage ratios on the air flow characteristics of air vents including velocity and pressure drop. The chosen air vent model for this study is the Proton Wira air vent. Results are obtained using computational fluid dynamics (CFD) analysis and by utilizing the free and easily available open source software via Code-Saturne. The parameters were set according to available literature. The study finds that the pressure drop increases with the increasing blockage ratio. The velocity drops almost 7% for blockage ratio greater than 3 and the pressure drop increases more than 4%.

Thermal performance of domed roof in air-conditioned spaces

Due to their thermal performance, domed roofs are one of the passive solutions that affect energy consumption in buildings. The thermal performance of domed roofs has been investigated in many naturally ventilated spaces. However, few studies have discussed their performance in conditioned spaces. Therefore, this study introduces a computational comparison between domed and flat roofs to investigate their impact on thermal comfort inside a conditioned mosque. At an earlier stage, field measurements were carried out inside a Bahraini mosque to acquire its indoor air conditions during the summer period of 2021, in addition to validating the computational model. The findings of this study confirm that, under mechanical cooling conditions, the flat roof offers a lower indoor temperature than the domed roof by 0.4 °C and 0.1 °C for open and closed doors, respectively. Similarly, the air velocity is lower by approximately 0.01 m/s for both door modes. The overall PMV values of the flat roof are also lower by 0.07 and 0.01, while the PPD values are lower by 0.20, and 0.34 for open and closed doors, respectively. Based on these small differences, it can be concluded that the thermal performance of both roofing systems behaves equally in conditioned spaces. However, the air patterns are substantially different, the overall thermal performance is similar. This similarity drives building designers to rethink the thermal performance of the domed roofs in air-conditioned spaces with such a hot climate, regardless of their aesthetic and acoustical behaviour.

Performance evaluation of activated carbon sorbents for indoor air purification during normal and wildfire events.

Volatile organic compounds (VOCs) are a significant class of indoor air pollutants and are known for their adverse effects on health. A common strategy to reduce indoor VOC levels is to use sorbents, including activated carbons (ACs). The amount of activated carbon is critical to achieving a reasonable AC filter lifetime in an air purification device. The study aims to estimate the amount of carbon needed in a typical indoor environment and in a heavy use setting such as during cooking, agriculture field fires, or wildfires. The problem is complex as various types of ACs are used, and the type and concentration of VOCs in the indoor environment also vary in different settings. Therefore, literature data on thermophysical parameters for 45AC-VOC pairs was used to estimate the required amount of AC under a given set of conditions. The study uses modeling distributions of the footprint of suitable carbon filters for the removal of common VOCs encountered indoors for a period of 30 days. It was found that while 50% of AC-VOC pairs surveyed will require about 190-370g at low indoor VOCs levels of 0.1-1μmol/m3(considered a good clean indoor environment), up to 1.1kg of ACs are needed for a carbon filter to survive 30 days in a typical indoor environment (VOCs levels of 10μmol/m3). On the other hand, 3-15kg or more AC will be needed in a filter to survive 30 days during adverse events such as wildfires. The objective of the present study is to aid consumers and businesses in making an informed decision on the type of AC-based indoor air filters that meet their needs. Using this data, an open-access online calculator is being developed to predict the amount of carbon needed in a filter/device at any specific indoor air condition.

A CABINE DOS Can the tractor's cabin allow the noise at the operator's station?PODE ATENUAR O RUÍDO NO POSTO DO OPERADOR?

Constant exposure to high noise levels can cause health problems for agricultural machinery operators. Machines equipped with closed cabs can attenuate noise and preserve the operator from an unhealthy condition. Some studies show that in cabin tractors it is possible to renounce the use of hearing protection, however indoor equipment and air conditioning can reach high levels of noise, which need to be further investigated. The present study aimed to evaluate the noise emitted by a cabined agricultural tractor, in different points, inside and outside cabin, in the engine rotations of 800rpm, 2180rpm and 2500rpm. In each reading, 100 noise intensity values were automatically collected, over two minutes with the aid of a digital decibel meter device. The results were compared with the levels assumed by Annex 1 of the regulatory Brazilian standard NR 15, and it was found that the cabin was able to isolate the noise emitted by the engine and its external components in 15%, however, the internal noise reached 81dB(A). The cabin can attenuate external noise and offer a healthy working environment, however, in long working hours it is recommended to use personal protective equipment such as ear protectors.

CFD modeling of the building integrated with a novel design of a one-sided wind-catcher with water spray: Focus on thermal comfort

The rising energy demand for buildings has enhanced public awareness of sustainable energy sources and technologies. In particular, natural ventilation systems such as wind-catchers have attracted considerable new attention. A new wind-catcher design with single-stage direct-air evaporative cooling was proposed for indoor air conditioning. An Eulerian-Lagrangian approach employing the Realizable k-ε model was utilized to conduct the CFD simulations. Furthermore, the effects of inclining the bottom surface of the wind-catcher and installing a baffle across the flow path on the air temperature drop, water mass fraction, and air velocity distribution were studied. The inclined bottom surface led to more flow uniformity in the room compared to the conventional geometry. The baffled wind-catcher with β = 0, 30, 45, and 60° and unbaffled wind-catcher showed different flow patterns and thermal comforts. A methodology for evaluating the thermal comfort performance of evaporative cooling systems integrated into natural or passive cooling devices was also proposed based on the generated CFD results. The baffled wind-catcher with β = 60° combined with an evaporative cooling system significantly reduced the air temperature inside the building up to 17.4 °C and improved the occupants’ thermal comfort. The most suitable design for thermal comfort was also determined.

Heat Transfer Intensification by Means of Convex-Strip Around Tube in Fin and Tube Heat Exchanger with Field Synergy Principle

Fin and tube is a compact heat exchanger, have been widely used in various engineering fields such as heating, ventilation, air conditioning, and refrigeration systems. An example, indoor and outdoor air-conditioning, the air is used as one of the heat exchanger media. However, over 90% of the total thermal resistance from air to liquid lies on the airside. Therefore, the reduction of thermal resistance should be made to increase heat transfer. This study is intended to investigate the effect of enhancing convex-strip surface to heat transfer and friction characteristic on the heat exchanger. Three-dimensional modeling of the convex fin and the plain fin was conducted on a constant tube temperature of 106℃. Tube with the configuration of the six staggered strands on the odd tube and five rows on the even tube is determined. The velocity variation in the fin gap is assessed under the Reynolds number range between 3,438 to 15,926. The enhancement of four convex-strips around the tube on the fin surface can generate the value of the field synergy angle on fluid flow. The simulation results also show that the improvement of convection heat transfer coefficient value in convex-strip fin with staggered configuration is 15.39% higher than plain-fin.

The application of solar integrated absorption cooling system to improve the air quality and reduce the energy consumption of the air conditioning systems in buildings – A full year model simulation

Due to the depletion of fossil fuels and increasing the atmospheric greenhouse gas emissions, employing equipment with low energy consumption levels, while benefiting the renewable energy sources have been wide spread these days. In this research, the application of a solar assisted absorption chiller/cooling system in a high cooling load required region of Iran was investigated. A building located in southeast region of the country as a high cooling load required region was considered for this purpose. The performance of the building existing cooling system was studied in terms of the provided indoor air conditions and energy consumption was using TRNSYS software. Then, the feasibility of replacing the existing cooling system with a solar assisted absorption chiller was explored. Three recommended standard solar panels, namely Evacuated Tube, Glazed Painted, and Unglazed solar collectors were examined to recommend the most desired configuration. The study was conducted based on two operating hours of 24 h. and 8 h. (office working hours) scenarios. The results showed that within the regular office working hours, the solar assisted absorption chiller system equipped with the Evacuated Tube, Glazed Painted, and Unglazed solar collectors improves the indoor temperature up to 3.08 °C, 1.68 °C, and 1.46 °C, respectively. It was also found that the reduction in power consumption by application of the solar assisted absorption chiller could be up to 84 %, 64 %, and 48 %, respectively compared to the currently used cooling system in the building. The performance comparison between the three examined solar thermal panels revealed that the solar absorption chiller equipped with the Evacuated Tube solar collector has the capability to provide the most desired indoor air conditions and power consumption level.

Effect of Working Fluid-Filling Ratio Combination on Thermosyphon Performance as Add-In Enhancer for Indoor Air Conditioning Devices

An experimental study is presented to account for the implementation of a two-phase closed thermosyphon pipe, for energy-saving purposes, in air conditioning systems in the context of COVID-19. The experimental setup consisted of a 0.5 m × 0.0127 m type L copper pipe which was employed as the body of the heat exchanger; an electric resistance heater of 0.1 m length located at the bottom; and a 0.25 m length water-cooled concentric condenser located at the top. The evaluation was conducted employing acetone, ethanol, and distilled water as working fluids; ranging the heat supplied at the evaporator from 25 to 125 W and the filling ratio from 20% to 40% of the total inner volume of the thermosyphon. From the data obtained, it was found that ethanol is the working fluid most susceptible to changes in operation conditions. Contrarily, distilled water was found to deliver consistent performance, up to a point that, for the analysed setup, it is considered to be independent of both, heat flow supplied at the evaporator and thermosyphon filling ratio. Meanwhile, acetone was found to be the only fluid tested that displays a directly proportional behaviour between heat absorption and dissipation. From compiling experimental data, response surfaces were constructed and used as direct and rough optimization tools. The information provided by this approach is considered to be particularly useful and is introduced for modelling and design purposes. Based on the results, it was found that acetone, within operation ranges of 34%<ϕ<40% and 75 W<Q˙Evap<125 W, was the most suitable working fluid to use in a two-phase closed thermosyphon for energy-saving purposes in air conditioning applications.