Use Of Air Conditioning Research Articles

Energy and thermal storage in clusters of grid-independent buildings

The extensive substitution of fossil fuels with renewables creates the U-shaped demand curve (duck curve) problem which is exacerbated in the summer months with the extensive use of air-conditioning. This study examines the hourly, daily, and yearly operation of a cluster of one hundred grid-independent buildings that completely rely on photovoltaics for electricity generation, including their air-conditioning needs. The cluster stores energy in hydrogen as the seasonal storage medium and chilled water for cooling as the daily storage medium. Thermal storage of chilled water and the use of efficient air-conditioning (refrigeration) equipment significantly reduces the needs for the generated electric energy and stored energy: The utilization of thermal storage in addition to chemical storage has three beneficial results: a) it reduces by about 40% the needed solar power installation; b) it reduces by a factor of three the losses associated with energy storage; and c) it reduces by factor of four the necessary hydrogen storage capacity. The improved performance of the system is expected to significantly reduce the overall cost associated with grid independent buildings.

Audit Energi Listrik pada Hotel Sotis Kupang

Abstract— The Energy Audit is an assessment of energy consumption and the identification of energy savings, as well as recommendations to increase the efficiency of energy consumption and use of energy sources in the context of energy saving.
 This study aims to describe the testing of electrical energy in the rooms of the Sotis Kupang Hotel from the 2nd (second) to the 6th (sixth) floor, taking samples of 7 (seven) different room types and carried out a test of electrical energy in relation to the use of lamps and air conditioning. The method used in this study is data collection, survey, observation and direct measurement of the use of light and AC (air conditioning). The data analysis technique used is to determine the estimated value of the electrical energy consumption and the value of the energy consumption intensity (IKE).
 The calculation and analysis show the value of IKE is 30.96 kWh / m2/ year, which is categorized as "very efficient". The IKE value for the use of AC (air conditioning) is 206.33 kWh / m2/ year and which is categories as "somewhat wasteful". The calculation of the PHE (energy savings) results in a PHE for the use of AC of 172.88 kWh / m2/ year, which falls into the category of "fairly efficient.

Urban warming and future air-conditioning use in an Asian megacity: importance of positive feedback

The impact of feedback between urban warming and air-conditioning (AC) use on temperatures in future urban climates is explored in this study. Pseudo-global warming projections are dynamically downscaled to 1 km using a regional climate model (RCM) coupled to urban canopy and building energy models for current and six future global warming (ΔTGW) climates based on IPCC RCP8.5. Anthropogenic heat emissions from AC use is projected to increase almost linearly with ΔTGW, causing additional urban warming. This feedback on urban warming reaches 20% of ΔTGW in residential areas. This further uncertainty in future projections is comparable in size to that associated with: a selection of emission scenarios, RCMs, and urban planning scenarios. Thus this feedback should not be neglected in future urban climate projections, especially in hot cities with large AC use. The impact of the feedback during the July 2018 Japanese heat waves is calculated to be 0.11 °C.

Impact factors of the real-world fuel consumption rate of light duty vehicles in China

Measuring real-world fuel consumption of light duty vehicles can be challenging due to the limited collection of actual data. In this paper, we use big data retrieved from the record of real-world fuel consumptions of different brands of vehicles in different areas (n = 106,809 samples from 201 brands of vehicles and 34 cities) in China to build up a real-world fuel consumption rate (RFCR) model to estimate the fuel consumption given the driving conditions and figure out the main factors that affect actual fuel consumption in the real world. We find the average deviation of actual fuel consumptions and the fitting results of RFCR model is 4.22% , which does not significantly differ from zero, and the fuel consumptions calculated by RFCR model tend to be 1.40 L/100 km (about 25%) higher than the official reported data. Furthermore, we find that annual average temperature and altitude factors significantly influence the fuel consumption rate. The results indicate that there is a real world performance discrepancy between the theoretical fuel consumption released by authorities and that in the real world, and some green behaviors (choose light duty vehicles, reduce the use of air conditioning and change to manual transmission type) can reduce energy consumption of vehicles.

Evaluating the effect of trees on UHI mitigation and reduction of energy usage in different built up areas in Cairo

Cairo experiences higher temperatures than its neighbouring rural and suburban areas. This is due to the lack of vegetation and the wide scale use of sealed surfaces. This phenomenon is known as Urban Heat Island (UHI). This leads to the greater use of air conditioning in indoor spaces during the summer time and the electricity bills are higher. This study seeks to find the best urban vegetation ratio in order to reduce the buildings' energy demand through mitigating UHI and enhancing thermal performance in high and low density built up areas in hot and arid climate. Two areas in Cairo were chosen (Imbaba - 65% urban density, and officers residential in Elsalam district - 23% urban density) with different sky view factor values. The two areas were compared in terms of the cooling effect of 30% trees, 50% trees and 70% grass scenarios using ENVI-met. Then the meteorological outputs for each scenario were used in DesignBuilder in order to calculate the energy consumption. This study shows that, while trees can reduce daily air temperature by 0.2–0.4 K in very high density built up areas, they also increase air temperature by 3 K in low density built up areas due to humidity and evaporation. Therefore, trees are effective at lowering air temperature and reducing energy usage in very high density built up areas, but ineffective in low density built up areas. Furthermore, trees reduce PET in both densities by 1–3 K.

Home environmental and lifestyle factors associated with asthma, rhinitis and wheeze in children in Beijing, China

BackgroundThe prevalence of asthma and allergic diseases has increased rapidly in urban China since 2000. There has been limited study of associations between home environmental and lifestyle factors with asthma and symptoms of allergic disease in China. MethodsIn a cross-sectional analysis of 2214 children in Beijing, we applied a two-step hybrid Least Absolute Shrinkage and Selection Operator (LASSO) algorithm to identify environmental and lifestyle-related factors associated with asthma, rhinitis and wheeze from a wide range of candidates. We used group LASSO to select variables, using cross-validation as the criterion. Effect estimates were then calculated using adaptive LASSO. Model performance was assessed using Area Under the Curve (AUC) values. ResultsWe found a number of environmental and lifestyle-related factors significantly associated with asthma, rhinitis or wheeze, which changed the probability of asthma, rhinitis or wheeze from −5.76% (95%CI: −7.74%, −3.79%) to 27.4% (95%CI: 16.6%, 38.3%). The three factors associated with the largest change in probability of asthma were short birth length, carpeted floor and paternal allergy; for rhinitis they were maternal smoking during pregnancy, paternal allergy and living close to industrial area; and for wheeze they were carpeted floor, short birth length and maternal allergy. Other home environmental risk factors identified were living close to a highway, industrial area or river, sharing bedroom, cooking with gas, furry pets, cockroaches, incense, printer/photocopier, TV, damp, and window condensation in winter. Lifestyle-related risk factors were child caretakers other than parents, and age<3 for the day-care. Other risk factors included use of antibiotics, and mother’s occupation. Major protective factors for wheeze were living in a rural/suburban region, air conditioner use, and mother’s occupation in healthcare. ConclusionsOur findings suggest that changes in lifestyle and indoor environments associated with the urbanization and industrialization of China are associated with asthma, rhinitis, and wheeze in children.

Analysis on the reliability of R290 rotary compressor in the high ambient temperature

The R290 rotary compressor is suggested to use in split room air conditioners in hot climate areas for its higher efficiency, environmental-friendly, and lower discharge temperature. However the higher condensing temperature and pressure would result in reliability problems. In this paper the reliability of rotary compressor with R290&MO and R290&SO (mainly including the motor reliability; the oil sump viscosity, temperature and solubility; the oil film thickness of bearings) under the ambient temperature of 35 °C,46 °C,55 °C were studied experimentally and numerically. The results show that the motor temperature in R290 rotary compressor is lower than the allowable maximum temperature even under the condition of EXT/8 (condensing temperature = 70 °C). In addition, the oil sump viscosity of either synthetic oil (SO) or mineral oil (MO) decrease with the increase of ambient temperature (SO: from 4.7cp to 3.1cp; MO: from 2.2cp to 1.6cp), while under any condition, the solubility of SO (15%–16%) or MO (22%–25%) varies little. Besides, in the high ambient temperature (46 °Cand 55 °C), it is feasible to increase suction superheat to satisfy the proper viscosity when MO is used, while it is infeasible to SO. Influenced by oil viscosity and load, the oil film thickness of main bearing, sub bearing and eccentric bearing decrease with the increase of ambient temperature.

Estimating Fine-Scale Heat Vulnerability in Beijing Through Two Approaches: Spatial Patterns, Similarities, and Divergence

High temperatures in urban areas cause a significant negative impact on the residents’ health. In a megacity such as Beijing, where both the land cover and social composition of residents are highly spatially heterogeneous, understanding heat vulnerability at a relatively fine scale is a prerequisite for place-based heat intervention actions. Both principal component analysis (PCA) and equal-weighted index (EWI) are commonly used in heat vulnerability studies. However, the extent to which the choice of these approaches may impact the results remains unclear. Our study aimed to fill this gap by estimating heat vulnerability at the jiedao scale (the smallest census unit) in Beijing based on socioeconomic characteristics, heat exposure, and the use of air conditioners. Our results show that the choice of methods had a considerable impact on the spatial patterns of estimated heat vulnerability. PCA resulted in a ring-like pattern (high in the central and low in the suburb), whereas EWI revealed a north–south discrepancy (low in the north and high in the south). Such a difference is caused by the weighting scheme used in the PCA. Our findings indicate that heat vulnerability pattern revealed by a single measure needs to be interpreted with caution because different measures may produce disparate results.

The Health Impact of Air Conditioning Use during the 2018 Heatwave in South Korea

The Health Impact of Air Conditioning Use during the 2018 Heatwave in South Korea

Ionic Liquids Can Enable the Recycling of Fluorinated Greenhouse Gases

Recycling fluorinated gases that have high global warming potential is crucial for a sustainable and responsible use of mobile air conditioners. In this context, five ionic liquids with different h...

Summertime thermal conditions and senior resident behaviors in public housing: A case study in Elizabeth, NJ, USA

As heat waves become more extreme, there is a growing concern for the health of elderly city dwellers who have poor living conditions and limited access to resources. Much research has documented socioeconomic links to heat vulnerability, but limited studies have investigated the detailed living conditions of vulnerable populations, despite increasing requests from local communities. In this paper, we examine the summertime thermal performance of 24 senior apartments within 3 public housing sites (2 conventional multifamily and 1 LEED-rated building), and the seniors' adaptive responses in Elizabeth, NJ, USA. Time-series data were collected from sensors, interviews and observations on the thermal environment and behavior, from May–October 2017. Our multi-level, occupant-centric approach utilizes the indoor heat index as a proxy for heat stress, against site and building characteristics, and environmental and personal variables. Panel regressions show thermal variations among sites/apartments and illustrate the significant effect of actions, such as window opening and air conditioner use. Results also show how the seniors' adaptive responses vary by site; residents with central air-conditioning use it, while residents from the two older sites engage in a wider range of adaptive actions, and in some cases achieve similar indoor heat indexes as apartments from the green building. Indoor heat stress experienced by low-income seniors can be greatly reduced through cost-effective strategies that target individual behaviors and outdoor amenities. This implies the need for integrated solutions to the heat waves problem across scales; including changes to residents' habits, building envelopes, building operations, and outdoor spaces.

Evaluating urban vegetation scenarios to mitigate urban heat island and reduce buildings' energy in dense built-up areas in Cairo

Cairo is characterized by high temperature compared to its surrounding areas, especially during the summer time. This effect is strengthened by the widespread use of sealed surfaces and the lack of vegetation. Therefore, the consumption of electricity in indoor spaces for cooling purposes is a critical problem especially in the summer time. The use of air conditioners has increased during the last 10 years enormously. Because of this, electricity bills increased in a huge way, which represents a burden on the citizens. Therefore, this study aims to find unconventional solutions for the reduction of energy through mitigating urban heat island (UHI) and enhancing thermal performance in Cairo.This paper studies various area cover factions of trees in an urban environment, which can be used to mitigate UHI, improve thermal performance in outdoor spaces and reduce energy consumption in high dense built up areas in Cairo. A small area of 250 m * 250 m from downtown Cairo was simulated as a case study using ENVI-met V.4.3.2. The comparison between reference scenario and suggested scenarios, which are 30% trees, 50% trees and 30% trees +70% grass, were conducted on a summer day in Cairo. The outputs were used to estimate the amount of energy in every scenario using DesignBuilder model. The results show that the scenario with 50% trees led to the best human thermal comfort (3 K cooler). Although for the demand of energy in the buildings, the street orientation as well as the aspect ratio (H/W) play an important role and should be considered.

Air-conditioning in low income households; a comparison of ownership, use, energy consumption and indoor comfort in Australia

Air-conditioning and energy use are important topics at present, particularly in Australia where rising electricity prices and a changing climate are placing increasing strain on one of the world's longest interconnected electricity networks. At the same time, there is a concern that some consumers are particularly vulnerable to these changes. This study analyses three data-sets consisting of energy use and survey information from several thousand households, with the aim of better understanding the ownership, use, energy consumption and comfort outcomes related to air-conditioning in low income households in Australia. The findings suggest that low income households do tend to own different types of air-conditioning appliances, are more likely to reside in different types of buildings, be located in non-metropolitan areas, and belong to an older age demographic. These differences may have a greater influence on air-conditioning use behaviours (including energy use and comfort), than simply the fact that a household has a low income. Hence it is suggested that potential vulnerability measures should not be based on income alone.

On the temporal dimension of adaptive thermal comfort mechanisms in residential buildings

In response to the change of indoor thermal environment, building occupants constantly interact with the surrounding environment through various adaptive behaviours. The purpose of this study is to better understand the adaptive thermal comfort mechanisms by investigating the interrelationship between the expectation of the occupants (the psychological adaption), their behavioural adjustment (the physical adaption), and the indoor thermal environment in the context of residential buildings. Eleven households in South Korea participated in this longitudinal field study carried out between 2015 and 2017. The indoor thermal environmental parameters, the occupant subjective evaluations of thermal comfort, and their adaptive behaviour pattern were monitored. On average, 1,512 datasets from each household and a total of 16,632 datasets were collected and analyzed. Our analysis focused on understanding both the temporal dimension (i.e. duration of thermal discomfort episodes) and the intensity of stimuli (i.e. deviation from the comfort zone) both before- and after the participants’ decision on the use of air-conditioners. The study proposes the constructs of ‘discomfort capacity’ and ‘comfort restoration’ as multi-dimensional indices to better understand the triggering mechanisms for household air-conditioner usage. Using these indices, the study quantified householders’ tolerance of thermal discomfort events before they resort to air-conditioning.

Ventilative cooling potential of buildings in Australia

The demand for space cooling is the fastest growing end-use of electricity in buildings since many rely on the use of air-conditioners only to control the indoor climate. Ventilative cooling is a passive cooling technique, which involves the use of outdoor air to lower buildings’ indoor air temperature. In order to determine whether ventilative cooling may have the ability to reduce cooling loads, a detailed analysis of the local climate is needed. The aim of this study was to identify which Australian geographical regions have a suitable climate for the utilization of ventilative cooling techniques. The assessment of climatic potential for each geographic location was carried using two approaches: (i) a methodology which does not require detailed knowledge of the building characteristics, and; (ii) building performance simulation of a ‘typical’ Australian detached home. Results showed that the most populated Australian cities would benefit from the use of ventilative cooling techniques whereas the northern coastal region does not have a suitable climate.

A holistic approach to natural ventilation studies

Natural ventilation in buildings can increase thermal comfort and reduce air-conditioning use. However, it is very challenging today to accurately determine the natural ventilation rate through a building. This paper outlines a method to calculate the wind distribution around a building site from information obtained at a meteorological station miles away. This paper also discusses the influence of surrounding buildings on the wind flow around a target building at the site, and presents various geometrical models. In addition, the use of hour-by-hour wind velocity typically available from a meteorological station may give rise to some errors because of the large time step. A correlation method can be employed to convert the hour-by-hour wind velocity to minute-by-minute velocity. One can then use CFD to calculate the airflow around the building and wind-driven cross ventilation through an apartment simultaneously. However, prediction of single-sided natural ventilation is difficult because of the bi-directional flow at the room opening and the complex flow around buildings. This paper presents an empirical model that can predict the mean and fluctuating ventilation rates due to the pulsating flow and eddy penetration of wind-driven single-sided ventilation in buildings with three types of windows. One must use the correct strategy in a building in order to achieve the maximum benefits of natural ventilation.

Infiltration of fine particles in urban buildings

Singapore is a tropical country that can be affected by outdoor fine particle air pollution. Little information is available on the penetration of outdoor fine particles into daycare environments. Our study attempted to address the following objectives: to measure indoor infiltration factor (Finf of PM2.5 from outdoor fine particles and to determine the building parameters that modifies the indoor PM2.5. We collected indoor/outdoor 1-min PM2.5. from 50 daycare environments. We noted high indoor and outdoor concentrations of fine particles due to the presence of regional haze pollution. Indoor and outdoor fine particle concentrations are significantly highest for daycares located near highways while indoor to outdoor ratios were significantly lower for air-conditioning use in daycares. Mean Finf±SD of 0.65±0.19 in daycare rooms which are naturally ventilated and lower Finf±SD values of 0.46±0.22 for those that are air-conditioned. The penetration coefficients and air exchange rates were higher in naturally ventilated daycares (0.78 vs 0.61 and 1.47 vs 0.86 h−1 respectively). Our findings show that children remaining indoor in daycares where air conditioning is used can reduce PM2.5 exposures during outdoor pollution episodes.

A holistic approach to natural ventilation studies

Natural ventilation in buildings can increase thermal comfort and reduce air-conditioning use. However, it is very challenging today to accurately determine the natural ventilation rate through a building. This paper outlines a method to calculate the wind distribution around a building site from information obtained at a meteorological station miles away. This paper also discusses the influence of surrounding buildings on the wind flow around a target building at the site, and presents various geometrical models. In addition, the use of hour-by-hour wind velocity typically available from a meteorological station may give rise to some errors because of the large time step. A correlation method can be employed to convert the hour-by-hour wind velocity to minute-by-minute velocity. One can then use CFD to calculate the airflow around the building and wind-driven cross ventilation through an apartment simultaneously. However, prediction of single-sided natural ventilation is difficult because of the bi-directional flow at the room opening and the complex flow around buildings. This paper presents an empirical model that can predict the mean and fluctuating ventilation rates due to the pulsating flow and eddy penetration of wind-driven single-sided ventilation in buildings with three types of windows. One must use the correct strategy in a building in order to achieve the maximum benefits of natural ventilation.

Assessment of technical-financial analysis of a zero energy building for Brazilian hot and temperate tropical climate

The growing concern about energy consumption and environmental resources has led to research on sustainable approaches in construction. Efficient buildings have been built not only to attract new investments but also to take environmental considerations into account. Zero Energy Buildings; use a variety of passive strategies for energy efficiency and to decrease the use of heating, ventilation and air conditioning. These techniques impact directly on cost benefit and energy performance. The objective of this research is to identify efficient approaches for housing, considering the influence of climate, the energy generation, for two Brazilian cities. The cities climates area classified as Af (tropical climate) and Cfb (hot and temperate). The methodological procedures were divided into three stages: simulation to determine energy consumption in the efficient building; estimation of the balance between electric demand and generation by means of a building-integrated photovoltaics (BIPV); assessment of the life cycle cost of the net present value of BIPV. The results show that for the tropical climate the payback is 6.75 years and Internal Rate of Return (IRR) of 15.06% and for the temperate, payback is 10.25 years and IRR of 8.49%. These outcomes demonstrate that in hot climate payback happens in less time, due to the high incidence of solar radiation in the year.

On the Energy Efficiency of Indoor Air Conditioning

The increase of average outdoor temperatures and their fluctuations over the past 20 years (as evidenced by the records of summer temperatures in our country) has significantly increased the need for air conditioning premises where people are present for a long time, especially when they are crowded (shops, entertainment halls, classrooms, etc.). The air conditioning process is quite energy-intensive, but the growth of well-being in many republics of the former USSR, as well as the increasing complexity of the physiological adaptation of the human body to rising outdoor temperatures make it possible (and at the same time necessary) to implement these systems on a large scale. It is important to take into account that electricity prices are currently maintained at a high level for homeowners, and in the coming years the prices will only grow. Therefore, the development of new ways of significant increase of the energy efficiency of the indoor air conditioning process is of a great interest. One of these methods is the use of laminar (or close to them) moving layers of conditioned air in a limited area of work or rest of people. Such a zone, about 1.0‒1.2 m height from a floor in each apartment is, e.g., living rooms (bedroom) in which standard temperature conditions are created by means of simple air supplying and air intake devices. In the case of sedentary work of people, the height of such a zone of conditioned air should be increased to 1.3‒1.5 m. It has already been established that the use of laminar (or close to them) air flows allows to reduce the power consumption by two or more times due to significantly reduced heat exchange with the surrounding heated surfaces. Besides, the simplicity of such systems ought to be noted. In particular, in conditions of modern systems of control and management of air conditioning, the "duties" of consumers include only the installation on the control device of the initial data relating directly to the required parameters of the microclimate. At the same time, it should be noted that there is currently no complete scientific and technical description of aerodynamic and heat exchange processes in the air conditioning zone. Even in modern conditions for countries with a sharply continental climate (Russia, Kazakhstan, etc.), the problem is the choice of the type of air conditioner for its effective use in hot periods of summer. In general, it can be noted that all the problems of energy-efficient use of air conditioners must find a comprehensive solution.