District-Level Summertime Air-Conditioning Electricity Consumption and the Sensitivity of Peak Cooling Loads to Urban Weather Conditions in Beijing

2020 ◽  
Vol 142 (6) ◽  
Author(s):  
Xiaoyu Xu ◽  
Jorge E. González ◽  
Shiguang Miao ◽  
Shuanghe Shen ◽  
Wenli Guo
Keyword(s):  
Air Temperature ◽  
Air Conditioning ◽  
Energy Use ◽  
Linear Regression Analysis ◽  
Weather Conditions ◽  
District Level ◽  
Specific Humidity ◽  
Heat Index ◽  
Rural Districts ◽  
Cooling Loads

Abstract Understanding how energy use responds to meteorological conditions is essential for anticipation of energy demands, which is of significance to maintain sufficient power supply and to prevent brownouts or blackouts during peak hours. Using the quarter-hourly and district-level electricity data for Beijing, this study calculates the district-varying cooling electric loads due to air-conditioning (AC) systems in five consecutive summers. Results show the occurrence of two major features that are common for summertime cooling loads in most districts, namely, double-peaked diurnal profiles and weekday–weekend fluctuations. With the increasing distance from the city core, the evening peak cooling load around 21:00 local time (LT) becomes more pronounced and comparable with its afternoon counterpart around 15:00 LT. Conversely, the weekday–weekend fluctuation is greatly weakened in suburban and rural districts due to the stable cooling demands on weekdays and weekends. The district-level sensitivity of peak cooling loads to surface meteorological factors is further investigated by linear regression analysis, and results show significant decreases from urban to rural districts. The correlation coefficients between peak cooling loads and heat index that combines air temperature and relative humidity reach up to 0.8–0.9 in most districts. If using air temperature or specific humidity solely, the coefficients of determination with peak cooling loads are roughly 0.1–0.3 smaller, possibly indicating the greater potential of heat index for effectively predicting peak cooling demands in Beijing.

scholarly journals Displacing air conditioning in Kingdom of Saudi Arabia: An evaluation of ‘fabric first’ design integrated with hybrid night radiant and ground pipe cooling systems

2018 ◽  
Vol 39 (4) ◽  
pp. 377-390 ◽  
Author(s):  
Jamil Hijazi ◽  
Stirling Howieson
Keyword(s):  
Air Conditioning ◽  
Architectural Design ◽  
Energy Use ◽  
Energy Savings ◽  
Significant Proportion ◽  
Cost Effective ◽  
Field Trials ◽  
Capital Costs ◽  
Reduce Carbon Dioxide ◽  
Cooling Loads

This paper presents an investigation into the viability of ‘fabric first’ intelligent architectural design measures, in combination with a hybrid cooling system.The specific aim is to displace air conditioning (AC) and reduce carbon dioxide, while maintaining thermal comfort, in a typical housing block in KSA. The results of thermal modelling and prototype field trials suggest that passive design measures combined with night radiant cooling and supply ventilation via ground pipes, can negate the requirement for a standard AC system. Such a strategy may also have a remarkably short payback period when energy savings, in use, are set against the additional capital costs associated with improved building fabric performance. Practical application: This study suggests that a significant proportion of AC cooling energy can be displaced by improving building fabric performance in combination with supply ventilation via ground pipes. As radiometer readings fell as low as 2.8℃ when the night sky is clear, roof-mounted high emissivity hydronic radiant panels can also provide a significant opportunity for additional heat flushing. In hybrid combination, these strategies have the potential to lower the carbon footprint of a typical housing block in KSA by over 80% and these measures and strategies will be equally applicable and cost-effective in all geographic regions of the world where cooling loads represent the predominant domestic energy use.

scholarly journals Air temperature equation derived from sonic temperature and water vapor mixing ratio for turbulent airflow sampled through closed-path eddy-covariance flux systems

2022 ◽  
Vol 15 (1) ◽  
pp. 95-115
Author(s):  
Xinhua Zhou ◽  
Tian Gao ◽  
Eugene S. Takle ◽  
Xiaojie Zhen ◽  
Andrew E. Suyker ◽  
...  
Keyword(s):  
Water Vapor ◽  
Eddy Covariance ◽  
Air Temperature ◽  
Water Vapor Pressure ◽  
Sonic Anemometer ◽  
Weather Conditions ◽  
Specific Humidity ◽  
Closed Path ◽  
Mixing Ratio ◽  
Water Vapor Mixing Ratio

Abstract. Air temperature (T) plays a fundamental role in many aspects of the flux exchanges between the atmosphere and ecosystems. Additionally, knowing where (in relation to other essential measurements) and at what frequency T must be measured is critical to accurately describing such exchanges. In closed-path eddy-covariance (CPEC) flux systems, T can be computed from the sonic temperature (Ts) and water vapor mixing ratio that are measured by the fast-response sensors of a three-dimensional sonic anemometer and infrared CO2–H2O analyzer, respectively. T is then computed by use of either T=Ts1+0.51q-1, where q is specific humidity, or T=Ts1+0.32e/P-1, where e is water vapor pressure and P is atmospheric pressure. Converting q and e/P into the same water vapor mixing ratio analytically reveals the difference between these two equations. This difference in a CPEC system could reach ±0.18 K, bringing an uncertainty into the accuracy of T from both equations and raising the question of which equation is better. To clarify the uncertainty and to answer this question, the derivation of T equations in terms of Ts and H2O-related variables is thoroughly studied. The two equations above were developed with approximations; therefore, neither of their accuracies was evaluated, nor was the question answered. Based on first principles, this study derives the T equation in terms of Ts and the water vapor molar mixing ratio (χH2O) without any assumption and approximation. Thus, this equation inherently lacks error, and the accuracy in T from this equation (equation-computed T) depends solely on the measurement accuracies of Ts and χH2O. Based on current specifications for Ts and χH2O in the CPEC300 series, and given their maximized measurement uncertainties, the accuracy in equation-computed T is specified within ±1.01 K. This accuracy uncertainty is propagated mainly (±1.00 K) from the uncertainty in Ts measurements and a little (±0.02 K) from the uncertainty in χH2O measurements. An improvement in measurement technologies, particularly for Ts, would be a key to narrowing this accuracy range. Under normal sensor and weather conditions, the specified accuracy range is overestimated, and actual accuracy is better. Equation-computed T has a frequency response equivalent to high-frequency Ts and is insensitive to solar contamination during measurements. Synchronized at a temporal scale of the measurement frequency and matched at a spatial scale of measurement volume with all aerodynamic and thermodynamic variables, this T has advanced merits in boundary-layer meteorology and applied meteorology.

scholarly journals A Study on Thermal Effectiveness of Multi-Stages Evaporative Air Cooling

2020 ◽  
Vol 8 (2) ◽  
pp. 1-14
Author(s):  
Alaa R. Al-Badri ◽  
Zahraa Mohsin Farhan
Keyword(s):  
Air Temperature ◽  
System Performance ◽  
Air Conditioning ◽  
Evaporative Cooling ◽  
Experimental Tests ◽  
Weather Conditions ◽  
Air Cooling ◽  
Air Velocity ◽  
Cooling Systems ◽  
Continuous Increase

The air conditioning system performance is significantly affected by temperature rise which causes continuous increase in electricity consumption and pollution problems to environment. Evaporative cooling systems are characterized by their low energy consumption so that they represent successful potential alternatives to traditional vapor compression air conditioning systems. This study investigates the performance of multi-stages evaporative cooling systems experimentally and theoretically. The experimental set-up is mainly composed of two parts: indirect unit to decrease the air temperature and direct unit to moisturize the air. The system is installed and equipped with temperatures, humidity, and air velocity sensors. The experimental tests were run continuously to monitor the system performance at various weather conditions between  to  in June and July months. A mathematical model for the system components was developed and implemented in the Engineering Equation Solver (EES) program to simulate the performance of multi-stages evaporative cooling systems. The results showed that the heat flux  increases with the increase in the Reynolds number Re of inlet air, velocity fraction  extracted air for sensible cooling, air temperature at the product-in , air velocity at the product-in , and the adiabatic efficiency . But, it is decreasing with increasing the spacing between the heat exchanger plates  and the relative humidity at the product-in . Optimum performance was obtained with very small space between plates which was bout 5mm. Good agreement have been shown between experimental and predicted data, where the  results. Uncertainty of experimental data was within the range 4.14 to 6.15.

scholarly journals Effects of trees, gardens, and nature trails on heat index and child health: design and methods of the Green Schoolyards Project

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Kevin Lanza ◽  
Melody Alcazar ◽  
Deanna M. Hoelscher ◽  
Harold W. Kohl
Keyword(s):  
Physical Activity ◽  
United States ◽  
Relative Humidity ◽  
Air Temperature ◽  
The United States ◽  
Heat Index ◽  
Activity Levels ◽  
Natural Setting ◽  
Physical Activity Levels ◽  
Nature Trails

Abstract Background Latinx children in the United States are at high risk for nature-deficit disorder, heat-related illness, and physical inactivity. We developed the Green Schoolyards Project to investigate how green features—trees, gardens, and nature trails—in school parks impact heat index (i.e., air temperature and relative humidity) within parks, and physical activity levels and socioemotional well-being of these children. Herein, we present novel methods for a) observing children’s interaction with green features and b) measuring heat index and children’s behaviors in a natural setting, and a selection of baseline results. Methods During two September weeks (high temperature) and one November week (moderate temperature) in 2019, we examined three joint-use elementary school parks in Central Texas, United States, serving predominantly low-income Latinx families. To develop thermal profiles for each park, we installed 10 air temperature/relative humidity sensors per park, selecting sites based on land cover, land use, and even spatial coverage. We measured green features within a geographic information system. In a cross-sectional study, we used an adapted version of System for Observing Play and Recreation in Communities (SOPARC) to assess children’s physical activity levels and interactions with green features. In a cohort study, we equipped 30 3rd and 30 4th grade students per school during recess with accelerometers and Global Positioning System devices, and surveyed these students regarding their connection to nature. Baseline analyses included inverse distance weighting for thermal profiles and summing observed counts of children interacting with trees. Results In September 2019, average daily heat index ranged 2.0 °F among park sites, and maximum daily heat index ranged from 103.4 °F (air temperature = 33.8 °C; relative humidity = 55.2%) under tree canopy to 114.1 °F (air temperature = 37.9 °C; relative humidity = 45.2%) on an unshaded playground. 10.8% more girls and 25.4% more boys interacted with trees in September than in November. Conclusions We found extreme heat conditions at select sites within parks, and children positioning themselves under trees during periods of high heat index. These methods can be used by public health researchers and practitioners to inform the redesign of greenspaces in the face of climate change and health inequities.

scholarly journals Overheating Risk and Energy Demand of Nordic Old and New Apartment Buildings during Average and Extreme Weather Conditions under a Changing Climate

2021 ◽  
Vol 11 (9) ◽  
pp. 3972
Author(s):  
Azin Velashjerdi Farahani ◽  
Juha Jokisalo ◽  
Natalia Korhonen ◽  
Kirsti Jylhä ◽  
Kimmo Ruosteenoja ◽  
...  
Keyword(s):  
Climate Change ◽  
Energy Demand ◽  
Energy Use ◽  
Residential Buildings ◽  
Weather Conditions ◽  
Extreme Weather ◽  
Living Room ◽  
Extra Energy ◽  
Cooling Unit ◽  
Indoor Conditions

The global average air temperature is increasing as a manifestation of climate change and more intense and frequent heatwaves are expected to be associated with this rise worldwide, including northern Europe. Summertime indoor conditions in residential buildings and the health of occupants are influenced by climate change, particularly if no mechanical cooling is used. The energy use of buildings contributes to climate change through greenhouse gas emissions. It is, therefore, necessary to analyze the effects of climate change on the overheating risk and energy demand of residential buildings and to assess the efficiency of various measures to alleviate the overheating. In this study, simulations of dynamic energy and indoor conditions in a new and an old apartment building are performed using two climate scenarios for southern Finland, one for average and the other for extreme weather conditions in 2050. The evaluated measures against overheating included orientations, blinds, site shading, window properties, openable windows, the split cooling unit, and the ventilation cooling and ventilation boost. In both buildings, the overheating risk is high in the current and projected future average climate and, in particular, during exceptionally hot summers. The indoor conditions are occasionally even injurious for the health of occupants. The openable windows and ventilation cooling with ventilation boost were effective in improving the indoor conditions, during both current and future average and extreme weather conditions. However, the split cooling unit installed in the living room was the only studied solution able to completely prevent overheating in all the spaces with a fairly small amount of extra energy usage.

scholarly journals Towards Sustainable Energy Retrofitting, a Simulation for Potential Energy Use Reduction in Residential Buildings in Palestine

Energies ◽  
2021 ◽  
Vol 14 (13) ◽  
pp. 3876
Author(s):  
Sameh Monna ◽  
Adel Juaidi ◽  
Ramez Abdallah ◽  
Aiman Albatayneh ◽  
Patrick Dutournie ◽  
...  
Keyword(s):  
Energy Consumption ◽  
Energy Use ◽  
Energy Savings ◽  
Residential Buildings ◽  
Residential Building ◽  
Simulation Models ◽  
Water Heating ◽  
Heating And Cooling ◽  
Space Cooling ◽  
Cooling Loads

Since buildings are one of the major contributors to global warming, efforts should be intensified to make them more energy-efficient, particularly existing buildings. This research intends to analyze the energy savings from a suggested retrofitting program using energy simulation for typical existing residential buildings. For the assessment of the energy retrofitting program using computer simulation, the most commonly utilized residential building types were selected. The energy consumption of those selected residential buildings was assessed, and a baseline for evaluating energy retrofitting was established. Three levels of retrofitting programs were implemented. These levels were ordered by cost, with the first level being the least costly and the third level is the most expensive. The simulation models were created for two different types of buildings in three different climatic zones in Palestine. The findings suggest that water heating, space heating, space cooling, and electric lighting are the highest energy consumers in ordinary houses. Level one measures resulted in a 19–24 percent decrease in energy consumption due to reduced heating and cooling loads. The use of a combination of levels one and two resulted in a decrease of energy consumption for heating, cooling, and lighting by 50–57%. The use of the three levels resulted in a decrease of 71–80% in total energy usage for heating, cooling, lighting, water heating, and air conditioning.

scholarly journals Evaluating CMIP5 models using AIRS tropospheric air temperature and specific humidity climatology

2013 ◽  
Vol 118 (1) ◽  
pp. 114-134 ◽  
Author(s):  
Baijun Tian ◽  
Eric J. Fetzer ◽  
Brian H. Kahn ◽  
Joao Teixeira ◽  
Evan Manning ◽  
...  
Keyword(s):  
Air Temperature ◽  
Specific Humidity ◽  
Cmip5 Models

scholarly journals Feasibility Study of Solar Adsorption Technologies for Automobile Air-Conditioning

Solar Energy ◽  
2005 ◽  
Author(s):  
M. O. Abdullah ◽  
S. L. Leo
Keyword(s):  
Feasibility Study ◽  
Ozone Depletion ◽  
Air Conditioning ◽  
Waste Heat ◽  
Environmentally Benign ◽  
Adsorption System ◽  
Adsorption Refrigeration ◽  
Adsorption Technology ◽  
Cooling Loads ◽  
Automobile Air Conditioning

An adsorption system driven by solar heat or waste heat can help to eliminate the use of ozone depletion substances, such as chlorofluorocarbons (CFCs) and hydro-chlorofluorocarbons (HCFCs). In recent years, adsorption system has witnessed an increasing interest in many fields due to the fact that this system is quiet, long lasting, cheap to maintain and environmentally benign. Although adsorption system is not commonly used for automobile air conditioning, adsorption-cooled mini-refrigerators have been marketed for recreational transports (motor homes, boats, etc). Hence, there exists a need for a creative design and innovation to allow adsorption technology to be practical for air conditioning in automobile. The objective of this paper is to present a comprehensive review on the past efforts in the field of solar adsorption refrigeration systems and also the feasibility study of this technology for automobile airconditioning purpose. It is a particularly an attractive application for solar energy because of the near coincidence of peak cooling loads with the available of solar power.

Design and experimental analysis of a solar thermoelectric heating, ventilation, and air conditioning system as an integral element of a building envelope

2018 ◽  
Vol 40 (2) ◽  
pp. 220-236 ◽  
Author(s):  
Irfan Ahmad Gondal
Keyword(s):  
Experimental Analysis ◽  
Air Conditioning ◽  
Energy Use ◽  
New Technologies ◽  
Thermoelectric Module ◽  
Electrical Current ◽  
Building Envelope ◽  
Coefficient Of Performance ◽  
Heating And Cooling ◽  
Cooling Effects

This study presents an innovative concept of a compact integrated solar-thermoelectric module that can form part of the building envelope. The heating/cooling modes use the photovoltaic electrical current to power the heat pump. The experimental analysis was carried out and the results of coefficient of performance were in the range 0.5–1 and 2.6–5 for cooling and heating functions, respectively. The study demonstrates that thermoelectric cooler can effectively be used for heating, ventilation, and air conditioning applications by integrating with solar panels especially in cooling applications. The system is environmentally friendly and can contribute in the implementation of zero energy buildings concept. Practical application: In order to help address the challenge of climate change and associated environmental effects, there is continuous demand for new technologies and applications that can be readily integrated into day-to-day life as a means of reducing anthropogenic impact. Heating, ventilation, and air conditioning, as one of the largest energy consumers in buildings, is the focus of many researchers seeking to reduce building energy use and environmental impact. This article proposes using facades and windows that have an integrated modules of solar photovoltaic cells and thermoelectric devices that are able to work together to achieve heating and cooling effects as required by the building without requiring any external operational power.

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