scholarly journals Effect of Extending Hot Weather Periods on Approach to Floor Construction in Moderate Climate Residential Buildings / Wpływ Przedłużających Się Okresów Występowania Wysokich Temperatur Letnich Na Podejście Do Projektowania Podłogi Na Gruncie w Budynkach Mieszkalnych w Krajach Klimatu Umiarkowanego

2016 ◽  
Vol 20 (1) ◽  
pp. 159-170 ◽  
Author(s):  
Anna Staszczuk ◽  
Tadeusz Kuczyński

Abstract The effects of changes in Global climate on the prolonging time and the frequency of the periods of very high outside air temperature at summer were shown in the paper with particular emphasis on European moderate climate countries. In these countries, residential buildings, are usually equipped neither in air conditioning equipment, nor in ordinary window blinds. As the most promising solution it is suggested to resign completely or partially from ground slab thermal insulation, directly utilizing ground heat storage capacity. The paper includes detailed simulations on potential effect of various kind of floor construction and actions preventing high indoor air temperatures in building approach on air temperature inside the one-storey, passive residential buildings during consecutive days of very high outdoor temperature and total energy used yearly for additional heating and air conditioning.

2020 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Qi Jie Kwong ◽  
Jim Yexin Yang ◽  
Oliver Hoon Leh Ling ◽  
Rodger Edwards ◽  
Jamalunlaili Abdullah

PurposeThe purpose of this paper is to analyse the thermal environment of two engineering testing centres cooled via different means using computational fluid dynamics (CFD), focussing on the indoor temperature and air movement. This computational technique has been used in the analysis of thermal environment in buildings where the profiles of thermal comfort parameters, such as air temperature and velocity, are studied.Design/methodology/approachA pilot survey was conducted at two engineering testing centres – a passively cooled workshop and an air-conditioned laboratory. Electronic sensors were used in addition to building design documentation to collect the required information for the CFD model–based prediction of air temperature and velocity distribution patterns for the laboratory and workshop. In the models, both laboratory and workshop were presumed to be fully occupied. The predictions were then compared to empirical data that were obtained from field measurements. Operative temperature and predicted mean vote (PMV)–predicted percentage dissatisfied (PPD) indices were calculated in each case in order to predict thermal comfort levels.FindingsThe simulated results indicated that the mean air temperatures of 21.5°C and 32.4°C in the laboratory and workshop, respectively, were in excess of the recommended thermal comfort ranges specified in MS1525, a local energy efficiency guideline for non-residential buildings. However, air velocities above 0.3 m/s were predicted in the two testing facilities, which would be acceptable to most occupants. Based on the calculated PMV derived from the CFD predictions, the thermal sensation of users of the air-conditioned laboratory was predicted as −1.7 where a “slightly cool” thermal experience would prevail, but machinery operators in the workshop would find their thermal environment too warm with an overall sensation score of 2.4. A comparison of the simulated and empirical results showed that the air temperatures were in good agreement with a percentage of difference below 2%. However, the level of correlation was not replicated for the air velocity results, owing to uncertainties in the selected boundary conditions, which was due to limitations in the measuring instrumentation used.Research limitations/implicationsDue to the varying designs, the simulated results of this study are only applicable to laboratory and workshop facilities located in the tropics.Practical implicationsThe results of this study will enable building services and air-conditioning engineers, especially those who are in charge of the air-conditioning and mechanical ventilation (ACMV) system design and maintenance to have a better understanding of the thermal environment and comfort conditions in the testing facilities, leading to a more effective technical and managerial planning for an optimised thermal comfort management. The method of this work can be extended to the development of CFD models for other testing facilities in educational institutions.Social implicationsThe findings of this work are particularly useful for both industry and academia as the indoor environment of real engineering testing facilities were simulated and analysed. Students and staff in the higher educational institutions would benefit from the improved thermal comfort conditions in these facilities.Originality/valueFor the time being, CFD studies have been carried out to evaluate thermal comfort conditions in various building spaces. However, the information of thermal comfort in the engineering testing centres, of particular those in the hot–humid region are scantily available. The outcomes of this simulation work showed the usefulness of CFD in assisting the management of such facilities not only in the design of efficient ACMV systems but also in enhancing indoor thermal comfort.


2013 ◽  
Vol 30 (8) ◽  
pp. 1757-1765 ◽  
Author(s):  
Sayed-Hossein Sadeghi ◽  
Troy R. Peters ◽  
Douglas R. Cobos ◽  
Henry W. Loescher ◽  
Colin S. Campbell

Abstract A simple analytical method was developed for directly calculating the thermodynamic wet-bulb temperature from air temperature and the vapor pressure (or relative humidity) at elevations up to 4500 m above MSL was developed. This methodology was based on the fact that the wet-bulb temperature can be closely approximated by a second-order polynomial in both the positive and negative ranges in ambient air temperature. The method in this study builds upon this understanding and provides results for the negative range of air temperatures (−17° to 0°C), so that the maximum observed error in this area is equal to or smaller than −0.17°C. For temperatures ≥0°C, wet-bulb temperature accuracy was ±0.65°C, and larger errors corresponded to very high temperatures (Ta ≥ 39°C) and/or very high or low relative humidities (5% < RH < 10% or RH > 98%). The mean absolute error and the root-mean-square error were 0.15° and 0.2°C, respectively.


2017 ◽  
Vol 41 (3) ◽  
pp. 225-246 ◽  
Author(s):  
Elizabeth Buechler ◽  
Simon Pallin ◽  
Philip Boudreaux ◽  
Michaela Stockdale

The indoor air temperature and relative humidity in residential buildings significantly affect material moisture durability, heating, ventilation, and air-conditioning system performance, and occupant comfort. Therefore, indoor climate data are generally required to define boundary conditions in numerical models that evaluate envelope durability and equipment performance. However, indoor climate data obtained from field studies are influenced by weather, occupant behavior, and internal loads and are generally unrepresentative of the residential building stock. Likewise, whole-building simulation models typically neglect stochastic variables and yield deterministic results that are applicable to only a single home in a specific climate. The purpose of this study was to probabilistically model homes with the simulation engine EnergyPlus to generate indoor climate data that are widely applicable to residential buildings. Monte Carlo methods were used to perform 840,000 simulations on the Oak Ridge National Laboratory supercomputer (Titan) that accounted for stochastic variation in internal loads, air tightness, home size, and thermostat set points. The Effective Moisture Penetration Depth model was used to consider the effects of moisture buffering. The effects of location and building type on indoor climate were analyzed by evaluating six building types and 14 locations across the United States. The average monthly net indoor moisture supply values were calculated for each climate zone, and the distributions of indoor air temperature and relative humidity conditions were compared with ASHRAE 160 and EN 15026 design conditions. The indoor climate data will be incorporated into an online database tool to aid the building community in designing effective heating, ventilation, and air-conditioning systems and moisture durable building envelopes.


Purpose. The aim of this research is detection of trends of changes (according to fact and scenario data) of extreme air temperature as a component of thermal regime in different regions of Ukraine because of global climate change. Methods. System analysis, statistical methods. Results. Time distribution of maximum air temperature regime characteristics based on results of observations on the stations located in different regions of Ukraine during certain available periods: Uzhgorod (1946-2018), Kharkiv (1936-2005), Оdessа (1894-2005), аnd also according to scenarios of low (RCP2.6), medium (RCP4.5) and high (RCP8.5) levels of greenhouse gases emissions. Meanwhile, air temperature ≥ 25°С was considered high (days with maximum temperature within 25,0-29,9°С are hot), ≥ 30°С was considered very high (days with such temperature are abnormaly hot). Trends of changes of extreme air temperatures were identified as a component of thermal regime in different regions of Ukraine within global climate changes. Dynamics of maximum air temperature and its characteristics in ХХ and beginning of ХХІ centuries were researched. Expected time changes of maximum air temperature and number of days with high temperature during 2021-2050 were analyzed by RCP2.6, RCP4.5 and RCP8.5 scenarios. There were identified the highest day air temperatures possible once in a century and also possibility of maximum day temperature more than 30°С by RCP4.5 scenario. Well-timed prediction of climate changes will help evaluate their impact on human and natural systems which will be useful for development and taking preventive measures towards minimization of negative influence of such changes. Conclusions. Processes of climate warming in Ukraine are activating. There was determined a strong trend on increasing of average maximum of air temperature in winter with speed 0.17-0,39 degrees centigrade/10 years. According to climatic norm this index mainly increased mostly (up to 3,3 degrees centigrade) in January in North-East of the country. In future such anomalies will grow. Determination of correlation between climate and health is the base for taking protective measures against perils for population health connected with climate.


2018 ◽  
Vol 18 (1) ◽  
pp. 195-207 ◽  
Author(s):  
Piotr Herbut ◽  
Sabina Angrecka ◽  
Dorota Godyń

Abstract The main aim of the presented investigation was to determine the effect of the air thermal conditions variability on cow’s milking performance in summer in a moderate climate. The analyses covered the summer months of 2012-2013 (June-September) and shorter, several-day periods characterized by the times of elevated or high air temperatures and by the declines and increases in milking performance. The research was conducted in a free stall barn for Holstein-Friesian cows. The study showed that the thermoneutral temperature for high yielding cows decreases gradually with the registered increasingly warmer summer periods. The decreases in milk yield already commence at an air temperature equal to 20°C and also depend on the dairy cattle sensitivity. July and August, with a high number of hot days, caused that in September the cows responded faster to a worsening of thermal conditions and the decline in milking performance happened almost simultaneously with the air temperature change, at milking yield recovery after the period of 3-4 d (r=-0.84, P<0.04). The percent duration in the individual temperature ranges which caused a decrease of milk yield was also determined. In June, and at the beginning of July, this was 90% of the time with temperatures above 20°C, and simultaneously 45% above 25°C occurred to milking performance decrease (r=-0.89, P<0.02). In September, this was only 30% of the time with temperatures above 20°C (r=-0.91, P<0.01).


2016 ◽  
Vol 1 (1) ◽  
pp. 37 ◽  
Author(s):  
Ali Rahmat ◽  
Abdul Mutolib

Increases in air temperature indicate a global climate change. Thus, information in the change of temperature regional scale is important to support global data. The present research was conducted in Gifu city and Ogaki city located in Gifu prefecture, Japan. The results showed that, average air temperatures in both cities are quite similar with a difference value of under 1<sup>o</sup>C. Maximum air temperature in Gifu city is significantly higher than Ogaki city, whereas minimum air temperature in Gifu city is significantly lower than in Ogaki city. Daily range of air temperature in Gifu city significantly higher than in Ogaki city. In both cities, air temperature relatively increased in three decades. This is because of different in land characteristics in both cities.


2018 ◽  
Vol 7 (4.38) ◽  
pp. 980
Author(s):  
Thanawuth Khunthong ◽  
. .

Thailand is located in a humid  tropical climate and near  the equator. Thus  the average air temperature is high throughout the  year.  Environmental factors   factors   such  as  the  sun,  wind  and  humidity affects   residential buildings especially, heat  from  the sun  is a main  factor,  which  leads  a problems of heat  inside  the  buildings (Prawewan Amornpong, 2001).  Therefore, Installling air conditioning inside  the buildings is the solution for this  problem. However, from  the  study  on  the  properties of  plants  it was  found  that  plants  are  effective in blocking  the   sun's   rays   as  well   as  effectively  maintaining  the   air   temperature  in  the   area   (Soontorn Boonyathikarn, 1999).  So, planting trees  to prevent the sunlight, as shade  to reduce  sun heat  in the buildings should   be  an  approach, which   could   be  adopted to  decrease the  use  of  air  conditioning and  also  energy consumption in buildings (Trungjai Buranasompob, 2000).  This  research aims  (1) to study  and  create  design guidelines on landscape models which  conforms to the environment of sunlight and wind  in the central region of Thailand and (2) to propose the guidelines on architectural landscape designs and plants’  setting  around the buildings in 8 directions; North  (N),  Northeast (NE),  East  (E),  Southeast (SE),  South  (S),  Southwe st (SW), West  (W)  and Northwest (NW).  The results   found  that the landscape model  included the setting  on plants  as shade  at all sides  of the building envelope during  08.00-17.00 PM  of the day  throughout the year.  These  can reduce  the  air  temperature of the  building envelope as well  as the  average temperature inside  the  buildings, this showed a decrease in temperature by as much  as 3.95°C or 13.478% compared with  the average exterior air temperature of the buildings throughout the year.    


Author(s):  
O. Obodovskyi ◽  
V. Grebin ◽  
S. Snizhko ◽  
I. Kuprikov ◽  
O. Shevchenko Shevchenko

This article presents the results of the verification of the homogeneity of the data of long-term observations on the average annual air temperature and annual precipitation amounts according to the data of 143 meteorological stations operating on the territory of Ukraine to date and have a long (in the vast majority of cases, more than 55-60 years) rows of observations within 14 areas of river basins and sub-basins that have been allocated within the country for research. To do this, the parametric criteria of Student and Fischer, as well as the non-parametric Wilcoxon criterion, were used. Briefly described these three criteria and statistical methods for assessing the homogeneity of hydrological and meteorological sequences in general. The basic concepts of mathematical statistics, such as the null hypothesis, the statistical criterion, the level of significance, the critical area, are deciphered. The number of used meteorological stations for each of the selected areas of river basins and sub-basins was determined. The heterogeneity of the series of average annual air temperature for all 14 selected areas of river basins and sub-basins was revealed. The rows of the long-term course of average annual air temperatures are homogeneous only at two meteorological stations within the boundaries of the Crimean river basin districts (Simferopol and Dzhankoy). Significant homogeneity of the rows of annual precipitation amounts for the overwhelming majority of areas of river basins and sub-basins was also revealed. It is noted that for five of the studied areas of river basins and sub-basins, the homogeneity index is 100 % for all three of the involved criteria of mathematical statistics. The lowest index of homogeneity of the rows of annual rainfall amounts is typical for the Wisla River basin district, where it is 60 %. This is one of the smallest selected areas, which occupies a very small area within Ukraine (about 4 %). The following conclusions are made: 1. The indices of homogeneity of the rows of annual precipitation amounts received for the territory of Ukraine according to 143 meteorological stations indicate that there are no directed changes in annual rainfall in most of the country. 2. The indices of homogeneity of the series of average annual values of air temperatures obtained for the territory of Ukraine according to the data of the same 143 meteorological stations according to different criteria testify to the violation of the homogeneity of this indicator on the territory of Ukraine since about 1989, which testifies to the climatic changes taking place in the country over the past decades, reflecting global climate change.


2011 ◽  
Vol 50 (5) ◽  
pp. 1107-1128 ◽  
Author(s):  
Francisco Salamanca ◽  
Alberto Martilli ◽  
Mukul Tewari ◽  
Fei Chen

AbstractIn the last two decades, mesoscale models (MMs) with urban canopy parameterizations have been widely used to study urban boundary layer processes. Different studies show that such parameterizations are sensitive to the urban canopy parameters (UCPs) that define the urban morphology. At the same time, high-resolution UCP databases are becoming available for several cities. Studies are then needed to determine, for a specific application of an MM, the optimum degree of complexity of the urban canopy parameterizations and the resolution and details necessary in the UCP datasets. In this work, and in an attempt to answer the previous issues, four urban canopy schemes, with different degrees of complexity, have been used with the Weather Research and Forecasting (WRF) model to simulate the planetary boundary layer over the city of Houston, Texas, for two days in August 2000. For the UCP two approaches have been considered: one based on three urban classes derived from the National Land Cover Data of the U.S. Geological Survey and one based on the highly detailed National Urban Database and Access Portal Tool (NUDAPT) dataset with a spatial resolution of 1 km2. Two-meter air temperature and surface wind speed have been used in the evaluation. The statistical analysis shows a tendency to overestimate the air temperatures by the simple bulk scheme and underestimate the air temperatures by the more detailed urban canopy parameterizations. Similarly, the bulk and single-layer schemes tend to overestimate the wind speed while the multilayer schemes underestimate it. The three-dimensional analysis of the meteorological fields revealed a possible impact (to be verified against measurements) of both the urban schemes and the UCP on cloud prediction. Moreover, the impact of air conditioning systems on the air temperature and their energy consumption has been evaluated with the most developed urban scheme for the two simulated days. During the night, this anthropogenic heat was responsible for an increase in the air temperature of up to 2°C in the densest urban areas, and the estimated energy consumption was of the same magnitude as energy consumption obtained with different methods when the most detailed UCP database was used. On the basis of the results for the present case study, one can conclude that if the purpose of the simulation requires only an estimate of the 2-m temperature a simple bulk scheme is sufficient but if the purpose of the simulation is an evaluation of an urban heat island mitigation strategy or the evaluation of the energy consumption due to air conditioning at city scale, it is necessary to use a complex urban canopy scheme and a detailed UCP.


2018 ◽  
Vol 14 (1) ◽  
pp. 44-57
Author(s):  
S. N. Shumov

The spatial analysis of distribution and quantity of Hyphantria cunea Drury, 1973 across Ukraine since 1952 till 2016 regarding the values of annual absolute temperatures of ground air is performed using the Gis-technologies. The long-term pest dissemination data (Annual reports…, 1951–1985; Surveys of the distribution of quarantine pests ..., 1986–2017) and meteorological information (Meteorological Yearbooks of air temperature the surface layer of the atmosphere in Ukraine for the period 1951-2016; Branch State of the Hydrometeorological Service at the Central Geophysical Observatory of the Ministry for Emergencies) were used in the present research. The values of boundary negative temperatures of winter diapause of Hyphantria cunea, that unable the development of species’ subsequent generation, are received. Data analyses suggests almost complete elimination of winter diapausing individuals of White American Butterfly (especially pupae) under the air temperature of −32°С. Because of arising questions on the time of action of absolute minimal air temperatures, it is necessary to ascertain the boundary negative temperatures of winter diapause for White American Butterfly. It is also necessary to perform the more detailed research of a corresponding biological material with application to the freezing technics, giving temperature up to −50°С, with the subsequent analysis of the received results by the punched-analysis.


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