scholarly journals Analysis of Wind Speed and Wind Pressure on the Facades in Frequency Domain for the Modelling of Air Change Rate

2020 ◽  
Vol 172 ◽  
pp. 09005
Author(s):  
Krystyna Pietrzyk
Keyword(s):  
Wind Speed ◽  
Frequency Domain ◽  
Wind Direction ◽  
High Frequency ◽  
Pressure Coefficient ◽  
Building Envelope ◽  
Wind Pressure ◽  
Change Rate ◽  
Air Change Rate ◽  
Air Exchange

Air exchange in buildings is driven by pressure difference across the building envelope caused by wind and difference in density between external and internal air. The evaluation of the influence of wind on the air change rate is usually limited to the analysis of the hourly mean wind speed. Wind is a random phenomenon characterized by the broad energy spectrum. The high frequency part can be responsible for the oscillation of the air through the openings resulting in the increased air exchange. Wind pressure coefficient on the leeward site mostly depends on the form characteristics of the object in relation to wind direction. The analysis of wind speed and wind pressure on the facades in frequency domain can deliver interesting data to air change rate model. Some of the results of continuous measurements carried out on a single-family house for 8 months are presented in frequency domain. The statistics of wind speed, wind direction and pressure differences across the 6 building components are calculated. The wind turbulence and the pressure fluctuations on the facades and the roof of the building are being investigated using energy spectra of their signals. Farther analysis of the experimental results is needed to be able to include high frequency wind in the infiltration model.

scholarly journals A Study on the Utilization of Natural Ventilation Systems in Institutional Buildings

2019 ◽  
Vol 7 (1) ◽  
pp. 73-81
Author(s):  
N Anuja ◽  
N Amutha Priya
Keyword(s):  
Mechanical Ventilation ◽  
Energy Consumption ◽  
Wind Speed ◽  
Energy Management ◽  
Energy Demand ◽  
Natural Ventilation ◽  
Wind Pressure ◽  
Air Flow Rate ◽  
Change Rate ◽  
Air Change Rate

In Buildings, Energy Management is an important sector. Use of natural ventilation is the only way to minimise the overall energy consumption in buildings. Natural ventilation at a point can vary significantly for every second due to the climatic change. This paper has investigated energy demand problems due to ventilation in an institutional building located in India and gives satisfactory solutions to the problem. The main aim is to utilise maximum natural ventilation instead of artificial systems by reducing the energy bills in the Institutional building. Several Factors such as Wind speed, Wind pressure, Mechanical Ventilation, Air Flow Rate, Air Change Rate, Ventilation Air Change Requirements, Ventilation at various points in a Classroom are considered, and a Questionnaire Survey is conducted among the students.

Indoor hygrothermal loads for the deterministic and stochastic design of the building envelope for dwellings in cold climates

2017 ◽  
Vol 41 (6) ◽  
pp. 547-577 ◽  
Author(s):  
Simo Ilomets ◽  
Targo Kalamees ◽  
Juha Vinha
Keyword(s):  
Field Measurements ◽  
Heating System ◽  
Building Envelope ◽  
Cold Climates ◽  
Outdoor Temperature ◽  
Change Rate ◽  
Levels Of Detail ◽  
Air Change Rate ◽  
Excess Value ◽  
Occupancy Rates

In this study, several years of field measurements of indoor hygrothermal loads in 237 dwelling units are analysed. Moisture excess is calculated from hourly values of temperature, and relative humidity measured both indoors and outdoors. Air change rate and moisture production in bedrooms are calculated on the basis of carbon dioxide measurements. It is found that indoor temperature profiles differ depending on whether a building has central heating, a stove or combined heating system. The determined average moisture excess value, 2.8 g/m3 with a standard deviation of 1.6 g/m3 for cold periods, can be used in stochastic calculations. Critical values for moisture excess at the 90th percentile, ranging from 3–8 g/m3, depending upon occupancy rates, can be used in the deterministic analysis. Averages and weekly maxima of moisture excess in the study are reported at different percentiles. Considerable deviations from the EN ISO 13788 standard are discovered, concerning the breaking point depending on outdoor temperature and moisture excess during the summer. The average and critical moisture production in bedroom is presented and insufficient ventilation determined based on measurements. During the heating period, the air change rate is relatively stable while moisture production levels increase along with the dropping outdoor temperature. Two indoor temperatures and three humidity models with different levels of detail and influencing factors are proposed. Temperature and humidity loads derived using the proposed models can be used to determine the indoor hygrothermal boundary conditions for the building envelope of dwellings in cold climates.

scholarly journals Towards upgrading strategies for nZEB-dwellings in Norway

2019 ◽  
Vol 25 (2) ◽  
pp. 35-42
Author(s):  
Lars Gullbrekken ◽  
Berit Time
Keyword(s):  
High Performance ◽  
Building Envelope ◽  
Passive House ◽  
Ventilation Control ◽  
Ongoing Research ◽  
Change Rate ◽  
Building Regulations ◽  
Air Change Rate ◽  
Upgrading Strategies ◽  
High Performance Level

Recent work suggests that upgrading in line with the Norwegian building regulations or by upgradingto the requirements of the national passive house norm, NS3700, can enable nZEB level to be achieved.The aim of this work is to explore the typical Norwegian housing typologies and some importantcharacteristics of the building envelope for these houses from different decades. The exploration involvedsurveying the typical technical qualities of Norwegian housing and how these have evolved – providingan important foundation to work addressing strategies and methods for upgrading dwellings to nZEBlevel in the next phases of the ongoing research project. The results of this work show that the buildingnorms and practices developed throughout the years have made dwellings more moisture resilient, withan increased drying-out potential through mechanical ventilation, control of the air change rate and theuse of more vapour-open wind barriers in the building envelope. Based on this, the work to follow willsuggest strategies for upgrading to nZEB level, solutions for upgrading building envelope componentsto high performance level and a methodology for risk reduction of moisture problems in the upgradeddwellings from the different decades.

scholarly journals Full-Scale Measurements of Translational and Torsional Dynamics Characteristics of a High-Rise Building during Typhoon Sarika

Materials ◽  
2022 ◽  
Vol 15 (2) ◽  
pp. 493
Author(s):  
Jiaxing Hu ◽  
Zhengnong Li ◽  
Zhefei Zhao
Keyword(s):  
Wind Speed ◽  
Frequency Domain ◽  
Wind Direction ◽  
Field Measurement ◽  
Full Scale ◽  
Induced Response ◽  
Wind Resistance ◽  
High Rise ◽  
High Rise Building ◽  
Translational Acceleration

The field measurement of wind-induced response is of great significance to the wind resistance design of high-rise buildings, in particular torsional responses measured from high-rise buildings under typhoons. The measured high-rise building, with a height of 108 m, has 32 stories and is supported by giant trusses with four massive columns. Acceleration responses along translational and torsional directions were monitored synchronously and continuously during the passage of Typhoon Sarika on 18 October 2016. The wind speed and wind direction at the height of 115 m, the translational accelerations on a total of six floors and the angular accelerations on a total of four floors were recorded. The time and frequency domain characteristics of translational acceleration and torsional angular accelerations were analyzed. The amplitude-dependent translational and torsional modal frequencies of the measured building were identified by NExT-ERA, SSI, and RDT methods. The full-scale study is expected to provide useful information on the wind-resistant design of high-rise buildings in typhoon-prone regions.

scholarly journals ЕКСПЕРИМЕНТАЛЬНЕ ДОСЛІДЖЕННЯ ЯКОСТІ ПОВІТРЯ ТА ПОВІТРООБМІНУ В ЗАКЛАДАХ ОСВІТИ ТА ЖИТЛОВИХ БУДІВЛЯХ

2021 ◽  
Vol 148 (4) ◽  
pp. 25-37
Author(s):  
В. І. Дешко ◽  
І. Ю. Білоус ◽  
В. О. Виноградов-Салтиков ◽  
І. О. Суходуб ◽  
О. І. Яценко
Keyword(s):  
Mathematical Modeling ◽  
Exchange Rate ◽  
Energy Consumption ◽  
Air Quality ◽  
Operating Conditions ◽  
Change Rate ◽  
Research Results ◽  
Air Exchange Rate ◽  
Air Change Rate ◽  
Air Exchange

Apply  integrated  approaches  for  the  air  exchange  rate  determination  based  on  CO 2  concentration in educational and residential buildings of Ukraine. Methods.  Taking  into  account  variability  of  building's  visitors  and  occupants  operational  and behavioral features experimental and calculated determination of the air exchange rate are considered. Results. Recommendations for providing comfort conditions in terms of air quality in the considered objects premises, recommendations on the premises operating conditions, ventilation schedule. Scientific novelty. The comprehensive approach to in-depth analysis of energy consumption has been developed,  procedures for assessing  the  air  quality  and  the level  of  air  exchange  in  buildings  have  been improved taking into account the variability of operating conditions. The practical significance. Experimental studies of changes in CO 2  concentration were conducted in three schools, in higher education institution and in residential building. The research results allowed to establish the actual level of CO 2  concentration and air change rate under different operational and behavioral conditions in buildings during working hours, subject to comfortable conditions, and during non-use hours. The research results also help to determine the dynamics of changes in the studied factor over time under the building  performance  indicators  influence.  The  obtained  results  allow  to  provide  recommendations  on ensuring the quality of indoor air exchange and on providing comfort working, studying and living conditions. The use of experimental and calculated air exchange rate values for various premises would allow to avoid in mathematical modeling the overestimation of the level of buildings energy consumption, which arises when standard air change rate values is using. So the obtained results allow to approximate more accurately the mathematical modeling results of buildings energy efficiency to the actual conditions and help to choose the optimal schedule for the building engineering networks managing considering comfort conditions with intermittent operation.

scholarly journals Transition from n50 to actual air exchange dependent on climatic conditions

2019 ◽  
Vol 282 ◽  
pp. 02101
Author(s):  
Tomasz Kisilewicz ◽  
Katarzyna Nowak-Dzieszko ◽  
Małgorzata Rojewska-Warchał
Keyword(s):  
Energy Demand ◽  
Natural Ventilation ◽  
Simple Procedure ◽  
Ventilation System ◽  
Climatic Conditions ◽  
Model Calculations ◽  
Change Rate ◽  
The Real ◽  
Air Change Rate ◽  
Air Exchange

The knowledge of the air flow and air exchange in the building is critical both on the design and operation stage of the building. Infiltration of air interferes with the mechanical ventilation and determines the proper functioning of the natural ventilation system, still commonly used in the standard buildings. The building airtightness can be described by n50 parameter, however it does not specify the real air exchange in natural conditions. According to the simple procedure of the standard EN ISO 13789, factor n50 may be easily converted to the monthly averaged air change rate. However, it is difficult to accept the same value of air change rate in any month of a year, as it is often done in the certification procedures. More precise, climate dependent conversion procedures have been elaborated in USA, but they were developed for the specific local building technology and local climate conditions. This paper presents the results of the preliminary measurements conducted in a single family house in Poland, built in a heavy-weight technology. The real air exchange rate was measured in various climatic conditions by means of gas tracing method, with CO2 as the tracer gas, in order to prove a relationship between the enhanced procedure and the external conditions. Acceptable agreement between the results of the measurement and model calculations was obtained. Based on the preliminary results, the authors determined the more realistic influence of the enhanced algorithm on the ventilation energy demand. The use of the simplified model resulted in case of the analyzed object in 15% overestimation of the ventilation thermal losses.

scholarly journals Evaluation of the Flow Distortion around the Campbell Scientific CSAT3 Sonic Anemometer Relative to Incident Wind Direction

2009 ◽  
Vol 26 (3) ◽  
pp. 582-592 ◽  
Author(s):  
Harry C. Friebel ◽  
Thomas O. Herrington ◽  
Alexander Y. Benilov
Keyword(s):  
Wind Speed ◽  
Momentum Transfer ◽  
Wind Direction ◽  
High Frequency ◽  
Surf Zone ◽  
Spectral Characteristics ◽  
Sonic Anemometer ◽  
Flow Distortion ◽  
Mean Wind Speed ◽  
The Mean

Abstract In June 2002, a high-frequency air–sea momentum system was deployed in the surf zone for 3 days as part of an experiment to quantify air–sea momentum transfer when the wind and wave direction were at angles. The system obtained measurements in the nearshore via a high-resolution Campbell Scientific CSAT3 3D sonic anemometer and five high-frequency saltwater wave staffs. An advantage of the air–sea momentum system is that direct measurements of the atmospheric turbulent fluctuations can be obtained and applied to the calculation of momentum transfer at the air–sea interface. The Campbell Scientific CSAT3 sonic anemometer was postcalibrated under turbulent wind conditions to determine incident wind direction measurements influenced by the geometry of the instrument. Measurement results are compared to a pre-established benchmark, constant tow speed; and the mean wind speed, incident wind direction, and spectral density characteristics are evaluated to resolve specific instrument orientations in which the measurements are corrupted by the head and probe supports of the sonic anemometer. Calibration testing of the sonic anemometer determined that the mean wind speeds are reduced by 16% over a 40° range for incident wind angles of 160°–200° relative to the head of the anemometer. Tilting the anemometer is found to decrease mean wind speed reduction influenced by the geometry of the anemometer. Variations in the measured wind directions were found to be greater than 1° for incident wind angles between 160° and 200° for 0° and 10° of tilt. Spectral characteristics were highly repeatable for all wind angles except for incident wind angles of 180° for 0° and 10° of tilt.

Assessment of exposure risk from hidden fungal growth by measurements of air change rates in construction cavities and living areas

2017 ◽  
Vol 41 (3) ◽  
pp. 209-224 ◽  
Author(s):  
Sofie M Knudsen ◽  
Eva B Møller ◽  
Lars Gunnarsen
Keyword(s):  
Field Study ◽  
Fungal Growth ◽  
Building Envelope ◽  
Exposure Risk ◽  
Tracer Gas ◽  
Change Rate ◽  
Health Symptoms ◽  
Air Change Rate ◽  
Gaseous Pollution ◽  
Growth Assessment

The transfer of particulate and gaseous pollution from hidden fungi growing on non-visible surfaces within the building envelope to occupied rooms is limited by the separating structure. Yet, growth, even in sealed construction cavities, is known to cause annoying smells and other more adverse health symptoms among the building occupants. This study analyses limitations of air change rate measurements in inaccessible construction cavities as well as analyses of the air exchange between living areas and accessible cavities such as crawl spaces and attics. It was necessary to invent a field study technique to use the tracer gas decay method in small and inaccessible cavities. This technique allowed further investigation on the exposure risk from hidden fungal growth. Assessment of the air transfer between crawl spaces and living areas indicate that the tightness of separating structure has an influence on the exposure risk.

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