scholarly journals The Impacts of Air Leakage Paths and Airtightness Levels on Air Change Rates

Buildings ◽  
2020 ◽  
Vol 10 (3) ◽  
pp. 55 ◽  
Author(s):  
Vitor E. M. Cardoso ◽  
Pedro F. Pereira ◽  
Nuno M. M. Ramos ◽  
Ricardo M. S. F. Almeida
Keyword(s):  
Natural Ventilation ◽  
Co2 Concentration ◽  
Climatic Conditions ◽  
European Countries ◽  
Air Leakage ◽  
Air Change Rate ◽  
Transient Simulations ◽  
Mechanical Extraction ◽  
Southern European Countries

Southern European countries have milder climatic conditions that differ from their colder northern counterparts, which greatly influence indoor ventilation strategies. The relation between a building’s airtightness and the air change rates remains a topic to be fully tackled in these countries, since natural ventilation is very frequent. In this work, the ventilation and airtightness of a case study were analyzed in-depth to support a discussion on this topic. CO2 concentration decay and blower-door measurements were used to characterize the infiltration and ventilation conditions of the case study. The case study represents a common Portuguese situation, with highly permeable envelopes, combined with highly variable air change rates. Transient simulations were carried out for the comparison of scenarios where different configurations of possible air paths were analyzed. The simulations included both natural and mechanical ventilation scenarios. An air sweeping effect from bedroom to bathroom only occurred when the mechanical extraction ventilation (MEV) was on. Different air leakage path configurations resulted in substantial offsets, up to 63%, of the air change rate (ACH) due to natural occurring forces. The results confirmed that the relation between airtightness and air change rates should be carefully analyzed in southern European countries, as indoor air quality, comfort of occupants, and energy efficiency are highly influenced by the considered variables.

scholarly journals Evaluation of the development and yielding potential of Chenopodium quinoa Willd. under the climatic conditions of Europe. Part one: accomodation of Chenopodium quinoa (Willd.) to different conditions

2012 ◽  
Vol 61 (1) ◽  
pp. 179-184 ◽  
Author(s):  
Krzysztof Gęsiński
Keyword(s):  
Seed Yield ◽  
Chenopodium Quinoa ◽  
Climatic Conditions ◽  
European Countries ◽  
High Yield ◽  
Green Matter ◽  
Southern European Countries ◽  
Very High ◽  
High Seed Yield

Based on the evaluation of selected varieties of <i>Chenopodium quinoa</i>, their requirements were identified; it was shown which varieties demonstrated the best effects in what conditions. It was found that the best varieties for Europe's conditions were E-DK-4-PQCIP and RU-5-PQCIP. E-DK-4-PQCIP variety showed the best effects under the conditions of cluster II which included e.g. Bydgoszcz (Poland) and cluster IV which included Southern European countries (Greece and Italy), while the best effects found in RU-5-PQCIP variety were identified in cluster I which included Sweden. E-DK-4-PQCIP variety in cluster II showed a very high yield of green matter and a mean seed yield, and in cluster IV - a very high seed yield and a high yield of green matter.

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 Energy Modelling and Calibration of Building Simulations: A Case Study of a Domestic Building with Natural Ventilation

Energies ◽  
2019 ◽  
Vol 12 (17) ◽  
pp. 3360 ◽  
Author(s):  
Carolina Aparicio-Fernández ◽  
José-Luis Vivancos ◽  
Paula Cosar-Jorda ◽  
Richard A. Buswell
Keyword(s):  
Energy Demand ◽  
Natural Ventilation ◽  
Transient Flow ◽  
Residential Buildings ◽  
Infiltration Rate ◽  
Energy Performance ◽  
Performance Modelling ◽  
Change Rate ◽  
Air Change Rate

In this paper, the building energy performance modelling tools TRNSYS (TRaNsient SYstem Simulation program) and TRNFlow (TRaNsient Flow) have been used to obtain the energy demand of a domestic building that includes the air infiltration rate and the effect of natural ventilation by using window operation data. An initial model has been fitted to monitoring data from the case study, building over a period when there were no heat gains in the building in order to obtain the building infiltration air change rate. After this calibration, a constant air-change rate model was established alongside two further models developed in the calibration process. Air change rate has been explored in order to determine air infiltrations caused by natural ventilation due to windows being opened. These results were compared to estimates gained through a previously published method and were found to be in good agreement. The main conclusion from the work was that the modelling ventilation rate in naturally ventilated residential buildings using TRNSYS and TRNSFlow can improve the simulation-based energy assessment.

Case study of wind-induced natural ventilation tower in hot and humid climatic conditions

2012 ◽  
Author(s):  
Lim Chin Haw ◽  
Omidreza Saadatian ◽  
A H Baharuddin ◽  
Sohif Mat ◽  
M. Y. Sulaiman ◽  
...  
Keyword(s):  
Natural Ventilation ◽  
Climatic Conditions

CASE STUDY: Regional Cultural Differences Within and Across Four Western European Countries

2018 ◽  
Vol 6 (1) ◽  
pp. 23-47
Author(s):  
Nadine Waehning ◽  
Ibrahim Sirkeci ◽  
Stephan Dahl ◽  
Sinan Zeyneloglu
Keyword(s):  
Cultural Values ◽  
Cultural Differences ◽  
European Countries ◽  
Cultural Value ◽  
Business Strategies ◽  
Business Plans ◽  
Regional Markets ◽  
Gender Education ◽  
Western European

This case study examines and illustrates within country regional cultural differences and cross border cultural similarities across four western European countries. Drawing on the data from the World Values Survey (WVS), we refer to the Schwartz Cultural Values Inventory in the survey. The demographic variables of age, gender, education level, marital status and income vary across the regions and hence, have significant effects on the cultural value dimensions across regions. The findings help a better understanding of the homogeneity and heterogeneity of regions withinand across countries. Both researchers and managers will have to justify their sampling methods and generalisations more carefully when drawing conclusions for a whole country. This case study underlines the limited knowledge about regional within country cultural differences, while also illustrating the simplification of treating each country as culturally homogeneous. Cross-country business strategies connecting transnational regional markets based on cultural value characteristics need to take these similarities and differences into account when designating business plans.

Investigation of the natural ventilation of wind catchers with different geometries in arid region houses

2020 ◽  
Vol 14 (3) ◽  
pp. 7109-7124
Author(s):  
Nasreddine Sakhri ◽  
Younes Menni ◽  
Houari Ameur ◽  
Ali J. Chamkha ◽  
Noureddine Kaid ◽  
...  
Keyword(s):  
Arid Region ◽  
Natural Ventilation ◽  
Reduction Rate ◽  
Internal Flow ◽  
Climatic Conditions ◽  
Maximum Pressure ◽  
Ventilation Technique ◽  
Window Position ◽  
The One ◽  
Flow Velocities

The wind catcher or wind tower is a natural ventilation technique that has been employed in the Middle East region and still until nowadays. The present paper aims to study the effect of the one-sided position of a wind catcher device against the ventilated space or building geometry and its natural ventilation performance. Four models based on the traditional design of a one-sided wind catcher are studied and compared. The study is achieved under the climatic conditions of the South-west of Algeria (arid region). The obtained results showed that the front and Takhtabush’s models were able to create the maximum pressure difference (ΔP) between the windward and leeward of the tower-house system. Internal airflow velocities increased with the increase of wind speed in all studied models. For example, at Vwind = 2 m/s, the internal flow velocities were 1.7, 1.8, 1.3, and 2.5 m/s for model 1, 2, 3, and 4, respectively. However, at Vwind = 6 m/s, the internal flow velocities were 5.6, 5.5, 2.5, and 7 m/s for model 1, 2, 3, and 4, respectively. The higher internal airflow velocities are given by Takhtabush, traditional, front and middle tower models, respectively, with a reduction rate between the tower outlet and occupied space by 72, 42, 36, and 33% for the middle tower, Takhtabush, traditional tower, and the front model tower, respectively. This reduction is due to the due to internal flow resistance. The third part of the study investigates the effect of window (exist opening) position on the opposite wall. The upper, middle and lower window positions are studied and compared. The air stagnation or recirculation zone inside the ventilated space reduced from 55% with the lower window to 46% for the middle window and reached 35% for the upper window position. The Front and Takhtabush models for the one-sided wind catcher with an upper window position are highly recommended for the wind-driven natural ventilation in residential houses that are located in arid regions.

scholarly journals A Planning Tool for Reliability Assessment of Overhead Distribution Lines in Hybrid AC/DC Grids

2021 ◽  
Vol 13 (11) ◽  
pp. 6099
Author(s):  
Giovanna Adinolfi ◽  
Roberto Ciavarella ◽  
Giorgio Graditi ◽  
Antonio Ricca ◽  
Maria Valenti
Keyword(s):  
Reliability Assessment ◽  
Reliability Function ◽  
Climatic Conditions ◽  
Planning Tool ◽  
Grid Resource ◽  
Distribution Lines ◽  
Ac Networks ◽  
Reliability Performance ◽  
Power Dispatching

Integration of DC grids into AC networks will realize hybrid AC/DC grids, a new energetic paradigm which will become widespread in the future due to the increasing availability of DC-based generators, loads and storage systems. Furthermore, the huge connection of intermittent renewable sources to distribution grids could cause security and congestion issues affecting line behaviour and reliability performance. This paper aims to propose a planning tool for congestion forecasting and reliability assessment of overhead distribution lines. The tool inputs consist of a single line diagram of a real or synthetic grid and a set of 24-h forecasting time series concerning climatic conditions and grid resource operative profiles. The developed approach aims to avoid congestions criticalities, taking advantage of optimal active power dispatching among “congestion-nearby resources”. A case study is analysed to validate the implemented control strategy considering a modified IEEE 14-Bus System with introduction of renewables. The tool also implements reliability prediction formulas to calculate an overhead line reliability function in congested and congestions-avoided conditions. A quantitative evaluation underlines the reliability performance achievable after the congestion strategy action.

scholarly journals Review of Intelligent Control Systems for Natural Ventilation as Passive Cooling Strategy for UK Buildings and Similar Climatic Conditions

Energies ◽  
2021 ◽  
Vol 14 (15) ◽  
pp. 4388
Author(s):  
Esmail Mahmoudi Saber ◽  
Issa Chaer ◽  
Aaron Gillich ◽  
Bukola Grace Ekpeti
Keyword(s):  
Control Systems ◽  
Natural Ventilation ◽  
Energy Use ◽  
Integrated Control ◽  
Climatic Conditions ◽  
Effective Control ◽  
Practical Implementation ◽  
Optimal Output ◽  
Heating And Cooling ◽  
Building Cooling

Natural ventilation is gaining more attention from architects and engineers as an alternative way of cooling and ventilating indoor spaces. Based on building types, it could save between 13 and 40% of the building cooling energy use. However, this needs to be implemented and operated with a well-designed and integrated control system to avoid triggering discomfort for occupants. This paper seeks to review, discuss, and contribute to existing knowledge on the application of control systems and optimisation theories of naturally ventilated buildings to produce the best performance. The study finally presents an outstanding theoretical context and practical implementation for researchers seeking to explore the use of intelligent controls for optimal output in the pursuit to help solve intricate control problems in the building industry and suggests advanced control systems such as fuzzy logic control as an effective control strategy for an integrated control of ventilation, heating and cooling systems.

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