scholarly journals Moisture Risk Analysis for Three Construction Variants of a Wooden Inverted Flat Roof

Energies ◽  
2021 ◽  
Vol 14 (23) ◽  
pp. 7898
Author(s):  
Agnieszka Sadłowska-Sałęga ◽  
Krzysztof Wąs
Keyword(s):  
Outer Side ◽  
Change Rate ◽  
Air Change Rate ◽  
Hygrothermal Performance ◽  
Excess Moisture ◽  
Flat Roof ◽  
Universal Solutions ◽  
Proper Performance ◽  
House Standard ◽  
Made In

The paper presents an analysis of the hygrothermal performance of an inverted flat roof with a CLT (cross-laminated timber) structure in a building that meets the requirements of Passive House Standard (PHS) with regards to the potential risk of moisture. The calculations were made in the WUFI®Plus and WUFI®Bio software. The following variants were taken into account: three structure configurations, three different external climates and different scenarios of microclimate control and air change rate. The results of the calculations show that, especially in cooler climates, there is an actual moisture risk in the structure despite the excellent thermal insulation. The structure of the inverted flat roof, due to the use of a tight membrane on the outer side, allows for the partition to discharge the excess moisture only to the inside of the building. Ensuring the comfort of users may require periodic humidification of internal air, which translates directly into an increase in moisture content of the structure. The performed analysis clearly showed that there are no universal solutions. It is important to point out that for the proper performance of inverted wooden roofs, it is crucial to analyse moisture, not only thermal and energy parameters.

scholarly journals Danish Dwellings with Cold Attics—Ventilation Rates and Air Exchange between Attic and Dwelling

Buildings ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 64
Author(s):  
Tessa Kvist Hansen
Keyword(s):  
Mould Growth ◽  
Single Family ◽  
Tracer Gas ◽  
Change Rate ◽  
Air Change Rate ◽  
Humidity Measurements ◽  
Excess Moisture ◽  
Ventilation Rates ◽  
And Diffusion ◽  
Air Exchange

Naturally ventilated cold attics are traditional in many Danish single-family homes. The moisture balance of these attics is dependent on sufficient ventilation for removal of excess moisture. Moisture is generated in the dwelling below, and transported to attic spaces through convection and diffusion. Therefore, airtight ceilings are vital for reduction of excess moisture, which may yield mould growth in the attic. If mould spores migrate to the dwelling it can cause risk of health concerns for occupants. The presents study includes analysis of tracer gas and temperature/relative humidity measurements, in 30 dwellings/attics. The measurements yielded results of both air change rates in attics and dwellings, as well as air exchange between the two zones. Four of 30 houses, met the recommended air change rate of 0.5 h−1, and only in summer. The air change rate in the attics was found to be higher, and with larger variation compared to the dwelling. Visible mould growth was found in three attics, which all exhibited low air change rates. Air exchange between zones occurred in houses both with and without vapour barriers. The downward air exchange in summer, was however slightly larger in cases without vapour barriers. These results highlight the importance of airtight ceilings for both dwelling and attic performance.

scholarly journals Comparison of Downdraught and Up Draft Passive Air Conduction Systems (PACS) in a Winery Building

Buildings ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 259
Author(s):  
Ádám László Katona ◽  
István Ervin Háber ◽  
István Kistelegdi
Keyword(s):  
Air Conditioning ◽  
Natural Ventilation ◽  
Dynamics Simulation ◽  
Computational Fluid Dynamics Simulation ◽  
General Applicability ◽  
Change Rate ◽  
Air Change Rate ◽  
Simulation Based ◽  
Ventilation Performance ◽  
Air Conduction

A huge portion of energy consumption in buildings comes from heating, ventilation, and air conditioning. Numerous previous works assessed the potential of natural ventilation compared to mechanical ventilation and proved their justification on the field. Nevertheless, it is a major difficulty to collect enough information from the literature to make decisions between different natural ventilation solutions with a given situation and boundary conditions. The current study tests the passive air conduction system (PACS) variations in the design phase of a medium-sized new winery’s cellar and production hall in Villány, Hungary. A computational fluid dynamics simulation based comparative analysis enabled to determine the differences in updraft (UD) and downdraught (DD) PACS, whereby the latter was found to be more efficient. While the DD PACS performed an air change range of 1.02 h−1 to 5.98 h−1, the UD PACS delivered −0.25 h−1 to 12.82 h−1 air change rate. The ventilation performance of the DD version possessed lower amplitudes, but the distribution was more balanced under different wind incident angles, thus this version was chosen for construction. It could be concluded that the DD PACS provides a more general applicability for natural ventilation in moderate climates and in small to medium scale industry hall domains with one in- and one outlet.

Hygrothermal performance of various Typha–clay composite

2018 ◽  
Vol 42 (3) ◽  
pp. 316-335 ◽  
Author(s):  
Ibrahim Niang ◽  
Chadi Maalouf ◽  
Tala Moussa ◽  
Christophe Bliard ◽  
Etienne Samin ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Optimal Composition ◽  
Volume Weight ◽  
Hygrothermal Behavior ◽  
Three Samples ◽  
Hygrothermal Performance ◽  
Absolute Density ◽  
Typha Australis ◽  
Hygric Properties ◽  
Made In

This article deals with the influence of both morphology and amount of Typha on hygrothermal behavior of a Typha–clay composite for building application. An agromaterial containing the fiber mix of Typha Australis and clay was made in three samples: three fiber mixtures were prepared with different amounts Typha and cut type (transversal or longitudinal). The physical properties of these materials were studied in terms of porosity, apparent and absolute density, thermal conductivity, and hygric properties. Results show a real impact of the Typha fraction type and its volume content on hygrothermal properties of the studied material due to the porosity. The transversal fraction of Typha (80% in volume weight) seems to be the optimal composition for a better hygrothermal behavior.

scholarly journals Estimation of a room ventilation air change rate using a stochastic grey-box modelling approach

Measurement ◽  
2018 ◽  
Vol 124 ◽  
pp. 539-548 ◽  
Author(s):  
Marcel Macarulla ◽  
Miquel Casals ◽  
Núria Forcada ◽  
Marta Gangolells ◽  
Alberto Giretti
Keyword(s):  
Change Rate ◽  
Room Ventilation ◽  
Air Change Rate ◽  
Modelling Approach

scholarly journals Quality of life control by selected methods of air exchange in a typical apartment building

2021 ◽  
Author(s):  
Iveta Bullová ◽  
Peter Kapalo ◽  
Dušan Katunský
Keyword(s):  
Air Quality ◽  
Indoor Air Quality ◽  
Indoor Air ◽  
Allergic Diseases ◽  
Well Being ◽  
Indoor Climate ◽  
Apartment Building ◽  
Change Rate ◽  
Air Change Rate ◽  
Negative Effect

Air change rate is an important parameter for quantification of ventilation heat losses and also affects the indoor climate of buildings. Indoor air quality is significantly associated with ventilation. If air change isn't sufficient, trapped allergens, pollutants and irritants can degrade the indoor air quality and affect the well-being of a building's occupants. Many studies on ventilation and health have concluded that lower air change rates can have a negative effect on people’s health and low ventilation may result in an increase in allergic diseases. Quantification of air change rate is complicated, since it is affected by a number of parameters, of which the one of the most variable is the air-wind flow. This study aims to determination and comparison of values of the air change rate in two methods - by quantifying of aerodynamic coefficient Cp = Cpe - Cpi – so called aerodynamic quantification of the building and the methodology based on experimental measurements of carbon dioxide in the selected reference room in apartment building.

scholarly journals МЕТАЛОГІДРИДНИЙ АКУМУЛЯТОР-КОМПРЕСОР ВОДНЮ З АВТОМАТИЧНОЮ СИСТЕМОЮ УПРАВЛІННЯ ТА КОНТРОЛЮ

2020 ◽  
pp. 53-60
Author(s):  
Михайло Романович Ткач ◽  
Борис Георгійович Тимошевський ◽  
Аркадій Юрійович Проскурін ◽  
Юрій Миколайович Галинкін
Keyword(s):  
Automatic Control ◽  
Metal Hydride ◽  
Block Diagram ◽  
Automatic Monitoring ◽  
Outer Side ◽  
Piping System ◽  
Air Cooling ◽  
Monitoring And Control ◽  
Compression Pressure ◽  
Made In

A project of metal hydride hydrogen compressor is presented, which can be used as an element of refueling complexes, hydrogen storage and compression systems. The capacity of the developed sample is 40 kg of hydrogen, the mass is 4,8 ton, and the maximum compression pressure is 15 MPa. The base metal hydride material on the basis of which this compressor battery model is developed is LaNi4.5Al0.5. the sorption capacity of hydrogen of which is determined experimentally, and is at least 1.38 % by weight. A feature of the developed compressor battery is the use of air cooling, the presence of an automatic monitoring and control system, I allow a number of operations to be performed in automatic mode, and the use of software, electrical and automatic protection against overpressure. Each accumulator-compressor is made in the form of a steel box in which six blocks (capsules) are placed. The block, respectively, is made in the form of a steel coaxial multilayer cylinder, on the outer side of which there is a heating element and a layer of thermal insulation. In the middle of the cylinder is a sealed capsule filled with metal hydride material. Capsules are interconnected with the collector through a piping system. Also, the piping system is equipped with an inlet valve connecting the volume formed with an external receiver. The battery-compressor is equipped with an external receiver, to which a hydrogen, vacuum, nutrient and consumable outline is connected. Each circuit is equipped with an electromagnetic valve, as well as measuring devices, which makes it possible to carry out automatic control of parameters and automatic control of the device in accordance with the operating mode. A list of equipment is presented, on the basis of which a system of automatic control and monitoring, a block diagram of the main operating modes, an interface of the developed software are developed. Depending on the mode chosen by the operator, the automatic control and monitoring system allows activation of metal hydride materials, purification of contaminants of harmful impurities, sorption and desorption of hydrogen.

scholarly journals Intra-Cage Air Change Rate on Forced-Air-Ventilated Micro-Isolation System-Environment within Cages: Carbon Dioxide and Oxygen Concentration.

1997 ◽  
Vol 46 (4) ◽  
pp. 251-257 ◽  
Author(s):  
Masakazu HASEGAWA ◽  
Yuzuru KURABAYASHI ◽  
Toshinori ISHII ◽  
Kazuya YOSHIDA ◽  
Nobukazu UEBAYASHI ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Oxygen Concentration ◽  
Isolation System ◽  
Change Rate ◽  
System Environment ◽  
Air Change Rate ◽  
Forced Air
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