scholarly journals Experimental field-trial design to investigate the effects of a defective internal vapour layer on timber frame wall constructions including initial findings

2019 ◽  
Vol 282 ◽  
pp. 02047
Author(s):  
Lee Corcoran ◽  
Prof Aidan Duffy
Keyword(s):  
Field Experiments ◽  
Thermal Characteristics ◽  
Simulation Models ◽  
Practical Experience ◽  
Building Envelope ◽  
Timber Frame ◽  
Test House ◽  
Building Components ◽  
Hygrothermal Analysis ◽  
The Impact

Hygrothermal analysis in multi-layered building components is becoming common practice. Low energy design criteria demands an increase in thermal and airtightness requirements resulting in more complicated building envelope designs to accommodate the necessary insulation and airtightness layers. Furthermore, in many cases materials are being chosen based solely on their thermal characteristics without fully considering other properties and this may lead to unintentional interstitial moisture-related problems. Much progress has been made in developing tools for undertaking hygrothermal simulations; however, there are on-going questions regarding how best to model imperfections and defects accurately using these software packages. Results of simulation models carried out in accordance with the new WTA guideline have been reported in literature as encouraging and confirming practical experience. Further verification of these simplified methods is therefore essential, including investigations of the relationship between model assumptions and typical defects in different construction types. Therefore, there is a need for specific field experiments and laboratory tests which gather the data necessary to validate and/or calibrate these models under a wider range of constructions types, defect types and climates. This paper describes the experimental design and fabrication of a full-scale timber frame test house that has been developed to assess the impact of a common defect in the internal vapour control/airtightness barrier, along with initial data results and findings. The data obtained will be used to validate existing commercial hygrothermal models and investigate different parameters and methods for modelling these vapour barrier defects.

Modeling Strategy in Evaluating Thermal Performance of an RF Module for Wireless Communications

2004 ◽  
Author(s):  
Victor Chiriac ◽  
Tien-Yu Tom Lee
Keyword(s):  
Thermal Performance ◽  
Thermal Characteristics ◽  
Simulation Models ◽  
Operating Conditions ◽  
Peak Temperature ◽  
Load Cells ◽  
Die Temperature ◽  
Rf Module ◽  
Modeling Strategy ◽  
The Impact

A detailed study was performed to evaluate the thermal performance of RF Modules and to identify meaningful correlations between specific design characteristics and the power dissipation needed to satisfy the required thermal budget under various critical operating conditions. The investigation focuses on the thermal characteristics of the RF module die layout and transistor cells, and on the thermal impact of the metallic air bridges connecting the load cells to the collector pads/vias to the overall thermal performance of the RF module. A first-pass modeling predicts higher temperatures than IR measurement, by ~20–30%. The addition of the die layout air bridges connecting the load cells in the detailed simulation models leads to a predicted air bridge temperature of ~9% higher than the IR measurement. Additional modeling reveals that between the open (not encapsulated) and the closed module, the die peak temperature differs by less than 3 °C, most of the heat being dissipated through the substrate and board to the heat stage. Thus, the impact of mold compound is insignificant. For a closed module, the mold compound helps dissipate the heat, so the die temperature is slightly cooler than for the open module (<<3°C). This suggests that the die peak temperature measured in an open module can be adjusted (by subtracting 2–3°C) to represent the die temperature in a closed module.

scholarly journals The effects of microclimate and time resolution of meteorological data on hygrothermal analysis of wood frame building facades

2021 ◽  
Author(s):  
Wai Ki Wu
Keyword(s):  
Meteorological Data ◽  
Weather Data ◽  
Climate Data ◽  
Frame Building ◽  
Hourly Data ◽  
Average Water ◽  
Building Components ◽  
Wood Frame ◽  
Hygrothermal Analysis ◽  
The Impact

When performing hygrothermal analysis for building envelopes, climate data is required as boundary conditions. This study investigates the effect of the microclimatic conditions using Toronto Pearson Airport and downtown hourly data. The results showed that the average water content of the wood frame building façade were similar throughout the study period. The high moisture content peaks reduced to average within days. The arithmetic averaged hourly weather data may also affect the analysis’ results. 5-minute weather data is collected from the Ryerson weather network. The hourly data is constructed from the 5-minute data by arithmetic averaging. The simulation results from both dataset followed closely to each other throughout the study period. The averaging of hourly data removed some details form the raw meteorological data. However, it does not affect the overall trend of the climate condition and the impact to the hygrothermal analysis of building components is very limited.

scholarly journals The effects of microclimate and time resolution of meteorological data on hygrothermal analysis of wood frame building facades

2021 ◽  
Author(s):  
Wai Ki Wu
Keyword(s):  
Meteorological Data ◽  
Weather Data ◽  
Climate Data ◽  
Frame Building ◽  
Hourly Data ◽  
Average Water ◽  
Building Components ◽  
Wood Frame ◽  
Hygrothermal Analysis ◽  
The Impact

When performing hygrothermal analysis for building envelopes, climate data is required as boundary conditions. This study investigates the effect of the microclimatic conditions using Toronto Pearson Airport and downtown hourly data. The results showed that the average water content of the wood frame building façade were similar throughout the study period. The high moisture content peaks reduced to average within days. The arithmetic averaged hourly weather data may also affect the analysis’ results. 5-minute weather data is collected from the Ryerson weather network. The hourly data is constructed from the 5-minute data by arithmetic averaging. The simulation results from both dataset followed closely to each other throughout the study period. The averaging of hourly data removed some details form the raw meteorological data. However, it does not affect the overall trend of the climate condition and the impact to the hygrothermal analysis of building components is very limited.

scholarly journals Operating Hardware Impact on the Heat Transfer Properties of Windows

Energies ◽  
2021 ◽  
Vol 14 (4) ◽  
pp. 1145
Author(s):  
Cezary Misiopecki ◽  
Robert Hart ◽  
Arild Gustavsen ◽  
Bjørn Petter Jelle
Keyword(s):  
Heat Transfer ◽  
Preliminary Investigation ◽  
Three Dimensional ◽  
Weighted Average ◽  
Simulation Models ◽  
Building Envelope ◽  
Approximation Technique ◽  
Thermal Transmittance ◽  
The Impact ◽  
Window Frames

Despite significant advancements in fenestration technology in the last two decades, the thermal transmittance of fenestration products is still significantly higher than that of walls. This corresponds to 60% of the total energy loss of a modern building envelope through the windows. Hence, further development and improvements of fenestration products are necessary. Increasingly stringent codes and standards for fenestration stimulate industry to work on improved solutions. Thus, it is crucial that assessment techniques are able to account for innovations accurately. The thermal effects of non-continuous hardware in window frames are currently ignored by international rating procedures. A preliminary investigation conducted by our team showed significant performance degradation in two of the three out-opening casement profiles caused by the presence of operating hardware. Frames with the structure made of vinyl and fiberglass consist of many air cavities that are penetrated by operating hardware made of highly conductive materials. In these frames, in order to have an accurate assessment, it may be required to employ three-dimensional modeling due to the convective nature of heat transfer within the cavities. However, in this study, we demonstrate that the three-dimensional (3D) effects of non-continuous hardware can be approximated accurately with simpler two-dimensional (2D) simulations. We then develop a simplified model based on weighted average capable of replacing the time- and computation-intensive 3D simulations with 2D simulations and validate it against market available frames and their corresponding hardware. Validation results show that our approximation technique results in discrepancies lower than 0.05 W/(m2K), or 3% of the total thermal transmittance. Thus, we conclude that simplified 2D simulation models may be used for predicting hardware impact in window frames with reasonable accuracy. As windows and glazing structures are becoming ever better thermally insulated, it is becoming even more important to be able to model the impact of the operating hardware on the total thermal performance in order to design the best windows possible and not let the operating hardware ruin an otherwise well-proven design, which is hence addressed in this study.

scholarly journals Hygrothermal Analysis of a Museum Storage Room for Metal Cultural Artifacts: Quantification of Factors Influencing High Humidity

Energies ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 3309
Author(s):  
Kazuki Ishikawa ◽  
Chiemi Iba ◽  
Daisuke Ogura ◽  
Shuichi Hokoi ◽  
Misao Yokoyama
Keyword(s):  
Influencing Factor ◽  
Simulation Models ◽  
Reinforced Concrete Beams ◽  
High Humidity ◽  
Outdoor Air ◽  
Cultural Artifacts ◽  
Storage Room ◽  
Building Components ◽  
Potential Factors ◽  
Hygrothermal Analysis

Several methods for appropriate control of the hygrothermal environment in museums to prevent the deterioration of cultural artifacts were presented in previous studies. However, few detailed hygrothermal simulation models have been used considering the hygrothermal performance of building components and airflow through gaps. Furthermore, hygrothermal properties of a type of storage facility with buffer spaces prevailing in Japan have not been quantitatively evaluated. The objectives of this study were to develop a detailed numerical model of a museum storage room with buffer spaces exhibiting high humidity during summer and to quantitatively evaluate the potential factors causing it; the inflow of humid outdoor air and indirect cooling caused by the air-conditioning system of a surrounding room. We analyzed the simulated temperature and humidity for various cases in which each influencing factor was suppressed. The humidity was reduced when the exhaust fan for the surrounding rooms was stopped or the windows were made airtight, but it hardly changed when the cooling ducts and the reinforced concrete beams were insulated. Thus, the high humidity in the room was attributed to the inflow of humid outdoor air accelerated by the ventilation of surrounding rooms. Although indirect cooling had a small impact on high humidity, its impact on energy loss could still be significant.

Impact of roof shading on building energy performance in warm & humid climatic places of India

2020 ◽  
pp. 50-64
Author(s):  
Kuladeep Kumar Sadevi ◽  
Avlokita Agrawal
Keyword(s):  
Energy Consumption ◽  
Energy Conservation ◽  
Energy Performance ◽  
General Assumption ◽  
Climatic Conditions ◽  
Building Envelope ◽  
Passive Cooling ◽  
Base Case ◽  
U Value ◽  
The Impact

With the rise in awareness of energy efficient buildings and adoption of mandatory energy conservation codes across the globe, significant change is being observed in the way the buildings are designed. With the launch of Energy Conservation Building Code (ECBC) in India, climate responsive designs and passive cooling techniques are being explored increasingly in building designs. Of all the building envelope components, roof surface has been identified as the most significant with respect to the heat gain due to the incident solar radiation on buildings, especially in tropical climatic conditions. Since ECBC specifies stringent U-Values for roof assembly, use of insulating materials is becoming popular. Along with insulation, the shading of the roof is also observed to be an important strategy for improving thermal performance of the building, especially in Warm and humid climatic conditions. This study intends to assess the impact of roof shading on building’s energy performance in comparison to that of exposed roof with insulation. A typical office building with specific geometry and schedules has been identified as base case model for this study. This building is simulated using energy modelling software ‘Design Builder’ with base case parameters as prescribed in ECBC. Further, the same building has been simulated parametrically adjusting the amount of roof insulation and roof shading simultaneously. The overall energy consumption and the envelope performance of the top floor are extracted for analysis. The results indicate that the roof shading is an effective passive cooling strategy for both naturally ventilated and air conditioned buildings in Warm and humid climates of India. It is also observed that a fully shaded roof outperforms the insulated roof as per ECBC prescription. Provision of shading over roof reduces the annual energy consumption of building in case of both insulated and uninsulated roofs. However, the impact is higher for uninsulated roofs (U-Value of 3.933 W/m2K), being 4.18% as compared to 0.59% for insulated roofs (U-Value of 0.33 W/m2K).While the general assumption is that roof insulation helps in reducing the energy consumption in tropical buildings, it is observed to be the other way when insulation is provided with roof shading. It is due to restricted heat loss during night.

Overseas Development Administration. A Guide to Social Analysis for Projects in Developing Countries. London: HMSO. 1995. viii+248 pages. Hardbound. £18.95.

1996 ◽  
Vol 35 (2) ◽  
pp. 189-190
Author(s):  
Mir Annice Mahmood
Keyword(s):  
Developing Countries ◽  
Social Change ◽  
Practical Experience ◽  
Development Projects ◽  
Social Analysis ◽  
Economic Perspective ◽  
Human Environment ◽  
The Past ◽  
The Impact ◽  
Overseas Development

This book, hereinafter referred to as the Guide, has been developed for those social analysts (e.g., anthropologists, sociologists, and human geographers) who have had little or no practical experience in applying their knowledge as development practitioners. In the past, development projects would be analysed from a narrow financial and economic perspective. But with the evolution of thinking on development, this narrow financial and economic aspect has now been broadened to include the impact on society as the very meaning of development has now come to symbolise social change. Thus, development is not restricted only to plans and figures; the human environment in its entirety is now considered for analysis while designing and implementing development projects.

INFLUENCE OF THE DIFFERENT SOIL PREPARATION METHODS ON THE PEA YIELD

2018 ◽  
pp. 16-20
Author(s):  
А. М. Grebennikov ◽  
А. S. Frid ◽  
V. P. Belobrov ◽  
V. А. Isaev ◽  
V. М. Garmashоv ◽  
...  
Keyword(s):  
Field Experiments ◽  
Morphological Properties ◽  
Mineral Fertilizers ◽  
First Year ◽  
Zero Tillage ◽  
Preparation Methods ◽  
Soil Preparation ◽  
Multifactor Analysis ◽  
The Impact ◽  
Central Chernozem

The article assesses the relationships between the morphological properties of agrochernozems and yield of peas on the plots, experience with different methods of basic treatment (moldboard plowing at the depth of 20 - 22, 25 - 27 and 14 - 16 cm, moldboard plowing to a depth of 14 - 16 cm, combined midwater moldboard, mid-water subsurface, surface to a depth of 6 - 8 cm and zero tillage) is inherent in V.V. Dokuchaev Research Institute of Agriculture of the Central Black Earth strip, in the fall of 2014. The research was conducted in 2015 - 2016, with the application of mineral fertilizers (N60Р60К60) and unfertilized background. The highest pea yields in the fertilized as the background, and without the use of fertilizers was observed in dumping plowing and especially in the variant with deep moldboard plowing, which creates in comparison with other ways of handling the best conditions for the growth and development of peas. The lowest yield of pea was obtained with zero processing. Apparently legalistic migrational-mizelial agrochernozems the Central Chernozem zone of minimum tillage in the cultivation of peas are not effective, what is evident already in the first year after the laying of experience with different basic treatments. As shown by the results of applying multifactor analysis of variance studied the mapping properties of the soil can have the same significant impact on the yield of agricultural crops, as options for the field experiments aimed at assessing the impact of various treatments on yield.

AMOUNT AND STRUCTURE OF THE BIOLOGICAL FERTILITY OF SOYA, DEPENDING ON THE SYSTEM OF MAIN TILLAGE OF SOIL AND MEASURES TO OPTIMIZE NUTRITION MODE

2020 ◽  
Author(s):  
M. Novokhatskyi ◽  
◽  
V. Targonya ◽  
T. Babinets ◽  
O. Gorodetskyi ◽  
...  
Keyword(s):  
Field Experiments ◽  
Optimal Number ◽  
Soil Tillage ◽  
Forest Steppe ◽  
Biological Productivity ◽  
Tillage Systems ◽  
Application Rates ◽  
Tillage System ◽  
Biological Yield ◽  
The Impact

Aim. Assessment of the impact of the most common systems of basic tillage and biological methods of optimization of nutrition regimes on the realization of the potential of grain productivity of soybean in the Forest-Steppe of Ukraine. Methods. The research used general scientific (hypothesis, experiment, observation) and special (field experiment, morphological analysis) methods Results. The analysis of the results of field experiments shows that the conservation system of soil cultivation, which provided the formation of 27.6 c/ha of grain, is preferable by the level of biological yield of soybean. The use of other systems caused a decrease in the biological yield level: up to 26.4 c/ha for the use of the traditional system, up to 25.3 c/ha for the use of mulching and up to 23.0 c/ha for the use of the mini-till. With the use of Groundfix, the average biological yield of soybean grain increases to 25.6 c / ha for application rates of 5 l/ha, and to 28.2 c/ha for application rates of 10 l/ha when control variants (without the use of the specified preparation) an average of 22.6 c/ha of grain was formed with fluctuations in soil tillage systems from 21.0 (mini-bodies) to 25.8 c/ha (traditional).The application of Groundfix (10 l/ha) reduced the seed abortion rate from 11.0% (average without biofertilizer variants) to 8.0%, forming the optimal number of stem nodes with beans, increasing the attachment height of the lower beans and improving other indicators of biological productivity soybeans. Conclusions. It has been found that the use of the canning tillage system generates an average of 27.6 cent soybean grains, which is the highest indicator among the main tillage systems within the scheme of our research. The use of Groundfix caused a change in this indicator: if the variants with a conservative system of basic tillage without the use of biological preparation (control) were formed on average 24.1 c/ha, the use of Ground Licks caused the increase of biological productivity up to 29.4 c/ha, and at a dose of 10 l/ha biological yield was 32.2 c/ha. It was found that both the use of Groundfix and the basic tillage system influenced the elements of the yield structure: the density of the plants at the time of harvest depended more on the tillage system than on the use of Groundfix; the use of Groundfix and increasing its dose within the scheme of our studies positively reflected on the density of standing plants; the height of attachment of the lower beans and reduced the abortion of the seeds.

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