Climate Load Research Articles

COMPUTATIONAL ANALYSIS OF HEAT AND MASS TRANSPORT IN CHARACTERISTIC DETAIL OF INTERIOR THERMAL INSULATION SYSTEM

Computational modeling represents useful tool for the assessment of newly designed or refurbished building materials and structures. Especially, when complex buildings elements need to be assessed from a hygrothermal point of view, the computational modeling is the right approach with desired power and accuracy. In this paper a historical wall element is investigated using two-dimensional simulation in order to study the effect of application of several insulation materials in various scenarios. In total two insulation materials are investigated (mineral wool, wood fiber boards) that are applied in three different scenarios. All simulations are performed under real climatic load. The results of the computational simulations reveal potential weak points in system application and can provide engineers and designers with valuable recommendations and practical information. The best results were obtained for thermal insulation from mineral wool. On the other hand, an improper system application can lead to a significant devaluation of the beneficial effects on the thermal performance of the studied brick element.

Analysis of Methods for Determining Climate Loads at a Specified Territory Point by Meteorological Data

Methods for determining the characteristic values of climate loads at the location of a building have been perfected. Based on comparative analysis, the method of levelling the values of climate loads with an exponential or triangular weight function is recommended. For four climate loads, appropriate equalization intervals are determined, ensuring the maximum amount of weather data taken into account, while maintaining their uniformity. In construction, the determination of the climate load is important for the location of the building. When prescribing building standards, the values of the climate load are determined according to the data of weather stations in relative proximity, which provides values within the limits of reliability. Such an approach can lead to an overestimation of the characteristic values of climate loads and consequently increase the consumption of the construction materials of the building or, in the opposite case, decrease the unnecessarily high-energy consumption to condition the space inside the building.

Dynamic Residential Energy Management for Real-Time Pricing

A home energy management system (HEMS) was designed in this paper for a smart home that uses integrated energy resources such as power from the grid, solar power generated from photovoltaic (PV) panels, and power from an energy storage system (ESS). A fuzzy controller is proposed for the HEMS to optimally manage the integrated power of the smart home. The fuzzy controller is designed to control the power rectifier for regulating the AC power in response to the variations in the residential electric load, solar power from PV panels, power of the ESS, and the real-time electricity prices. A self-learning scheme is designed for the proposed fuzzy controller to adapt with short-term and seasonal climatic changes and residential load variations. A parsimonious parameterization scheme for both the antecedent and consequent parts of the fuzzy rule base is utilized so that the self-learning scheme of the fuzzy controller is computationally efficient.

Mechanical Calculation of Flexible Wires Loaded with Concentrated Loads

Calculating of wires sag and tension under various modes is the task of mechanical calculation. The article derived formulas for the curve of the wire sag under the action of one or several concentrated forces and with various tensioning insulators strings in the span. Formulas for estimating the distance to the maximum sag have been obtained. Based on the length of the system of “first tension insulators string – conductors – second tension insulators string” that depends on the supporting beam reactions and beam lateral forces in the corresponding sections, the system load factor was determined taking into account structural elements for different climatic loads. The formulas to calculate the load factor for solving the equation of state in the case of different insulators strings in span loaded with one or several concentrated forces have been obtained. The resulting expressions can also be applied in case of horizontal wind loads; in this case the equation of state should take this component into account when calculating the resulting reduced load on the wire in an inclined plane. The reliability of the formulas was proved by the coincidence of the results for the particular case of the arrangement of the insulators strings. An algorithm for calculating sag under the combined action of vertical and horizontal loads, as well as in the case of the location of wire suspension points at different heights, is given. A formula has been proposed for estimating the sag increase factor due to the presence of concentrated forces uniformly distributed along the span and various insulator strings in the span. The dependence of the coefficient of increase of the sag on the distance to the concentrated force in the presence of one and two forces in the span is drawn.

Assessment of risk of freeze-thaw damage in internally insulated masonry in a changing climate

Buildings are susceptible to gradual changes in climate and to extreme events. The scale and severity of climate change are expected to be spatially heterogeneous. There is a necessity to consider changing climate in the operation and maintenance of buildings, as buildings have a long-term service life. In this study, the impact of climate change on the risk of freeze-thaw damage for internally insulated masonry wall in two regions in Switzerland (Zurich and Davos) for two future periods is investigated. A hygrothermal model that considers coupled moisture and heat transport in freezing and non-freezing building materials is used. The risk of freeze-thaw damage is evaluated with an indicator, called the FTDR Index. Climate projections under A1B and A2 emission scenarios from ten different climate model chains are chosen to cover a wide range of possible future climates. The risk of freeze-thaw damage at Zurich is relatively high in the reference period. An increase in air temperature in the cold period that leads to less freeze-thaw cycles is the main reason for the lower risk of freeze-thaw damage in the future periods. By comparison, the risk of freeze-thaw damage at Davos is low in the reference period. An increase in temperature and precipitation in the cold period is the main reason for the higher risk of freeze-thaw damage in the future periods at Davos. In the face of climate change, the future requirement on frost resistance of building materials and components at Davos should take the future climate loading into account.

Assessment of the Wind and Temperature Loads Influence on the PVC Windows Deformation

The PVC windows application experience in various climatic conditions shows that at their operation the windows profile deformations can be observed. One of the reasons for these deformations is the climatic loads influence on the windows – wind pressure, solar radiation, negative outside temperatures. The profile elements deformations affect the window tightness and the normal window hardware operation. The calculated loads combinations on windows in winter and summer were analyzed. For window as external element of building is more critical winter loads combination – the combined effect of wind pressure and negative temperature. The work was done the analysis of the effect of negative temperatures and wind pressure on the PVC window deformation. The studies were performed in laboratory conditions on the basis of two testing centers. Three PVC Windows with different profile thickness were tested. The temperature deformation of the casements and mullions profiles of this windows were analyzed. These deformations have to take into account in the static calculations. But the engineering methods creation for calculating windows for the wind and temperature loads effect requires additional research. They are associated with the study of the joint work of the windows constituent elements (profiles, insulating glass units, hardware).

Heat Transfer Through Insulating Glass Units Subjected to Climatic Loads.

One of the structural elements used in the construction of insulating glass units (IGUs) are tight gaps filled with gas, the purpose of which is to improve the thermal properties of glazing in buildings. Natural changes in weather parameters: atmospheric pressure, temperature, and wind influence the gas pressure changes in the gaps and, consequently, the resultant loads and deflections of the component glass panes of a unit. In low temperature conditions and when the atmospheric pressure increases, the component glass panes may have a concave form of deflection, so that the thickness of the gaps in such loaded glazing may be less than its nominal thickness. The paper analyses the effect of reducing this thickness in winter conditions on the design heat loss through insulating glass units. For this purpose, deflections of glass in sample units were determined and on this basis the thickness of the gaps under operating conditions was estimated. Next, the thermal transmittance and density of heat-flow rate determined for gaps of nominal thickness and of thickness reduced under load were compared. It was shown that taking into account the influence of climatic loads may, under certain conditions, result in an increase in the calculated heat loss through IGUs. This happens when the gaps do not transfer heat by convection, i.e., in a linear range of changes in thermal transmittance. For example, for currently manufactured triple-glazed IGUs in conditions of “mild winter”, the calculated heat losses can increase to 5%, and for double-glazed IGUs with 10–14 mm gaps this ratio is about 4.6%. In other cases—e.g., large thickness of the gaps in a unit, large reduction in outside temperature—convention appears in the gaps. Then reducing the thickness of the gaps does not worsen the thermal insulation of the glazing. This effect should be taken into account when designing IGUs. It was also found that the wind load does not significantly affect the thickness of the gaps.

Climate data analysis to assess resilience of wall assemblies to moisture loads arising from the effects of wind-driven rain

In North America, and abroad, there currently exist standard test protocols for assessing the watertightness of wall assemblies and fenestration components although most of these methods are not directly related to expectations of in-field conditions as might be experienced by a wall assembly over its intended service life. How useful might such test protocols be to help determine the longevity of wall assemblies to future climate loads? Existing walls may, depending on their geographic location, be vulnerable to future climate loads and thus risk premature deterioration. For the design of new wall assemblies consideration ought to given to the non-stationarity of the climate and implications on the moisture loads on walls and the expected performance over the long-term. To permit assessing the resilience of wall assemblies to the effects of a changing climate as may occur in the future, and indeed, perhaps heightened moisture loads, one requires sufficient information on the watertightness of the assembly in relation to specified wind-driven rain loads and wall air-leakage conditions from which wall moisture retention functions could readily be developed. Such moisture functions are the basis of input of moisture loads to hygrothermal models and from which the expected long-term wall moisture performance can subsequently be derived. In this paper, a description is provided of the strategies used to analyze the WDR load for generating experimental input for a watertightness test protocol under development to assess resilience of wall assemblies to moisture loads arising from the effects of wind-driven rain in consideration of both historical climate loads and those as may arise from a changing climate.

Research of reliability of light emitting diodes to mechanical and climatic loads

Research of reliability of light emitting diodes to mechanical and climatic loads

Nonlinear analysis of extreme snow fragility of reactor hall frame

This paper gives the results of the safety analysis of the nuclear power plant structures in Slovakia in case of the extreme climatic loads. The linear and nonlinear analysis of NPP structures with the reactor VVER 440/213 in the case of the extreme external even is presented. On the base of the meteorological monitoring of the locality the extreme snow load was defined for the return period 104 years. There is showed summary of calculation models and calculation methods for the nonlinear analysis of the structural resistance in system ANSYS. The fragility curves of the critical structure elements were calculated using the FORM method.

EFFICIENCY OF THIN-WALLED GALVANIZED PROFILES FOR ARCH ELEMENTS

Purpose. To carry out an engineering estimation of the effectiveness of using steel thin-walled galvanized profiles on the example of an engineering structure in the form of an arch. To formulate recommendations regarding the appropriateness of using such profiles in comparison with other more traditional types of assortment profiles. Methodology. To achieve this goal, a series of numerical calculations of an arch structure made of three types of steel assortment profiles – seamless hot-deformed pipes, electric-welded straight-seam pipes and thin-walled galvanized profiles – was carried out. At the same time, the spans of the arch structure were varied in the range from 12 to 24 m and the step of its arrangement in the range from 3 to 6 m. The effect of snow and wind loads was also separately considered in accordance with the current standard of Ukraine. The calculations were done using the finite element method based on the Lira for Windows project complex. Findings. According to the results of analysis and comparison of the obtained data of numerical calculations, it was found that the least costly is the use of galvanized steel profiles, the structures of which have the lowest cost for all the variants considered. Steel arches based on electric-welded straight-seam pipes turn out to be approximately on 50…80 % more expensive, and arches based on seamless hot-deformed pipes are on average in three times more expensive. At the same time, both the average market value of the profiles and the cost of manufacturing an arch structure from them were taken into account. Originality. The most effective type of steel assortment profiles for use in arched structures, which are the supporting elements of the frames of lightweight fast-mounted buildings, is determined. In particular, the high efficiency of modern thin-walled galvanized profiles for this type of structure has been proven. Practical value. In the course of the research, engineering data were obtained, regarding specific types of thin-walled galvanized profiles, which must be used for load-bearing arched elements of fast-mounted buildings. The data are presented in a tabular form convenient for use in engineering practice, depending on the climatic loads, spans and steps of the supporting elements of the frame of such buildings.

Climate Change: Impacts on Climatic Actions and Structural Reliability

Climatic loads on structures are commonly defined under the assumption of stationary climate conditions; but, as confirmed by recent studies, they can significantly vary because of climate change effects, with relevant impacts not only for the design of new structures but also for the assessment of the existing ones. In this paper, a general methodology to evaluate the influence of climate change on climatic actions is presented, based on the analysis of observed data series and climate projections. Illustrative results in terms of changes in characteristic values of temperature, precipitation, snow, and wind loads are discussed for Italy and Germany, with reference to different climate models and radiative forcing scenarios. In this way, guidance for potential amendments in the current definition of climatic actions in structural codes is provided. Finally, the influence of climate change on the long-term structural reliability is estimated for a specific case study, showing the potential of the proposed methodology.

Freeze-thaw Damage Dependence on Wind-driven Rain of Outdoor Exposed Concrete – A Case Study

Abstract It has been shown in previous studies that the existing precast concrete element building stock in Finland has quality issues, especially with freeze-thaw durability and reinforcement corrosion. In addition, it has been presented that deterioration rate is the fastest in coastal area and decreases towards north which has been supposed to be a reason of lower amount of wind-driven rain (WDR). The aim of this study was to examine the connection between the amount of WDR on structures and the freeze-thaw damage more comprehensively. Condition investigation reports of 472 precast concrete element buildings were reanalysed to study the relation and the results were compared to climate data of the same time period to study the correlation between condition investigation observations and the amount of WDR. In addition, the observations made in a condition investigations and their relation to climate load at the same building were studied as a case study. The results show that there is a significant connection between the WDR related climate load and the freeze-thaw damage occurrence. The results can be used to plan protective methods and be a base for service life estimations.

Indoor climate loads for dwellings in different cold climates to assess hygrothermal performance of building envelopes

This study tests the performance of an EN ISO 13788 occupancy modified model for indoor temperature and humidity in dwellings by comparing the model with the measured indoor temperature and relative humidity in Canada. The performance of EN ISO 13788 occupancy modified model is tested in 13 outdoor climates and compared with the simplified approach given in the ASHRAE 160 standard. It was found that the Estonian model’s proposed indoor temperature profile works reasonably well in accordance with the measured indoor temperatures in Vancouver, Canada, which are dependent on the outdoor climate; on the other hand, the ASHRAE 160 indoor temperature profile might not be the best for cold climates. Drawbacks were noted concerning the humidity loads given as a simplified approach in the ASHRAE 160 with the suggestions for the possible future renewal. A new approach for selecting the indoor humidity load for dwellings in cold climates is proposed.

Durability and Climate Change — changing climatic loads as may affect the durability of building materials, components, and assemblies

Durability and Climate Change — changing climatic loads as may affect the durability of building materials, components, and assemblies

Study of Deflection in Insulating Glass Units Under Climatic Loads Simulation

Insulating glass unit (IGU) is a commonly used filling element in transparent building partitions. The component glass panes in the unit are connected to each other on the edges by a spacer in such a way, that the space between them forms a tight gap filled with gas. The state of the gas in the gap can be described, with sufficient accuracy, by the law of ideal gases. Periodic changes in external climatic factors, above all atmospheric pressure and temperature, result in deflection of the component glass panes, which generates secondary loads associated with the change of gas pressure in the gap. The static quantities in the glass panes (deflection, stress) are therefore the result of the state of temporary equilibrium between the gas pressure in the gap and the external pressure. Measuring the deflection of component glass panes in operating conditions is time-consuming, because it requires waiting for changes in weather factors – these changes are often unpredictable. The aim of this article is to develop the concept of a test stand allowing the measurement of the deflection of the IGU models under the conditions of climatic loads changes simulation, where these changes can be controlled over time and generated in an orderly manner. The presented project meets these requirements. The stand is built from a massive main frame, which is the basis for the placement of deflection sensors, which is accompanied by a supporting frame, that allows placing glass panes with different thicknesses. The tested model of IGU is equipped with threaded elements, thanks to which it is possible to regulate the gas pressure inside the gap and monitor its temperature. An additional function of the stand is the ability to assess the tightness of the connection of component glass panes with the spacer, which may be an alternative to the standard way of testing this parameter.

An integrated conceptual approach for the monitoring and modelling of geo-structures subjected to climatic loading

Advancement of knowledge on the behaviour of unsaturated soil through constitutive modelling is an area of active research within the geotechnical community. Given that most of the Earth surface can be considered unsaturated and most of the geotechnical infrastructures constitute of compacted soil, advancements in predictive modelling are needed for reliable management of geo-infrastructures. Moreover, the complex processes of soil collapse, shear failures and excessive soil swelling underneath artificial and (or) natural structures necessitates continuous monitoring or periodic assessment of relevant field parameters. To address this problem, geophysical and proximal optical sensing methods can be utilised for high-density spatial characterisation of relevant soil properties and features for monitoring of geotechnical structures. In this paper, we combined knowledge in unsaturated soil behaviour on the basis of the recent Monash-Peradeniya-Kodikara (MPK) framework and surface/subsurface soil characterisation using proximal soil sensing techniques and discrete sensing for ground-truthing to envisage a combined observation and predictive modelling paradigm for geo-infrastructures. We discussed the concepts by demonstrating its usefulness in predicting potential landslides and slope stability issues. The overarching impact of the ideas discussed in this paper is expected to generate new research priority areas that can be highly beneficial in monitoring geo-infrastructures subjected to climate loading. Furthermore, we identified future research areas that can provide modern benefits of geophysical techniques in geotechnical problems. In particular, we note that developments in pedophysical transfer functions relating soil resistivity to commonly utilised geotechnical soil properties can be highly beneficial to geotechnical practitioners involved in monitoring of critical geo-infrastructures.

Problems with Maintaining in Required Technical Condition and Revitalization of Medieval Defense Fortries

Often, in the centers of some towns you can find remains of defensive fortifications, which are not always cared for according to their uniqueness and historical values and sometimes are no longer recognizable. These objects in the eighteenth century have become unnecessary due to changes in the tactics of waging war and a significant modernization of armaments and war craft. Their appearance still gives the impression of massiveness, but in reality it often goes beyond the truth. In the 19th and 20th centuries these buildings were neglected and brought to a ruinous state, transformed into residential or public buildings, and even quite often dismantled. A large part of them no longer exists, hence the overriding goal now is to save their remains and revitalize. In the article, on the example of several such fortifications, their actual state and described activities that are undertaken in order to restore their technical and utilitarian efficiency will be approximated. As part of the article, a static and endurance analysis of the remains of a medieval defense wall of the length of about 70 m, located in one of the cities of south-western Poland will be carried out. Problems related to the implementation and effectiveness of ongoing repairs, reinforcements and structural maintenance will also be discussed, which coped well in times of its magnificence, in exceptional situations, i.e. burden of warfare, but currently they cannot resist climatic and environmental loads.

Experimental investigations of wooden beam ends in masonry with interior insulation: Measured data in real-scale experimental walls exposed to semi-continental climatic conditions

This article deals with the hygrothermal performance of wooden beam ends embedded in brick masonry walls. The real-scale experiment involving three interior insulation systems with different water vapor resistances and different treatments of joist pockets was monitored for three consecutive years. The moisture load of test walls was controlled during the experiment. First, humidity of indoor air was increased in the cold season (2016–2017). Then, an artificial short-time intensive rain event brought liquid water onto the external surface of the test walls in July 2017. Despite relatively mild external climatic loads, relative humidity was unsatisfactorily high in unsealed joist pockets. Vapor and airtight sealing of the joist pockets improved the microclimate of the wooden beam ends. However, even in this case, relative humidity approached critical values for the onset of mold growth. The artificial rain load applied on the experimental walls noticeably worsened the hygrothermal conditions in the joist pockets. Relative humidity in the joist pockets further increased to a level where massive mold growth could be expected. Visual inspection of the wooden beam ends during reconstruction of the experiment, however, revealed only a small spot of mold on a single beam located in an unsealed joist pocket. Mold growth on samples of organic thermal insulation material was found by microscopic investigations. Molds were localized in small separated colonies. These in situ and laboratory investigations do not confirm the calculated values of mold growth index. In conclusion, sealing of wooden beam ends improved their hygrothermal performance in the experiment.

Test methodology for performance assessment of structural sealant glazing systems at superimposed mechanical and climatic loading

Abstract Reliable performance of structural sealant glazing (SSG) systems is necessary to utilise advantages of SSG in glass facades. Conventional durability assessment of structural sealant joints is based on separated weathering tests and empirical fatigue testing. This work presents a new test methodology for performance assessment of SSG-joints at simultaneous weathering and two-dimensional mechanical loading. The climatic and mechanical load function were derived from common loading scenarios according to a worst case approach. A system test specimen, resembling a common SSG-joint, was exposed to 24 h of combined loading in a custom-designed test facility. From the recorded mechanical system response, characteristic parameters were evaluated to assess the performance of the system at varying climatic and mechanical conditions. These experimental results reveal effects of ambient conditions, previous loading and deformation amplitude peaks on the system response. The proposed test methodology opens up for new performance-related approaches in durability testing.