scholarly journals Evaluation of Thermal Bridges Using Online Simulation Software

2020 ◽  
Vol 172 ◽  
pp. 08010
Author(s):  
Ligia Moga ◽  
Ioan Moga
Keyword(s):  
Finite Difference Methods ◽  
Building Envelope ◽  
Simulation Software ◽  
Heat Losses ◽  
Modelling And Simulation ◽  
Zero Energy ◽  
Online Simulation ◽  
Thermal Bridge ◽  
Thermal Bridges ◽  
The Impact

In order to reach nearly Zero Energy Buildings, a thorough design must be given in designing proper junctions, which will overall reduce the impact of the thermal bridges on the thermal performance of the building envelope. It is well-known that a thermal bridge is a weak thermal area of the building envelope through which increased heat losses occur. For the thermal bridges' evaluation, several numerical simulation software exist on the market, but their usage implies knowledge regarding the numerical modelling and simulation using various numerical methods (i.e. finite element method, finite difference methods, and others). Due to time constraint, designers use thermal bridges atlases that provide values for the linear heat transfer coefficient for several types of thermal bridges. Nevertheless, the multitude of existing thermal bridges requires more and more atlases which are not feasible in elaborating, due to time constraints. In order to respond to this demand, the authors developed a software for the modelling and simulation of thermal bridges that can be easily accessed by practitioners. The paper presents the software its components and the way that the user can interact with it.

scholarly journals Analysis of the temperature distribution in the place of fixing the ventilated facade

2019 ◽  
Vol 97 ◽  
pp. 01041
Author(s):  
Adam Ujma ◽  
Marta Pomada
Keyword(s):  
Heat Transfer ◽  
Thermal Conditions ◽  
Building Envelope ◽  
Heat Demand ◽  
Thermal Bridges ◽  
Ventilated Facade ◽  
The Impact ◽  
New Buildings ◽  
The Heat Balance ◽  
Very High

Designers more and more often choose facade systems with ventilated layers for external walls, especially in the case of new buildings. They are also used to modernize existing buildings. Mechanical connectors are a characteristic element of these constructions. Often, they are ignored in calculating the heat balance of rooms and the entire building. Because they pierce the thermal insulation layer they cause point thermal bridges. The influence of thermal point bridges, usually made of aluminum, i.e. a material with very high thermal conductivity, for heat transfer turns out to be significant. Such thermal bridges significantly increase heat losses through building partitions. This situation increases the heat demand in the rooms to compensate for the heat loss. The article presents the results of the analysis of the impact of mechanical fasteners in ventilated facade systems on heat transfer in the building envelope. The influence of various materials and constructional solutions on the thermal conditions in these walls was investigated.

scholarly journals The Impact of Infiltration on Heating Systems Dimensioning in Estonian Climate

2020 ◽  
Vol 172 ◽  
pp. 05004
Author(s):  
Raimo Simson ◽  
Taaniel Rebane ◽  
Martin Kiil ◽  
Martin Thalfeldt ◽  
Jarek Kurnitski
Keyword(s):  
Air Temperature ◽  
Indoor Air ◽  
Energy Performance ◽  
Simulation Software ◽  
Heat Losses ◽  
Climatic Data ◽  
Heating Systems ◽  
Air Temperatures ◽  
The Impact ◽  
Calculation Models

In this study we analysed the climatic conditions for infiltration estimation, different calculation methods and infiltration impact on heat load for heating systems dimensioning. To determine the wind conditions at low air temperatures of the coastal- and inland climatic zones in Estonia, 42 years of climatic data for Tallinn and Tartu were investigated. Calculation models with detailed air leakages were constructed of a single and two-storey detached house using dynamic simulation software IDA ICE. Simulations were carried out with the constructed calculation models, simulating various wind and sheltering conditions to determine the heating load of the buildings under measured wind conditions at the design external air temperatures. The simulation results were compared with results calculated with European Standard EN 12831:2017, methodology given in the Estonian regulation for calculating energy performance of buildings and with simulations using the default settings in IDA ICE based on the ASHRAE design day conditions. The percentage of heat losses caused by infiltration was found as 13-16% of all heat losses for the studied buildings. Simulations with historical climate periods showed that even in windy weather conditions the heating system dimensioned by the methods analysed may not be able to provide the required indoor air temperature. Analysis using the coldest and windiest periods showed that when systems are dimensioned by the studied methods, the highest decline in indoor air temperature occurs on the windiest day and not on the coldest day. The impact of high wind speeds and low sheltering conditions resulted up to 50% of all heat losses.

scholarly journals The Influence of Different Facings of Polyisocyanurate Boards on Heat Transfer through the Wall Corners of Insulated Buildings

Energies ◽  
2020 ◽  
Vol 13 (8) ◽  
pp. 1991 ◽  
Author(s):  
Tomas Makaveckas ◽  
Raimondas Bliūdžius ◽  
Arūnas Burlingis
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Heat Flux ◽  
Thermal Insulation ◽  
Transfer Coefficients ◽  
Heat Transfer Coefficients ◽  
Thermal Bridge ◽  
Thermal Bridges ◽  
The Impact ◽  
Heat Flow Meter

Polyisocyanurate (PIR) thermal insulation boards faced with carboard, plastic, aluminum, or multilayer facings are used for thermal insulation of buildings. Facing materials are selected according to the conditions of use of PIR products. At the corners of the building where these products are joined, facings can be in the direction of the heat flux movement and significantly increase heat transfer through the linear thermal bridge formed in the connection of PIR boards with facing of both walls. Analyzing the installation of PIR thermal insulation products on the walls of a building, the structural schemes of linear thermal bridges were created, numerical calculations of the heat transfer coefficients of the linear thermal bridges were performed, and the influence of various facings on the heat transfer through the thermal bridge was evaluated. Furthermore, an experimental measurement using a heat flow meter apparatus was performed in order to confirm the results obtained by numerical calculation. This study provides more understanding concerning the necessity to evaluate the impact of different thermal conductivity facings on the heat transfer through corners of buildings insulated with PIR boards.

scholarly journals A new method to estimate point thermal transmittance based on combined two-dimensional heat flow calculation

2020 ◽  
Vol 172 ◽  
pp. 08005
Author(s):  
Jaanus Hallik ◽  
Targo Kalamees
Keyword(s):  
Heat Flow ◽  
Three Dimensional ◽  
Multiple Linear Regression Model ◽  
Building Envelope ◽  
New Method ◽  
Two Dimensional ◽  
Thermal Transmittance ◽  
Thermal Bridge ◽  
Thermal Bridges ◽  
Third Dimension

A well-insulated, airtight and thermal bridge free building envelope is a key factor for nearly zero energy buildings (nZEB). However, increased insulation thickness and minimized air leakages increase the effect of thermal bridges on overall energy efficiency of the nZEBs. Although several more prominent linear thermal bridges are accounted for in the practice the three-dimensional heat flow through vast array of fixation elements, mounting brackets and other point thermal bridges are usually neglected due to time-consuming model preparation routine, lack of input data as well as high number of different thermal bridges that have to be assessed for a single project. In this study a new method was proposed for predicting three-dimensional heat flow and the point thermal transmittance of thermal bridges caused by full or partial penetration of the building envelope with metal elements with uniform geometry in third dimension based on multiple two-dimensional numerical heat flow calculations. A new parameter (equivalent length of thermal bridge) was defined which incorporates the effect of additional thermal transmittance in third dimension when multiplied by the difference of two thermal coupling coefficients derived for two-dimensional cross section. Multiple linear regression model was fitted on database with 102 cases and verified with separate case of window to wall connection incorporating metal penetration at fixation points. The proposed methodology can be useful in general practice where the design team lacks the skills or software tools for conducting detailed numerical analysis in three dimensions.

Thermal Bridges Minimizing through Typical Details in Low Energy Designing

2014 ◽  
Vol 899 ◽  
pp. 62-65 ◽  
Author(s):  
Rastislav Ingeli ◽  
Boris Vavrovič ◽  
Miroslav Čekon
Keyword(s):  
Energy Efficiency ◽  
Thermal Insulation ◽  
Energy Demand ◽  
Building Energy ◽  
Building Envelope ◽  
Low Energy ◽  
Building Energy Efficiency ◽  
Low Energy Buildings ◽  
Thermal Bridges ◽  
The Impact

Energy demand reduction in buildings is an important measure to achieve climate change mitigation. It is essential to minimize heat losses in designing phase in accordance of building energy efficiency. For building energy efficiency in a mild climate zone, a large part of the heating demand is caused by transmission losses through the building envelope. Building envelopes with high thermal resistance are typical for low-energy buildings in general. In this sense thermal bridges impact increases by using of greater thickness of thermal insulation. This paper is focused on thermal bridges minimizing through typical system details in buildings. The impact of thermal bridges was studied by comparative calculations for a case study of building with different amounts of thermal insulation. The calculated results represent a percentage distribution of heat loss through typical building components in correlation of various thicknesses of their thermal insulations.

scholarly journals The impact of building envelope retrofit measures on postwar MURBS in Toronto

2021 ◽  
Author(s):  
Sara Damyar
Keyword(s):  
Energy Consumption ◽  
Energy Saving ◽  
Energy Use ◽  
Energy Savings ◽  
Building Envelope ◽  
Simulation Software ◽  
Energy Simulation ◽  
Reduce Energy Consumption ◽  
The Impact ◽  
Current Standards

Building envelope retrofits is one of the options available to reduce energy consumption of postwar MURBs in Toronto. This study evaluates the impact of building envelope retrofits that meet current standards on energy consumption of a Toronto postwar MURB; utilizing eQUEST energy simulation software. Further upgrades also take place to evaluate how the impact of building envelope retrofits on energy use can be increased and optimized for all assemblies of building envelope and airtightness. Moreover, the retrofit strategies are ranked based on cost and energy-saving effectiveness. The results of the analysis reveal that building envelope retrofit based on OBC-2012 standards can reduce the energy consumption by up to 44%. Furthermore, the optimal RSI values of all building envelope components were found to be equal or less than code requirements which outcomes significant energy savings. Lastly, the ranking of the strategies helps to identify the best option according to the priorities of a project.

scholarly journals Upgrading the Smartness of Retrofitting Packages towards Energy-Efficient Residential Buildings in Cold Climate Countries: Two Case Studies

Buildings ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 200 ◽  
Author(s):  
Laurina C. Felius ◽  
Mohamed Hamdy ◽  
Fredrik Dessen ◽  
Bozena Dorota Hrynyszyn
Keyword(s):  
Thermal Comfort ◽  
Life Cycle Cost ◽  
Energy Savings ◽  
Residential Buildings ◽  
Cost Effective ◽  
Energy Performance ◽  
Building Envelope ◽  
Heat Losses ◽  
Cold Climate ◽  
The Impact

Improving the energy efficiency of existing buildings by implementing building automation control strategies (BACS) besides building envelope and energy system retrofitting has been recommended by the Energy Performance of Buildings Directive (EPBD) 2018. This paper investigated this recommendation by conducting a simulation-based optimization to explore cost-effective retrofitting combinations of building envelope, energy systems and BACS measures in-line with automation standard EN 15232. Two cases (i.e., a typical single-family house and apartment block) were modeled and simulated using IDA Indoor Climate and Energy (IDA-ICE). The built-in optimization tool, GenOpt, was used to minimize energy consumption as the single objective function. The associated difference in life cycle cost, compared to the reference design, was calculated for each optimization iteration. Thermal comfort of the optimized solutions was assessed to verify the thermal comfort acceptability. Installing an air source heat pump had a greater energy-saving potential than reducing heat losses through the building envelope. Implementing BACS achieved cost-effective energy savings up to 24%. Energy savings up to 57% were estimated when BACS was combined with the other retrofitting measures. Particularly for compact buildings, where the potential of reducing heat losses through the envelope is limited, the impact of BACS increased. BACS also improved the thermal comfort.

Comparison of Thermal Bridges Calculate Method through Window Jamb

2013 ◽  
Vol 855 ◽  
pp. 130-133
Author(s):  
Rastislav Ingeli
Keyword(s):  
Heat Conduction ◽  
Thermal Conductance ◽  
Theoretical Background ◽  
Building Envelope ◽  
Building Construction ◽  
Building Envelopes ◽  
Thermal Bridge ◽  
Detailed Specification ◽  
Flow Through ◽  
Thermal Bridges

This paper is focused on comparison of thermal bridges calculate method through window jamb in building envelopes. The present approach is based on an integrated 2D dynamic simulation. The theoretical background of the adopted approach is presented. The reliability of this approach in evaluating thermal bridges as well as its applicability to different geometric shapes is proved. Detailed specification and calculation of each thermal bridge in these buildings should be taken into account. the heat flow through a building construction is considered to be of the onedimensional (1D) type. This is because the thermal conductance and temperature differential in this direction are much greater than that in the lateral directions. The thermal bridge is the part of the building envelope through which heat conduction is multi-dimensional. Therefore, in recent studies, the problem of heat conduction in the building construction has been treated as a multi-dimensional.

scholarly journals Instantaneous field measurements of thermal bridge parameters in ground floor residential room

2019 ◽  
Vol 112 ◽  
pp. 01016 ◽  
Author(s):  
Martin Ivanov
Keyword(s):  
Energy Demand ◽  
Field Measurements ◽  
Building Design ◽  
Building Envelope ◽  
Ground Floor ◽  
Thermal Bridge ◽  
Significant Temperature ◽  
Thermal Bridges ◽  
Infrared Thermal Images ◽  
Heating Energy Demand

The “thermal bridges” are defined as an isolated building’s areas, where the construction elements have higher thermal conductivity, compared with the rest of the building envelope. Thus, at cold winter conditions, a significant temperature difference may occur between neighbouring solid and air volumes within the construction. Moreover, it has been documented, that the heating energy demand of a building may be increased with more than 30%, due to the existence of thermal bridges and the increased heat losses from the indoors. Consequently, in the recent years, norms and standards have been developed, for avoiding thermal bridges during the building design process. But still, thermal bridges exist in the indoor environment, especially in older buildings, where no energy efficient measures have been applied. That is why, the presented study focuses on instantaneous field measurements of thermal bridge parameters in real existing ground floor residential room. The thermal bridge propagation is analysed relative to the indoor and outdoor air temperature and relative humidity, as well as with infrared thermal images of the affected external walls. The achieved results give valuable information about the generic conditions for thermal bridge existence, without considering the building envelope properties.

scholarly journals A Comparative Study between Jordanian Overall Heat Transfer Coefficient (U-Value) and International Building Codes, With Thermal Bridges Effect Investigation

2021 ◽  
Vol 3 (1) ◽  
pp. p10
Author(s):  
Ammar Alkhalidi ◽  
Suhil Kiwan ◽  
Haya Hamasha
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Energy Demand ◽  
Building Envelope ◽  
Overall Heat Transfer Coefficient ◽  
Thermal Bridge ◽  
U Value ◽  
Thermal Bridges ◽  
Heating Degree Days

Depletion of fossil fuel and the environmental effect associated with the use of it have made the topic of “thermal insulation regulations” a major concern in country Jordan and worldwide. This paper reviews the overall heat transfer coefficient U-value in Jordanian code for the building envelope, which represents how much the building envelope transfer heat to the outside environment. U-value was reviewed with respect to the following factors, heating degree days, the heating load required to achieve thermal comfort. Based on the review a new U-value of 0.65 W/m2.K was proposed and it was found that this value reduces the energy demand almost 50%. Moreover, the thermal bridge effect was investigated and it was found that an obvious increase in the U-value is present when having thermal bridges; this will affect the energy demand, almost 200%.

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