Thermal bridge calculation service
We have been developing a quick and reliable thermal bridge analysis technique and report generation based on Therm 7.2. You get a fully detailed calculation report and supplement downloadable data.
How it works?
- You e-mail us a two-dimensional, in scale drawing (.dwg or .dxf) file or Sketchup (.skp) file. Use jaanus.hallik [ät] ut.ee to contact us.
- We reply by e-mail to confirm if your information is sufficient and specify price.
- You reply by e-mail to confirm that you agree with price offer.
- You get the calculation report and downloadables in specified time.
Although the finite element calculation software Therm 7.2 is free and anyone can start to experiment with isotherm visualisations, the process of getting really trustworthy psi-values (linear thermal transmittance [W/mK]) is rather complicated. It requires, after all, the post-processing of the finite element calculation results. The work-flow should include among others a step of specifying the adequate boundary conditions, material properties and correct approximations in more complicated cases, which requires a deep understanding of the modelling situation. Usually, the psi-value has to play an important role in further heat balance calculations or labelling. The calculation should end up with a documentation you can rely on or refer.
That's why we have been putting in a lot of effort, to work out a quick and reliable process aimed to help practitioners. In their daily work-flow and communication with customers, the response on an exact drawing detail or alternative situations should be often quick. We have been focusing to enable it.
The team behind the service
Calculation is performed by specialist of Institute of Technology, University of Tartu, Estonia. The energy efficient building core facility is in operation since 2006 and has a solid background for thermal processes simulation and interpretation.
Which methodology is applied?
The LBNL Therm 7.2 software is based on two-dimensional finite element calculation method. The creation of the calculation model and assignment of the boundary conditions along with material properties as well as model simplification in the case of several three-dimensional effects follow the methods and requirements specified in following European standards:
- EN ISO 10211 (Thermal bridges in building construction - Heat flows and surface temperatures - Detailed calculations),
- EN ISO 10077-2 (Thermal performance of windows, doors and shutters - Calculation of thermal transmittance - Part 2: Numerical method for frames),
- EN ISO 6946 (Building components and building elements - Thermal resistance and thermal transmittance - Calculation method)
- EN ISO 13788 (Hygrothermal performance of building components and building elements - Internal surface temperature to avoid critical surface humidity and interstitial condensation - Calculation methods).
Additionally, special aspects regarding the boundary conditions specified by PHI (Passsivhaus Institute) can be applied if requested by the client.
As an university lab we have developed a semi-automatic work-flow of finite element calculation for our research practices. Based on that experience we saw a qood opportunity to simplify and streamline the creation of the calculation model as well as post-process the results of multiple Therm models (or sub-models of single analysis problem, to be correct). The only time consuming part of the process is the assignment of material and boundary conditions and of course quality control and error-check of the input-output data and results. The report generation and visual representation of all relevant input-output data is covered with special automated procedures.
How can I be sure the report is error-free?
We apply double control measures in our quality control routines. All inputs and outputs are analysed by automatic scripts to identify a deviation from expected range of values. Additionally the model goes through strict manual control by our lab staff who have practical experience and knowledge in finite element calculations as well as in building physics and standardized methods in this field.
What I get exactly? Do you have sample report?
You will get a full pdf report. Additionally, you will get the original Therm 7.2 (.thm) calculation files, main graphics as separate pdf documents, and all text with numeric data included in .txt format, which you can easily include in your own report if needed.
In a full report file for single construction detail you will get the linear thermal transmittance (psi-value) according to both measuring systems (internal and external dimensions) along with indication of surface condensation index (fRsi) for the weakest point of internal surface. Numerical data of assigned material properties, boundary conditions and error estimation are also provided with color coded legend along with geometric model visualization with all relevant measures. The figures of temperature distribution (isotherms), heat flux vectors and calculation mesh are also provided.
How can I use the results I get exactly, could you provide example?
You can compare the calculation results with the required limiting values, for example if psi value at exterior dimensions is less than 0,01 W/mK, you can declare it "thermal bridge free” in Passive House method. The exact psi value can be entered into your heat balance calculation and you can provide the information about that as attachment to calculation for certification purposes. For instance, in Passive House Planning Package (PHPP), you should enter the psi values in the “Areas” worksheet.
In which form should be the information I send to you?
It is important that we can fully understand the materials and exact measures of the provided detail. So it should be two-dimensional, in scale, drawing file (typically .dwg, .dxf) or a simple Sketchup file (.skp) if you do not have access to specialized engineering software (Trimble Sketchup is very simple and intuitive 3D modelling software freely available or download from www.sketchup.com). Examples of the input .dxf fail and .skp fail.