U-VALUE calculations

Screen+Shot+2016-08-06+at+09.03.20.png
 

The use of a Rainscreen Facade provides an opportunity to achieve low U-values. 

InOpera Facades can provide early design stage guidance as to the performance of a Rainscreen Facade. We  provide detailed U-value calculations in accordance with BS EN 10211 / BRE 443 Convections for U-values by project. We use the support system setting out to determine the heat loss through the construction and model it three dimensionally. 

Take a look at our process below and for further information, request a call back using the form to discuss your project in more detail. 

U-VALUE CALCULATION PROCESS

1: FACADE MATERIAL SELECTION

The Facade material is selected by the Architect/Designer/Contractor. Information is gathered to input into a Static Calculation:

  • Building Location
  • Facade Material Weight Kg/m2
  • Intended Facade material Size(s) mm
  • Intended Cladding Zone mm
  • Facade Material Fixing method  Visible/Secret
  • Sub Structure
  • Target U-value W/m2K
  • Insulation type(s) PIR, RockFibre, PU

Assumptions at this stage can be made to provide a starting point for the calculation process, however changes to the Facade material/U-value requirement, will have an effect on the calculation and subsequently need to be re-assessed. 

 

2: STATIC CALCULATION

The Static calculation is carried out to understand the maximum permissible position based on the input data, for the Facade Support System.

  • Façade load kN/m2
  • Wind speed m/s
  • Dynamic pressurekN/m2
  • Direct external wind pressure kN/m2
  • Direct internal wind pressure  kN/m2
  • Rail Configuration
  • Distance between primary fixings m
  • Horizontal spacing between profiles m
  • Distance from end of profile to bracket m
  • Substrate Fixings
  • Bracket Type
 

3: MODEL CREATION

These results provide a basis to create a 3d Model of the repeating elements within the Rainscreen Construction.

It is at this point we are able to include and vary:

  • Insulation Types
  • Cladding Zones
  • Use of Isolator Pads
  • Substrate Types

We then process the calculation to determine the heat loss generated through the construction.

Multiple calculations are required for multiple bracket types and cladding zone conditions, to enable SAP/SBEM calculations to calculate a weighted average U-value. 

 

4: HEAT FLOW RESULTS

Once the Heat flow has been determined through the construction it can then be converted to understand the repeating element U-value. 

This is done by the following:

U = Q / (Ti –Te)·L·W

Q is the heat flow rate/heat flux (W/m) 

Ti –Te is the temperature difference between internal and external environments 

L·W is the projected size of the model

The resulting U-value W/m2K and  specific Psi (x) Value W/K are then available. 

 

Our aim is to process U-value calculations within 48hours. Factors such as number of calculations and complexity of Support system geometry contribute to these times and as such may increase. 

For projects specifying InOpera Facade Materials and Support Systems there is no charge for this service. 

For projects involving materials outside of InOpera Facades palette, a nominal charge of £350+VAT per calculation is applicable. 

All enquiries can be submitted under no obligation. 

Name *
Name
Please enter the project postcode or if unknown the City
Please tell us your intended Facade material
Static Calculation output showing the MAXIMUM permissible spacing for the Facade Support System.
Model Geometry created using HEAT Software NB: Insulation removed for Clarity
Example of results of Heat Flow Cut through facade construction.