Online ETTV U-value calculator
The sequence of material layers. Mateiral 1 is the outmost layer
Library: standard materials defined in ETTV; User: materials input by user; Air gap: standard air gaps defined in ETTV
Material name; editable for user materials only
Material display color in the schematics; editable for user materials only
Material thermal conductivity in W/(m⋅K); editable for user materials only
Material thickness in mm; editable for all materials, with 3 thickness options for air gaps
Calculated thermal resistance (R-value) of each material layer
Outside surface film resistance:
Thermal resistance of outdoor air; automatically determined by wall/roof type
Inside surface film resistance:
Thermal resistance of indoor air; automatically determined by wall/roof type and inside surface type
R-value =  (m2K)/W
R-value is the overall surface-to-surface thermal resistance, with the outdoor and indoor air layers excluded
U-value =  W/(m2K)
U-value is the overall air-to-air thermal transmittance, with the outdoor and indoor air layers included
How to use the online U-value calculator?
The calculator is based on BCA ETTV code.
Get your wall/roof system U-value with a few simple steps:
- Specify the number of material layers: both solid and air layers;
- Select wall/roof type: vertical wall, horizontal roof or sloped roof;
- Input material properties: from ETTV material library, user-defined materials or standard ETTV air gaps
- Select inside surface type: low-emissivity for an inside surface covered with aluminum foil
The thermal resistance of each layer, overall system R-value and U-value are automatically calculated, according to the BCA ETTV code.
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Comments or feedback?
Please feel free to leave your comments or feedback to this online calculator in the “Leave a Reply” section at the bottom of this page. We will improve this online calculator regularly.
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