Documented steady one-dimensional case
Planar-Wall Thermal Resistance & Heat-Transfer Calculator
Sum documented homogeneous layer and surface resistances, calculate U-value, and preserve the sign and direction of the steady heat-transfer rate.
Documented planar-wall result
Implemented arithmetic
Rlayers = ΣRi
Rtotal = Rsi + Rlayers + Rse
U = 1/Rtotal
q = U(Ti−Te)
Q = A·q
Thickness d is converted from millimetres to metres. Conductivity λ is entered in W/(m·K), resistance in m²·K/W, U in W/(m²·K), heat flux in W/m² and total rate in W. Positive Q means transfer from the entered inside side toward the entered outside side; negative Q means the reverse direction.
Standard status and scope
ISO 6946:2017, edition 3, is Published and was confirmed in 2022; ISO lists a corrected English version dated 2021-12. Its scope covers calculation of resistance and transmittance for building components using appropriate design conductivities or resistances and thermally homogeneous layers. The ISO page excludes doors/windows/glazing, curtain walling, ground heat transfer and components designed for air permeation, and states that bridged/inhomogeneous cases require additional treatment.
This page performs only the displayed series-resistance arithmetic. It does not claim an ISO 6946 compliance calculation because it does not implement the complete licensed procedure, air-layer rules, inhomogeneous-layer method or Annex F corrections. No ISO clause or table is asserted without checking the licensed text.
Why fixed defaults and presets were removed
The former calculator silently imposed Rsi=0.13 and Rse=0.04 m²·K/W, supplied unsourced conductivity presets and generic “typical U-value” ranges, and used |Ti−Te| so an outside-to-inside heat gain was still labelled heat loss. Surface resistance and design conductivity depend on the documented boundary and product/application case; this version therefore requires their sources and preserves the sign. An Energy Saving Trust report published by Ofgem documents missing λ-source evidence and a real calculator error caused by treating air layers with a fixed conductivity; this ledger therefore accepts only an explicitly selected solid homogeneous d/λ model.
Not an energy-code or condensation assessment: verify national annexes and code methods, design conductivity/resistance, geometry, surface orientation and environment, repeating/non-repeating bridges, openings, junctions, ventilation/infiltration, moisture/condensation, solar and long-wave radiation, transient conditions and uncertainty.
Nikolai Shelkovenko
Nikolai Shelkovenko is a vibration analysis engineer and the founder and CEO of Vibromera. For more than 15 years he has balanced rotating equipment in the field rather than on a test bench: mulchers, industrial fans, crushers, centrifuges, shafts and spindles. That work is what the Balanset instruments grew out of — they were designed as a tool a specialist can carry to the machine and use alone, on site, not as laboratory equipment. Vibromera was founded in 2017 and has been based in Porto, Portugal, since 2023. Development, assembly and support of the Balanset line all happen here. The flagship instrument is the Balanset-1A, a portable analyser for single- and two-plane balancing and for vibration diagnostics. Nikolai is personally involved in customer support, in working through difficult balancing cases and in the development of the software. He works with customers worldwide, in any language.
