PÉCLETBuilding Physics
PÉCLET / Disciplines / 01θ — °C · U — W/m²K

Thermal

Heat does not respect drawings. It moves through whatever you build, at a rate the assembly decides.

QuantityTemperatureTransportConduction · Convection · RadiationInteractionMove the pointer across the section to change where heat enters. Drag to raise or lower the exterior temperature.
Fig. 01 — Envelope sectionMove across the section to add a heat source
Temperature difference across the assembly: 13.2 kelvin.
A cross-section through a wall assembly, drawn as five vertical layers from exterior cladding through a ventilated cavity, insulation, structure and interior finish. Particles carrying heat cross the section from the warm side to the cool side, slowing markedly inside the insulation layer and accelerating through the cavity. A temperature gradient runs across the section, warm on the exposed face and cool on the protected face.

The position

Every envelope is a resistance network. Layers of cladding, cavity, insulation, structure and finish each slow heat by a different amount, and the weakest continuous path — not the average — sets what the building actually loses.

Thermal bridging, thermal mass and the daily swing between inside and outside decide whether a room is comfortable at four in the afternoon or merely compliant on paper. We work in the difference between those two things.

What we ask

  • 01Where does the insulation line actually run, and where does it break?
  • 02How much heat crosses the envelope on the worst day of the year?
  • 03Does the mass in this building help, or does it store the wrong thing?
  • 04What is the surface temperature a person is standing next to?

How we answer it

  • 01Steady-state and dynamic envelope assessment
  • 02Thermal bridge analysis at junctions
  • 03Surface temperature and comfort mapping
  • 04Assembly build-up development with the design team