ESP-r Convection

During assessments a surface energy balance is maintained at each face of each surface. Each face of a surface has a single temperature at any moment in time and each constituent of the surface energy balance is consistent across the whole of the face of the surface. The default treatment of convective heat transfer at the inside face of a surface uses Alamdari-Hammond based on the surface orientation, and the current surface and air temperatures. Optionally one of these standard buoyancy driven flow regimes can be applied within the zone:

  • buoyancy from floor heating
  • buoyancy from heated wall panel
  • buoyancy from another temperature difference
  • heater in room under window
  • heater in room not under window
  • within an open vertical channel

    • Or one of these mechanically driven flow regimes can be applied within the zone:

  • VAV cooling with CV heating
  • VAV for cooling and heating
  • CV with variable temperature supply
  • circulation fan in room.

    • Or one of these mixed mode buoyancy plus mechanically driven flow regimes:

  • VAV cooling with CV heating
  • VAV cooling with CV heating
  • VAV for cooling and heating
  • CV with variable temperature supply

    • Optionally the user can schedule fixed heat transfer coefficients at the inside and other face of each surface or use select one of the following correlations:

  • Alamdari & Hammond for vertical surfaces
  • Alamdari and Hammond horizontal surfaces
  • Alamdari and Hammond stably strat at horiz surf
  • Awbi and Hatton
  • Awbi and Hatton horizontal surfaces
  • Halcrow time invariant low for vertical surfaces
  • Halcrow time invariant low horizontal surfaces
  • Halcrow time invariant high horizontal surfaces
  • Halcrow time invariant low stratified horiz
  • Halcrow time invariant high stratified horiz
  • CIBSE for vertical surfaces
  • CIBSE for horizontal surfaces (hc4.3)
  • CIBSE (stratified) horizontal (hc1.5)
  • Khalifa & Marshall non heated vertical surfaces
  • Khalifa & Marshall fan in room or floor heating
  • Khalifa & Marshall room radiator not under window
  • Khalifa & Marshall fan heater in room wall oppos fan
  • Khalifa & Marshall window over radiator
  • Khalifa & Marshall windows w/o a radiator
  • Khalifa & Marshall ceilings rad @win or htd wall
  • Khalifa & Marshall ceilings fan htr or floor htg
  • CEN for vertical surface (hc2.5)
  • CEN for horizontal surfaces (hc5.0)
  • CEN (stratified) horizontal (hc0.7)
  • Fisher & Pedersen for radial ceiling diffuser
  • Fisher thesis for radial ceiling diffuser
  • Fisher for free horizontal jet
  • Fisher thesis mixed convection radial ceil diffu
  • Fisher & P floor forced mixed with rad ceil dif
  • Fisher thesis floor forced mixed w rad ceil dif
  • Fisher thesis floor forced mixed with horiz jet
  • Fisher floor forced-free with rad ceil diffu
  • Fisher & P ceiling ASHRAE with radial ceil difus
  • Fisher thesis ceiling with radial ceil difuser
  • Fisher thesis ceiling with free horizontal jet
  • Fisher thesis ceiling mixed with radial diffuser
  • Molina & Maestre ventilated channels
  • Bar-Cohen buoyancy ventilated channels
  • ISO 15099 corr buoyancy flow in vented vert chan

    • Surface boundary conditions

    Surfaces have a boundary condition attribute that specifies the nature of thermophysical interactions at the other face of the surface which also implies a convective regime from the following list:

  • EXTERNAL ‐ in contact with ambient weather conditions. By default convection at each external surface is resolved via the current wind speed, wind direction and surface orientation. Optionally one of these outside heat transfer correlations can be specified:
  • McAdams wind tunnel test(Energy Simulation in Building Design by Clarke J A)
  • MoWiTT model from M.Yazdanian(Measurement of the Exterior Convective Film Coefficient for Windows in Low-rise Buildings )
  • Aya Hagishima & Jun Tanimoto equations (Field Measurements)
  • Ya Liu equations derived from roof wind speed (PhD thesis)
  • Ya Liu equations derived from wall wind speed (PhD thesis)
  • Aya Hagishima & Jun Tanimoto equations (Field Measurements)
  • Ya Liu eqations derived from weather station wind speed (PhD thesis)
  • D.L.Loveday & A.H.Taki derived from roof wind speed (Field Measurements)
  • D.L.Loveday & A.H.Taki derived from wall wind speed (Field Measurements)
  • CIBSE guide (CIBSE Guide C3)
  • D.L.Loveday mixed convecive correlation (CIBSE Guide C3)
  • British Standard equation (British Standard)
  • ASHRAE Task Group equations (Full-scale Measurements by S.Sharples)
  • Sturrock equation(Convective Heat Transfer Coefficients at a Plane Surface on a Full-scale Building Facade)
  • Keith Nicol equation(The Energy Balance of an Exterior Window Surface,Inuvik,N.W.T.,Canada)
  • S.E .G.Jayamaha equations(Measurement of the Heat Transfer Coefficient for Walls)

    • ESP-r includes concepts that the other side of a partition faces a room with the same temperature and radiant environment (e.g. an adjacent cellular office) or a user specified temperature and radiant environment (a cold store).

  • SIMILAR environment e.g. if it is hot in the room it is hot on the other side and the default heat transfer coefficient is used.
  • CONSTANT ‐ a fixed temperature and radiant environment .e.g a cold store and the default heat transfer coefficient is used.
  • MONTHLY ground temperature profile ‐ direct contact with the ground and the heat transfer coefficient is set to 1000 W/m2/K.
  • ANOTHER surface ‐ in this zone (internal thermal mass) or a surface in another zone (a partition) with the default XX used unless another specification is given.
  • ADIABATIC ‐ no heat flux passes at the other face with the default used unless otherwise specified.
  • CEN 13791 ‐ used for validation tests. Direct sunlight falls on both sides of partitions equally (unreal physics) and the default Alamdari & Hammond is used unless otherwise specified.

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    ©Copyright 2017 Energy Systems Research Unit, Glasgow, Scotland. License: GPL V2. Last edited by JWH, 23 Aug 2016