ESP-r: Long wave radiation
Current capabilities
ESP-r capabilities for long wave radiation are as follows:
- Default grey body area/emissivity weighted exchanges
between surfaces in a zone (default treatment)
- Explicit calculation of view factors between surfaces in a zone
(of arbitrary complexity).
- External exchanges use specified view factors
to the sky and ground based on qualitative descriptions (e.g. rural
location) or explicitly set by the user.
Primary routines
- esrubld/subsys.F MZELWE - calculates sky, ground and neighbouring
building temperatures and thus external long wave flux
- esrubld/precal.F MZVFCL - alculates the black body geometric view
factor between each internal surface pair for each zone based on
an area weighting technique
- esrubld/subsys.F MZCFGG - calculates internal grey body exchange
- esrumrt - module for calculating black body view factors
Primary variables
- COMMON/COE31 - grey body radiation coefficients present and future values
- COMMON/V2 - black body view factors
Issues arising
-
The same external view factors assumed for all vertical building surfaces. The
data model could be expanded to support a surface-by-surface definition.
- Calculation of sky/ building/ ground temperatures could be examined
with a view to supporting different soil types and top surface properties.
- Internal viewfactors are currently restricted to viewfactors between
surfacs within one zone. Radiant exchanges between zones are often
observed and would be possible if the viewfactor matrix was
expanded to include all surfaces in the model. This would require
changes in the data structure and the calculation engine, but it would
improve the treatment of physical rooms which are composed of
more than one thermal zone.
- Zone controls to use mean radiant sensors to approximate
human comfort.
Last edited April 2005