[esp-r] Standard 13791 validation tests

[P Strachan]

There have been some recent questions on Standard 13791.

CEN Standard EN ISO 13791 contains a number of tests for simulation programs. Some national bodies require these to be passed as part of their accreditation procedure.

There are 4 sets of tests in the Standard:
1. Heat conduction through opaque elements
2. Internal long-wave radiation exchanges
3. Evaluation of short-wave radiation transfer (calculation of shaded area of window due to external obstructions)
4. Whole model validation

ESP-r passes all these tests.

There has been some delay in passing the last of these. The reason is that the boundary conditions specified in the Standard for solar radiation (e.g. solar radiation on the other side of the ceiling at each timestep equals the radiation on the floor in the test room) and for convection (similar rules) has required some code additions. Secondly, some of the test specifications are not physically realistic - internal surfaces with absorptivity less than 1, but with no solar radiation being lost through the window of the room (i.e. solar radiation enters but does not leave).

However, the boundary condition code changes have now been made and passed into the development branch ready for the next release of ESP-r, which will probably occur early next year. All results are within the prescribed tolerance bands. A report of the test results will be made, and the tests included in the standard validation tests accessible through Project Manager.

Regards
Paul