Very powerful simulation softwares are available today. They should allow rational choices from early design stages, among many different alternatives. When using such tools, the bottle neck is no more on computer side but in the modelling. Better and better compromises have always to be found...

If renewable energy sources are to be successfully utilised within the built environment then accurate simulation tools have an important role to play. This paper addresses a very specific part of the overall simulation process: that of earth-contact heat transfer which can be the cause of...