Evaluation of thermal comfort during a selected period (e.g. during the hottest part of summer), using a classical dynamic simulation computer code connected to the LESO-COMFORT code itself. The program uses the data already defined for LESOSAI, and only a very few additional data have to be introduced by the user.


thermal comfort, load calculation, energy



Expertise Required

Average level of PC computer practice; understanding of basic solar radiation concepts.


Introduced in September 1999.


Architects, engineers, researchers.


The LESO-COMFORT software is basically an intelligent and user-friendly interface to a conventional dynamic building simulation program. The user does not have to describe the building to be studied from scratch. Instead, the building is supposed to be already defined, using the LESOSAI software.
The LESO-COMFORT input interface allows then to complete the description and write the additional characteristics needed for a dynamic simulation into the .BLD file produced by the LESOSAI software:

  • wall, roof and floor characteristics (choice of one element from a list of library elements);
  • thermal zone characteristics (occupancy, heating/cooling, air renewal and window opening, artificial lighting use);
  • global building characteristics (simulation times, heating/cooling season).


The output interface allows the user to get the results of the simulation in a convenient way. The priority has been given to graphical output, in the form of x/t diagrams (a variable plotted in function of simulation time) and histograms (repartition of variable values into classes). Several variables are available, among them the comfort indexes like the PMV (Predicted Mean Vote) or the PPD (Predicted Percentage of Dissatisfied Persons) following the Fanger's formalism. Tabulated values are also available, and can be read by a standard spreadsheet software like Excel.

Computer Platform

: IBM-PC compatible, 486 or higher, Windows 95 or later, Windows NT 4 or later

Programming Language

C, Visual Basic


The definition of data needed for the simulation is rather simple, since only data additional to the already defined LESOSAI building data has to be entered. The software allows a good flexibility of technical equipment use (blinds, ventilation, etc). The output can be given at different detail levels, for instance:

  • a complete hour by hour tabulation of any temperature or comfort index;
  • an histogram of any temperature or comfort index;
  • a global statistical value such as the proportion of time where the PMV is higher than a given limit or lower than another given limit.


: Only one heated zone (this is a limitation of LESOSAI software). LESOSAI software is needed for the first part of the building definition. Some of the comfort indexes are subject to discussion, especially by very hot conditions. The simulation can take a little time, especially when using a rather old CPU. The integration with the other software of the same family (LESOSAI, LESOSHADE, LESOCOOL, etc) is not yet operational.





LESO Building
Lausanne CH-1015


+41 (21) 693-45 46


+41 (21) 693-27 22






CHF 200 or 100 (non-profit organizations), available in English, French and German language versions.