Natural Ventilation — Heating load increases

Last Updated: 

Thursday, September 7, 2017

Software/Versions Affected:

• COMFEN›4
• COMFEN›5

You may notice an increase in the heating load when running a scenario with natural ventilation. We are still investigating the exact cause of this in the EnergyPlus simulation engine, but what we are seeing when we look at the time step reports (15 minute increments or less) is that every time the fans come on the heat also comes on. The program then checks the zone temperature, determines whether the heat really needs to be on, and if it doesn't, turns it off. So in the periods where heating is not actually needed, it is not on for very long (15 minutes or less) but over the entire year, that adds up in terms of a heating load. We are working with the EnergyPlus development team to understand the cause of this behavior in the program, and will update the COMFEN EnergyPlus model when a solution is found.