Hello,

I have a question about how the Kiva Foundation object is initialized in an EnergyPlus simulation using the accelerated initialization method.

I am running simulations of a model that includes a basement with a foundation:kiva object for ground heat transfer. For reasons specific to my project, the initial temperature setpoint of the baseboard heater in the basement is very high (30°C). Throughout my simulation, the setpoint is eventually reduced to 21°C but the zone temperature of the basement stays mostly constant at 25°C for the entire winter; there are no other sources of internal heat gains other than from occupants, lights, and some plug loads.

My questions are:

1) Could this odd behaviour be due to the initialization (warm-up) of the foundation:kiva object? I understand that it uses the initial temperature setpoint of any adjacent zones to initialize the ground temperature; over a warm-up period of months, could my basement temperature setpoint of 30°C be creating a huge thermal battery in an adiabatic system, preventing the basement from dropping in temperature?

2) If 1 is true, is there a recommended range of temperature setpoints that should be strictly followed when dealing with kiva foundations to avoid this behaviour?

I know that my situation is a bit odd with the initial temperature being set to 30°C (we need to observe thermal responses from many different conditions) but if anyone has any idea about what we're observing, it would help a lot!

Thanks to whoever took the time to read this, David Sun