Hi, we have a project with a certain number of 'back up' systems for air conditioning. The main system is a geothermal ground loop but there is an air cooled chiller that will be installed as back up and to take up any extra load that can't be handled by the ground loop. The instalation is the first of its kind in the area hence the back up chiller. However all calculations and modelling show that the ground loop is sufficient for all times of the year, how do we then incorporate this in the final modelling? Capacity of ground loops and associated heat pumps is sufficient for the loads reported in the simulation. Is it acceptable to model all plant components and just show that the back up equipment never comes on?