# How do energy solutions interact with each other in Open Studio?

So i have modeled a building and I am applying energy solutions to observe the evergy savings of each solution.

For the first energy saving solution i add insulation to the external walls of the building (Solution A). For the second one i reduce the infiltration of the building (Solution B). For the third and last one, i combine the two previous solutions, so i end up with a building with insulated walls and reduced infiltration (Solution AB).

When checking the savings of each solution i realized that the energy savings of solution A + the energy savings of solution B are less than the energy savings of solution AB. Does anybody know why that is?

Which numbers are you looking at exactly? Have you looked at hourly (or even 'Detailed' timestep) results to see when you actually get a discrepancy? Do you have AC for the summer in your building? I'm trying to understand what

interactivitybetween both measures could explain it.I am looking at the total electrical energy consumption which comes from the electrical devices, lighting and the AC. Yes i have looked at more detailed timestep and it seems that AB solution savings are closer to A+B savings in the winter. In the summer AB savings are slightly lower than A+B savings.

The AC is set at 26C in summer and 22C in winter although it is fixed for all the above scenarios. I can't seem to understand how these two solutions interact with each other that leads to that decrease in the savings.

https://prnt.sc/1qlo3in

This is a diagram that i made with the savings of A,B and AB where A is B and B is D in the diagram and also the Utilizability Index which is basically (AB savings)/((A savings)+(B savings))

Is this just the impact of thermal lag creating slightly different interior/exterior temperature gradients, which in turn partially determines the magnitude of conduction and infiltration. Specifically, if the HVAC perfectly supplied enough energy to maintain the 26C setpoint AB would equal A+B, but the impact of thermal lag should prevent that, creating: deviations from the 26C; setpoint, deviations in the temperature difference, and thus deviations in the magnitude of A and B when modeled together.

I get what you are saying and it is something that i had on my mind but answer me this. Thermal lag applies to all solutions (A, B and AB). What makes thermal lag in Solution AB different from the thermal lag happening in A and B? That is what i am trying to figure out.