S(t+1)=S(t) + G(t) - I(t) - H(t) - N(t) - U(t) + E(t)
It's interesting that your responding variable (result, in this case S[t+1]) has the [t+1]. I think I get what you're getting at, but the mathematician in me has to point out that the responding variable should be S(t), or amount of stormlight you have rather than S(t+1) or the amount you will have in one unit of time. As I am interpreting your equation, I see the formula as
S(t)=S(t-1) + G(t) - I(t) - H(t) - N(t) - U(t) + E(t)
The significant change is that I assumed that you have stormlight equal to what you had before minus what you are using now rather than stormlight later being now minus now... hard to explain in english, but basically my formula has immediate effects, and has a properly formatted responding variable, as far as my understanding of math goes. I am not a math major.