For me I'm really far from this treshold...
From the different datasheets, the consumption of the both captors is really weak: MPL115A1(10µA Max) & SHT15(25µA Max).
About the SD-shield Sparkfun, I don't know.
For me the current level is not the problem, at the beginning I used the project directly on the USB plug. Now, I'm using a new 9V battery, just to avoid a degradation on my computer...
Currently, my project is running correctly, but I need to use the 5V.