First poster but longtime reader on this site. Thought I'd throw my two cents in on the ZEH and lighting control.
My wife and I just finished our home June last year. We've gone half the way on a ZEH but not to the extreme that you are going. It's a story and a half home with 2500 sq. ft. conditioned downstairs and an unfinished attic with around 2000 aq ft. upstairs. We're conditioning the downstairs and maintaining the upstairs at an increased setpoint temperature. What I’ve seen is that the upstairs heat pump doesn't run during the winter but is used as a "buffer" from the hot sun during the summer. The home construction utilized 4-1/2" wall and 10-1/4" roof SIPS panels. The home is entire electric including well water. I work for a geothermal manufacturer so naturally installed a couple of our units. We live in the middle of the plains and constantly have 10+ mph winds and would love to install a wind turbine but with an electricity cost of $0.10kwH it doesn’t make economical sense.
What I can tell you from living in the home for a year is your goal of a ZEH you will really need to focus on other items besides hot water and space conditioning. Our base load for a couple months last fall (ie, very little space conditioning) with just the two of us, both working during the day was ~800kWh. This was the load from regular items such as oven, cooktop, lights, TV, electronics, refrigerator, freezer, washing machine and drier. As you can see, just basic appliances can push you almost to the 1000kWh/mo limit. I'm not saying that it can't be done, just very difficult. If we had any kids, as you mentioned, I imagine our base load would be higher yet. I'm really, really wanting to get a Brultech or equivalent to see what items I need to focus on to get the base load lower. You can also see this trend from some research homes done by ORNL at: www1.eere.energy.gov/femp/pdfs/tir_zeroenergyhouses.pdf.
Enough on that, now to your original question...lighting control. I installed all Levition Vizia and Vizia RF switches. After looking into all of the technologies it really came down to the look of the device and how they could match with the other switches and receptacles in the home. I'm not going to lie, they were expensive but I really like the look and have had not problems with them except a few glitches during initial setup. I'm running 24 different switches/controllers in critical locations mainly due to the cost of having them installed everywhere. I’m currently using ThinkEssentials to control the lights but am working on integrating them in with my Elk security system. I haven’t measured the vampire draw on these switches so I can’t comment on that aspect.
I agree with other posters that the ELK works great for security but it’s HA capability is limited. I haven't looked hard into Premise, Vera, or Homeseer to see how much better of an option they might be for HA than the ELK.
Also, if you are looking into lights I’m using some of the Cree LR6 LED’s and absolutely love them. They have dimmable version called the CR6 that you can get at Home Depot as well.