The green building movement is toward net Zero, where a building produces as much renewable energy as it uses overall. It is a reachable and measurable goal that is attractive for its clarity and obvious environmental benefit. If all of our houses and buildings become net zero we would do a lot to reverse the damages of fossil fuels that contribute to climate change, water pollution, Mountain top removal, oil spills in our oceans and neighborhoods, asthma cases, mercury poising etc. Buildings in the US account for nearly half of the energy we use and nearly half of the greenhouse gas, carbon dioxide, we emit.
The Building Sector Must Lead
Humans have seen the huge benefit lots of cheap energy can bestow and we don’t want to give it up. It lets us live longer and have more comfortable and productive lives. So far.
If we want to continue to enjoy this situation without ruining it for us and the next generations, getting to zero in our buildings is part of the solution.
In order for this to happen we need to find the most affordable way to pull it off. It is a bit of a moving target as the cost of producing renewable energy comes down and the efficiency of lighting, appliances and Heating and Cooling goes up. Basically you can reduce your demand and you can include production through renewables to get to zero. The HERS rating system will model your house plan to give you a good indication of what you are likely to achieve . The standard new home, based on “prevailing federal minimum efficiency” , is assumed to be 100, a net zero home is zero.
We just built a house that ended up with a HERS rating of 8. It was 45 before the 3.78 Kw Photovoltaic system was accounted for. It was a 1000 sq ft 2 bedroom home. 
We reduced the energy demand of the house through:
1. Design- passive solar . Cost $0
2. Increased insulation values Walls- R 26, ceiling R60
Added Cost $800.
3. Decreased air infiltration. Cost- $paid attention.
4. Energy star doors and windows. Assumed
5. Heat Pump water heater. Added Cost $500.
6. Energy star appliances. Always
7. Efficient lighting, mostly CFL and some LED.
Total cost of the house without the lot and Solar PV system – $154,000. Solar system before credits was $14,000.
Credits for Solar PV are now 35% from North Carolina and 30% from the Fedral Govt. https://www.dsireusa.org/
We also qualify for a $4000. HERO rebates from
Duke Energy Progress because of our certified HERS rating.
So we did not make it to Zero but we are close. Better windows would make a big difference but at a significant cost. Solar PV will likely cost less by next year. Rebates and tax credits are always in flux and will need to watched, especially in North Carolina. Even with all of the unknowns Zero is the place to be.