I expect my response to this question won't be as definitive as many of the answers found on GreenHomeGuide; however, I do have several thoughts that may provide insight into a few of the questions posted in your query.
Cost and other general advice
First, ICFs are a solid building choice and I'm confident you have made the decision based on criteria particular to your building conditions.
I won't suppose that I know the reasoning behind your decision to build with ICFs (fire, wind, sound, bugs, etc.), but given the geometry of the home plans you've provided, I suggest you researchSIPSfor the above-grade sections of the home.
With regard to cost, I would expect ICFs to increase the price of the home by six figures. This assumes the average cost was determined via stick framing and fiberglass insulation. There are a number of different factors such as grade beams or wood joists, along with your willingness to make changes to the geometry to decrease cost, that can significantly move the cost needle up or down.
The value of hiring a design professional
Starting with stock plans can be a great way to gain insight into the footprint, flow, style and function of your new home.
However, hiring a design professional to transform this basic outline into construction documents will be the best money spent on your project.
- He/she will have the ability to redraw your plans to conform to the ICF specifications you've chosen and make changes to ensure the construction portion flows smoothly and cost-effectively.
- Given the budget for this project, I would venture to say that the design professional fee would be absorbed by the money you will save versus building on the fly with stock plans.
LEED for Homes advice
In terms of LEED for Homes certification, you've mentioned several methods of securing valuable LEED points under the LEED for Homes program (renewable energy, renewable materials, and extreme energy efficiency).
However, the size of the home will provide some obstacles to achieving certification. A quick calculation using the home size threshold equation for this 5400 sq ft home indicates that this home would require 72 points to be certified (45+27 additional points).
At the risk of sounding sarcastic -- and I sincerely do not mean for it to come out that way -- the biggest tip for achieving LEED certification for this home is to cut the size of the home in half.
For more information on getting started on your LEED home, see my GreenHomeGuide blog post"Getting started on your LEED home."
For more information:
Read "What do you know about ICF construction? I am thinking about building a new home." a Q&A answered by William Janhonen.