Money ..... Cost. Time to build the "new features. Payback. Return on investment for what you pay for the property vs what you can charge for rent. Energy savings vs. cost of building the new features. Looks and access (useability!) vs "architectural touchy-feely feel-good" attitude.
Liability of the "new" features:" You want to be responsible in 5 years, 10 years, and 15 years and 20 years when those lead-acid batteries need to be disposed of .... after not savings ANY money for the past twenty? You going to pay insurance for a potential hydrogen-gas-sufuric acid bomb is sitting in the basement?
Those are the ONLY questions my clients ask me about.
If You mean built to last, simple and inexpensive to maintain, then You've got my vote.
Here's a few things I consider important.
1. Site selection.
I see too many housing developments being built on "bad ground", prone to flooding, or ground displacement due to soft or landfilled ground, also resulting in settling of the foundations, etc.
Trees for shade, proper grade for runoff, proper groundcover to eliminate erosion.
2. No design for the climate.
Someone else mentioned proper shading for the sun. Solar heating can reduce costs in winter, but proper overhang of the roof / eaves, can also reduce cooling costs in summer.
Designing roofs/eaves for latitude allows sunlight to enter homes in the winter but not in summer.
Proper walls can conserve energy.
Since moving to the Kansas City area some 30 years ago, I have seen numerous homes with NO Insulation!
How the (heck) do You save on energy costs when the house isn't insulated?
3. Energy Management
Homes do not utilize energy efficiently.
Aside from Major Utilities like Kitchen stoves, air conditioning, furnaces, most appliances and electric/electronic items run on 110v./120v power, and most are available in 6v.,9v.,12v. versions.
Many, if not most, electronic devices are transistorized today, and actually use step down transformers that provide the low voltages required to run these devices.
The simple step of removing electrical power losses due to transformers could result in 5% or 10% reduction in community energy consumption in this country.
Likewise, incorporation of solar energy for general low power consumption items, like outdoor night lighting would save millions every year.
Ever since the Arab Oil embargo, the means to use alternative energy, incorporated into homes and offices has been available.
Granted, it would not replace oil, but sustained research and development since the Carter administration could very well have put a dent in our nation's energy bills.
Of course, personal energy independence is anathema to the Energy and Power industries, thus legislation promoting alternative energy use is killed in congress on a regular basis.
I spent some time in Germany while in the army.
I was singularly impressed with many of the old homes there, some of which were more than 800 years old.
I was also impressed with the new homes being built.
Solidly framed, built to last, every window containing solid, insulated shutters, warm in winter and cool in summer.
Europe pays a lot more per BTU than Americans do. They have learned to conserve quite a bit over there.
Enough said, I hope my "opinion" is worth something.
If nothing else, it gave me a chance to rave a bit.