>1- I am not sure what kind of house you are talking about, but typical costs for energy efficiency result in less than a 10% increase in total costs.

It was only an example from experience, anecdata if you prefer, of course it depends on a lot of factors, besides size of the house and country where it is built, it also depends on what is the current "base level" (coming from either local regulations or "common uses") from which you start.

In EU there are levels for houses from G (worst) up to A (and then a few better ones A+ and A++) very similar to the more generic EU Energy Label:

https://en.wikipedia.org/wiki/European_Union_energy_label

Since 2010:

http://eur-lex.europa.eu/legal-content/EN/TXT/HTML/?uri=CELE...

And the construction of new buildings have progressively shifted since 2010 from a "minimum acceptable" of Class C to currently Class A and soon Class A+ and A++, here is a good sum up:

http://gildera.com/timber-frame-homes/low-energy-house/

>3- The savings can be much greater than that. Insulation alone has an amazing bang for the buck. And its passive.

But they can be also much less, it was just an example, it depends on country, size of the house, costs of energy, etc., etc.

>4- Added maintenance for windows? They don't require a diamond polisher to be cleaned. Who replaces their windows and doors every 20 years? What specifically needs extra maintenance?

Essentially locking systems and seals/gaskets.

Also hinges (or rolling sets), modern double/triple glass is thick and very heavy and put extra stress on hinges or - in the case of sliding windows/doors to the rollers.

Understandably everything fits with very small clearances and it is not uncommon to have to register (besides lubricating) hinges, locks (and/or rollers) once a year.

Depending specifically on the way the window were installed there may be some sealing that needs to be replaced every 5 years or so.

Double/triple glass have one or more "air chambers" that are actually pressure filled with "noble gases", usually Argon or Kripton, and then sealed.

It is not uncommon (particularly on windows subject to extreme temperature stress) that in 10, 15 or 20 years time the sealing lets the noble gas out and some air (and moisture) enters the air chamber.

>5- Even if you are not living in the house, you can capture a higher profit margin by including utilities in the rental price, or marketing it as an energy efficient house. This is a real edge case though. Interest rates are about 3.5% now. Even in your inflated cost estimate, that translates to $700 in interest for 6 months. Not exactly game changing IMHO.

Again it greatly depends on country, etc., etc. but the point was only about the fact that energy saving not necessarily means money savings, as a matter of fact till now the energy saving (good) came with an initial increase of the construction costs that not necessarily you can recover.

>You are also missing an important point - energy efficient houses also tend to be a lot more comfortable, there are less drafts, less swings in temperature, less affected by outside noise. And you get the satisfaction of not having to care so much if energy prices increase.

Actually you are missing the point I was trying to make, a well built energy saving house can be a lot more comfortable, but - with some exception of course - very few houses are actually well built and when they are not well built they are besides uncomfortable also unealthy.