I have noted before that if you want to build an efficient green house at an affordable price, you have to use the KISS principle and Keep It Simple, Stupid. And small. And control the window sizes. This doesn't apply in North America, where vinyl windows are cheaper than walls, and where the only number that matters is the price per square foot, so in fact the bigger the house, the cheaper it is.
But in Europe, and in Germany in particular, this is how you build an economical house. SoHo Architektur uses basic but durable materials (corrugated cement panels on roof and walls). They keep the design really simple because every jog and projection costs money and is a potential thermal leak. The really expensive but efficient windows are used sparingly. (Professor Prangnell always said that a window should frame a view). They use simple finishes, like exposed concrete floor on the ground floor. They keep it small, in this case 90 square meters (968 square feet). The result is a house that costs 125,000 euros, or $162,137, or $167 per square foot.
Meanwhile, in Florida, you can buy a house for $ 59.32 per square foot, including the land. It's 4,163 square feet. Which would you rather live in?