There is no absolute prototype for a farmhouse, but most folks can recognize one once we see it. By definition, the originals were located on farms and were integral to the life and work of these farm families who lived there.
Depending on when and where those homes were built, they might be made from stone, brick, shingles or clapboard. Most farmhouses had porches since there was no air con and lots of farm and family chores were undertaken there. The porch roof provided shelter from the sun and rain yet allowed the cool breezes to flow through and help make those steamy summers tolerable.
The center of family life within the farmhouse was the kitchen. Meals were prepared and sometimes eaten there also as home pickling and canning for the long winters (in the North). within the older farmhouses, a cooking fireplace was essential. Additional fireplaces were wont to heat as many rooms as possible.
I sleep in an old farmhouse originally built around 1790 then added onto within the 1800s and more recently added onto by my family. I even have come to understand the straightforward detailing the wide board floors and delightful fireplaces.
When designing a contemporary farmhouse, porches, wide board floors and delightful fireplaces are welcome. the ground plan is often center hall, side hall or a variation of the 2. Gathering places within the house is as important today as they were 200 years ago. Modern farmhouses include big bright kitchens to accommodate the inevitable influx of friends and family.
These days many families spend most of their time within the kitchen cooking, eating, talking, studying and just visiting. Energy efficiency is vital, with some farmhouses using geothermal heating and cooling and solar panels on the barns.