In roughly chronological order, considering heating only:
- Build a fire in the center. To get warmer, make a bigger fire or stand closer to it. To get cooler, move away from the fire or let it go out.
- Heat the perimeter with baseboard heat or radiators (or forced air outlets) supplied with heat from a central heating plant controlled by thermostats in living areas (i.e., a controlled fire). To get warmer, turn up the thermostat. To get cooler, turn down the thermostat.
- Heat the perimeter as above and add some insulation to reduce the cost of heat.
- Heat something massive like interior masonry walls or concrete floors (thermal mass) to absorb heat and then release it slowly. To get warmer or cooler, you can adjust the thermostat, but plan ahead, because this is a slow acting system. Remember to dress appropriately while you wait.
- Add enough insulation, an air-tight envelope, and a ventilation system with heat recovery so that a conventional active heating system is unnecessary. A little heat anywhere should result in uniform temperature throughout. Set for comfort, there is no reason to feel too cold or too warm.
#1 is the concept founded by early humans and carried on today around fireplaces, wood stoves, and campfires.
#2 and #3 – heating the perimeter – have enjoyed zealous support even in the face of proof that sufficient air tightness and insulation can eliminate the need for perimeter heat.
#4 is the central concept of “in slab” radiant heating, and it was also a central concept in passive solar houses built during the last half of the 20th century
#5 is the Passive House concept. Unlike passive solar, Passive House is from the German Passivhaus, a concept initiated in Germany in response to the 1973 oil embargo and continuing today throughout Europe, North America, and other parts of the world. The Passive House concept is responsive to the need and desire for comfort, energy efficiency, good indoor air quality, and reduction of harmful carbon emissions.