Casa Locarno doesn’t use any conventional energy at all. Instead, all of its power is generated by rooftop solar panels and underfloor heating. What energy is not used immediately is stored in a 1,050 gallon water tank in the basement. And during winter, when it’s cloudy, additional energy can be captured through a heat exchange system linked up to the cozy indoor fireplace. Naturally lit and insulated up the wahoo, this home is the quintessential sustainable Swiss villa.