I am a retired mechanical engineering professor, still doing research on buildings that are heated and cooled with ambient energy (from the sun, sky, air and ground). I developed a "FreeHeat" computer program to simulate such buildings. The program is intended for predesign to establish building characteristics (solar gains, internal heat gains, envelope losses, ventilation cooling, and thermal mass) that will maintain indoor comfort year-round without conventional heating and cooling systems. Whether you prefer classic or modern Passive Solar, Passive House, Earthship, or High Thermal Mass styles, this Ambient House design approach encompasses all of these and provides a quantitative prediction of hourly indoor temperature throughout the year. Based on these simulations, we built a house that is 99+% passive solar heated (we use a fireplace for up to about 20 hours per year) and 100% cooled by nighttime ventilation.