Monolithic Domes are amazing. The insulation, coupled with the concrete’s thermal mass, creates an atmosphere that is hard to describe. Simply put, it feels the same today as it does in the middle of summer. If you set the thermostat at 70 (21°C), it just stays there. During the two-degree, 24 hour period, my heater ran for a total of 9 hours. This is a small heater, with only 30,000 BTUs. Most homes the size of mine have 100,000 BTU heaters, but even my neighbors with electricity struggled to stay warm with heaters running nearly 24/7.