I am looking at the ICC Intl Mechanical Code, in section 309.1
309.1 Space-heating systems. Interior spaces intended for human occupancy shall be provided with active or passive space-heating systems capable of maintaining an indoor temperature of not less than 68°F (20°C) at a point 3 feet (914 mm) above floor on the design heating day. The installation of portable space heaters shall not be used to achieve compliance with this section.
I am wondering what this means. e.g., capable if you set the thermostat on 80 and it gets up to 68 in that room?
Let's say you have some cold rooms in a house. Most of the house - you set the thermostat at 70, those rooms are about 70 - but in some rooms is struggles to get over 65. Is that a code problem or it is okay because you could turn the heat up to 80 and then that room would be able to get over 68?
Also what exactly does it mean to "maintain" the temperature? e.g., you get it to 68 but it cools off very quickly by a few degrees within an hour?
How is this part of code actually applied?