Im a builder.
Like all builders I need to have a permit before I can begin construction, and that includes meeting the energy code.
Long story short: I was required to install a furnace of a certain small size in a new house. It was 20 below the morning I went in to plead the case for a larger furnace.
The code outlined that I could have a 60 degree temperature rise, and so I asked the code guy So, you want me to install this furnace, and the house will be a stable 40 degrees inside in weather like we had last night?
Total silence.
He graciously allowed me to install a two stage furnace to get around the code..
Wrong temperatures, sorry.
It was 10 below that night, not 20, the allowed temperature raise is 60 degrees, the stable inside temperature would be 50 degrees.
All permits will have to be filed by the third week in January for the 'scheduled' upcoming work for the year. And...so forth.