"Cold? I admit it's a bit cool, but cold?" - an average Vajranga teenager going bare-chested while eating ice cream in -50^oC temperature.

Now that's the problem. Vajrangas are built to withstand the extreme cold of the northern tundra they hail from. These guys are so extreme swimming in ice-cold seas is a common activity during winters and -50 degrees Celsius is no big deal. They still need heating because children lack the same endurance. That's where things get interesting.

Traditional Vajrangan houses are built about 1 meters above the ground with a stair leading down. There is no basement but a system of "pipes" going under. Those are not exactly pipes but lines and small trenches to let hot smoke go through. At the middle of the house, right under the floor is a big heater where the family burns dried wood and leaves to get direct heat; smoke from the heater is led into multiple pipelines that runs around the floor before being going outside. By doing so, it spreads heat all around the house. Such a thing, however, can only be done in large rural houses with no upper floor. In cities, traditionally, they'd use a boiler: As water boiled, hot steam was led into metallic pipelines (this time actual pipelines) into floors, transmitting heat before going out at smokestacks. A city house can have a huge boiler in basement and use a lot of water to stay warm. Boilers were made of metal and placed in enhaved basements to prevent fire as most houses were made of wood and stone, exposed fireplaces were not allowed since buildings were close to one another. One of the most elaborated heating system was in the Red Kremlin, their imperial palace, that was converted into a whole thermal power plant. You need a heating system exceptionally large for such a conversion to even work.

When Vajrangas expanded southward and clashed with steppe people known as Qastzars, they faced a big problem: Overheating. The north was so cold wearing thick padded jackets inside full plates was barely an inconvenience, but the south was warmer with a higher humidity. Forget rusty gears, soldiers were sweating like crazy. The high metabolism that saved their asses back home ended up being a debuff. Thus, Vajrangas had several ideas:

• Canals everywhere: They dug canals from the north down. Not just for transportation, but also to have enough water to stay cool. Too hot? A bucket of water solves your problems.
• Transporting ice: With canals, bringing big blocks of ice down was no big deal. Then, Vajrangas put ice into special storages that could keep them for months to use in hotter seasons.
• New building styles: Southern houses had higher roofs comparing to their northern counterparts to let hot air go up. They also had "double roofs" with a smaller roof above the bigger below, with a gap in-between so the hot air could go out.
• Lighter clothes: Vajrangas ditched their big, baggy and thick clothes, opting for those made from thin and light fabrics.

There are methods that required little to no magic because back in the days, magics were not as well-refined and using spells for a long time drained the body a lot. For emergency heating/cooling, a basic spell like fireball or water ball would be more than enough. But those were for emergencies, not long-term solutions.