OK, I've checked and nobody's suggested this before, so here it goes:
Have you ever thought that it was stupid how Steve can simply walk around in near-Arctic environments, through snow and freezing cold water, and not even shiver?
As far as I'm aware, there is no mod that adds a "temperature bar". Here's how it'd work:
-You have a bar with flame and ice-drop icons
-When you heat up (By being exposed to the sky in a desert-type biome, being near a source of flame) you gain more flame icons and lose ice icons.
-When you cool down (By being exposed to the sky in an Arctic-type biome, being near a source of cold) You gain more ice icons and lose flame icons.
-Having a full ice bar will slow you down, make you nauseous, and freeze to death.
-Having a full flame bar will set you on fire.
-You have a separate "Thermal armour" bar, which can be increased by wearing "fur armour", Fur Hood, Fur Coat, Fur Trousers(/skirt?), Fur Boots (Fur being a drop from wolves, making the killing of said wolves necessary), made from wool and fur. They reduce the amount of transferred heat or cold.
-Radiators: Blocks or wall-mounted blocks (like luminator models) that provide a moderate (read: non-set you on fire) source of heat. They are powered by electricity and can be turned on by redstone. Can be disabled.
-Steam Radiators: Like standard radiators, but have a different texture and run off of RC steam. Supply with coolant or water to cool. This feature can be disabled.
-Electric Firebox: RC compatibility block. Runs off of electricity.
-Tiny Electric Firebox: Generates very small amounts of steam in return for a fairly decent amount of power. For radiator powering.
-Extremely Low Pressure Boiler: Only one boiler can be placed, cheaper and smaller than a low pressure boiler.
-Heated Suit: Actively stabilises temperature.
-Wetsuit: Hazmat upgrade, Contains: Snorkel (Replenishes bubbles if near block of air), Wetsuit (Thermal Insulation), Wetsuit Leggings (More speed whilst swimming), Flippers (Better diving)
-Desk Fan: Small blocks or wall-mounted blocks (like luminator models) that provide a small source of cold. They are powered by electricity and can be turned on by redstone.
-Air Conditioner: blocks or wall-mounted blocks (like luminator models) that provide a moderate source of cold. They are powered by electricity and can be turned on by redstone.
-Nuclear reactors are affected by temperature. Could become new way to cool reactors?
These have not been EVER suggested before, neither has there been a mod made that has all or any of these features (except maybe mo' creatures, which adds a fur suit). Please tell me what you think.
and 
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