A quest line in my game features the kidnap of someone from 'The Hotlands' and taken to an area known as 'The Ice Hills'.

The people from 'The Hotlands' require high temperatures to function correctly, and mostly live in volcanic areas where temperatures can easily reach boiling point. They can function, although badly, down to around 15°c.

The people from 'The Ice Hills' are the very opposite where they require extreme colds to function and survive. They mostly live in areas of around -2°c but can function, badly, at up to 20°c.

There are also 'Middle-Worlders' who are like normal people, but the other 2 people find it difficult to trust these people. (Although they run the forges and smith items for the people of the ice hills.)

Using technology from the dark ages, how can they keep him above 15°c so he doesn't die, but below 20°c so the people of the ice hills can speak with him.

I want to refrain from using magic of possible.

So far I can only think of lighting fires in some sort of greenhouse.

A quest line in my game features the kidnapping of someone from The Hotlands to an area known as The Ice Hills.

The people from The Hotlands require a hot body temperature to function correctly, and mostly live in volcanic areas where temperatures can easily reach boiling point (100 °C [212° F]). They can function, although badly, down to around 15 °C(59° F).

The people from The Ice Hills are the very opposite where they require an extreme cold body temperature to function and survive. They mostly live in areas of around -2 °C(28.4° F) but, they can function, badly, at up to 20 °C(68° F).

There are also Middle-Worlders who are like normal people. The other two people find it difficult to trust the Middle-Worlders. (Even though they run the forges and smith items for the people of The Ice Hills.)

Using technology from the dark ages how can they keep him above 15 °C(59° F) so he doesn't die but, below 20 °C(68° F) so the people of The Ice Hills can speak with him.

I want to refrain from using magic if possible.

So far I can only think of lighting fires in some sort of greenhouse.

A quest line in my game features the kidnap of someone from 'the hot lands' and taken to an area known as 'the ice hills'.

The person kidnapped requires high temperatures to even survive.

Using technology from the dark ages, how can they keep him above $15^o$C ($59^o$F) so he doesn't die, but below $20^o$C ($68^o$F) so the people of the ice hills can speak with him.

I want to refrain from using magic of possible.

So far I can only think of lighting fires in some sort of greenhouse.

A quest line in my game features the kidnap of someone from 'The Hotlands' and taken to an area known as 'The Ice Hills'.

The people from 'The Hotlands' require high temperatures to function correctly, and mostly live in volcanic areas where temperatures can easily reach boiling point. They can function, although badly, down to around 15°c.

The people from 'The Ice Hills' are the very opposite where they require extreme colds to function and survive. They mostly live in areas of around -2°c but can function, badly, at up to 20°c.

There are also 'Middle-Worlders' who are like normal people, but the other 2 people find it difficult to trust these people. (Although they run the forges and smith items for the people of the ice hills.)

Using technology from the dark ages, how can they keep him above 15°c so he doesn't die, but below 20°c so the people of the ice hills can speak with him.

I want to refrain from using magic of possible.

So far I can only think of lighting fires in some sort of greenhouse.

A quest line in my game features the kidnap of someone from 'the hot lands' and taken to an area known as t'he ice hills'.

The person kidnapped requires high temperatures to even survive.

Using technology from the dark ages, how can they keep him above 15c so he doesn't die, but below 20c so the people of the ice hills can speak with him.

I want to refrain from using magic if possible.

So far I can only think of lighting fires in some sort of greenhouse.

A quest line in my game features the kidnap of someone from 'the hot lands' and taken to an area known as 'the ice hills'.

The person kidnapped requires high temperatures to even survive.

Using technology from the dark ages, how can they keep him above $15^o$C ($59^o$F) so he doesn't die, but below $20^o$C ($68^o$F) so the people of the ice hills can speak with him.

I want to refrain from using magic of possible.

So far I can only think of lighting fires in some sort of greenhouse.