The sense of heat is provided by Group C nerve fibers found in the skin. These fibers are sensitive to changes in temperature, and they respond to both warm and hot stimuli. When something with heat comes into contact with the skin, it stimulates the group C nerve fibers, sending signals to the brain to process, which we perceive as a sensation of heat.
Although the physiological mechanics are different, heat thermoception goes together with cold thermoception, and like with cold thermoception, sensing heat requires a baseline that we can use to experience the differential in temperature. This baseline can be the ambient or tepid temperature, or for more dramatic effect, we can use colder temperatures to have a wider swing. This is interesting, because we can move between three regions of temperature, creating at least six different relationships. What does going hot to cold mean versus cold to hot? How does tepid to hot or hot to tepid compare to cold to hot or hot to cold? How about the effects of swinging temperatures between these ranges? Can we tell a story with just these?
To use heat thermoception, we must understand what the meaning or understanding this sense brings. Heat will bring warmth and comfort, but it can also bring burning and pain. Furthermore, are there some groups that disdain warmth, or can they only thrive within it? What does warmth or heat symbolize culturally? This, as with most of the other senses, must be understood and used by the designer, because without this, the impact of the design would be lessened or lacking.
Like with cold thermoception, heat thermoception requires we use heat intermittently for the user to acknowledge the presence and use of the sense. Otherwise, the user will sit within the heat, not fully experiencing it and the knowledge or code being transmitted by the designer will not be taken or comprehended. Of course, the sense will be acknowledged if the designer has taken the time to create a meaning behind the use of the sense, and it is evident that not working through the full extent of meaning will result in a design that is lackluster. Therefore, the designer should have this narrative spelled out, like a story card, through the drawings and models of the project.
If a design were only heat thermoception, there would be a very narrow array of information that could be conveyed through the sense. Although we can sense heat, we have a limited range that we can feel it, meaning that the use of the sense is more or less off or on, and the way we understand how much greater the heat is, is through secondary effects on the body, such as sweat, overheating, and exhaustion. Without these other results, we are not able to produce a variation on the effects of heat, other than through the simple stimulation of the area that heat is sensed.
Other than controlling the ambient temperature, heat thermoception is typically ignored or avoided. Again, it is important to have a cultural understanding and knowledge of the context, and this is how the designer is able to organize and manage the narrative. Without the sense of heat, it is possible and most likely preferred for some designers that the sense is ignored. However, we must remember that it is another arrow in our quiver that allows us to tell a story and create interesting designs.
We can use heat to map on our bodies and in a space the locations of events and with the difference in temperature, we have a variable to provide a story. In other ways, we can encourage the interaction of people with the use of heat and heat sensing. This is interesting, because we can use heat at a distance for some communication, but by touch for very specific needs. The question is how do we define the language and grammar with limited variables. Time and area are useful and of course the use temperature helps. However, it might be simply a binary language or something akin to Morse code that we use. Again, is there any inherent meaning or symbolism present for the incorporation of heat into the design? Is it possible to create new meaning and symbolism?
We can retrofit an existing structure to incorporate heat by ensuring the temperature of the space is constant, and we can provide moments throughout the space that use heat thermoception. This cannot be continuous, or the variation and transmittance of information will not be observable. As mentioned above, we need to have differentiation in temperature over time, as well as through space. This change in temperature can be synced with other senses to create a sensory program. Can heat be used with smell to provide kind and friendly feelings? Can heat thermoception be used with pressure to create great intensity? How about using heat with sound to create off-balance designs for some purpose, such as psychedelia or evoking feelings?