The temperature of a material would not seem to be an obvious propert. Why reflect on it?
Increasingly the design community is incorporating product perception, whereby a material’s cuddle factor plays an important rol. And temperature is part of this. A banister, the sit of a park bench, your desk, the bathroom floor; any reflecting on surfaces a person comes into barefoot contact with must include the factor temperature sensation.
A person determines a material’s temperature through the skin. There are several factors that determine how our skin perceives the temperature of a material. First, the material’s heat conductivity coefficient. Then, structure and the degree of surface contact. Plus, color and reflection grade.
Heat Conductivity Coefficient
A material feels cold to the touch at a high heat conductivity coefficient; because a material with a high heat conductivity coefficient extracts heat from the body at a fast rate. Only when the material has a higher temperature than the body will it feel warm to the touch. For instance, our office contains only desks made of stainless steel. In itself a material with a cold surface, were it not for the fact that the desks are situated over radiators; the radiated heat is conducted by the material the desks are made of so that in winter they are lovely and warm to the touch and in summer they are lovely and cool to the touch.
Comparing heat conductivity coefficients of materials, we encounter quite a few surprises. Below are listed a number of materials ranging from “cold to the touch” to “warm to the touch” computed by average values. Oddly enough glass, a material quite cold to the touch, comes under “warm to the touch”. And an artificial material proves to be relatively cold to the touch.
Not only material type determines temperature sensation; its application does too. For instance, aluminum foam is warmer to the touch than a sheet of aluminum because its contact surface is smaller. Equally for brick; a coarse sanded brick is warmer to the touch than a clean lined tight form brick, while both are made of the same clay.
There is a myth about the color of a radiator, i.e. darker colors emit more heat (infrared radiation) than lighter colors. However, the color of a radiator does not affect heat emission.
Darker colors emit precisely the same heat radiation as lighter colors, except metallic paints; these emit less heat than common paints. A black surface in the sun does get hotter than a white surface. The reason is that the “visible” portion of sunlight is transformed into heat. A white surface reflects much sunlight and transforms only some of it into heat, a black surface absorbs the rays, transforming them into heat. Radiators and stoves only emit heat, they do not emit light as the sun does. So a white radiator gives off as much heat as a black one.
Roxipan makes wood panels with a decorative top coat of concrete. This unit received a warm golden colored structure resulting in a warmer perception than its solid gray smooth cousin.
Foin; metal “chain mail” in various metal colors. The copper “golden” version results in a warmer perception than the aluminum version but this is merely a deception played on our eyes.
Juicy Glass; this magnificent manually shaped glass is a celebration of colors, transparency and “warm” golden shades.
Romanoff; wallpaper covered in tiny glass pearls, in white and golden colors.
Regupol; carpet made of recycled rubber. Warm, soft and insulating.
Somic; makes textile out of paper yarns. Paper has a lower heat conductivity coefficient than wood; this factor in combination with the rough texture of the textile makes this material feel warm to the touch.
Ice Pearl; the name says it all. This marble feels cold, chilling and ruthless. And it is. With its smooth sealed surface and, after metal, highest heat conductivity coefficient this material requires some serious under-floor heating.