It’s often asserted by people in the building trade that tiles are one of the coldest flooring materials available. But is this really the case? In this article we put that assertion to the test.
Thermal Conductivity of the Material
Heat transfer involves the movement of heat from a relatively hot object to a cooler one, rather than the transfer of ‘coldness’ between the two bodies. So when we grab a lump of ice and our hands get cold, we are not actually absorbing the ‘cold’ from the ice. Rather, heat is transferring out from our warm hands into the colder ice, and thus our hands become colder (and the surface of the ice starts to melt).
Not every material transfers (or in scientific terms ‘conducts’) heat at the same rate. Some materials - such as metal or stone - conduct heat very effectively, whereas others - such as cloth or air - have low conductivity and thus act as good insulators. Tiles, for example, are a far superior conductor of heat than carpet or wood. Thus, when you step out of your bed onto carpet on a cold morning, the carpet does not have the conductive ability to remove the heat from your feet as easily as a tiled floor. Consequently the carpet feels warmer than the tiles, despite the fact that both the carpet and tiles are at the same ambient temperature.
Density of the Material
Although often presented as such, the full reason why tiles feels colder than carpet on a cold day is not quite as simple as above. A further variable that plays a considerable role in creating the illusion that one surface is colder than another, even though both are at the same temperature, is the density of the materials involved. In practice, if you have two different materials of equal size (i.e. volume) at, say, 10°C and you wish to increase their temperatures to 20°C, the denser of the two materials will need to absorb more heat energy to reach the desired temperature. Thus as tile is considerably denser than carpet, it will draw more heat energy out of your foot than a similar volume of carpet.
Why Tiles Feel Colder than Carpet - When the Floor is Cold
To get a better understanding of this physical reality, let’s take a look at what’s going on at a more microscopic level. As soon as your bare foot meets carpet, the fibres you come into contact with - which are not particularly dense - warm up relatively quickly without drawing much heat energy away from your skin. As carpet is a poor conductor, the heat in these fibres is not conducted away to other parts of the carpet and thus the carpet feels warm – whereas in fact the carpet is not especially warm, rather the fibres you stepped on have rapidly absorbed heat from your foot and retained that heat.
But if you step on a tile on a cold morning, first of all it will absorb more heat energy per unit volume from your foot due to its high density. And secondly, as it’s an excellent conductor, the heat it draws out of your foot will quickly be dispersed to other parts of the tile leaving you with that cold feeling underfoot. It is this double process that creates the illusion that the tiles are colder than the carpet. And for the very same reason, people dread the “freezing” porcelain toilet seat on a winter’s morning. In fact, the seat is no colder than any other material - such as the towel - in the bathroom. It simply has a higher conductivity and density and thus removes more heat from your relatively warm body more rapidly. Thus any statement that tile is one of the coldest floor materials is, quite simply, a misconception. Tiles are no colder than any other material, but they are perceived as being cold.
If all of this seems a bit complicated, then have a look at the following short video in which the Canadian science communicator Derek Muller explains this concept in an entertaining, jargon-free fashion:
Tiles Feel Warmer than Carpet (when the floor is hot)!
Essentially, your sense of whether an object is hot or cold depends on the direction of heat flow between it and your skin. An easy way to demonstrate this is by dipping one of your hands into warm water and the other into cold water. If you then dip both hands immediately into room temperature water, your warm hand will tell you that the water is cool, whereas your cold hand will trick you into believing that the water is warm. So when heat flows from your body to any other object (such as the floor), that object feels cold. And conversely, when heat flows from any object into your body, that object feels warm. And if that object is a good conductor of heat, then it will transfer heat to your relatively cold body quicker than a poor conductor at the same temperature.
And this is where tiles really come into their own when it comes to heating! A heated tile floor will transfer heat to you much quicker - and actually feel much hotter – than a heated carpet or wood floor. A heated tile can conduct heat into your feet very rapidly – just as rapidly as a cold tile can conduct heat away from your feet. We saw this same principle in the above video where the ice melted far quicker on the aluminium than on the plastic, even though both were at the same temperature.
And it’s for this reason that of all flooring materials, tile is the very best material to use with under-floor heating, a topic we’ll cover in our next article.
Tile is denser and transmits heat far more effectively than other common flooring materials such as carpet, wood, laminate, and vinyl. For this reason tile is often said to be ‘colder’ than these types of flooring. However the reality is that tile is no colder than any other material in the room. It simply feels colder when the floor is cold as it conducts more heat energy out of your feet at a faster rate than other flooring material. However conversely, if you have a well heated floor (and let’s be honest who doesn’t want one of those in their lives), then there’s no better material than tile to convey that snug, comfy feeling of warmth into your body. So let’s kill the fallacy here and now – tile is not cold, cold floors are cold.