Glass is generally more heat-efficient than tiles when it comes to thermal conductivity. Glass has a lower thermal conductivity compared to tiles, which means it conducts heat less effectively. The thermal conductivity of glass is typically around 0.8 W/m·K, whereas tiles can range from 1.8 to 2.5 W/m·K, depending on the type of tile material. This lower thermal conductivity in glass results in better insulation properties, making it more energy-efficient for applications where heat retention or control is a concern.

The reason glass is more heat-efficient lies in its molecular structure and composition. Glass is an amorphous solid, meaning it lacks a regular, repeating pattern of atoms. This structure contributes to its lower thermal conductivity. Additionally, glass is often treated with coatings or tints that further reduce its thermal conductivity, enhancing its heat-insulating capabilities. For instance, low-emissivity (Low-E) glass coatings can reflect infrared radiation, which helps maintain indoor temperatures.

On the other hand, tiles are made from various materials such as ceramic, porcelain, stone, or glass. These materials have higher thermal conductivities due to their crystalline structures and denser compositions. Tiles are also thicker than glass, which increases their thermal mass and further enhances their heat retention properties. However, this also means that tiles are less efficient at conducting heat compared to glass, especially when considering the same thickness.

Data from the American Society for Testing and Materials (ASTM) provides further evidence of the thermal conductivity differences between glass and tiles. According to ASTM standards, the thermal conductivity of glass typically ranges from 0.8 to 1.0 W/m·K, while ceramic tiles can range from 1.8 to 2.5 W/m·K. This data reinforces the notion that glass is more heat-efficient than tiles.

In conclusion, glass is more heat-efficient than tiles due to its lower thermal conductivity and molecular structure. This makes glass a preferable choice for applications where heat retention or control is a priority, such as in windows, skylights, and solar panels. While tiles have their own advantages, such as better heat retention and durability, glass outperforms them in terms of heat efficiency.