Screed radiant floor

A floor build-up in which a coil of pipes, embedded in the screed, turns the whole floor into a large low-temperature heat emitter. The heat rises by radiation, even and silent; the same system can cool in summer. Below, a studded insulation panel directs the heat upward and holds the pipes.

The radiant floor replaces the local heat emitters (radiators) with an extended, mild surface: the whole floor. A network of pipes embedded in the screed circulates low-temperature water (30-40 °C), and the floor releases heat by radiation upward. The result is even comfort, with no air movement or raised dust, and excellent performance with renewable sources.

The energy advantage comes from the large radiant surface: to heat a room, water only a little warmer than the air is enough (30-40 °C against the 60-70 °C of a radiator). This low temperature is the ideal regime for heat pumps and solar systems, which perform far better when they have to produce warm rather than hot water. The floor also stores heat in its mass and releases it gently, damping the swings.

The mass of the screed is both the strength and the limit of the system. On one hand it stabilises the temperature and lets one exploit tariffs and the sun; on the other it makes the system slow to respond: rapid on/off has no effect, and the control must be set on weather-compensated logic and anticipation. Screed thickness, cover over the pipes and coil pitch must be balanced to combine good output with manageable inertia.

By circulating cool water (16-18 °C), the same floor can cool in summer. But here a physical limit appears: if the surface falls below the dew point of the indoor air, condensation forms on it, slippery and harmful. For this reason radiant cooling always requires humidity control (dehumidification) and a control strategy that keeps the floor temperature above the dew point. The cooling output is therefore more limited than the heating one.