Self-Regulating Floor Heating Systems in Low Energy Buildings

The performance of an inexpensive floor heating system is studied by means of a numerical simulation tool. The study deals with an energy efficient detached single-family house. A building with such low space heating demand (25-30 kWh/m2/year) yields a low floor surface temperature and this in turn means that the so-called self-regulating effect is significant. Initially, the design of the pipe circuits is studied. Especially the allocation of heat between different rooms are studied; the purpose is to find a design where the set-up of required fluid supply temperatures are as uniform as possible among the pipe circuits. Detailed simulations of the heating season is conducted for two simulation cases, one with a constant supply temperature, derived from the initial simulations; and a second case with a variable supply temperature. The results yield an apparent effect of self-regulation; the heat flux from the embedded floor heating pipes increases when the indoor air temperature declines and can be totally blocked when high indoor temperatures arise. Furthermore, excess heat is transferred from over-tempered zones towards the manifold assembly in the hydronic system. The occurrence of heat extraction trough floor heating pipes in certain zones has a levelling effect of the indoor temperature distribution