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The Best Heating Is under the Window to Prevent Draught


The University Centre for Energy-Efficient Buildings of the CTU has been examining the influence of four different types of electric heating on the air flow in the room. This research has also shown that even buildings with low energy consumption can encounter problems with draught that causes local thermal discomfort at some places when it is freezing.

Tests of heating surfaces produced by the FENIX Trading company from Jeseník took place in a simulation of a real environment that was prepared by scientists in the parallel climatic cabin in UCEEB laboratories in Buštěhrad. Tests of an electric convector, glowing heating panel, floor heating and ceiling heating were carried out. It was proven that even well-insulated buildings with low energy consumption encounter local problems with draught at outside temperatures under the freezing point. The draught gets developed in front of windows, doors and other filling constructions which have worse thermal-insulation abilities and, as a result, lower surface temperatures as compared to walls.

Heating surfaces located directly under the window proved the known fact that unlike large-area systems (floor heating and ceiling heating), these can totally limit the influence of cold air flow from the window. The price for this is faster air flow in the room and higher temperature stratification (change of air temperature depending on the height). Large-area systems of heating proved the ability of ensuring uniform temperature conditions in the heated room. However, they are not able to stop the infiltration of the air flow from the window to the room. As a result, thermal comfort at the ankle level gets poorer in the distance of about 2 meters from the window.


Proudění vzduchu v okolí okna v zimních podmínkách

Air flow around the window in winter conditions