Before ordering a window actuator, you should know how much force it needs. If the actuator is too weak, the window will not open or the motor runs constantly at its limit. Three steps give you a good estimate: determine the sash weight, apply the approximation formula, plan a reserve.<\/p>\n\n\n\n
In brief:<\/strong> You estimate the force a window actuator needs in three steps: determine the sash weight, apply the approximation formula, plan a reserve. For rooflights F \u2248 0.54 \u00d7 G applies, for bottom-hung and top-hung sashes in the fa\u00e7ade F \u2248 0.54 \u00d7 G \u00d7 stroke \/ H. Snow, wind and seals require additional reserve.<\/p>\n\n\n The glass weighs the most. As a rule of thumb: 1 m\u00b2 of glass weighs about 2.5 kg per millimetre of glass thickness<\/strong>. Double glazing with 2 \u00d7 4 mm glass therefore weighs around 20 kg per m\u00b2. Add the sash frame. If you want to know exactly, ask the window manufacturer or weigh the removed sash.<\/p>\n\n\n Window actuator manufacturers use simple formulas for a first estimate. Here G<\/strong> is the weight force of the moving sash in newtons (weight in kg \u00d7 9.81), Stroke<\/strong> the Stroke length<\/a> and H<\/strong> the sash height:<\/p>\n\n\n The difference is large: a vertical tilt window needs only a fraction of the force because the actuator hardly has to lift any weight. A rooflight, on the other hand, has to be lifted almost completely.<\/p>\n\n\n Why 0.54 and not 0.5?<\/strong> Physically, an actuator opposite the hinge side gives a factor of 0.5, because the centre of gravity lies in the middle of the sash. Manufacturers add a safety margin, for example 0.54 (Aum\u00fcller) or 0.68 (GEZE for the E 740 chain actuator). In this guide we use 0.54. The binding sizing follows the documentation of the actuator and window manufacturers.<\/p>\n\n\n\n The formulas take into account neither wind nor snow, seals or stiff fittings. Therefore always plan a clear force reserve; correspondingly more for roof windows and rooflights with snow and wind load. An actuator with reserve runs more quietly and lasts longer. More on the influences: Technical design of window drives<\/a>.<\/p>\n\n\nStep 1: Determine the sash weight<\/h2>\n\n\n
Step 2: Apply the approximation formula<\/h2>\n\n\n
Step 3: Plan a reserve<\/h2>\n\n\n
Calculation examples<\/h2>\n\n\n