Glazing ratios

It is possible to design a Passivhaus with lots of glazing. PHPP allows us to balance the high losses with extra gains and additional insulation. We can then design out the resultant summer over heating by adding shading in the form of overhangs and blinds. This might work in a model but in reality it is a very expensive way to meet the Passivhaus standard and it will be very difficult to regulate summer temperatures.

A far better approach is to design for good, but not excessive daylight, with a maximum of about 25% of the internal south facade as glazing. All other orientations should ideally have only as much glazing as is needed for views, daylight and ventilation.

As a rule of thumb total glazing area (excluding frame) of around 15-20% of treated floor area (TFA) is a good starting point for design. 

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