Design and planning principles 20°C Solid construction with composite thermal insulation system
20°C 20°C –10°C –10°C –10°C
Unfavourable window position psi-value of installation (Y): 0.104 W/mK Uw-value (installed): 1.074 W/m2K surface temperature frame/ wall: 17.1 °C Space heat demand for standard building with Passive House insulation and energy-efficient ventilation unit: single-family home: 18.6 kWh/m2a multi-family home: 16.1 kWh/m2a
Favourable window position psi-value of installation (Y): – 0.007 W/mK Uw-value (installed): 0.755 W/m2K surface temperature frame/ wall: 18.6 °C Space heat demand for standard building with Passive House insulation and energy-efficient ventilation unit: single-family home: 12.8 kWh/m2a multi-family home: 12.4 kWh/m2a
Brettstapel wall with lightweight, insulated cladding
20°C
–10°C
Unfavourable window position psi-value of installation (Y): 0.062 W/mK Uw-value (installed): 0.935 W/m2K surface temperature frame/ wall: 17.5 °C Space heat demand for standard building with Passive House insulation and energy-efficient ventilation unit: single-family home: 17.6 kWh/m2a multi-family home: 15.1 kWh/m2a
Favourable window position psi-value of installation (Y): 0.002 W/mK Uw-value (installed): 0.778 W/m2K surface temperature frame/ wall: 17.5 °C Space heat demand for standard building with Passive House insulation and energy-efficient ventilation unit: single-family home: 13.9 kWh/m2a multi-family home: 13.0 kWh/m2a 4.16
a
b
4.17
a
b
4.18
40
The importance of window placement The development of detail solutions for windows and other glazed openings has a significant impact not only on the appearance of the building. The way in which they are fitted also affects aspects of construction and building physics. Choice of window frame Due to the large variety of window products and other glazing systems (e.g. framed glazing), the initial step in the detailing of openings should include which kind of frame and, more precisely, which product is best suited to the task. The depth and the width of the frame, including the profile, are fundamental aspects that determine the overall appearance of the window in its opening. The amount of solar gain is also dependent on the frame. Furthermore, the design of the frame determines the extent as to which the window can be wrapped in insulation (either on the rear side or on the top of the frame). In terms of creative, ecological and technical viewpoints, the frame material and surface finish are also important aspects. The energy performance values are also of great importance when choosing the window product since they have a considerable impact on the energy balance. These include the U-value of the frame and the glazing, the g-value of the glass and the psi-value of the spacer. Window position According to the principle of homogeneity, the windows in Passive House buildings should always sit in the same layer as the insulation, since this is the only way to ensure a good continuation of the insulation plane. The ideal position in the middle of the wall insulation is however fairly difficult to accomplish due to the window brackets. In the case of solid masonry walls, a solution, now established as common practice in Passive House buildings, is to fit the window immediately in front of the exterior wall. This involves structurally supporting the window either with steel angles and/or a bottom bracket using either a timber batten or high strength insulation board, which can function as a fixing base. The heat loss rises considerably if the window is positioned in the same plane as the masonry wall (fig. 4.16). The same applies to timber constructions; however, in this case, the position of the window can be determined more freely since the actual fixing is not limited to a single position. The detailing of the