uPVC for Passive House Design

uPVC for Passive House Design

Passive House design principals incorporate a holistic approach to the construction of a building, which means that all the methods used in the construction of the building work together to achieve the end result. The Australian Passive House Association lists the design principals of a Passive House as:

  • Airtightness
  • Thermal Insulation
  • Mechanical Ventilation Heat Recovery
  • High Performance Windows
  • Thermal Bridge Free Construction

So, as manufacturers of uPVC windows you may have already guessed where we fit in, but what are the specifics that we can provide with the windows and doors that will work into a passive design? Read on for some of the ways where Ultimate Windows can contribute using our uPVC frames.

High Performance Windows

Let’s start with the frames design, using a uPVC frame, such as the Legend system offered by Ultimate Windows, you can eliminate any thermal bridge in the window frame, meaning that there will be no transfer of temperature from the outside of the building to the inside through the frame of the window or door. This is because of the properties of the uPVC material; uPVC is a non-thermally conductive material and will not transfer the temperature from its outside surface to the inside surface.

When combined with the right glass type for the situation you can reach u-Values as low as.

1.7 for Double Glazing*

1.2 for Triple Glazing*


uPVC windows can come in all shapes and sizes, but a key element to a Passive Design is the airtightness of the building. The goal is to limit the number of cracks or gaps in the building’s envelope. This enables the resident to fully control the air in the internal environment. An important consideration is the type of windows used for this method of construction. Ultimate Windows recommends looking at window and door systems that will provide a gasket seal of the window sash to the window frame. Window and Door types that include a gasket seal in the Legend System include:

  • Tilt & Turn (Door or Window)
  • Tilt & Slide (Door or Window)
  • Hinged Doors (Door)
  • Tilt in (Window)
  • Lift & Slide (Window)

Thermal Bridge Free Construction

The use of great insulation, high performing window frames and creating an airtight envelope need to be supported by the construction method to ensure there are no inlets for thermal transfer. When it comes to the installation of the windows this means filling in gaps around the frames and the use of thermal tapes and membranes to ensure the internal and external environments are kept apart from each other. We also provide options in regard to revealing the window frames to allow thermal breaks to be maintained lowering the risks of increased energy consumption, condensation and negative impacts to thermal consumption.

Through the use of our Legend system in Triple Glazing, Ultimate Windows can assist with ensuing that your windows and doors will meet the standards required to build your passive home. By providing not just the windows and frames that meet the standard but also the advice and trouble shooting for you to maintain the thermal envelope in your project.

*u-Value 1.7 achieved with double glazing in gasket sealed window system using: Clear Low-E 4mm / 16mm argon gap / Clear 4mm, using warm edged spacer.

**u-Value 1.2 Achieved with Triple glazing in gasket sealed window system using: Clear Low-E Plus 5mm / 16mm argon gap / Clear Low-E 5mm / 16mm argon gap / Clear Low-E 5mm, using a warm edge spacer.

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