Beautiful, Sustainable Building Design

PassivHaus

Passive House (or PassivHaus to our European cousins) is a fabric first approach to building design. It assumes that indoor comfort is the primary goal and that the energy efficient delivery of comfort is the logical and morally sensible pathway to achieve it.

Passive House shares many similarities with Passive Solar Design. If you want to understand the differences, see our Passive Solar Design vs Passive House 101.

Passive House defines indoor comfort as being 20-25ºC with no more than 10% of the year exceeding 25ºC. It also includes limits on humidity. A Passive House building will consume no more than 15kWh/m2/year for heating (and cooling of installed).

All Passive House buildings have five key elements:

  • Solar control
  • Appropriate insulation
  • Airtightness
  • High performance windows
  • Balanced ventilation with heat recovery
  • Solar Control

A Passive House carefully regulates the amount of direct sun entering the building. Appropriate orientation and shading devices ensure that enough winter sun is admitted for warmth while avoiding overheating in summer.

  • Appropriate insulation

The design process for a Passive House ensures that the appropriate levels of insulation are provided. This guarantees thermal comfort but also optimises the cost of the build; genuine value engineering.

  • Airtightness

Airtightness is critical to Passive House performance. By achieving the low infiltration rates of 0.6 air changes per hour (measured at 50Pascals) the air within the building is carefully controlled. Low air leakage prevents unwanted heat transfer, increases the predictability of building performance and allows all building elements to be reliably optimised.

  • High Performance Windows

Great windows are crucial in a Passive House building. They are a key element in controlling heat flow into and out of the building. They need to be air tight and have good insulation values (measured as U values for windows, lower numbers are better). In Australia these will need to be double glazed, in some colder climates triple glazing may be necessary. Generally, the better quality glazing also improves the acoustic performance of the windows too.

  • Balanced ventilation with heat recovery

An airtight building needs a reliable source of fresh air for both human comfort and building longevity. While you can still open doors and windows the Heat Recovery Ventilation (HRV) system will continually deliver 35m3/hour of fresh air person regardless of outdoor weather conditions.  A Passive House HRV has an efficiency of at least 85% and uses very little electricity to run; in UK social housing it is a mandatory lease requirement that the units are not turned off as the fresh air is so important and the energy use so negligible.

This 90 second video gives a great explanation of Passive House. Note the cold climate focus and bear in mind how the same principles work just as well in warmer places.

The design process for a Passive House requires that the building be modelled in the Passive House Planning Package (PHPP). This software is the most accurate in the world in terms of predicted performance measured against real world performance.

A great design tool, Envirotecture use the PHPP to optimise the building finding efficiencies with each iteration.

Envirotecture director Andy Marlow is a certified Passive House Designer.

Tried and tested

There are over 40,000 certified Passive House buildings in the world across all climate zones. They consistently deliver high levels of comfort and low energy use

Contact us to find out how a Passive House building can work for you. Envirotecture home

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