Passive principles for good design

Windows may be double or triple glazed.

By Danielle Kutchel

Passivhaus is gaining traction in Australia for its innovative ways to save money, save the environment and still create a cosy home for all types of families.

IN case you’re not familiar with the term, Passivhaus is a German word for a set of governing standards for house design.

It first emerged in Germany in the late 1980s, after a conversation between Bo Adamson of Lund University, Sweden, and Wolfgang Feist of the Institute for Housing and the Environment, Darmstadt, Germany.

The first row of Passivhaus town houses was built in Darmstadt in 1990.

It has since developed into a housing performance standard for energy efficiency and is ideal for people looking to save money on energy bills. Passivhaus design offers numerous benefits to home owners, including less energy usage as the house stays within a comfortable temperature range, less dust and mould, and fresh clean air

There are five core elements that underpin Passivhaus design. These are:

1. Insulation blanket

2. High-performance windows and doors

3. Elimination of thermal bridging

4. Air tightness

5. Ventilation

Each of these plays an important part in creating an energy-efficient home.

Insulation blanket

A house designed according to Passivhaus principles is highly insulated, far more so than a typical house. Insulation is used in the walls, floor and ceiling, or the house can be constructed from insulating materials like straw bales. The high level of insulation works to minimise radiant heat gain in hot weather, and conductive heat loss in colder months.

High-performance windows and doors

Typically, the doors and windows in a Passivhaus are also well insulated. Windows may be double or even tripled paned, depending on where the house is built and what the conditions are like. Low-emissivity glass may be used instead; this is a type of glass that has a thin coating to reflect heat. Gaps between the panes are filled with still air or gas. Special air seals and thermal break window frames add to the insulation and noise-reduction.

Elimination of thermal bridging

A true Passivhaus is designed with thermal bridging in mind. Thermal bridging refers to a part of a house where heat or cold is easily conducted in and out. In a Passivhaus, this should be minimised or eliminated through continuous insulation throughout the building.

Air tightness

Passivhaus principles call for total air tightness in the building according to strict calculations. All joints are sealed over, and air transfer is managed by controlled ventilation, resulting in high quality internal air. Air tightness helps the house maintain a comfortable temperature for longer.

Ventilation

While natural ventilation can be employed, typically a Passivhaus uses mechanical ventilation with heat recovery. The ventilation unit recovers heat and cool from within the house to be dispensed throughout, while also filtering air that comes into the house to flush out stale air. Passivhaus designs usually don’t need heating or cooling to be installed as the ventilation and heat recovery system maintains the house’s temperature at a comfortable level.

It is possible to have a house that borrows some Passivhaus principles, without being a true ’Passivhaus’. For example, double glazed windows are becoming more and more popular as home owners and builders realise just how effective they are at keeping a house at a comfortable temperature and minimising noise. Many Passivhaus principles can be expensive to install, however rumours suggest the Australian building industry will move to incorporate many of the Passivhaus standards and measurements into Australian building standards – so expect to see and hear more about them in the coming years.

Regardless, the principles can be applied today in various degrees to create an energy-efficient, comfortable and environmentally-friendly dwelling.