What is Passivhaus/Passive House?

Comfortable

Passivhaus/Passive House homes maintain comfortable temperatures above 20°C in every room all throughout winter.
The air is still and there are no draughts. You don’t need to open windows.
The heat is ‘everywhere’. Like a warm blanket, the floor, walls, windows and ceiling are roughly at the same temperature and change temperature very slowly.
In summer the inside temperatures are kept mostly below 25°C.
There are no hot spots on the walls or ceiling. Heat from the hot sun can’t get in.

Efficient

Passivhaus/Passive House homes use very little energy and cost less to run than conventional houses.
Small low cost heaters and coolers are adequate for keeping the entire house warm in winter and cool in summer.
There is no need for gas and so it can be disconnected along with the supply charge.
There is less reliance on high-tech gadgets – just low-maintenance components like insulation, windows, and draughtproofing.

Healthy

The air inside a Passivhaus/Passive House is always fresh and is replenished 7 times a day – even with
the windows closed on chilly winter days.
Pollen, dust and pollution are filtered out of the incoming air stream, a must for allergy sufferers.
Bathroom floors dry out because they are ventilated every minute of the day, not just while the exhaust fan is running.
Mould has a hard time growing because of the lack of condensation on windows and walls.

How does it work?

Super Insulation

Passivhaus buildings are designed for their climate.
The insulation levels in the walls and roof are higher than mandatory standards.
The insulation is protected on the exterior using a breathable weatherproof barrier.
In cool climates, insulation is placed under slabs.
They are also designed for the site, so you can compensate for poor orientation using better insulation.

Advanced windows

Passivhaus buildings rely on advanced windows.
The window frames are made from insulating materials like wood, uPVC or thermally broken aluminium.
Glazing is double or triple paned with high insulation values yet allow good solar energy penetration.
They are designed to close airtight with double compression seals.
The size and location of the windows is critical and so modelling is performed to estimate summer heat gains and winter heat losses.

External Shading

Passivhaus buildings rely on external shading to keep cool in summer.
Deep overhangs are the simplest form of shading.
External vertical shading devices are most effective on west and east facing windows.
External motorised roller and venetian blinds are the most flexible types of shading.
Calculations are used to ensure there is enough sun shading in summer yet enough sun penetration in winter.

Airtightness

Passivhaus buildings are sealed tight.
They are draught-free for better comfort.
They are exceptionally quiet because sound can’t get in via air leaks.
Heat-leakage is avoided for better energy efficiency.
Moisture is managed to avoid damage inside walls.
The airtight seal is built for longevity and tested to assure quality.

Ventilation

The air in a Passivhaus is supplied through a mechanical ventilation system.
Fresh air is delivered continuously from the outside even when it is too cold to open the windows.
Heat recovery is used to transfer heat from the old air into the new air stream. This avoids cold draughts and saves on energy bills.
Filters remove pollen, insects and dust for cleaner air and better health.

Thermal Breaks

Passivhaus buildings make use of thermal breaks.
A thermal break is used to prevent a conductive material piercing through an insulation layer. It avoids heat leakage and condensation problems.
Some common thermal breaks:
Insulated blocks to separate slabs from footings
Rigid insulation to separate garage and house slabs
Thermally broken metal door thresholds
Insulated timber lintels above windows instead of steel
The remaining thermal losses are modelled to calculate their influence.

About H³Space

H³Space is a home energy efficiency consultancy business based in Canberra offering services to clients around Australia.

We specialise in Passivhaus/Passive House and low energy buildings. Although we don’t design buildings ourselves, we work can work with your architect, building designer, structural engineer and builder to ensure your home is comfortable, healthy and efficient to run.

For clients wanting the highest performance levels and guaranteed results, we can ensure your new or retrofit home is certified to meet the rigorous international Passivhaus standard.

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