Passivhaus Design

As certified European Passivhaus Designers Eco Design Consultants can design your new home or any building to one of the three Passivhaus Standard, classic, premium or plus; or if retrofitting existing buildings, to the EnerPHit standard. The Passivhaus Standard is a construction standard developed by the Passivhaus Institute in Germany ( for highly energy efficient buildings utilising passive solar energy using windows that take in more heat energy than they lose (triple glazed with a window U value of less than 0.8W/m²K). The standard can be met using a variety of design strategies, construction methods and technologies and is applicable to any building type.

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The Passivhaus Standard is a specific construction standard for buildings which results in good comfort conditions during winter and summer, without traditional space heating systems and without active cooling. The primary focus in building to the Passivhaus Standard is directed towards creating a thermally efficient envelope which optimises free heat gains in order to minimise space heating requirement. Structural airtightness (reduction of air infiltration) and minimal thermal bridging are essential. A whole-house mechanical heat recovery ventilation system (MHRV) is used to supply controlled amounts of fresh air to the house. The incoming fresh air is pre-heated, via a heat exchanger, by the outgoing warm stale air.

If additional heat is required, a small efficient backup system (using a renewable energy source, for example) can be used to boost the temperature of the fresh air supplied to the house. Of course, windows are fully openable should you wish to do so.

One of the main advantages of Passivhaus design is COMFORT. In order to maintain high comfort levels in any building, heat losses must be replaced by heat gains. Heat losses occur through the building fabric due to transmission through poorly insulated walls, floor, ceiling and glazing as well as from uncontrolled cold air infiltration through leaky construction and poorly fitted windows and doors.

In a Passivhaus, the heat losses are reduced dramatically (through better insulation and airtight detailing) so that internal gains and passive solar gain contribute a relatively high proportion of the total need. As a result of this, a smaller space heating system is therefore required compared to that needed in a conventional poorly performing dwelling.

Passivhaus Classic:

• Specific space heating demand ≤ 15 kWh/(m2a)

• Specific space cooling demand ≤ 15 kWh/(m2a)

• Heating load ≤ 10 W/m2

• Specific primary energy demand ≤ 120 kWh/(m2a)

• Air changes per hour ≤ 0.6 @ n50