A Passive House (Passivhaus) is a building in which a comfortable interior climate can be maintained without active heating and cooling systems. The passive house is the ultimate in low energy building and is recognised worldwide as the most advanced in terms of energy performance of buildings. The passive house offers one of the most desirable technological and economical solutions for comfortable living and working.

The Passivhaus standard was developed by Professor Wolfgang Feist of the Passivhaus institute in Germany. The passivhaus standard set out a way to reduce energy use for space heating and cooling by 90% compared to a standard house.

The standard formally sets out the criteria for this so that a dwelling can be certified as being Passivhaus.

To meet the standard, software called the Passivhaus Planning Package (PHPP) is used to enter full details of the project in question – such as U values of walls, cold bridging details, solar gain etc. Irish Eco Homes have our own PHPP experienced designer  

The principle minimises heat loss in these main ways:

• Excellent levels of insulation
• Minimal cold bridging in the external frame
• Excellent levels of air tightness
• Controlled internal air quality by mechanical ventilation system
• Clever design of solar gain and summer shading to maximize winter heat gain from the sun.
• Use of low energy household appliances and lighting.

Formally the principle is defined as the total energy demand for space heating and cooling is less than 15kWh/m2/yr of treated floor area - a standard house uses around 110kWh/m2/yr. The total primary energy use for all appliances, domestic hot water and space heating and cooling is less than 120 kWh/m2/yr.

Construction Issues 

A particularly important aspect to meeting the standard is extreme attention to detail on site during construction. For example to achieve the air tightness specification demands no worker on site cuts corners – inspection of work and attention to detail are critical to avoid breaks in the air-tight layer. Good detailing around windows are doors is also vital to avoid drafts going right through the building fabric. Small breaks in the external air tight layer means cold air can pass straight through the insulation making it ineffective.