Technical Information
The Passive House standard can be resumed by five fundamental principles, to which we believe it is essential to add a sixth technical design consideration tailored to Portugal’s geographical context and climate conditions:
High Levels of Insulation in the Building Envelope
Walls, roofs, and floors must be insulated well beyond conventional requirements, with the goal of minimising unwanted heat losses and gains, maintaining a stable indoor temperature with very low heating or cooling demand.
High-Performance Windows and Doors
Windows and doors must feature high thermal efficiency, using double or triple glazing with low-emissivity coatings and inert gas fills. They should be strategically positioned to maximise solar gains in winter and minimise overheating in summer.
Mechanical Ventilation with Heat Recovery (MVHR)
Airtight Building Envelope
The building must be continuously sealed to prevent uncontrolled air infiltration and exfiltration, which significantly reduce efficiency and often lead to moisture-related pathologies like condensation and mould. Airtightness is verified using a Blower Door Test, and must meet the strict limit of 0.6 air changes per hour at 50 Pa.
Thermal Bridge-Free Construction
Thermal bridges are areas where heat escapes easily from inside to outside in winter, or vice versa in summer. Their elimination is crucial to improve energy efficiency and prevent condensation and structural pathologies.
Solar Orientation, Shading, and Solar Gains
In Portugal’s climate, with substantial thermal variations between winter and summer, special attention must be given to the solar orientation of the building.
The design should maximize passive solar gains in winter, while incorporating effective passive shading strategies to prevent overheating in summer. Proper glazing orientation and passive shading systems are essential to achieving Passive House certification in this climatic context.
Criteria for Passivhaus Certification
Heating
Annual Demand
<15 kWh/(m2.yr)
Peak Demand
<10 W/m2
Cooling
Annual Demand
<15 kWh/(m2.yr)
Peak Demand
<10 W/m2
Primary Energy
Total Primary Energy (PE)
<120 kWh/(m2.yr)
Renewable Primary Energy
(PER)<60 kWh/(m2.yr)
Air Tightness
n50 (pressurisation test)
< 0.6 renewals/hour
Thermal Comfort
Temperature between 20ºC (Winter) and 25ºC (Summer)
Excess Temperature
< 10% of the summer time (ideally between 2% and 5%)