The passive building principle
The passive principle
It all fits on a sheet of paper.
Five principles and a few figures worth knowing. Scroll: the sheet folds itself.
Folded
One house, one rule per face.
It turns to show each face in turn. You can also spin it with your finger.
Envelope
A continuous coat, an airtight line, no weak point.
- Roof, ground floor
- U ≤ 0.10 to 0.15 W/(m²·K)
- External walls
- U ≤ 0.15 W/(m²·K)
- Thermal bridges
- Ψ ≤ 0.01 W/(m·K)
- Airtightness
- n50 ≤ 0.6 h⁻¹
Windows
Sun comes in, heat stays in.
A window is judged as a whole: glazing, frame, spacer and installation in the wall.
Uw = (Ug·Ag + Uf·Af + Ψg·Lg + Ψinstall·Linstall) / (Ag + Af)
g: glazing · f: frame · Ψg: spacer · Ψinstall: junction with the wallHeat-recovery ventilation
Fresh air arrives already lukewarm.
Stale air going out hands its heat to the fresh air coming in.
- Supply air
- 30 m³/h per person
- Extract air
- 20 to 60 m³/h per room
- Heat recovery efficiency
- ≥ 75 %
- Electricity use
- ≤ 0.45 Wh/m³
Opaque elements
A wall is a sum of layers.
Each layer resists according to its thickness and its material. You add them up.
U = 1 / ( Rsi + Σ d/λ + Rse )
d: layer thickness [m] · λ: thermal conductivity [W/(m·K)] · Rsi, Rse: surface resistancesUnder the roof
Air flows through the whole house.
Supplied to the living rooms (blue), it passes under the doors (green) and is extracted in the kitchen and bathroom (orange).
- Air change rate
- 0.3 to 0.5 h⁻¹
- Air speed in ducts
- 2.5 to 3 m/s
Pmax = airflow × 0.33 × (Ts − Ti)
Heating through supply air: Ts 52 °C at most, Ti 20 °C · 0.33 Wh/(m³·K): heat capacity of airThe criteria
Passive is a calculated result.
- Heating demand
- ≤ 15 kWh/(m²·a)
- or heating load
- ≤ 10 W/m²
- Cooling demand
- ≤ 15 kWh/(m²·a)
- Overheating (above 25 °C)
- ≤ 10 % of the time
- Airtightness
- n50 ≤ 0.6 h⁻¹
- PER
- Generation
- Classic
- ≤ 60
- –
- Plus
- ≤ 45
- ≥ 60
- Premium
- ≤ 30
- ≥ 120
