Passive House design

Living Logic are certified Passive House consultants, working with you on new build or refurbishment

‘Passive House’ is not a brand name but a tried and tested construction method that can be applied by anyone, anywhere.

It is a building standard that is energy-efficient, comfortable and affordable at the same time, yet a Passive House is more than just a low-energy building.

Passive House explained

Wanting to know more?  Before reading on watch this video for a quick explanation…

Benefits of Passive House design

  • Passive House design allows for heating and cooling related energy savings of up to 90% compared with typical building stock and over 75% compared with average new builds.  In terms of heating oil, a Passive House building uses less than 1.5 litres per m2 of living space per year – far less than typical low-energy buildings
  • Passive House buildings also praised for the high level of comfort, using energy sources from inside such as body heat from the residents or solar heat entering the building, making heating a lot easier
  • Superior windows and a building shell consisting of highly insulated exterior walls, roof and floor slab keep the desired warmth within the building – or undesirable heat out
  • A ventilation system consistently supplies fresh air making for superior air quality, without causing any unpleasant draughts, and a highly efficient heat recovery unit allowing for the heat contained in the exhaust air to be re-used

Passive House criteria

For a building to be considered a Passive House, it must meet the following criteria:

  • Space Heating Energy Demand

    Not to exceed either 15 kWh per m2 of net living space (treated floor area) per year, or 10W per m2 peak demand. In climates where active cooling is needed, the Space Cooling Energy Demand requirement roughly matches the heat demand requirements above, with a slight additional allowance for dehumidification

  • Primary Energy Demand

    The total energy to be used for all domestic applications (heating, hot water and domestic electricity) must not exceed 120 kWh per m2 of treated floor area per year

  • Airtightness

    A maximum of 0.6 air changes per hour at 50 Pascals pressure (ACH50), as verified with an on-site pressure test (in both pressurised and depressurised states)

  • Thermal comfort

    Must be met for all living areas during winter as well as in summer, with not more than 10% of the hours in a given year over 25°C (for a complete overview of general quality requirements (soft criteria) see Passipedia)

Passive House principles

All of the above criteria is achieved through intelligent design and implementation of the 5 key Passive House principles:

Passivhaus priciples
All opaque building components of the exterior envelope of the house must be very well-insulated. For most cool-termperate climates, this means a heat transfer coefficient (U-value) of 0.15 W/(m²K) at the most, i.e. a maximum of 0.15 watts per degree of temperature difference and per m2 of exterior surface are lost
The window frames must be well insulated and fitted with low-e glazings filled with argon or krypton to prevent heat transfer. For most cool-temperate climates, this means a U-value of 0.80 W/(m²K) or less, with g-values around 50% (g-value = total solar transmittance, proportion of the solar energy available for the room)
Efficient heat recovery ventilation is key, allowing for a good indoor air quality and saving energy. In Passive House, at least 75% of the heat from the exhaust air is transferred to the fresh air again by means of a heat exchanger.
Uncontrolled leakage through gaps must be smaller than 0.6 of the total house volume per hour during a pressure test at 50 Pascal (both pressurised and depressurised)
All edges, corners, connections and penetrations must be planned and executed with great care, so that thermal bridges can be avoided – thermal bridges which cannot be avoided must be minimised as far as possible

If you have a house or other building you are going to develop and are interested in the Passive House design concept, then please do contact us to find out more and ensure you achieve a building fit for the 21st Century.