The Passivhaus Standard

By Adam Cohen

Passivhaus is the world’s strictest standard for building energy performance, and the most effective path to achieving net-zero energy use buildings. Unlike other green design standards, Passivhaus brings a laser-like focus on operating energy, which over the lifetime of a traditional building, quickly exceeds embodied energy (the energy used in the production and transport of construction materials, and the construction process itself).

Description = Passivhaus cross-section, English annotation |Source = Copied to Commons from http://en.wikipedia.org. Original source Passivhaus Institut, Germany – http://www.passiv.de

Passivhaus buildings achieve overall energy usage reductions of 60 – 80% (and space heating and cooling demand reductions of 90%) through a combination of five strategies:

  • Superinsulated, airtight, thermal bridge-free envelope – minimizes heat transfer through surface conduction and air movement.
  • Balanced ventilation with energy recovery – provides 100% fresh air, preconditioned through high efficiency heat exchange.
  • Efficient mechanical systems – decrease energy demand and internal heat gains.
  • Passive elements – utilize building orientation and shading to optimize natural light and solar heat gain.
  • Readiness for renewable integration – allows building to achieve net-zero energy by way of photovoltaics, solar thermal, geothermal, wind power, etc.

Unlike “check box” style green certifications like LEED, Passivhaus is entirely performance-based. Builders and Certified Passive House Consultants work together in Passivhaus design and construction to ensure that buildings perform to specification. To achieve Passivhaus certification, three key metrics must be met:

  1. 1.4 kWh/ft2 or 4.75 kBTU/ft2 annual heating and cooling demand
  2. 11.1 kWh/ft2 or 38.1 kBTU/ft2 annual total primary energy demand
  3. 0.6 ACH @ 50pa of air leakage

Copied to Commons from http://en.wikipedia.org. Original source Passivhaus Institut, Germany – http://www.passiv.de

Besides the obvious advantage of reduced operating costs through lower energy use, Passivhaus high performance buildings set a new bar for building in the 21st century:

  • Increased occupant comfort – by eliminating drafts and maintaining a maximum temperature differential of 4°C/7.2°F between the warmest and coolest indoor surfaces.
  • Improved indoor air quality – through a constant, controlled supply of filtered, fresh air.
  • Little to no marginal cost – increased costs to achieve the Passivhaus standard can be offset by downsized HVAC equipment; investment payoff occurs in 7 – 10 years.
  • Passive resilience – as a result of their low-energy design, Passivhaus structures can maintain superior comfort over traditional buildings even in the event of power outages or other unforeseen circumstances.
  • Potential for carbon neutrality – low energy demand, integrated with renewable energy technologies, can lead the way to a sustainable, carbon-free future.