What is a Passive House?

May 19, 2016

Courtesy of Paragon Real Estate

A Passive House is built to rigorous performance standards for comfort, health, energy efficiency and quality. Passive Houses require super insulation, an airtight building envelope, heat recovery ventilation, and triple-glazed windows. Extensive software modeling and testing during design and construction is required to receive Passive House certification.

How does a Passive House compare to a house built to code?

A Passive House is built to code, yet its features far exceed traditional building code standards:

  • A Heat Recovery Ventilation (HVR) system exchanges stale indoor air for highly filtered fresh air 24/7.
  • Triple-paned windows.
  • Super insulation—up to three times what code requires.
  • Airtight building envelope.
  • Blower door testing throughout construction to test for air tightness.
  • A physics-based software program that measure the effects of all building choices, from seasonal shading to wall thickness.

What is Net Zero?

A Net-Zero building is one with zero net energy consumption, meaning that the amount of energy used by the building is equal to the amount of renewable energy created by the building. The Passive House at 2127 Castro uses so little energy —70 to 90 percent less than a conventional home—that achieving Net-Zero is easily done. It features solar electric and hot water panels.

What is LEED?

LEED (Leadership in Energy and Environmental Design) is the most widely used, third-party verification of green building standards. LEED certification is given for how a house is built. Passive House certification is awarded for how a house performs over its life. The Castro Street house will achieve both certifications.

What is an HRV?

Heat recovery ventilation or HRV, is a mechanical system that removes stale air from inside a Passive House and exchanges it 24/7 for fresh air from outdoors, filtered to remove pollutants and pollen. Depending on the season, the incoming fresh air is heated either by the exiting air or cooled by it, saving energy.

Why is this house so comfortable? So quiet? So fresh?

The calming hush of a Passive House is all about its super insulation, but what makes it so comfortable? Along with really good insulation and high performance windows and doors, it’s the filtered air from the Heat Recovery Ventilator (HRV). Quiet and comfortable, the house temperature rarely varies four degrees, plus, there are no drafts or cold spots.

The New York Times recently commented, “The air inside the house feels so fresh, you can almost taste its sweetness”

What is a blower door test?

A blower door test uses a mounted fan to test for air tightness. Standard houses have results of about 6-20 ACH50 (the number of times the air volume in a house changes per hour at 50 Pascals pressure difference.) A Passive House must receive a result of 0.6 ACH50 to be certified—that’s at least 10 times the air tightness of a new code-built home, and often more than 20 times better than an older home.

Who is Ewen Utting and ENU Construction?

Ewen Utting might be San Francisco’s most passionate advocate of Passive House construction. He built the city’s first Passive House to be sold; the last one he built was included on the AIA home tour. Picked for its appealing design it proved that sustainable building and beautiful design go hand in hand. He is the only San Francisco builder specializing in Passive House construction.


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