Passive House Concept

The Passive House Institute (Passivhaus Institut) is a distinctly German independent research institute that focuses on the development of the Passive House concept.  This concept is the only internationally recognized, performance based standard in the construction industry.  The Passive House Institute performs research into new building materials, products, and performs certifications worldwide.  To become Passive House certified a building must meet several performance standards.

Important Performance Standards: 

Heating Demand

  • Less than or equal to15  kWh/m^2 annually
  • Or less than or equal to 10 W/m^2
Cooling Demand

  • Less than or equal to 15 kWh/m^2 annually
  • Or less than or equal to 10 W/m^2
Primary Energy

  • Less than or equal to 120 kWh/m^2 annually
Airtightness

  • Less than or equal to 0.6 ACH50 (Air Changes per hour pressurized at 50 pascal)

Although there are several more specific standards for what materials and devices may / must be used in homes that hope to be Passive house certified, these performance standards are the most well known.

Construction Principles:

(Passivhaus Institut Website)

A Passive House must have high quality insulation, and this includes doors, windows, and every other surface exposed to the outside.  Since Passive House construction calls for such an airtight home, it is necessary that there is ventilation to to ensure an adequate supply of fresh air.  To accomplish this without losing all the energy used to heat that circulating air, these homes use a device called a heat recovery ventilator (HRV).  The HRV draws fresh air into the home while extracting the heat from the exhaust air and transferring that energy to the fresh air being brought in.

Lastly, the home must be built with careful attention to thermal bridging, which occurs when something with a low insulation value (structural framing, for example) is allowed to bypass wall insulation and transfer the heat energy from the home to the outdoors.  A well-designed Passive House minimizes thermal bridges.

Impact on Performance:

The Passive House Institute website states that employing the Passive House concept will result in 90% energy savings compared to the average home in central Europe, and about 75% energy savings compared to a newly constructed home in Central Europe.

The Passive House concept is not limited to residential construction.  A Passive House hotel was built in the small town of Torbole, Italy.  This hotel meets the rigorous Passive House standards and allows the public to experience a night in a Passive House so they can decide if they would like to invest in either building a new one for themselves or retrofitting their existing home to Passive House standards.

(zephir.ph)

How the Passive House Concept Stacks Up:

In America we are used to LEED (Leadership in Energy and Environmental Design) certification when it comes to energy efficiency and green construction.  The main difference between LEED and Passive House is that LEED is built on a point system where varying levels of points will get you different levels of certification (LEED Gold, Platinum, etc.).  This can be an issue because a building could have average efficiency, but become LEED certified based on other factors like having a sustainable site and an innovative design process.

With Passive House certification there is never an issue with hiding efficiency since the certification process is based on fulfilling all of the requirements rather than simply getting enough points from a wide list of different possible checkpoints.

If you were directed to this article from the “Like It’s Not Even There: Net Zero-Energy ADUs” blog article, then you know some of the complaints that people have with the idea of net zero-energy homes.  Namely, that some net zero-energy homes are averagely efficient, but simply put enough solar PV panels on the roof to make up for that fact.  With a Passive House building it’s easy to use very few solar panels to reach net zero-energy.

Custom 1,500 Square Foot 2 bedroom 2 bath Home in Berkeley, CA

Size: 1100 square feet on the ground floor, 400 on the second floor
2 stories
2 bedrooms, plus a playroom and office
2 baths.

This home in Berkeley’s historic Elmwood neighborhood has both a colorful past and future. When the owners purchased their main home they inherited a dilapidated house in their backyard that was built in 1908. This house was most likely an earthquake shack that was thrown together after the San Francisco earthquake of 1906

A New Avenue partner architect and local contractor worked with the owners to bring a new future to this collapsing backyard cottage. The new home was designed in compliance with the zoning rules and kept some of the original walls. The owners both have a great eye for style and a mind for sustainability. Some of the original redwood was salvaged and used in the new home and sustainable and alternative options – like spray foam insulation, metal roofing, cement siding and radiant floor heating – were used in the new construction.

The new home is now almost 1500 square feet. There are two bedrooms and a bath on the first floor and two rooms and a bath upstairs. The upstairs rooms could be a 3rd and 4th bedroom but instead are currently used as an office and a playroom.

This home was built with sustainability in mind and also serves as an investment strategy for the owners. The home is located just up the street from several coffee shops, restaurants and stores on College Avenue. With a BART station and all these amenities nearby the neighborhood achieves a perfect walk-score of 100. It is a prime rental apartment for UC Berkeley students or young professionals, and it is in an area where rental for homes like this range from $4,500-$5,000. The monthly financing cost for this home is just over $1,500 per month. For this family, the cottage is a great annuity that is paying the tuition bills for two daughters who are in college.

Living room
Living room
Stairs to loft
Stairs to loft
Living room
Living room
Loft
Loft
Master bedroom
Master bedroom
Master bedroom
Master bedroom
Kitchen
Kitchen
Loft office
Loft office
Living room
Living room