Passive House

The Passive House Standard has shifted both the US and Canadian construction industry.  Developers and businesses are turning to Passive House to deliver high-performance buildings to save on operational costs and differentiate themselves from the competition.  Passive House building’s utilize design tools, energy modelling, and high-performance components to cost effectively optimize a building to lower the energy consumption.  The cost to conserve energy is cheaper than the cost to generate it.

What is Passive House?

The term Passive House (Passivhaus in German) refers to a rigorous, voluntary world leading standard in energy efficient construction for both new and renovated buildings.  Passive House is currently a niche construction market that may potentially achieve mainstream adoption in both USA and Canada.  Passive House has been recognized at a national level as governments develop policies to encourage energy conservation in buildings.  At a local level, see how municipalities like Vancouver, BC, Canada advocate Passive House.

Why is Passive House important?

Nothing is more important than the health and comfort of your family.  Acute health and discomfort effects due to poor indoor air quality are a common problem in many conventionally constructed buildings.  The source of the poor indoor air quality stems from the lack of adequate fresh-air intake/air filtration, improper exhaust ventilation, and contaminates produced from off-gassing building materials, volatile organic compounds (VOC), and mold.  Conventional construction depends on active mechanical systems to heat interior surfaces to reduce condensation on areas of low thermal resistance (windows, thermal bridges, etc.).  This is very difficult to accomplish in colder climates resulting in condensation, mold, and mildew forming on the interior side of the building enclosure.  A building with inadequate ventilation builds up carbon dioxide and can cause drowsiness, fatigue and reduced cognitive function.

Passive Houses must utilize a heat recovery ventilation (HRV) system delivering constant fresh filtrated air resulting in better indoor air quality and lower levels of carbon dioxide, creating a healthy space to live.  HRV systems are only functional with airtight building enclosures to ensure all infiltrating and exfiltrating air is controlled.  The airtightness of a Passive House must be verified with a Blower Door Test.

Passive House is a building standard

The Passive House Standard was developed by the Passive House Institute (PHI), located in Darmstadt, Germany.  The standard has been in use for over 25 years and has been effectively demonstrated to more than 50,000 residential and non-residential projects worldwide. The Passive House Standard is composed of several performance requirements for new building construction.  PHI also developed EnerPHit for certified energy renovations, which has slightly more lenient performance requirements.  Passive House buildings consume 75% to 90% less heating energy than conventional ones with a construction cost premium of only 8% to 11% on single-family house projects.  Savings from annual operating (utility) costs can exceed the added mortgage cost making a Passive House more affordable from year one.  The construction cost premium is lowered with larger buildings (5% or less for apartment buildings).  Passive Houses achieve this enormous energy conservation through the use of good quality building components and design techniques including:

• super-insulated building enclosure
• energy efficient windows
• reducing thermal bridges through the building enclosure
• airtight building enclosure (0.6 air changes per hour or less at 50 Pascal)
• heat recovery ventilation (HRV) (system allows heat contained in the exhaust air to be re-used to pre-heat the fresh air supply)
• utilize heat sources inside the building such as body heat from the residents, heat from appliances, computers, and solar heat entering through windows
• eliminating/minimizing the need for cooling with shading and HRV system

Simplicity is the beauty of Passive House design and does not rely on any on-site renewable technology or complex mechanical systems that tend to be expensive to purchase and maintain.  The Passive House Standard results in truly high end, durable, energy efficient, comfortable, healthy (free of mold and dangerous levels of typical indoor air contaminants), economical and ecologically viable buildings.  Whether the project is a moderate sized house, apartment building, or cabin off the grid – the Passive House Standard just works.

Passive House is a methodology

Passive House is a methodology to achieve the rigorous performance requirements of the standard.  A Passive House should first look to maximize free energy from the sun through passive measures such as orientation to the south (in the northern hemisphere), massing and passive solar design.  Reducing thermal losses is more difficult to accomplish and usually requires a super-insulated and airtight building envelope.  Because the building is airtight, a continuous supply of filtered fresh air is supplied to the living room and bedroom spaces and stale air is exhausted from the kitchen and bathrooms.  This provides balanced and controlled ventilation to maintain very high indoor air quality and enables the heat recovery ventilation system to function properly.  The Passive House Institute (PHI) qualifies designers to help ensure that the design and construction are completed with the highest competence possible.

Akira Living has been working within this methodology since Cody completed the Passive House Design/Construction Course in 2012.  Subsequently he wrote the Certified Passive House Designer Examination and was awarded the Certified Passive House Designer (CPHD) designation by PHI in Darmstadt, Germany.  Cody provides energy modeling and project guidance to homeowners, architects, residential designers, developers and builders considering Passive House projects.

Passive House is a building

A Passive House is a building that is designed and constructed with Passive House methodology and aims to meet the Passive House Standard performance requirements, which include the following:

• Use of less than 15 kWh/(m²yr) for heating/cooling or ensure the heating/cooling load is limited to a maximum of 10 W/m²
• Primary energy demand use may not exceed 120 kWh/(m²a)
• Airtight building enclosure ≤ 0.6 air changes per hour at 50 Pascal verified with Blower Door Tests (this test verifies the airtightness of a building and reveals how leaky/drafty it is)
• In warmer climates and/or during summer months, excessive temperatures may not occur more than 10% of the time

To become an official Certified Passive House, a professional certifier accredited by the Passive House Institute (PHI) must be retained to review extensive documentation including the energy modelling completed with the Passive House Planning Package (PHPP) software that shows that all performance requirements have been met.  The certifier will submit all necessary documentation to a third party PHI to be verified.  The pending Passive House project’s energy consumption will be monitored for one full year to ensure it meets the performance requirements, and if so, will be acknowledged as a Certified Passive House.

The PHPP software is a useful tool for optimizing system sizing and evaluating the cost effectiveness of various design choices.  PHPP energy models by professionally trained Certified Passive House Designers (CPHD) provide accurate estimates of how the real building will perform.

Passive House in Vancouver, BC, Canada

The City of Vancouver recognizes the Passive House Planning Package (PHPP) as an alternative to the energy modeling software program, HOT2000, to demonstrate compliance with energy code requirements for single- and two-family homes.  Also, the zoning and development bylaws have relaxed restrictions on Certified Passive Houses including an increase in maximum building height and a wall thickness exemption.  A few voluntary single-family Passive Houses have been completed in Vancouver to date, with several Passive House developments underway including townhouses and a six-storey apartment building.

The City of Vancouver announced a goal to become the Greenest City in the world and derive 100% of the energy used in Vancouver from renewable sources before 2050.  The City recognizes that the most cost-effective way to a renewable energy future is to significantly reduce the energy demand of the building stock.  City Officials report plans to implement new policies focused on reducing energy demand by creating performance based standards for new construction through the use of Passive House or alternate ultra-low thermal demand design methodology.  Passive House is identified as the best tool to meet performance based standards forecasted in future energy codes.  City Officials also report that the first performance based thermal demand requirement will be enforced when rezoning to develop four to six storey apartment buildings in 2018.

Passive House + BC Energy Step Code

The Government of British Columbia has provided the framework on how all buildings will need to progress to net-zero ready by 2032.  The Passive House Standard set limits on energy consumption, which is necessary to achieve Net Zero for most building sites.  All steps (Step 1 to Step 5) in the BC Energy Step Code will require energy modelling and air barrier commissioning, similar to Passive House.  Energy Modelling pre-construction will be required on every project to generate the proposed building’s Thermal Energy Demand Intensity (TEDI), which is a metric of building enclosure performance to determine if a minimum level of energy-efficiency is met.  By 2032, all buildings are required to be net-zero ready with a minimum TEDI of 15 kWh/m²/year.  That is the same level of energy-efficiency required by the Passive House Standard, coincidence?  However, for Part 9 projects aiming at Step 5 – requires a minimum airtightness level of 1.0 air change per hour or less.  Passive House requires a minimum airtightness level of 0.6 air change per hour or less.

To accomplish this goal, the construction industry will require hundreds of qualified professionals to design, construct and retrofit the high performance buildings of tomorrow.  In preparation for the shift towards high performance based standards, British Columbia’s provincial government has contributed funding to the Canadian Passive House Institute West (CanPHI-West) to run a higher frequency of training programs for designers, contractors and trades.