Passive House Principles
Passive building comprises a set of design principles used to attain a quantifiable and rigorous level of energy efficiency within a specific quantifiable comfort level. "Optimize your gains and losses" based on climate summarizes the approach. To that end, a passive building is designed and built in accordance with these five building-science principles:
- Employs continuous insulation throughout its entire envelope without any thermal bridging.
- The building envelope is extremely airtight, preventing infiltration of outside air and loss of conditioned air.
- Employs high-performance windows (double or triple-paned windows depending on climate and building type) and doors - solar gain is managed to exploit the sun's energy for heating purposes in the heating season and to minimize overheating during the cooling season.
- Uses some form of balanced heat- and moisture-recovery ventilation.
- Uses a minimal space conditioning system.
Passive building principles can be applied to all building typologies – from single-family homes to multifamily apartment buildings, offices, and skyscrapers.
Passive design strategy carefully models and balances a comprehensive set of factors including heat emissions from appliances and occupants to keep the building at comfortable and consistent indoor temperatures throughout the heating and cooling seasons. As a result, passive buildings offer tremendous long-term benefits in addition to energy efficiency:
- Superinsulation and airtight construction provide unmatched comfort even in extreme weather conditions.
- Continuous mechanical ventilation of fresh filtered air provides superb indoor air quality.
- A comprehensive systems approach to modeling, design, and construction produces extremely resilient buildings.
- Passive building principles offer the best path to Net Zero and Net Positive buildings by minimizing the load that renewables are required to provide.
The Performance Standard
North American building scientists and builders with funding from the U.S. Department of Energy (DOE) and the Canadian government were the first to pioneer passive building principles in the 1970s. In the late 1980s the German Passivhaus Institut (PHI) built on that research and those principles and developed a quantifiable performance standard that continues to work well in the Central European and similar climate zones.
However in practice, the PHIUS Technical Committee, PHAUS members, and project teams in North America learned that a single standard for all North American climate zones is unworkable. In some climates, meeting the standard is cost prohibitive, in other milder zones it's possible to hit the European standard while leaving substantial cost-effective energy savings unrealized.
As such, in cooperation with Building Science Corporation under a U.S. DOE Building America Grant, the PHIUS Technical Committee developed passive building standards that account for the broad range of climate conditions, market conditions, and other variables in North American climate zones. The result was the PHIUS+ 2015 Passive Building Standard – North America, which was released in March of 2015. That standard has been updated to PHIUS+ 2018. The PHIUS Technical Committee will continue to periodically update the standard to reflect changing market, materials, and climate conditions.
Third-party RESNET approved quality assurance/quality control
Earns U.S. Department of Energy (DOE) Zero Energy Ready Home (ZERH) status
Earns U.S. Environmental Protection Agency (EPA) Indoor airPLUS label
Includes HERS rating
The PHIUS+ Certification Program is the leading passive building certification program in North America. It is the only passive building certification that combines a thorough passive house design verification protocol with a stringent Quality Assurance/Quality Control (QA/QC) program performed onsite by highly skilled and specialized PHIUS+ Raters and Verifiers. The benefits of PHIUS+ certification include:
PHIUS+ Climate-Specific & Cost-Optimized Performance Metrics*
The PHIUS+ Passive Building Standard targets the sweet spot where aggressive energy and carbon reduction overlap with cost effectiveness, taking into account a full range of variables including climate zone, source energy, and costs. The PHIUS Technical Committee and Building Science Corporation developed the standard over three years under a U.S. DOE Building America Grant. Read more about the PHIUS+ Passive Building Standard here.
Comprehensive Design and Energy Model Review
Passive buildings in North American climates present unique design challenges; even small missteps can lead to big problems. The PHIUS Certification team is made up of some of the most experienced passive house professionals in North America. They thoroughly review projects at the design stage, identify problems, and work with project designers to help projects achieve performance targets.
Rigorous Quality AssuranceProject testing and inspections are conducted by experienced HERS Raters, trained by PHIUS to work on PHIUS+ projects. The on-site inspections and testing help to assure PHIUS and the project teams that the buildings will perform as designed.
Earn U.S. DOE Zero Energy Ready Home Status
In partnership with the U.S. Department of Energy (DOE), PHIUS has incorporated the DOE’s Zero Energy Ready Home (ZERH) protocol into the PHIUS+ Certification program. ZERH certification in turn requires all homes/units to also be certified to U.S. Environmental Protection Agency (EPA) ENERGY STAR and Indoor airPLUS requirements for new homes and includes additional construction specifications that ensure high-performance homes so energy efficient all or most annual energy consumption can be offset with renewable energy. The benefit for a builder is the ability to offer the buyer a PHIUS+ certified passive house that performs far above the industry standard for energy efficiency while also ensuring industry leading performance for comfort, health, and durability. For questions about Zero Energy Ready Home, contact Zero@newportpartnersllc.com. Refer also to the program’s national program requirements and resources, and learn more about how to join Zero Energy Ready Home.
For more information on specific performance requirements of the standard and to see how PHIUS+ certification stacks up against other programs, download the PHIUS+ DOE "Cliffs Notes" PDF
Earn U.S. EPA Indoor airPLUS labelPHIUS+ certification also incorporates U.S. Environmental Protection Agency (EPA) Indoor airPLUS protocol. EPA’s Indoor airPLUS qualification builds on the foundation of EPA's ENERGY STAR requirements for new homes and includes additional construction specifications to provide comprehensive indoor air quality protections in new homes. The benefit for a builder is the ability to offer the buyer not only a home that performs above the industry standard for energy efficiency, but also a safer, healthier, more durable home and additional peace-of-mind. For questions about Indoor airPLUS, contact Indoor_airPLUS@epa.gov. Refer also to the program’s Construction Specifications: Version 1 (Rev. 03), Indoor airPLUS Technical Guidance, and learn more about how to Join Indoor airPLUS.
Learn more about the Indoor airPLUS program in this free webinar or download this informational overview of program requirements and resources
RESNET HERS Index Score
Most PHIUS+ projects will automatically receive a RESNET HERS Index score as part of certification. The RESNET HERS Index is the leading industry standard by which a home’s energy efficiency is measured. Many local, state, and federal financial incentive programs require a HERS Index to demonstrate compliance with these programs.
Listing on the PHIUS+ Certified Projects Database
PHIUS+ certified projects are included with pertinent project information and photos on the PHIUS+ Certified Projects Database.
- Review this Guidebook, which summarizes all requirements, covers energy modeling protocol, and includes vapor control recommendations and other technical details.
- Visit the Submitting a Project for Certification page on the PHIUS website to find a stepby-step outline of the certification process.
- Contract: Review and sign the PHIUS+ Certification Contract.
- This contract must be requested using the form in Step 1 of the ‘Submitting a Project’ page linked above.
- Email executed contract to email@example.com.
- Payment: Make online payment via PayPal or request invoice for payment by check.
- Log on to the PHIUS+ Certified Projects Database.
- If necessary, PHIUS will create account or give access to submit projects.
- For CPHCs, this should not be necessary.
- Create a project by adding at minimum a project name and location. Other information can be added at a later time.
- Once a project is created, PHIUS certifiers will be informed by the database. At this time, PHIUS will create a DropBox folder for the project, and invite the Submitter to the folder. The Submitter may invite other members of the project team.
- When all documents have been prepared, uploaded to the DropBox, and the project is ready for review, the team must use the form on the Project Certification Review Queue page to add the project into the queue.
- The project will be added into the PHIUS+ review queue as of the forms’ submit date. This is a manual process, so please allow one business day before the project status is updated on the public queue.
- Email notifications will be re-directed to use the submission form.
- We recommend to keep a record of your submissions.
- The project review will not begin until the contract and payment are both received.
Quality Assurance and Quality Control (QA/QC)
- The QA/QC components of PHIUS+ Certification performed by PHIUS+ Raters/Verifiers are an essential part of the PHIUS+ process.
- That PHIUS+ component is covered under a separate contract between the project team and the Rater/Verifier.
- Before pre-certification is awarded to a project, PHIUS requires a letter of intent from the PHIUS+ Rater/Verifier on the project, stating they have been hired to complete the on-site verification process.
- PHIUS encourages project CPHCs to clearly communicate the following to the Rater/ Verifier as early as possible so that on-site verification can be performed as efficiently and effectively as possible:
- Foundation condition and insulation strategy.
- Primary whole-building air barrier/infiltration control strategy.
- Intended insulation materials, installed thicknesses and R-values for all building enclosure assemblies.
- HVAC and hot water system strategies, equipment and design drawings.
- Intended labeled window performance values.
- Known project thermal bridges and associated mitigation strategies/products.
- Window install and sealing strategies.
- Window shading strategies, including adjacent site shading, overhangs and/or external movable shading.
- Intended tested whole-building infiltration values, including intended midconstruction infiltration testing values.
Updated local and national incentives can be found on PHIUS’ Incentives webpage.
- With the addition of a QA/QC process, PHIUS+ projects are now able to gain more performance-based incentives.
- Since 2013, PHIUS has partnered with the DOE’s Zero Energy Ready Home program as well as ENERGY STAR for Homes. These programs are pre-requisites for PHIUS+ Certification. Your PHIUS+ Rater/Verifier will complete documentation for all of these programs during their on-site visits, and the project will be awarded recognition from all three.
- Most projects will automatically receive a RESNET HERS Index score as part of certification. The RESNET HERS Index is the leading industry standard by which a home’s energy efficiency is measured. Many local, state, and federal financial incentive programs require a HERS Index to demonstrate compliance.
Final Stages of Certification
- The PHIUS+ Rater/Verifier must upload all on-site documentation to the project DropBox.
- The CPHC should update the WUFI Passive energy model to match any known as-built changes as well as final test results. All changes should be tracked in the PHIUS+ Feedback form used during pre-certification.
- Once ready, submit the project for final review using the form on the Project Certification Review Queue page.
- PHIUS’ QA Manager will review the submission and provide feedback requesting further documentation, or comments for clarification.
- If not adjusted by the CPHC, before final certification is awarded, PHIUS adjust the final WUFI Passive energy model to match the verified results for:
- Air-tightness test results
- Average continuous ventilation rate
- Measured ventilation fan wattage
- Project team to upload final drawings, documents, pictures, etc. to the DropBox.
- Once all documentation is reviewed and approved, PHIUS issues a formal email notification and mail (3) copies of the PHIUS+ Certified Project Certificate to the CPHC.
- Purchase PHIUS+ Certified Project Plaque
Estimates for larger buildings:
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