Introducing the Passive House system: A new standard for building green

Getting certified
How do buildings get certified? An important part of the standard is the Passive House Planning Package (PHPP), which includes an energy-modeling tool so the design team can analyze building components and specific design elements to study how various options affect energy performance. For example, one could change the amount or type of insulation or the size and location of windows, and output data on how those changes affect the building’s overall efficiency.

Since PHPP comes early in the certification process, the design team and owners can often determine from the project’s outset—even before concept and site selection, in some cases—some key design and specification criteria. Ultimately, a set of documentation is required to prove the standards are met, and checklists are provided through the organization’s websites.

It is highly recommended to involve a Passive House-certified consultant with the design team and overall process to ensure every detail is considered to meet the guidelines. Increasingly, architectural practices are training staff members to the standards. The Passive House Institute and PHI-US each offer varied educational opportunities from a one-day introductory lecture to a professional, 10-day Passive House Designer course.

The Passive House standard is typically geared to new construction. With so many retrofit projects undertaken today to meet Passive House, though, the parallel standard EnerPHit was launched in 2012. EnerPHit acknowledges existing buildings are more challenging in terms of achieving energy efficiency goals. Existing conditions may require costly installation methods to achieve levels similar to those for new construction.

Another issue is the orientation of existing buildings that respond to criteria other than maximizing useful solar gain. In northern climates, without solar access to act as the primary heating system, the amount and cost of insulation required can be prohibitive. With these issues in mind, EnerPHit’s certification rules are less stringent than those for Passive House—but still quite rigorous. Studies listed on the online resource Passipedia show EnerPHit projects yield about 85 percent greater efficiency levels than typical retrofits.

Highlights of EnerPHit standards include:

• less than 25 kWh/(m²) (about 7.9 kBtu/sf) for annual heating and cooling;
• airtightness better than 1 ACH50; and
• total annual energy usage £ 120 kWh/m²
  (38.1 kBtu/sf).

With Passive House, it is the fabric first and relies on the building alone to achieve the standard. However, net-zero buildings and net-positive buildings have gained momentum, especially with the launch and success of the Living Building Challenge. While the term has several definitions, a net-zero building is generally understood to offset its electrical consumption with an alternative energy source on site. A net-positive building is one that produces more power than it consumes and shares that resource with the local utility grid or adjacent buildings.

PHI’s founder Fiest has taken notice, and recently launched two additional Passive House certifications to address this: Passive House Plus for net-zero buildings, and Passive House Premium for net-positive buildings.

Conclusion
Developers and building owners often ask the design team, “What is the return on investment for construction to Passive House?” This is a good question considering the reputation green building holds as an incremental or additional expense to construction overhead. In Europe, these standards have been in practice for so many decades buildings tend to be delivered at the same cost as standard construction. In the United States, there is a wide range of options and opinions, so local attitudes and labor rates may affect the budget. In urban areas, five to 15 percent is the driving standard for greater energy efficiency, and does not account for the real payback to the owner, which depending on utility rates can be as fast as 18 months.

Additionally, there are multiple co-benefits that are difficult to quantify, such as improved comfort, better indoor air-quality (IAQ) controls, and more durable buildings with greater resale value and market longevity. Passive House projects also tend to provide for excellent resiliency and thermal comfort in emergency situations, such as power outages.

While the design community searches for solutions on how to meet the ever-increasing energy efficiency demands, Passive House is proving to be a leading path for designers and specifiers. The standard is becoming a nationally accepted tool beyond single-family dwellings, and growing in the commercial and multifamily sectors. As future energy costs rise, developers and building owners will demand more cost-effective solutions. One should expect Passive House buildings to stand among your neighbors in future developments; while certification is a lofty goal, it can only be beneficial in our climate-changing world.