AIA Redwood City Balanced Ventilation Event


On June 20, Hayward hosted the American Architects’ Institute (AIA) of San Mateo County and members of the Passive House community for presentations from Dr. Kara Rosemeier and Bill Hayward on “Balanced Ventilation in Passive Houses.” The event, which took place Hayward’s Redwood City facility focused not only on the critical roles air tightness and balanced ventilation play in passive houses, but also on how they work together to provide the foundation for a healthy home by ensuring superior indoor air quality.

Dr. Rosemeier is an expert in ventilation for residential buildings, with a special focus on healthy and affordable housing in New Zealand. She is the chair of the Passive House Institute New Zealand and teaches part-time at the architecture department of Unitec in Auckland.  She was in the Bay Area as part of a North American organized by the North American Passive House Network and hosted locally by Passive House California.

Dr. Rosemeier spoke about how to design an efficient residential ventilation system. Her presentation covered the role of an airtight thermal envelope in ensuring good indoor air quality, the importance of continuous air exchange, and the advantages and disadvantages of different options for continuous ventilation.  She also covered typical layouts and design challenges of heat recovery ventilation systems.

Bill Hayward is CEO of Hayward and founder of Hayward Healthy Home. Eight years ago, he set out to discover what about his family’s dream home was making them all sick. The result? A realization that indoor air quality was paramount to good health and a set of four principles to ensure that every home could be a healthy home. Recognizing that many elements of a passive house, which not only lower energy consumption but also provide superior comfort, indoor air quality, and resilience, supported his ideas about a healthy home, he decided incorporate those elements into his home as well.

Since the home was completed almost two years ago, four separate indoor air quality studies have been done. Analysis of the data resulted in several thought-provoking conclusions including:

  • There are far more chemicals, particles and VOC’s (volatile organic compounds) found in new houses than expected, even when non-toxic, no-to-low VOC, and other “green” products are used exclusively;
  • Higher ventilation rates in the first 12 months after construction are needed to protect occupants from off-gassing and may be necessary longer-term depending on occupancy, behaviors, and personal sensitivities;
  • Air tightness, a key component of passive houses, needs to be offset by a balanced ventilation system in order to optimize health.

In addition, Mr. Hayward presented data from “The Impact of Green Buildings on Cognitive Function,” a new study from the Harvard T.H. Chan School of Public Health’s Center for Health and the Global Environment, that found that improved indoor environmental quality doubled occupants’ cognitive function test scores.

All in all, the evening provided the attendees with a lot of new information about the role of ventilation in home design and why air tightness and balanced ventilation is critical for building healthy homes.