Absurdity of Natural Ventilation

I’ve been meaning to post something about the absurdity of the almost religious devotion some people have to “natural” ventilation in a building. How is a double-hung window “natural”, by the way? That’s why I prefer the term manual ventilation.

Fortunately, the Passive House Academy of New Zealand beat me to it with a great Google+ post.

Would you throw your laundry into a river and hope to pick the clothes up cleaned somewhere downstream? Are you doing all your laundry by hand? Do you get fresh air in your car only by opening the windows? Probably not.
Yet, there is this absurd insistence on natural ventilation when it comes to houses – despite research demonstrating poorer outcomes for indoor air quality, comfort and energy efficiency. In many aspects of our daily routines, we accept that a machine can do a better job. What’s different with ventilation of houses? In a mechanically ventilated home, the windows can be opened and closed at will. Freedom of choice! In a manually ventilated home however, the windows cannot be closed without risking the build-up of air contaminants and moisture indoors. The effectiveness of this form of ventilation furthermore depends mainly on the direction and force of wind. In other words: it is relying on the weather. With mechanical ventilation, there is no reliance on power – as in a power outage, occupants can still fall back to manual ventilation. For most of the heating season however, they enjoy great indoor air quality, while saving massively on heating costs, and not having to worry about opening and closing of windows.
Note: ventilation in a Passive House is – deviating from the experience that most of us have with cars or offices – silent, non-draughty, the air is typically not conditioned at all, and sourced filtered directly from the outdoors. Fresh as!

In the past ten years, the efficiency of mechanical ventilation with heat recovery has improved so much that manual ventilation is rarely the most appropriate strategy.

UPDATE: An analysis out of Ireland showed a savings of 643 euros per year for a Passive House with heat recovery ventilation versus natural ventilation.

Book: The Greenest Home: Superinsulated and Passive House Design

The Greenest Home: Superinsulated and Passive House Design

Julie Torres Moskovitz’s book showcases eighteen recent Passive House projects from around the world, including the first certified Passive House retrofit in Connecticut. Duncan Architect was the Passive House consultant for this project.

If I ran the world—or at least the planning departments of the world—every house would be a Passive House (not to mention every school, hospital, office building). Each house in this inspiring book is beautiful on the outside and brilliant within. Each merges bold aesthetics with common principles: they’re well insulated, high performing, and ridiculously efficient in their resource usage. The real mystery is why Passive House principles aren’t standard best practice yet. They will be. They must.

—Allison Arieff, Contributing Columnist, New York Times


Passive House Books

Westport Bauhaus Passive House Retrofit in Treehugger

Before and after shots of the Passive House retrofit project in Westport, Connecticut, an hour or so northeast of New York City. Duncan Architect was the Certified Passive House Designer working with architect Ken Levenson to create a comfortable, healthy, energy-efficient building. Treehugger recently profiled our project and the owner/builder Doug Mcdonald.

Commercial Retrofit in Brooklyn, New York

Increasing the occupants’ comfort and ability to do their job by reducing noise and drafts while also reducing utility bills.

A preliminary blower door test revealed major air leaks in the existing masonry. These gaps were not obvious from a visual inspection and would have created huge problems with water leaks, uncomfortable drafts, noise transfer, and a high risk of condensation and mold growth. Fortunately we discovered them before the drywall went up so that the contractors could patch them.

After the test, the contractor installed regular fans in the windows to create a pressure differential to reveal where the air leaks were. Sophisticated equipment is required to measure the rate of air leakage but not to simply find the leaks.

The next step after installing the mineral wool installation is to put up a vapor retarder—on the warm side—that also acts as the primary air barrier. Intello, available from 475 High Performance Building Supply in Brooklyn, is a “smart” vapor retarder that prevents moisture transfer into the wall assembly while allowing it to dry out if it becomes accidentally saturated. After the air barrier is complete, but before the drywall is up, we will conduct another blower door test to make sure that the building’s airtightness is below the Passive House retrofit standard of 1 ACH50. Finally we will install a service cavity of 1-5/8″ furring to protect the airtight membrane.

Below is a view of the building from the F train platfrom with the old plumbing supply sign painted on the brick and One World Trade Center in the background.

For more information please email greg@duncanarchitectpllc.com

and check out video of a successful blower door test from our friends at Dwell Development in Seattle.

Brooklyn Passive House Video

Brooklyn Independent Television features the energy-efficient retrofit condo, 96 St. Marks Avenue, that I consulted on for architect Ken Levenson. See the Passive House Buildings Project Data Sheet for technical information and haus96.com for the marketing website. Located in a historic district in Prospect Heights, this townhouse renovation combines historic preservation and modern technology for a beautiful, comfortable living space with extremely low heating costs. Comfort is assured by the quality of the building fabric and by giving the owner of each unit control over their own heating, air conditioning, and fresh-air ventilation. This type of retrofit serves as a model for future real estate development in New York City and beyond.

Please contact Gregory Duncan Architect for more information.

Commercial Passive House Retrofit Tour in Brooklyn

On Sunday, November 11, tour a commercial Passive House retrofit of a 7000 SF
warehouse for the Hatzolah Central non-profit ambulance dispatch
service. See the project under construction as the ventilation system
and windows and doors are being installed. It’s conveniently located
near the 18 Ave F stop on McDonald Ave and 47th Street. The address is
1950 47th Street and I will be giving tours from 1:00-3:00. Coffee and
donuts courtesy of Zola Windows.

Gregory Duncan Architect is the acoustical and Passive House consultant on this project.

Passive House Tours November 10 and 11

Gregory Duncan Architect is proud to have three Passive House projects open for tours as part of the International Passive House Days on November 10 and 11.

Saturday, Nov 10:

Brooklyn, NY: Haus 96, the first condo building in the United States to be retrofit with Passive House components and methodology.

Sunday, Nov 11:

Westport, CT: Retrofit of a derelict, energy-guzzling single-family house designed in the International Style in the 1930’s by a disciple of Frank Lloyd Wright. “Their effort continues the spirit of technical innovation embodied by the original design,” according to the Westport Historic District Commission, which gave the house a Preservation Award.

Brooklyn, NY: Commercial retrofit of a 7000 SF warehouse for the Hatzolah Central non-profit ambulance dispatch service. See the project under construction as the Passive House windows and doors are being installed.

See the New York Passive House site for more tour information.

Tour Multifamily Passive House in Brooklyn

Haus 96, the first multifamily Passive House retrofit building in Brooklyn, will be open for guided tours on Saturday, November 10, 2012. This project proves that historic preservation, comfort, healthy indoor air, and dramatically reduced energy costs are compatible.

Duncan Architect performed the energy modeling for this project for architect Ken Levenson. Building science geeks may appreciate the following data:

  • Heat Demand 27 kWh/m²a
  • Cooling Demand 5 kWh/m²a
  • Primary (Source) Energy Demand 111 kWh/m²a
  • Airtightness 1.98 ACH50

See New York Passive House’s listing of upcoming tours for more information.


Tour Energy-Efficient Home in Westport, Connecticut

On Sunday, November 11, 2012, there will be an opportunity for a guided tour of the Bauhaus Residence in Westport, Connecticut. Designed in 1934 by a disciple of Frank Lloyd Wright, the home was in dire need of renovation in 2011. The cast-in-place concrete structure is a striking example of the International Style in rural New England. Unfortunately the original concrete walls required a tremendous amount of energy to keep warm in the winter. In order to increase the energy efficiency and comfort of the house, architect Ken Levenson clad the entire building in ten inches of Foamglas insulation. With a passive solar hot water heating system, triple-glazed European windows, and an energy recovery ventilator, the award-winning project is going for Passive House retrofit (EnerPHit) certification. Gregory Duncan Architect performed the energy modeling and thermal bridge calculations required for certification.