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Green Building News

A Passive House Take on the Hudson Valley

Just east of the Hudson River in upstate New York, this project embraces the region’s rural character and strives seriously for Passive House performance standards

Hudson Passive House has about 1,650 sq. ft. of interior space.
View Gallery 7 images
Hudson Passive House has about 1,650 sq. ft. of interior space. In addition to a Zehnder ComfoAir heat recovery ventilator, the house is equipped with a Mitsubishi mini-split heat pump and electric baseboard heaters for backup. Bill Stratton Building Company lifts the frame on June 25, 2010. The frames are 25 ft. at their apex. Structural insulated panels were used for the exterior walls as well as the roof. Inside the south wall, October 8, 2010. The north end of the building on November 12. A mini-split heat pump is installed in the center of the wall in the loft. A scene from the project’s Hard-Hat Tour, held November 13 and 14, 2010.

Hudson Passive House, in New York’s Columbia County, though only recently completed, is already familiar to Passive House fans in the region.

Last month, for example, the 1,650-sq.-ft. timber-frame home played host to 20-plus members of New York Passive House (NYPH), a New York City-based group of “Passivists” (consultants, contractors, architects, engineers, homeowners, developers, and others) who caravanned two hours north of the city to the project site in Claverack, a scenic town a few miles east of the Hudson River. Joined by several people from the community, the NYPH contingent participated in what the project’s architect, Dennis Wedlick, and other project partners called the Hudson Passive House Hard-Hat Tour, a show-and-tell event held November 13 and 14.

The three-bedroom, two-bath house also has been the subject of an American Institute of Architects/NYPH presentation, a segment on WABC-TV’s Sunday-morning feature program “New York Viewpoint,” and write-ups in print and online publications, including a recent EcoHome post that brought it to our attention.

A well-sealed envelope

So as new as it is to the landscape, the barn-like Hudson Passive House, whose 25-ft. bow-arch beams were raised in late June, has been successfully marketed into modest celebrity. Structural insulated panels were used for the walls and roof, bringing their respective R values to 48 and 54. The foundation floor is insulated to R-60 with six layers of expanded polystyrene and, on the interior and exterior of the foundation walls, extruded polystyrene.

Mechanical ventilation is provided by a Zehnder ComfoAir 200 heat-recovery ventilator, while space heating is provided by a minisplit air-source heat pump that is mounted in the wall of the loft space at the north end of the building.

The building is exceptionally airtight, even by Passive House standards. A blower-door test showed 0.149 air changes per hour at a pressure difference of 50 Pascals. Wedlick told EcoHome that construction costs likely will range from $200 to $250 per sq. ft. ($330,000 to $412,000).

The NYPH organizers apparently liked what they saw and, in a blog post about their visit in November, suggested they might make another trip to the house in the dead of winter “so we can actually experience the PH really ‘working.’”


  1. J Chesnut | | #1

    Exterior Shading
    I would expect that the fully glazed south wall would require exterior shading in addition to the overhang to avoid overheating. Can anyone comment on this aspect? Also I'd be interested to know what windows were used.

  2. GBA Editor
    Martin Holladay | | #2

    Response to J Chesnut
    It looks like the house has windows from Serious Energy:

    That might explain the south facade -- most of the low-U-factor windows from Serious are also low-SHGC.

  3. GBA Editor
    Richard Defendorf | | #3

    More on project details
    NYPH's coverage of Hudson Passive House also includes a copy of the project data sheet:

  4. J Chesnut | | #4

    Thanks for the responses. This is the glazing spec from their PH factsheet:

    Manufacturer: Serious Materials, FAKRO Products: SeriousWindows 725 Series, SeriousWindows with suspended coated film glass package with warm-edge spacer system (ecospacer and metal spacer), FAKRO Roof window: Double glazed, low-e coating, inert gas filled with toughened exterior pane
    Ug-Wert = 1,02 W/(m²K)
    g-Wert = 51 %

    I can't find the terminology "g-Wert" in my PHPP manual but I am assuming this is the SHGC number.
    51% is pretty high.

  5. mike eliason | | #5


    g-wert (gesamtenergiedurchlassgrad) is the german equivalent of SHGC.

  6. GBA Editor
    Martin Holladay | | #6

    Response to J Chesnut
    Remember that the g-Wert will be a glazing-only number, not a whole-window number.

    The Serious Materials spec sheet for their 725 window series shows that their 725 casement windows can be ordered with two glazing options. One has a SHGC of 0.21, and the other has a SHGC of 0.39.

  7. homedesign | | #7

    J Chesnut's comment about summer shading
    My thoughts exactly when I first saw the photo.
    I don't think the shape of this house lends itself to 4 season solar management.

  8. Ken Levenson | | #8

    Whether the windows "work" or the solar is "managed" is all determined in the PHPP, the computer modeling tool developed by the Passive House Institute - and an essential element in producing a successful Passive House project. If the specs work out in the PHPP modeling, AND the building is actually constructed accordingly, then the chances of the windows "working" and the solar being "managed" in the 4 seasons is very high indeed.

    Intuitively large south facing glass with some overhang and almost no east/west glass, sounds like a very logical place to start. With the rest of the PH methodology of continuous insulation, elimination of thermal bridging, air-tightness and continuous low volume ventilation with high efficiency heat recovery - it seems like it should be "easy" to achieve great interior comfort and the deep energy savings that characterizes Passive House.

    Also, just to note - NYPH is an affiliated chapter of the National Passive House Alliance. And on a personal note, I'm on the board of both.

  9. homedesign | | #9

    Lessons Learned?
    Have you seen the comments from this blog

    Solar heat is only good when it's cold outside
    Although the house passed the test in the heating department, Dr. Feist voiced concern that the large amount of unshaded south glazing might cause overheating in summer. He was right. "The first couple of years, it was tough," Katrin admitted. She constructed a grape trellis, and when the vines finally reached the top of the structure, the home stayed comfortable on even the hottest days.

  10. mike eliason | | #10

    summertime overheating
    PHPP has a tag that shows whether your building is overheating in summer, and various methods to mitigate the overheating, including shading outside the thermal envelope, night ventilation, etc.

    also to note, contrary to standard thinking, you can achieve PH with a sizeable portion of north glazing.

  11. Ken Levenson | | #11

    Lessons Learned
    Thanks for the link - I'll ask Katrin about it - and the PHPP inputs. Shading is an important input in the PHPP. As Mike notes the PHPP shows pretty clearly if you have an overheating problem - but you do need to be very careful, as Feist noted. Still, with the PHPP one has much more control and a better sense of how the building should perform.
    Hopefully many of these early projects - and many more going forward - are going to get wired for data collection. We want the data on how these buildings are performing - what is working and what isn't.

  12. homedesign | | #12

    PHPP is fantastic
    mike & Ken,
    thank you both for the feedback.
    I am a big fan of Passivhaus, Passive House &PHPP
    I hope to be working with a consultant in the near future.

  13. homedesign | | #13

    further discussion?
    This news blog will be moving down the que soon

    If anyone cares to discuss summer shading or this project further
    here is a link to the Q&A section

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