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.

Foam-Free Air Sealing for Energy-Efficient Buildings

Presentation of air sealing strategies for high-performance buildings without relying on spray foam or rigid foam insulation.

+Ken Levenson presenting foam-free air sealing techniques for a NYC townhouse with interior insulation and a continuous “smart” vapor-retarding air barrier.

This technique is important for Passive House retrofits and should be considered best practice for any gut rehab of a brownstone where exterior insulation isn’t practical. Air tightness eliminates drafts for better comfort and reduced energy bills. It also prevents moisture buildup from condensation that can lead to mold and structural damage. Add filtered fresh air ventilation with heat recovery to optimize indoor air quality and energy performance.

Exterior insulation is preferable from a building science point of view. New buildings should be airtight, allow drying to exterior and to interior, and have exterior insulation.

The following example for a brownstone retrofit can be modified for new, non-combustible construction as well:

Integrating a window in the airtight layer – brick/brownstone retrofit case

US Army Corps of Engineers High Performance Building Envelope Symposium

March 6-8, 2012 in San Antonio, Texas: High Performance Building Envelope Symposium by the Army of Corps of Engineers and the Passive House Institute.

HPSB Flyer (PDF)

High Performance Building Envelope Workshop Draft Program (PDF)

It’s great to see the Army Corps of Engineers take such an interest in the Passive House standard for high performance buildings.

Joe Lstiburek showing two images of finned radiators, one of which won an award from AIA Chicago

The symposium featured lectures from leaders in building science (alphabetical by last name):

  • Wagdy Anis, Wiss Janney Elstner Associates
  • Lee Durston, Brown Connally Rowan Architects
  • Wolfgang Feist, founder of the Passive House Institute (by video)
  • Matthew Heron, Pie Forensic Consultants
  • Linda Jeng, Dow Building Solutions
  • Berthold Kaufmann, Passive House Institute
  • Mark Lawton, Morrison Hershfield
  • Joe Lstiburek, Building Science Corporation
  • Tomas O’Leary, Passive House Academy
  • Ray Patenaude, The Holmes Agency
  • Craig Shipp, Shwinco
  • Alexander Zhivov, US Army Corps of Engineers Construction Engineering Research Laboratory (CERL)

While the focus was on high performance building envelopes, the lectures also included discussion of ventilation with heat recovery, high efficiency HVAC systems, and mold prevention.

Based on Lstiburek’s explanation of the “perfect wall”, I like to think of the building envelope in terms of control layers, which must be as continuous as possible. From exterior to interior:

  • exterior finish (aesthetic control layer)
  • cladding (physical intrusion control layer)
  • water control layer
  • thermal control layer (insulation)
  • vapor control layer
  • air control layer
  • structure (elements can be intermittent, of course, but connections must be continuous)
  • service cavity
  • interior finish (protective control layer)
  • interior finish (aesthetic control layer)

A single material can act as one or more of these control layers. For instance, glazing performs all of these functions, including, to a limited extent, structural support.

Revit and Passive House Energy Modeling with PHPP – Updated Workflow

I’ve updated my technique for using Revit with PHPP. The previous workflow used walls to create a schedule that could be exported to PHPP. The obvious limitation is that it doesn’t work for roofs and floor slabs. The new technique uses curtain panels hosted on a mass object.

Step One:

Create an in-place mass representing the thermal envelope. Do not include elements that are outside the thermal envelope, like a rainscreen or a parapet. A mass is useful to give you the gross volume and surface-to-volume ratio. And if you start modeling the building with the conceptual mass, then there is little extra work involved.

Step Two:

Host a curtain system on the mass using a simple curtain panel style. If you make changes to the mass, you will have to update the curtain system by selecting it and clicking on “Update to Face”. Assign the mass and curtain system to a future phase called “Energy Modeling” so that they don’t interfere with scheduling other building components.


Step Three:

Set up instance parameters for the curtain panels that match the required PHPP inputs. Create a schedule for the PHPP areas.

Step Four:

Export the schedule as a delimited text file with the default options.

R > Export > Reports > Schedule

Step Five:

Open PHPP and the text file in Excel. Accept the default options when opening the text file in Excel. Link the PHPP cells to the exported schedule. You can delete the text file. Excel will maintain the values when the linked file is deleted.

What’s missing is an automatic way to determine the orientation of the walls and windows. You can create a curtain panel that knows its orientation via a reporting parameter. See this video. However, this only works, as far as I know, with pattern-based curtain panels, so it isn’t as useful as having a curtain system hosted to a mass object.

Email for more information about Revit and PHPP.

Passive House consulting

Measuring Airtightness of Buildings with a Blower Door Test

Gregory Duncan performing a blower door test to determine the airtightness of a Passive House project under construction in Pennsylvania.

Use a blower door to test the airtightness of a building. For very small buildings or spaces, use a duct blaster.

Pressurization test with air flows due to leaks with negative pressure. Measuring the pressure difference in the building.

source: Passipedia

Building owners benefit from an airtight building envelope because it reduces:

  • water problems
    • a small air leak will allow a lot of moist air to get inside a wall and condense, risking structural damage and mold
  • heat transfer (heat loss in winter and heat gain in summer)
  • environmental tobacco smoke (ETS) nuisance between apartment units
    • involuntary exposure to second-hand smoke is likely to become even more of a liability for landlords in the future
  • transfer of smoke and heated gases from a fire
  • noise transmission
    • if there are air gaps, sound will find a way through the wall or ceiling assembly
    • to minimize noise between occupancies, use the airtight drywall approach (ADA) even for interior partitions

There are two main ways to document the airtightness of a building. One is to take the leakage in cubic meters per hour or cubic feet per minute and divide it by the area of the building envelope. The other method is to determine the number of air changes per hour (ACH) by measuring the leakage and dividing by the air volume. For example a 1000 m3 building with a measured air flow leakage rate of 1000 m3/h would have an airtightness rating of 1 h-1 since 1000 m3/h/1000 m3 = 1 h-1 . Using non-metric units: 583 CFM * (60 min/hr)/35,000 CF = 1 ACH. The Passive House standard requires testing at 50 Pascal while USACE requires 75 Pa. Testing at a higher pressure yields more accurate results, especially for larger buildings. (See the US Army Corps of Engineers Air Leakage Test Protocol PDF.) In order to distinguish between the natural leakage rate and the tested leakage rate at 50 Pa pressure, the airtightness number is noted as n50 or ACH50.

“Build tight and ventilate right” is a popular saying among building science consultants. Proper ventilation is essential for healthy indoor air quality, especially for airtight buildings. Building codes require mechanical ventilation if natural ventilation is not sufficient. Beyond code requirements, relying on open windows for natural ventilation can be problematic due to street noise, dust, rain, and extreme outdoor temperatures. Does a building need to breathe? That’s a confusing metaphor because there are two distinct issues. One is uncontrolled air leakage (bad) and the other is vapor permeability (usually good).

Use a blower door to find air leaks, not just to determine ACH50. Before the drywall goes up, pressurize the building with a blower door and use theatrical smoke, fingers (surprisingly effective), or an infrared camera to find leaks. The first test can be at a higher pressure to make it easier to find leaks. At this point, it might be interesting to determine the ACH50 using the Passive House methodology, but it isn’t really necessary until all the leaks have been fixed. In the US and the UK, count on three or four iterations of testing and sealing to get below the limit of 0.6 ACH50. In Austria and Germany, where Passive House construction methods are more standardized, they often just do one blower door test towards the end.

A guide to Volume Calculations for Passivhaus Air Tightness Testing and the Difference with the UK Method

Blower Door Basics

Email to schedule a blower door test and air tightness field report.