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Comments on The North American Passive House Network 2014 Conference

Posted by David Kaufman on January 01, 2015
Comments on The North American Passive House Network 2014 Conference
Visiting the construction site of a Passive House during the conference.

I recently attended the conference for the North American Passive House Network (NAPHN). NAPHN promotes and mobilizes North American building industries to implement the international Passive House Standard and dramatically improve the quality and sustainability of our built environment. The Internation Passive House Association, headquartered in Germany, has been around for 27 years and recently certified its 1 millionth square meter (10,764 millionth square foot).

A very well-attended conference, albeit with a lean though interesting tradeshow.

Wolfganfg Feist came from Germany to keynote and regale the attendees with data on Passivhaus construction optimized for Portland, Maine (sunnier and colder than Germany and the other Portland, by the way).

Assuming 50-year lifecyle and 1.5% real interest rate, and an energy price of 8 cents kwh (not distinguishing between electricity and heat in the presentation), his findings were quite remarkable:

An external wall would be insulated to between 7-14” of cellulose, with R-44 being the least-cost optimum.

Other details, broken down on a cost-per-kwh-saved basis, were fascinating.

The figures below are taken from Feist’s slides, which may or may not have been converted from eurocents to local construction costs and US-cents, but either way the message is clear:

  • Thermal-Bridge-Free details: <1 cent/kwh
  • Highly Efficient low-e Glazing: 2-3 cents/kwh
  • PassivHaus Window, fully insulated frame: 4.5 cents/kwh
  • Heat Recovery Ventilation: 10 cents/kwh

The customary Passivhaus attention to details was evident.

For example, the criteria for certifying a ventilation unit to Passive House specifications noted a maximum acceptable level of 25 db in living spaces and that air supply temps are always >16.5 c. (at least, above -10C).

(Note that certification of components alone cannot be relied on for achieving PH-certified buildings.)

Passive House will be making an international list of suitable components for the EnerPhit retrofit program available by the end of 2014 for seven different climate zones.

Finally, Passive House will soon debut two official new categories:

  1. The customary “Classic” (maximum of 75 kwh/m2/y)
  2. The “Plus” (60 Kwh/m2/year maximum consumption, but also a minimum of 60 kwh/year renewable on-site supply, a.k.a Net Zero), and the “Premium” (45 Kwh/m2/year demand, 120 KwH/m2/y supply).

Other presentations looked at the Passive House certification standards, comparing those for HRV’s to certifications from Energy Star or HVI. Differences were pronounced. For instance, it was concluded that HVI certification by itself certainly was not indicator of  adequate performance for PH (or even low-energy) buildings.

Probably the most astonishing presentation came from Belgium.

The city of Brussels, population 1.1.million, has been promoting energy-efficiency in buildings since 2001, when its old building stock and weak codes left it at the bottom of the heap in the EU. Between 1990 and 2004, energy use climbed +16.3%, but from 2004-2011, it reversed and fell 12.8%!

At present, over 8 million square feet of Passive House buildings are under construction or planned in Brussels, with 5.4 million square feet to be completed by 2015. Building on the success of hundreds of “exemplary” buildings which proved low-energy construction could be achieved at reasonable cost, Brussels has passed the most ambitious perhaps requirements of any major city in the world: from January 2015, every new building in Brussels must be built to Passive House standards!

If that’s not enough, even substantial renovations must be brought to low-energy standards.

The Passive standards are being implemented in a manner that many find more flexible than the official certification.

Recent experience there showed not only is there “no panic on construction sites” but other key strategies have emerged. Some are obvious - KISS (Keep It Simple Stupid), among them.

They also anticipate 2,500 new jobs as well as substantial economic benefits over the years to the region.

Many examples of the benefits and feasibility of Passive House (as well as some of the hiccups) were presented at the conference, ranging from manufactured housing in Vermont to skyscrapers in Germany. The claim was made that for very large buildings, over 25,000 square feet, Passive House certification can be achieved at minor or no added cost.

One interesting figure cited: non-settling density for cellulose is 3.5#/ft2 for 6” depth, but 12” wall needs 3.7#/ft3 and an 18” deep wall (this is clearly Passivhaus folks talking!) needs 4#/ft3.

I would speculate that this greater density may decrease the R-value somewhat.

A particularly interesting project was a PH residence in Canada. Over a year, the building would be heated 54% by passive solar from various windows, 32% by internal gains from lighting etc., and  measly 14% (9 million btu) from the heating system. At these levels, even a future doubling or tripling of energy costs would cause minimal hardship for a homeowner, or for a society.

David Kaufman is an energy consultant with Energy Solutions in Maine.

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