[Greenbuilding] Aggressively Passive: Building Homes to the Passive House Standard

[John Straube]

While this is a nice advertising blurb for the German PassivHaus standards it is not very factual.
I know of many many homes that have no cold corners or drafts and heating bills half the norm, that are not PassivHaus standard.  In fact, there are thousands of these.
The 90% savings number is based on space heating only, for old German houses vs PassivHaus.  Half or one third the norm is actually a better comparison vs code built homes in Illinois or Canada.
PassivHaus is one extreme way to get there.  As stated in the article, its principles are solidly based on those developed in North America in the 70's and 80s.  Ironically, one of the sparks was the Lo-cal house from the Illinois small homes council.
The principles are well known and developed: insulate well (including a consideration of all thermal bridges) airtighten (blower door test to confirm), use good windows (much better windows are available today than 30 years ago) and ventilate (preferably to each room with heat recovery). now use efficient lights, appliances, and equipment.  These principles have been applied by many builders, rating programs, etc for about 30 years now.
PassivHaus is a German standard that applies required numerical targets to these principles based on central European climate conditions, occupants, and construction types.  It sets a high goal, and measures it quite carefully.  These are good things.  However, PH does make you do some silly things, like measure areas using a German standard, and measure window performance at 32F rather than 0F, dont require HRVs to be tested at cold temperatures, use a monthly bin energy program rather than an hourly program, etc.  Some think they make you do even sillier things like heat the house with ventilation air (but officially this is not required).  A higher standard than the PH one is a NetZero energy house.  This takes things further and sets a numerical energy target of Zero, considerably less than the PH standard.  Dozens and maybe hundreds of such homes have been built.

  It costs me more than $10/month for my electrical utility before I use a single kWh.  Somehow, these folks manage to have bills of under $10 per month.  Hmm.The hyperbole and misinformation around this stuff is amazing to me and disheartening.



On 2011-01-07, at 10:07 PM, Doug Kalmer wrote:

> Direct gain, passive solar used in the Passive House standards helps to achieve 90%+ reduction in energy useage, proving south facing windows do fit in with efficient building design-
>  
> Imagine spending a long Illinois winter in a cozy house with no cold corners or drafts—and heating bills half the norm—or sailing through a sultry Louisiana summer in cool comfort with bills that cost a fraction of the neighbors’. Passive House, the latest set of building standards sweeping North America, uses seven simple principles to make these housing dreams come true.
> Passive Houses are so well designed, insulated, sealed and ventilated that they require as little as 10 percent of the energy standard homes use for heating, cooling and lighting. A tight envelope (roof, exterior walls and floor) and thick, heavily insulated walls keep winter cold and summer heat at bay with little reliance on furnaces and air conditioners. In winter, Passive Houses hold in heat from the sun, inhabitants’ bodies, lights and appliances. In summer, they keep cool air in and hot air out, though additional cooling may be needed in very hot, humid climates. Energy-recovery ventilators (ERVs) circulate fresh air for even temperatures and humidity. 
> Margaret and Gregory Stanton, who built a Passive House in Urbana, Illinois, don’t feel altruistic. “We’re selfish,” Greg jokes. “We’re free from volatile energy prices.” The Stantons love their thick walls and deep windowsills, energy savings and the absence of drafts. In response to Urbana’s cold winters and hot, humid summers, the Stanton house has R-87 roof insulation (20 to 24 inches of loose-fill cellulose), 18-inch-thick R-64 walls and a thick slab floor insulated to R-51. Direct solar gain provides much of their heat, backed up by a heat pump and an inline heater in their ERV.
>  Renters have lived in 204House for almost a year. “The renters love it,” Saft says, “and we’ve shown that not only can Passive House principles work in this climate, but that they also work financially.” Despite its 10 percent higher-than-average construction costs, 204House’s market-rate rental income covers expenses, with money left over for repairs. In fall, spring and part of the winter, the home’s utility bills are extremely low—averaging less than $10 a month.
>  
> Read more: http://www.naturalhomemagazine.com/sustainable-homes/aggressively-passive-building-homes-to-the-passive-house-standard.aspx#ixzz1APQSyVK8
>  
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Dr John Straube, P.Eng.
Associate Professor
University of Waterloo
Dept of Civil Eng. & School of Architecture
www.buildingscience.com

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