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Letters: September/October 2011

September/October 2011
This article originally appeared in the September/October 2011 issue of Home Energy Magazine.
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Passive House No Magic Bullet

I attended the North American Passive House Conference in Portland last year and am generally a supporter of the Passive House program. However, I have a problem with how the program is currently being marketed and discussed. In the article "Passive House Gets Active" (Mar/Apr '11, p. 22), the author repeats a common misconception that I have seen in numerous other articles and publications: "If you can achieve these [Passive House] goals, you have reduced energy consumption of the building by roughly 90% over a typical code-built building. Once you reduce your utilities that much, it's easy to get to net zero energy. " This statement is simply wrong.

The Passive House program focuses on superinsulation and airtightness. This may reduce the space-heating energy of the building by 90% over a typical code-built building, but space heating is only a fraction of the energy consumed by a building. The rest is water heating, fans, lights, appliances, cooking, and miscellaneous plug loads. Even if the heating load were to be completely eliminated, this still leaves well over half of the energy use of the building in most climates. It is not going to be "easy" to get to net zero energy without addressing these other loads in addition to the space-heating load.

The Passive House program is a great program to reduce space-heating energy, but it is not a magic bullet that will solve all our energy efficiency problems.

Jonathan Heller, P.E.
Ecotope, Incorporated
Seattle, Washington

Author Steve Mann replies:

Thank you for your comment. You're absolutely right—the Passive House approach is not a magic bullet. As is true of all systems, the results you get depend on the specifics of the situation. As you point out, the program focuses on superinsulation and airtightness, but it focuses on overall energy reduction as well, including items like lighting and appliances. The Passive House system was originally designed for climate zones that are heating dominated, so I think it's entirely possible that it can result in a 90% reduction in total consumption over a code-built house. However, to blindly repeat the Passive House marketing mantra, as you point out, is inappropriate, because like all things, it depends.

Blown Cover?

A reader glancing at the cover of the July/August 2011 issue of Home Energy could come away with some incorrect ideas about the integration of windows with the drainage plane in new construction.

Specific details vary depending upon whether the window has an integral flange or brick mold/casing, but neither uses straight flashing in the way shown in the picture.

 

All components (house wrap, sill panning, window, and straight flashing) must be installed shingle style. In the picture on the magazine cover, the straight flashing on the side jam would direct water from the drainage plane into the rough opening. The result would be unhappiness. The installation of the house wrap at the top of the opening is incorrect as well; that needs to be cut into a flap so it can be dropped down over the top flange of the window (if it has a flange) or over the drip cap if there is no flange. Under no circumstances would a piece of straight flashing go over the necessary 45 degree cut that would integrate the window flange or casing with the drainage plane; putting it there would be a waste of material. It's also a missed opportunity that we can't see the critically important sill panning.   But excellent details are at www.buildingscience.com/documents/information-sheets/pan-flashing-for-exterior-wall-openings/? searchterm=window/.

 

For a complete protocol, see www.finehomebuilding.com/how-to/install-replacement-windows-and-flashing-correctly. aspx/.

Please excuse my zealousness, but absent/improper window flashing and the lack of kickout flashings are perennial pet peeves around here. And yes, I know I need to get a life!

-— Ed Voytovich
Building Efficiency Resources, LLC
Syracuse, New York

Errata

There were some errors on p. 39 of the article " Integrating Energy Efficiency and Healthy Homes, " in the July/August 2011 issue. The Green and Healthy Homes Initiative (GHHI) was established in 2008 by the Coalition to End Childhood Lead Poisoning, not by the Federal Healthy Homes Work Group or the National Center for Healthy Housing (NCHH) as stated in the article. GHHI was launched as a national partnership in January 2009 with the Council on Foundations, White House Office of Recovery, HUD, the Centers for Disease Control (CDC), The Annie E. Casey Foundation, and 14 project sites. The Federal Healthy Homes Work Group was established by HUD, not NCHH.

On p. 8 of the July/August ' 11 issue, a photo covers some of the text. The editors apologize for the mistake and the confusion it has caused our readers. The article, " Carbon Monoxide Around the House: Comparing CO Monitors, " reviews several CO monitors. The review of the Bacharach Monoxor III CO monitor, which was partially obscured by the photo, is reprinted below.

Bacharach Monoxor III. The Monoxor III is really in a different class, and I have included it here only because it is often used both for ambient and for undiluted CO testing. One drawback to that approach is that the unit cannot be used for both purposes at once. If the probe is in the throat of the water heater measuring the undiluted CO, it can't be measuring the ambient CO in the room. Nor is the Monoxor III well suited to walking around the house taking ambient CO readings. The pump is running all the time, which is a bit noisy; it is somewhat bulky; and it is particularly awkward if the hose and probe are attached to the body of the unit. The unit has no alarm function, so you have to be looking at it to monitor CO levels in the house.

However, in order to conduct a complete building analysis, you need a means of measuring the undiluted CO and the ambient CO. Although it is a compromise, the Monoxor III is one of the least expensive ways of measuring both.

 

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