Carl and Abe Write a Textbook
‘Green Building’ is a new book by Carl Seville (the Green Curmudgeon) and Abe Kruger
Carl Seville, this website’s resident green building curmudgeon and blogger, has teamed up with Abe Kruger, an energy rater and BPI Building Analyst, to write a new textbook, Green Building: Principles and Practices in Residential Construction.
The book fills a gap, and fills it well. Until now, there hasn’t been a good, comprehensive introduction to green residential construction that was suitable for use in classrooms. Anyone who’s been waiting for a solid reference book on the topic of green residential construction should go out and buy this book.
This 521-page hardback includes soup-to-nuts coverage of the following topics:
- Defining green building
- The house as a system
- Planning a house
- Insulation and air sealing
- Foundations, floors, walls, roofs, and attics
- Exterior finish materials
- Patios and decks
- Interior finishes
- HVAC(Heating, ventilation, and air conditioning). Collectively, the mechanical systems that heat, ventilate, and cool a building. equipment
- Electrical systems
- Water heaters
- Renewable energy systems
Every page of the book includes at least one clear illustration or photograph. The well-chosen illustrations and photos will certainly facilitate comprehension for any student of green building — especially “visual learners” who are more likely to grasp concepts displayed in pictures than concepts explained in words.
Since Carl is a member of the GBAGreenBuildingAdvisor.com team, the information he presents is consistent with the advice found on the GBA website. The authors’ perspective is firmly based in building science, and the book is free of any taint of greenwashingDissemination of misleading or false information designed to make an organization or product appear more environmentally friendly than it actually is..
Here are samples of the wisdom found in Green Building:
- “Occupants of green homes are typically more satisfied than owners of standard homes. … Green homes generally have fewer callbacks for HVAC and comfort problems, drywall cracks, paint peeling, and other issues that can be improved through green building techniques.”
- “To create a green home, you must first understand how heat, air, and moisture interact within the interior and exterior of the building, its subsystems, and its occupants.”
- “To be effective in keeping the house comfortable and efficient, the building envelopeExterior components of a house that provide protection from colder (and warmer) outdoor temperatures and precipitation; includes the house foundation, framed exterior walls, roof or ceiling, and insulation, and air sealing materials. must be continuous and complete. The building envelope on most existing homes (and many new ones) is neither.”
- “The challenge is to properly size the south-facing glazingWhen referring to windows or doors, the transparent or translucent layer that transmits light. High-performance glazing may include multiple layers of glass or plastic, low-e coatings, and low-conductivity gas fill. to balance the heat gainIncrease in the amount of heat in a space, including heat transferred from outside (in the form of solar radiation) and heat generated within by people, lights, mechanical systems, and other sources. See heat loss. and heat loss properties without overheating.”
- “Smaller homes do not require sacrifice. … Smaller homes may lead to smaller mortgages, which, along with smaller utility bills, can provide more financial security for homeowners.”
- “The performance of a particular insulation in a building component is affected as much by the quality of the installation and the completeness of the air barrierBuilding assembly components that work as a system to restrict air flow through the building envelope. Air barriers may or may not act as a vapor barrier. The air barrier can be on the exterior, the interior of the assembly, or both. as by the rated R-valueMeasure of resistance to heat flow; the higher the R-value, the lower the heat loss. The inverse of U-factor. .”
- “This air barrier may consist of one or a combination of the following: properly sealed housewrap, sealed exterior sheathingMaterial, usually plywood or oriented strand board (OSB), but sometimes wooden boards, installed on the exterior of wall studs, rafters, or roof trusses; siding or roofing installed on the sheathing—sometimes over strapping to create a rainscreen. , or interior drywall. … The primary barrier must be combined with sealants at joints between framing members, at drywall edges, at mechanical penetrations, and at rim joists.”
- “Whenever air permeable insulation is installed in walls, an air barrier must be installed to provide the required six-sided air seal behind metal fireplaces, at framed soffits, behind tubs and showers, at knee walls, at cantilevers, and anywhere else that air could flow freely through cavity insulation.”
- “Modern [attic] ventilation standards are largely based on research from the 1930s by the U.S. Forest Products Laboratory and a 1942 document from the Federal Housing Authority. These studies were limited in scope and modern research has disproven many of the assumptions. Studies have shown that most traditional methods of roof ventilation are not as effective at removing moisture as intended, and they do not have significant effect on the life of the roofing material.”
In short, most of the information in this book is both accurate and valuable.
Am I allowed to quibble?
However, I didn’t agree with a few of the authors’ statements. For example, Carl and Abe are occasionally too quick to advise readers to hire experts. We learn that when installing a foundation, “an experienced arborist should be consulted to help maintain a healthy tree canopy.” (In some areas of the country, especially areas where trees grow like weeds, this advice seems a little over the top.)
Elsewhere, the authors advise homeowners to arrange for “twice-annual inspections of [HVAC] equipment.” Twice a year? Well, I’m sure that the HVAC contractors support that advice.
Here are a few other sentences that had me muttering “Really?”:
- “The only way to confirm that loose-fill fiberglass insulation has been installed at the proper density is to have core samples taken from random locations and the result weighed to confirm the results.” How about the bag-count method?
- “Recessed light fixtures in insulated ceilings must be airtight units that typically have gaskets that seam them to the drywall.” I disagree; I don’t think that recessed light fixtures belong in an insulated ceiling — especially in a green home.
As can be seen with the illustrations (Images #2 and #3) I've reproduced here, the book proposes using fiberglass batts in ways that aren't particularly appropriate for green buildings.
A few errors crept into the text
Like the first edition of any textbook, Green Building includes errors. Most are minor —
for example, misspellings like “Durasol” for “Durisol” and “Holliday” for “Holladay”) — but a few are more serious.
The authors write that “Low-e coatings are fragile, so they are applied to one or more of the inside surfaces of the glass before it is assembled into an insulated panel.” Actually, this statement is only true of sputtered (soft-coat) low-eLow-emissivity coating. Very thin metallic coating on glass or plastic window glazing that permits most of the sun’s short-wave (light) radiation to enter, while blocking up to 90% of the long-wave (heat) radiation. Low-e coatings boost a window’s R-value and reduce its U-factor. coatings; pyrolytic (hard-coat) low-e coatings are durable, and are regularly used on single-pane storm windows.
A table on page 117 reports that “standard new homes” have an air leakage rate of 8 to 12 ach50. This range seems much too high to me. Although Texas homes may be that leaky, cold-climate homes are much tighter. For example, a 2002 study of 24 new Wisconsin homes showed a median air leakage of 3.9 ach50. That was ten years ago; I imagine that new Wisconsin homes are now even tighter.
The authors inform us that “There are two types of moisture: bulk moisture (water) and vapor.” Actually, there are at least three types of moisture that occur in buildings — liquid water, water vapor, and ice — and most building scientists, including William Rose, recognize a fourth state: absorbed (or bound) moisture.
The definition of R-value (on page 28) confuses R-value with U-factorMeasure of the heat conducted through a given product or material—the number of British thermal units (Btus) of heat that move through a square foot of the material in one hour for every 1 degree Fahrenheit difference in temperature across the material (Btu/ft2°F hr). U-factor is the inverse of R-value. . The authors explain that “The R-value states how much heat transmits through 1 square foot of a surface … in one hour with a 1 °F difference between opposite surfaces.” In fact, the sentence is actually a rough definition of U-factor, not R-value. R-value isn’t a measure of heat flow; rather, it is a measure of a material’s resistance to heat flow.
The confused paragraph goes on to state that “R-value is measured in BTUBritish thermal unit, the amount of heat required to raise one pound of water (about a pint) one degree Fahrenheit in temperature—about the heat content of one wooden kitchen match. One Btu is equivalent to 0.293 watt-hours or 1,055 joules. per hour per degree Fahrenheit per square foot.” Again, the authors meant to write U-factor, not R-value.
It isn’t always true, as the book states, that “R-values are calculated for a given thickness of material.” While it is possible to say that fiberglass insulation has an R-value of 3.7 per inch, it’s also possible to say, “This is an R-13 batt,” without any reference to the batt’s thickness.
Confusing Btu and Btu/h
On page 33, the book confuses Btu with Btu/h. According to the example in the book, an 8x12 wall has a heat flow of 771,724 Btu/h. That’s scary! It would take at least 10 residential-sized furnaces, operating full blast, to balance the heat loss of such a (relatively small) wall. It appears that the authors intended to refer to the number of Btu (not Btu/h) that flow through the 8x12 wall in one heating season.
On page 40, the book notes that “The water vapor permeability of a material is inversely proportional to its thickness.” Actually, permeability is independent of thickness; the authors are describing permeance, not permeability. Permeance varies with thickness, while permeability does not. The same error is repeated on the next page, where a table of permeance values is mislabeled as a table of “permeability values.”
Textbooks strive to be error-free, so the lapses in Green Building matter. However, I have every reason to believe that all of these errors will be corrected in the book’s second printing.
To balance the impersonal tone of most of the book’s prose, Green Building includes bylined sidebars in a more conversational style. Many of the authors of these short articles will be familiar to GBA readers; they include Sam Rashkin, Bruce Harley, Sarah Susanka, Michael Chandler, Mike Guertin, Peter Yost, Katrin Klingenberg, Armin Rudd, and Gary Klein.
These sidebars are one of the book’s strengths. However, the refreshingly clear voices highlighted in these sidebars point to one of the book’s weaknesses.
Like most textbooks, Green Building strives to be comprehensive rather than prescriptive. In other words, it provides few opinions and almost no advice. Whoever the editors of the volume were, they probably had to tell Carl to tone down his usual lively prose style.
Sadly, Curmudgeonly Carl (and Opinionated Abe) are absent from this volume, and they are sorely missed. In their stead, we get textbook-speak. For example, a section of the book with advice on when to open windows is called “Fenestration Management.” That heading must have been dreamed up by the publisher’s obfuscation specialists — and must have driven Carl nuts.
Too much description and too little advice
Many of the chapters consist of little more than descriptions of available equipment. For example, the “Mechanical Systems” section describes furnaces, boilers, air-source heat pumps, ground-source heat pumps, air conditioners, evaporative coolers, duct systems, hydronic distribution systems, and dehumidifiers. At the end of this chapter, the reader knows what each type of equipment does — but is left wondering, “Are all of these listed options equivalent?”
How does all of this technical knowledge help the student design a green building, if Carl and Abe won’t tell us how to think about designing heating and cooling systems?
Similarly, the chapter on solar thermal system fills many pages with descriptions of batch heaters, thermosyphon systems, flat-plate collectors, evacuated-tube collectors, parabolic concentrating collectors, solar water tanks, solar controls and pumps. But there is precious little (if any) guidance to help a student answer the fundamental question: Does it ever make sense to install any of this equipment on a house?
In a way, the authors of this book had to struggle with a question that also bedevils GBA: were they writing a book about residential construction or a book about green building?
Much of the information in the book is basic: “Roof slopes are described by their rise (vertical height) over their run (horizontal length). A 6:12 slope means that the roof rises 6 inches for each 12 inches of horizontal run.”
We also learn that “The roof structure consists of the framing members to which sheathing is attached, and the finish roofing material installed on top of the sheathing.”
Eventually, the reader has to ask: What makes this information “green”?
Apologies from a curmudgeonly reviewer
Having criticized the impersonal prose voice of Green Building, I’ll move to the other side of the aisle and rise to defend it. This is a textbook, after all, not a blog. It’s an excellent resource that will provide college students the building blocks of knowledge they need to make decisions about house design and green construction. Once they’ve finished reading the textbook and gotten an A from their professors, they’ll be able to digest more opinionated information sources, and will eventually be able to wrestle with the complicated decisions required to design and build a house.
No other existing book approaches the comprehensive nature of this volume, and it will stand as a useful reference for many years — long enough, I hope, for the publisher to release new editions that correct some of the weaknesses found in the book's first printing.
Green Building: Principles and Practices in Residential Construction is available for $84.49 from Cengage Learning or for $63.67 from Amazon. You can Download a sample chapter here at GBA if you're on the fence.
Last week’s blog: “An Introduction to Photovoltaic Systems.”
- Cengage Learning
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Sun, 02/26/2012 - 05:54
Mon, 02/27/2012 - 11:21
Thu, 03/01/2012 - 08:16