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Musings of an Energy Nerd

Carl and Abe Write a Textbook

‘Green Building’ is a new book by Carl Seville (the Green Curmudgeon) and Abe Kruger

Image 1 of 3
The book is generously illustrated with clear detail drawings. This illustration reminds readers that the walls of a skylight well need to be insulated, and the insulation needs to be protected by an air barrier on the attic side. Download a sample chapter
Image Credit: Cengage Learning
The book is generously illustrated with clear detail drawings. This illustration reminds readers that the walls of a skylight well need to be insulated, and the insulation needs to be protected by an air barrier on the attic side. Download a sample chapter
Image Credit: Cengage Learning The detail shown here is one of the few I disagree with. I don't think that fiberglass batts should be used to insulate a crawl space wall. Better choices include rigid foam or spray polyurethane foam.
Image Credit: Cengage Learning
This isn't a good way to secure fiberglass batts in a crawl space ceiling. In just a few years, these batts will not longer be in contact with the subfloor above. The caption should include a warning that the crawl space vent depicted in the illustration is counterproductive in many U.S. climate zones.
Image Credit: Cengage Learning

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
  • Windows
  • Exterior finish materials
  • Patios and decks
  • Landscaping
  • Interior finishes
  • HVAC equipment
  • Electrical systems
  • Plumbing
  • 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 GBA 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 greenwashing.

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 envelope 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 glazing to balance the heat gain 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 barrier as by the rated R-value.”
  • “This air barrier may consist of one or a combination of the following: properly sealed housewrap, sealed exterior sheathing, 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-e 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-factor. 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 BTU 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 8×12 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 8×12 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.

Excellent sidebars

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.”


  1. User avater
    Danny Kelly | | #1

    In defense of the arborist consultation
    Martin - I think you may be a little too quick to criticize my friends on suggesting to call an arborist. I would assume they are not advising to have every fast growing weed inspected as you suggested but to give some thought as to the number, size, type, location and most importantly, the age of the trees on the lot and proceed with caution. As the authors are from Atlanta, I would think the majority of green building in the area is infill housing. It is these areas where there are 100+ year old oak trees lining the streets that are in danger. I do not think enough builders think about these trees during construction. They drive heavy equipment over the roots, trench through the roots with footings and sewer lines. Most do not understand the harm they do to the trees since it takes the trees about four years to die after the roots are destroyed. The tree still has leaves at the end of construction so put some pine straw around it and everything is great - they are not around four years later when the homeowner has to cut down the one big nice tree in the yard. Even in parts of the country where they grow like weeds - there is no quick fix for a missing 150 year old willow oak.

    Builders should have arborists on their team as much as they should have a plumber and a carpenter. If you have one that you use often like your other trade partners, most will not charge you for a site consult. We call our arborist out before beginning any job that has a large tree on the lot - he will suggest ideas to minimize the impact to the roots and in certain circumstances will recommend treatments to the tree before and/or after construction to help with root repair and growth. He will even provide us with free mulch to put over the roots if there is no other option but to drive over them. Spending a few hundred dollars up front is much cheaper than having to remove a large tree after a house is constructed, sometimes costing thousands of dollars (kind of like upgrading the HVAC on the front end to save money down the road)

    I think it is great advice that more builders and remodelors should embrace - there is no need to discourage this practice. You appear much more professional to your customer when you surround yourself with other professionals. Day #1 on the job can be spent driving over roots or installing tree protection - which is more green?

  2. User avater GBA Editor
    Martin Holladay | | #2

    Response to Danny Kelly
    Of course there are many job sites where it makes sense to consult an arborist, and you have provided examples of when such a consultation makes sense. I never said that arborists weren't useful professionals who can provide help on a green construction project.

    However, I think the advice given in the book was overly broad and needed qualification. Consulting an arborist is sometimes required -- but often it's not.

  3. User avater
    Kent Mitchell | | #3

    Martin, I'd like to quibble one of your quibbles! I think if can lights are installed, sealed and insulated properly are going to work just fine, and, more importantly, satisfy many of our customers and clients.
    Looking forward to this book!

  4. User avater GBA Editor
    Martin Holladay | | #4

    Response to Kent Mitchell
    Most so-called airtight can lights leak air. Most experienced home performance contractors who have conducted blower door tests for years can confirm this.

    In addition to the fact that most recessed can lights leak air, they have at least two other problems: they create hot spots in insulated ceilings that can lead to snow melt and ice-damming (most commonly, when the can lights are installed in a cathedral ceiling, but also when installed in a flat ceiling, if the can light is near the eaves), and they reduce the thickness of the insulation by taking up space in the insulated framing bay.

  5. User avater
    Carl Seville | | #5

    Thanks for the review
    Martin - Thanks for the thorough review of our book. I appreciate the time you obviously put into digesting the information. Although you did find some flaws, considering the depth and breadth of the subject and the time (3 years) we put into it, I feel like we didn't miss too much. I've been on a short vacation so I haven't taken the time to dig into your specific comments on errors and disagreements, but will do so with Abe and follow up soon.

    On a couple of specific comments - I appreciate your concern that we didn't address the problem with recessed lights in insulated ceilings more strongly. We talk early in the book about the importance of the building envelope and where to locate it, but I see that the electrical chapter could use a recap of that issue as it relates to fixture selection.

    On the HVAC, we did include a 2 page chart listing the pros and cons of different types of systems. we all have our preferences for what to use, but they are going to be influenced by climate, building type, occupant behavior and preferences, and available fuel sources. In a text like this, it is almost impossible to make specific recommendations that apply to all readers - we need to provide them with appropriate information for them to make their own decisions.

    Finally, for today, I have to take responsibility for "fenestration management". We went back and forth with calling that chapter Windows, Doors, and Skylights, and ultimately chose to call it fenestration to be more accurate and cut down on the words used in each sentence. I think that particular section could use a better title but some things just slip through the cracks.

    We're in the process of reviewing the text for the next printing and will be able to make some minor changes and corrections, big adjustments will need to wait for the next full edition in a few years.


  6. Elizabeth Kormos | | #6

    Alternatives to can lights
    When we built our house 17 years ago we put in two sets of large track lights with 4 lights each in the ceiling of our 2 story family room. We can turn on all 8 or only four on and they are on dimmers. They are directed toward the walls and give a nice light. With the dimmers we can go from romantic evening all the way to full light. I will be putting track lights in our new home. Much better than cans.

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