Zero-Energy Homes Start With Air-sealing, Insulation, and Weatherproofing - Fine Homebuilding

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Zero-Energy Homes Start With Air-sealing, Insulation, and Weatherproofing

comments (16) May 11th, 2010 in Blogs
1 | 2 | 3 | 4 | 5 > View all

In this excerpt from their book Toward a Zero Energy Home, authors David Johnston and Scott Gibson outline the basics of designing a comfortable and durable home.

By rethinking how we design and build the envelope to achieve zero energy, all other decisions like heating, ventilation, and air-conditioning (HVAC) and active solar become less expensive.

From a design standpoint, the guiding force in zero energy homes is solar orientation (specifically, Which direction is south?), which is discussed in detail in chapter 2. If we begin the design process thinking about how we can use the sun to its fullest potential, many other decisions become easier and less expensive. Zero energy homes take advantage of subtle energy flows, such as sunlight turning into heat and how to move that heat inside the building. The building envelope requires very careful design and construction beyond what seemed adequate just a few years ago. Zero energy homes are often 50 percent or more energy efficient than their local energy codes require.

 

image of a super-insulated houseA super-tight, well-insulated building envelope is the starting point for any zero energy home.

Building Science 101

Energy conservation in the building envelope is the initial focus for all the zero energy homes featured in this book. Reducing loads—the amount of fossil energy required to provide comfort year round—by half or more makes installing HVAC equipment much more affordable, as a smaller system is needed. Reducing loads requires getting all the building science right, which means understanding how building science principles work in a house: heat flow (thermodynamics), air flow, convection, the stack effect, controlling air with mechanical ventilation, and water flow (hydrodynamics). The key concept here is durability, so the house lasts as long as buildings built by our forebears. A durable home includes strategies for managing water in all forms (liquid, gas, solid), heat loss, heat gain, ultraviolet light, pests, and natural disasters.

Thermodynamics, or how heat moves (from thermo, meaning “heat,” and dynamics, meaning “movement”), is something we are all familiar with, but the basics often escape us when we build. Heat moves from hot to cold—always—even though it may seem that it is the cold that makes us uncomfortable. That is why we call it “heat loss."

 

 

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posted in: Blogs, energy efficiency, insulation, water and moisture control, air sealing, flashing, comfort, building envelope

Comments (16)

bumpin bumpin writes: This is extremely useful for money crunching times like these. It reminds me of another website I've been checking out: http://www.toolbase.org/Home-Building-Topics/zero-energy-homes/zero-energy-home-project

Posted: 9:49 pm on August 2nd

cragar cragar writes: Exactly what we all need to learn more about, and what our building codes need to reflect. The other part of the equation is of course, workmanship...
Posted: 7:19 am on June 17th

Jimrod Jimrod writes: As a LEED AP I am always looking for perspectives on energy efficient construction and renewable energy. I will definitely check this book out.
Posted: 11:05 pm on May 13th

pathearty pathearty writes: I am pressently building an energy efficient home using information that I found in FindHomebuilding. I would certainley read this book an apply any information that would improve on my design. WE will be living off grid so saving energy is important.
Posted: 8:41 pm on May 13th

pathearty pathearty writes: I am pressently building an energy efficient home using information that I found in FindHomebuilding. I would certainley read this book an apply any information that would improve on my design. WE will be living off grid so saving energy is important.
Posted: 8:41 pm on May 13th

briants58 briants58 writes: The excerpt from chapter one makes the case for a better built home. Taunton and its contributors certainly know how to do things right. The biggest question I've formed from this is how will the needed specifications make it into the blueprint and what will the pricing for a desireable home become? I am solidly behind moving the art of building into a zero energy home but I am skeptical that one could ever locate all the talents needed for one of these builds. Johnston and Gibson makes the point that methods and processes must change. Provide some tools for organization and I'm in!
Posted: 7:21 pm on May 13th

captklennedy captklennedy writes: I'm retired and would like to build a house in the next few years. It seems to me a Zero Energy Home (or darn near ZEH) would be the only way for me to go as I don't have the luxury of having my retirement resources keep up with inflation. we know that oil will increase dramatically and Cap & Trade will severely exacerbate that even more.

If we want to be warm in the winter and cool in the summer, we must build much more wisely. Keep the books coming as well as articles like the reality of geothermal heat pumps.

the truth will keep us warm!

PCK
Posted: 7:17 pm on May 13th

daveross daveross writes: first chapter easy to read, understand. love to see what the rest reads like.
Posted: 4:57 pm on May 13th

Evergreenlbh Evergreenlbh writes: Looks like another great book from the authors. I first borrowed from the library and then purchased their previous book, "Green From the Ground Up". I'd love to have a copy of their new book to refer to as we proceed through the design and building process for our new passive solar, super insulated house. With the new house, we are working toward a ZEH by having a good designer who is keyed into the ZEH process, being very involved in the design and construction process and planning to meet with all of the subs so they understand what we want and need in the new house. Our current home is passive solar, super insulated and built with the best technology from 1986. We've enjoyed living here and, most of all, writing very small checks to the propane company each month as compared to our neighbors.
Posted: 3:01 pm on May 13th

humperdink humperdink writes: The authors state that most windows are installed incorrectly. This is not surprising to me, as I see many examples of sloppy work in my own home that was built in 1987. How useful are thermodynamic fine points when the people doing the work don't care or are not trained properly, and doesn't this point out the need for greater attention to these matters by local building inspectors?
Posted: 12:45 pm on May 13th

Jasper_50 Jasper_50 writes: I am finally on board for "green energy" after listening to the pros and cons arguments for years. Having the project pay you instead of the other way around is certainly the way to go. The novel idea is way beyond what I could have hoped for. Sign me up.
Posted: 12:12 pm on May 13th

kengorman kengorman writes: Someday all my homes will be ZEH. Air sealing insulating is the key....orientation.....we have been offering and implimenting these upgrades for years. Products will become more energywise and more mainstream purchases. Manufacturers are on the fast track with R & D. to replace 19th century products with energywise products without increased cost. Thats when it will explode. I hope to build my first ZEH soon.
Posted: 11:38 am on May 13th

MAMArshall3 MAMArshall3 writes: We just built an energy efficient home. Now I need to figure out how to get off the grid. This book will help a lot.
Posted: 11:37 am on May 13th

bombardier bombardier writes: Great primer, I would read and comment. Would be interesting if it will contain practical applications to homes, especially the vast majority of us that live in homes built in the 70's and 80's which seem to have very little of the innovations and "energy" concerns of today.

Posted: 10:38 am on May 13th

bartbill bartbill writes: This webpage is a timely discovery for me. We need to downsize and it looks like we'll need to build a small energy efficient place to live in. Started with "A House so Small"? Starting research into what we need and want.
Posted: 10:35 pm on May 11th

JAGQueen JAGQueen writes: Looks interesting. I would happily read the book and comment on it. I would even see if it had any applicability to the historic home I am renovating...
Posted: 2:34 pm on May 11th

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