Friday, November 12, 2010

Cool Technology of the Week

As I have written about many times, my plan in retirement is to create a small cabin, incorporating Japanese architectural principles and lifestyles, to serve as a base for an outdoor focused lifecycle.

Part of this dream is live off grid and achieve a minimal carbon footprint through Green Engineering principles.

Recently, my second in command of IT at BIDMC,  John Powers, went to a Green Engineering seminar, since he's pursuing the Green construction dream too.

Here are his lessons learned:

"The conference was an educational session for builders, architects and others on the new NH building code based on the International Energy Conservation Codes for 2009 (IECC 2009).

It was not a LEED or Energy Star course.  These are far more comprehensive and cover building standards plus many other “green living” topics such as sustainable landscaping, pest control alternatives, water re-use, green appliances and so forth.

ARRA incentivized States such as NH to more aggressively adopt stringent energy conservation codes.   My goal was to become a more educated consumer in preparation for building our “cabin” on a farm we purchased in northern NH.  

Among lessons learned was green building was THE topic at the annual NH Builder’s Conference.   This year’s banner was “Energy Efficient, Sustainable Building”.  See the “Building NH Show Guide” a

Other States have similar organizations into which home owners can tap.  Unfortunately, I had only time to attend the day long session on the new code.   Looking over the Show Guide made me realize how much learning is still ahead.   It emphasized the need to work with a builder and architect who understand the topic well.

The good news is there is an abundance of free material on the topic.  Among the sites that have relevant content are

A refresher in basic building science, especially types of heat transfer.  Radiation and conduction are important, but convection (heat transfer through air motion) is most important.  Air leakage is the focus of many parts of the energy code.   To drive home the point, the instructor provided an example.  A 4’x8’ sheet of wall board will diffuse 1/3 of a quart of water a year.   Punch a one square inch hole in it and it will exfiltrate (air leakage) 30 quarts of water a year.

The code refers to a “thermal envelope”.   It’s the space you heat and/or cool.  The envelope needs to be surrounded by a very, very tight thermal and air barrier.  These barriers need to be next to one another (as in touching) and contiguous (no gaps).   Use of strapping, odd structures such as dormers, stairs, rim joists, chases, shafts, penetrations, and the like require special attention.

With common use of 2”x6” for outside walls, it may no longer be necessary to use 16” on center studding for structural soundness.  A typical outside wall may be 20 percent wood using routine construction standards.  The “R” value of wood is 1 for every 1 inch thickness.  Compare that to R22 for high density spray foam.    Reducing outside wood surface, if structural soundness is not sacrificed, promotes a better thermal barrier.

Heat moves from areas of high temp to low temp.   Heat does not always rise.  Warm air rises, but heat can move in any direction.  If you intend to heat your basement, it needs to be insulated and included in the thermal envelope.

You cannot average “R” values.  For example, an attic insulated with one-half R-50 insulation and one-half R-10 insulation is not equivalent to (50+10)/2 or R-30.    It’s far less or the equivalent of R-17.

There is a home energy rating system (HERS) that was developed by the Residential Energy Services Network (  It rates the energy efficiency of a building relative to one built using the IECC 2006 codes.  The latter would have a value of 100.  A “zero energy” home would be rated “0”.   The lower the score the better.   For every point drop, there is a 1 percent reduction in energy compared to the index house.

The Department of Energy has issued a builders’ challenge to have, by 2030, cost-neutral, net-zero (NZEH) energy houses available in every location in the US."

Green Engineering is exciting stuff and I'm looking forward to the sheer geekiness of re-learning my thermodynamics and participating in the engineering of an energy efficient cabin in the woods.    For now, I'll live vicariously through John Powers' project, but in another 10-15 years, I'll pursue my own.    Green Engineering to save the planet - that's cool!


Unknown said...

A great site for building science education is It is the first source I look at.

There is a ton of information there, including design guides, contractor guides, and science based information on how a building envelope works. I'd highly recommend this to anyone interested in building an efficient building.

Another good source is the Whole Building Design Guide This is a program of the National Institute of Building Science (NIBS).

Anonymous said...

I hate to be the skunk at the picnic and I know you do much of this for your own personal reasons but I was listening to a report of a shipping company CEO on CNBC the other day. What he said was just staggering about China and their development. China has 200 cities with the population of Chicago. Their year over year imports of coal and iron/ore are up 25%... that's 25% since last year while our growth is close to zero. They open a new coal fired power plant every couple of weeks. I know the line by John Kennedy... "one man can make a difference and every man should try" but I fear the growth of China and India alone are going to make our minor efforts in reducing our carbon footprints look insignificant. We can cut back a little here and there but there is no way to balance off what is happening in other parts of the world and I see this trend going in the wrong direction.

Ryan Capers said...

Great post - my organization, GDS Associates, is actually coordinating the training workshops for the new NH Energy Code (International Energy Conservation code 2009) and really happy to hear you and John were able to find our workshop useful. I also just wanted to mention that we have a lot of similar information, including copies of the presentations you reference up at - so if anyone is interested in attending one of these workshops - or would like to receive a copy of the residential presentation, feel free to visit the website above, or contact me directly at

Thanks again for the great post!

-Ryan Capers, GDS Associates

Tomcat said...

Careful with making a home too tight. At least here on the far North Atlantic coast, when houses started tightening up with lots of thermal and moisture barriers and double and triple pane windows to keep the heat in, they also found that that kept the moisture in, and houses were being riddled with mold. Heat recovery air exchangers mitigate the heat loss that comes with freshening the air, but there still is quite some loss. We fought mold for a year or two before installing some an air exchanger, then voil'a: No more mold.

kul bhushan said...

John ,
If you plan to be off the grid .My understanding is to have old fashion lead batteries and solar panel to store and generate electricry. The system should be also a direct current system. 24 volt chargeable batteries could be used to ride electric bikes for several miles.Then you probably will waite till very old for that.It is fun to see you discuss sustainability.
Why it is in america every body talks about solar panels and connecting back to grid.Are we too comfortable with the system we have even when we want change.

Unknown said...

Tony K is right. You have to have ventilation (outside) air and you have to control humidity. To clarify, that is not an argument against tight construction, but an argument for good HVAC practices.