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Blog Review: Thriving on Low Carbon

Blogging from his new home on Martha’s Vineyard, energy guru Marc Rosenbaum writes about deep energy retrofits, the Passivhaus standard, and reducing his carbon footprint

Posted on May 12 2011 by Scott Gibson

Marc Rosenbaum is a well-known energy consultant who for 25 years lived in a house he called Nerdwood in Meriden, NH. It was heated mostly by wood and the sun. Rosenbaum’s company, Energysmiths, took on a variety of consulting jobs, including some for South Mountain Company on Martha’s Vineyard, which developed a cohousingDevelopment pattern in which multiple (typically 8 to 30) privately owned houses or housing units are clustered together with some commonly owned spaces, such as a common workshop, greenhouse, etc. Automobiles are typically kept to the perimeter of the community, creating a protected area within where children can play. Usually, residents are closely involved in all aspects of the development, from site selection to financing and design. community there called Island Cohousing.

Then, last June, Rosenbaum left New Hampshire and moved with his companion Jill and their dog to a rented house at Island Cohousing and went to work for South Mountain. They have since purchased the house and settled into the 16-house community, which describes itself as an “ongoing experiment in collaborative living.”

This spring, Rosenbaum also started a blog called Thriving on Low Carbon that talks about his experiences in his new home.

“As most new homeowners know, every direction you look, you can imagine a way to spend money,” Rosenbaum writes in an early blog entry. “Living as we now do in a maritime location, I can tell you that at least a house is not as bad as a boat, which I learned is an acronym for Bust Out Another Thousand$.”

Still, Rosenbaum is finding plenty to do. The houses in his community were more carefully built than the average house (Rosenbaum, in fact, consulted on the specs), but there were a number of improvements that could be made. Rosenbaum hooked up his trusty blower door, got out his theatrical fogTo fog a room or building is to use a fog machine during a blower door test, revealing locations of air leaks where the fog escapes. The fogging material is usually a glycol-based solution, completely non-toxic. machine and went to work finding and fixing air leaks. And he removed the oil-fired boiler that had been providing hot water and heat and replaced it with a ductless minisplit heat pumpHeating and cooling system in which specialized refrigerant fluid in a sealed system is alternately evaporated and condensed, changing its state from liquid to vapor by altering its pressure; this phase change allows heat to be transferred into or out of the house. See air-source heat pump and ground-source heat pump.. No doubt there’s a lot more to come.

The subtitle for Rosenbaum’s blog is “How I’m thinking about our house, transportation, food and waste, to minimize environmental impact, while improving quality of life and having fun.”

That seems about right. There is some geeky stuff here, but nothing off-putting or overly technical. Instead, it’s a readable mix of technical information and observations of a more personal nature. The tone is open, friendly and informative.

Here are a few excerpts:

On teaching and lineage

“In Buddhism, lineage is the line of teachers who have passed the Dharma from teacher to student in a recurring and unbroken cycle - the student becomes the teacher of the next student... Lineage is vertical and successional. In contrast, community is lateral and evolving. To continue with the Buddhist analogy, the word is sangha. Sangha is a mutually supportive community composed of members with a shared vision and set of values. The environmental/solar/energy efficient building community has been my sangha for over thirty years. I've made a number of my closest friends from this community, and I've learned almost all I know about the work I do from it.”

My carbon footprint

“A few years ago, probably after reading Jim Merkel's book Radical Simplicity, I worked through one of the carbon calculators. My carbon footprint was different than most Americans, because I lived in a house that I designed to run primarily off of renewable energy. It was eye-opening to see that four domestic airplane flights annually, three of them in the eastern US, and one to the west coast, were half my carbon footprint. Forty percent of the total was driving a car - 18-20,000 miles a year, even though it was a 40 mpg car. Over two-thirds of this was work-related, so I rationalized it, but I actually don't like driving and therefore had a double motivation to reduce auto miles.”

The problem with payback

“At some point in every workshop or seminar I teach, whether it's on Zero Net Energy Homes, or Deep Energy Retrofits, or Passive HouseA residential building construction standard requiring very low levels of air leakage, very high levels of insulation, and windows with a very low U-factor. Developed in the early 1990s by Bo Adamson and Wolfgang Feist, the standard is now promoted by the Passivhaus Institut in Darmstadt, Germany. To meet the standard, a home must have an infiltration rate no greater than 0.60 AC/H @ 50 pascals, a maximum annual heating energy use of 15 kWh per square meter (4,755 Btu per square foot), a maximum annual cooling energy use of 15 kWh per square meter (1.39 kWh per square foot), and maximum source energy use for all purposes of 120 kWh per square meter (11.1 kWh per square foot). The standard recommends, but does not require, a maximum design heating load of 10 W per square meter and windows with a maximum U-factor of 0.14. The Passivhaus standard was developed for buildings in central and northern Europe; efforts are underway to clarify the best techniques to achieve the standard for buildings in hot climates. principles, someone stands up and makes an impassioned speech about how all this is well and good but what's the payback?...The quickest response I have is, if you predict the future price of energy over the lifespan of these improvements, I'll tell you the payback. My habit when pushed to actually do some financial analysis is to present it in the form of scenario planning - I'll often select three rates of energy inflation and do the calcs showing the Net Present Value of the investment in each inflation scenario. The longer you project it out, the more dramatic are the differences. The usual result of this exercise is that those who are the decision makers begin to act from a position of risk avoidance, because the highest inflation rates in fuel costs get scary.”

Why heating with oil had to go

“If you arrived at this blog, you don't need to be convinced that it's a worthy goal to burn less fossil fuels. That's not the only reason to want the oil system gone, though. Have you ever been in a house where there has been a spill of fuel oil? It soaks into the ground below. You can smell it for decades. The cost of clean up can exceed the value of the house.”

About heating with biomass

“What about biomass? Advocates often say that biomass is carbon neutral, because a tree absorbs carbon as it grows, and as it decays, that carbon is released. By burning biomass, we're just hastening the release. I don't think it's quite that simple. Pellets, especially if they are made from wood chips (they used to be wood waste, less so today) need to have the wood chipped, then dried, then ground up and pressed into pellets. There is some fractional PE factor there. Firewood cut on your own place with a handsaw has a pretty low [primary energy] factor!”



Image Credits:

  1. Marc Rosenbaum
  2. Martin Holladay

1.
Fri, 09/07/2012 - 14:58

Carbon Calculator for Home Construction
by Miki Cook

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anyone have any experience using the Athena Institute Impact Estimator? I'd like to model alternative construction scenarios to see how much impact each has on reducing the carbon footprint of design elements, material and system choices. Need some help navigating the tool.


2.
Fri, 09/07/2012 - 15:18

Response to Miki Cook
by Martin Holladay, GBA Advisor

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Miki,
The best place to post your question is on GBA's Q&A page:
www.greenbuildingadvisor.com/qa

That way you are more likely to get a variety of answers from several GBA readers.


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