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Jeff Christian and the Zero-Energy House
David Zaks, 30 Jan 07
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Jeff Christian directs the Buildings Technology Center at the Oak Ridge National Labs. Over the last four years he has conducted research on five prototype houses that cost between 60 cents and one dollar a day in energy costs to operate. The talk was part of the Weston Global Distinguished Lecture series sponsored by the Center for Sustainability and the Global Environment (Disclaimer: I am pursuing my graduate degree there).  The 3-hour long seminar that he delivered is available on the web as both slides and video (Zero Energy Series pt 1 & 2).

David Zaks:
Jeff, why don't you tell me a little bit about what you do.

Jeff Christian: The Oak Ridge National Laboratory is a multi-disciplinary laboratory, and as far as energy efficiency, is the largest of the national laboratories in the country working on all aspects: transportation, industry, utilities and buildings. In the buildings area, there are about sixty of us that are working on various aspects of buildings everything from individual components, residential buildings, commercial buildings, combined heating and power, pretty much the whole gamut. As far as sponsorship, historically, most of our work is with the Department of Energy, although when it comes to buildings, it is the Energy Efficiency and Renewable Energy that comes out of DoE. The Building Technology Center is an interesting concept in it is a user facility, so it houses some fairly expensive pieces of equipment for making measurements on new roofs, walls, foundations, and appliances and heating and air conditioning equipment. We invite manufacturers, individuals and entrepreneurs to come in to use these facilities and the idea is not "we work for money" but we want you to come in a collaborate with us and the idea is that they wouldn't have to invest in expensive research equipment, we would have that and be able to work with them to help. The underlying theme is energy improvements in the improvements of buildings, or components of buildings.

DZ: Last month we reported that in the next 10 years all new houses in the UK are going to be zero-carbon.  How close is the US to this kind of goal. What is it going to take to get there?

JC: At this point, I think we are quite a long ways away, but I am part of a program called Building America, and that is a major theme coming out of the Department of Energy where they have set as a goal, and the year of attainment is something like the year 2020 that we would have zero-energy buildings and the technical definition of that is quite precise and you would have expected energy services, so we aren't talking about radical lifestyle alterations to get there. We have been progressing towards zero-energy and we have committed ourselves and Congress and the people who fund us that we will make gradual improvements as the years go on. We are not working with a very isolated group, major builders who are building 50,000 houses a year embrace our participation. We help them get to the Energy Star level, and if they weren't doing it, why not? Today, we are at somewhere between 30-40%, from our base code-built house in 2004, cost effectively. It is great to be able to find a market where people demand these type of houses from their builders, is what really has to happen, although there is clearly some research and development that needs to be there to do this on a cost effective basis.

DZ: What do think it is going to take to get the demand to be there? What steps from the public and private realms need to be taken to educate consumers about the benefits of zero-energy home?

JC: It is going to be a combination. Codes and standards are getting more and more rigorous, and all help to raise the bottom end, but we are very much going way beyond that. Today in places like California, there are entire subdivisions that are going in as very near zero-energy and if you look at the Sacramento Municipal Utility District, there are examples of developments whose results are very positive. It is the combination of a little bit of solar and energy efficiency. I have watched energy efficiency go from front page to past the classifieds, back to front page and it hasn't stuck and I think that if you look at people's attention spans in crises, that is what has taken place. The idea of the pizazz of a little bit of solar and at times actually running meters backwards has created a revenue stream that is quite attractive, and I think when that is realized we will accelerate towards our goal of zero-energy housing.

DZ: Higher upfront costs can severely limit the implementation of more efficient technologies, even though they more than pay for themselves in the long-run. What strategies are available for builders and owners to overcome these financial challenges?

JC: I am working on a group of houses in Tennessee, and with the revenue stream, if indeed the utilities could recognize that there are benefits in this, like peak load reductions, they may be mandated to have a certain fraction of renewables. We are very close to having zero-energy cost, not zero-energy consumption, and quite frankly that is what our market surveys tell us that is what people care about. If builders can say "I guarantee that I can build you this house, and you are reasonable with your other uses, it will attain zero-energy cost" and that is a big stepping stone and if utilities would buy back the green power at something like $0.22 - $0.23 in our area, then we would be at this zero cost. Right now they are buying back at about $0.15, so we are very close to that very critical stepping stone.

DZ: Buildings commonly have 50 year or longer lifespans. While the fraction of buildings that turnover are inherently going to be more efficient, what work is being done to retrofit buildings to reduce their energy consumption?

JC: There are some enormously valuable resources readily available for people to take and run with, but something that is really a groundswell is something called a Home Energy Rating System (HERS) and the resources at and there are an enormous number of folks around the country that are being trained and certified to do this, but the information is pretty publicly available for do-it-yourselfers. First you need an audit to generate a prioritized list of where to get the biggest bang for your buck. Oak Ridge has developed a weatherization assistant that is currently being used in 35 states to help in the weatherization programs, where someone can come in very quickly, assess where this house is at, and if you have $2,000 to spend, how it can be spent the most effectively.

DZ: Zero-energy housing is an essential step for the high-carbon intensity developed societies. What ways can this technology be used to help developing countries 'leapfrog' to to provide the necessary shelter with the minimal environmental impact.

JC: One of the concepts that we have been working on is with low-cost panels and there is a variety of these kind of panels, and as a class they are called structural insulated panels (SIPs). There are some wonderful things coming made from straw, soybeans that would be very sustainable and could be produced very locally. One concept is that these panels could be configured very simply, just getting people off the dirt, particularly in countries where tents is the upscale housing. These panels could be reconfigured as time went on to more permanent housing as time went on. The skins for these are also showing a lot of promise, some very thin concretes that are very strong and lightweight. We have been involved in demonstrations in the Caribbean where people want one room that they can go to when it is really hot and are able to turn on their window air-conditioner and remain cool. It turns out that with a little bit of science, you can have a house with a historic and open layout to it to use that one air-conditioner for the whole house.

DZ: Imagine that the way we currently define a building as being "zero-energy" changed from looking at the daily energy budget of a building to having a 50-year time span. How would your activities change in terms of acquisition of good, transportation of materials and the embodied energy in the technologies you implement.

JC: When looking at the annual energy consumption of houses for heating / cooling / hot water is so large compared to many of the material selections, and it has been largely our focus to get down those annual loads. We hope and recognize that the things we are plugging into our homes today are hard to get a handle on. It comes down to entertainment centers and home offices and lots of times where people are making decisions that are preventing them from ever coming close to becoming a zero-energy house. There are some very simple low-tech solutions that are buried in algorithms in the appliances. We can sense CO2, we can sense motion and if people aren't using it, shutting it off.

At Oak Ridge we have tested over 400 walls, such as straw bale and rammed earth and we put them in an energy perspective context of how our other systems compare and there are great applications for it, these are things that we need to have whether they be out of appropriate materials or that we have an energy comparison for. Sustainable products also have to be durable. I had a workshop called "sustainable roofs" thinking people would show up with green roofs, and lot of it came down to making the standard roof last a longer time.

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Excellent article David. It's striking how efforts like this, and the Passivhaus efforts in Europe, are focused on simple, prosaic, physics-based efficiency efforts. In "green" architecture, some of the least-glamorous efforts are among the most effective.

Nomenclature matters, and perhaps it's a mistake to call these "zero-energy" houses. With time and effort, we might call them "zero-carbon" houses. I like to think of them as "renewable-ready" houses. They demonstrate that we shouldn't think about using renewable energy sources to power our current wasteful practices. It's through these kinds of superb efficiency improvements that the remaining loads are so low that they can feasibly be met by solar, wind, biofuels or other renewable energy sources.

Posted by: David Foley on 31 Jan 07



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