Category Archives: Building Performance

Nauhaus Prototype Gets Plastered

Exterior and interior plastering is underway on the carbon neutral Nauhaus prototype.

The interior surface of the hempcrete walls has a base coat of earthen plaster consisting of sub-soil harvested from the construction site and mixed with sand and water. The mix was chosen after testing sixteen different compositions, a process spearheaded by intern Shannon Levenson. Earth plaster serves the Nauhaus prototype mission because it requires almost no energy to make or transport, and therefore has very little carbon emissions associated with it. In addition, earth plastering is fairly easy to learn, requires few tools, and is instantly gratifying, both because it’s beautiful at any skill level and very similar to playing with mud pies, a therapeutic experience that many adults realize they have been neglecting for too long. Whatever the reason, the earth plastering process attracted volunteers and interns like flies to…well, compost.

The exterior wall surface has been covered with a base coat of lime-based plaster supplied by Lime Technology as part of the hempcrete wall system. Both interior and exterior plasters were applied directly to the hempcrete which proved to be an excellent plaster substrate. Fiberglass mesh, similar to mesh drywall tape, were embedded in plaster over any joints or cracks in the hempcrete. Together these plasters over hempcrete create a vapor permeable wall system, sometimes called a “breathable wall”. The idea is to create a wall that is open to taking on and giving off water vapor in response to humidity levels in the air inside or outside the building.

We believe vapor permeable walls will last much longer and help create better indoor air quality than cavity wall systems that dominate US residential construction. As any builder will tell you, it’s pretty much impossible to keep water out of walls. Permeable walls are designed with the idea that it’s okay if some water gets in as long as it can get out just as easily and won’t cause any damage in the process.

Nauhaus Radio Interview

radioMike Figura and I did an interview about the Nauhaus prototype with Ned Doyle for his radio show, “Our Southern Community”. Okay, the interview was in February and I’m just getting around to listening to it. I’ve been busy, so sue me.

Anyway, this is still accurate and has good information about our work, though some things have changed. For example, Mike now wears a tie.

Here’s the interview divided into two parts:

Nauhaus Interview Part 1

Nauhaus Interview Part 2


Nauhaus Primer: Talking Head About Carbon Neutrality and the Nauhaus Prototype

We recently recorded this video intended as a draft to help us work on our public spiel. It needs a lot of work, but I thought I’d post it anyway because it’s a fairly thorough introduction to what we’re doing generally and the prototype in particular.  Just pretend you’re in high school and lunch is next period…Go generic sports team with some sort of mammal as its mascot!

Carbon Neutrality and The Nauhaus Prototype from Clarke Snell on Vimeo.

Legalize Industrial Hemp Nau

Well, it’s Hemp History Week.  Here’s the short version of the industrial hemp rant:

If you think the US is a capitalist country, think again. We can buy all the industrial hemp products we want, but we can’t grow the raw material to make the products ourselves. Can you say, “trade imbalance”? To learn a bit more, watch these two short videos we were involved in that discuss industrial hemp generally and then specifically as it applies to our Nauhaus prototype:

Building Fundamentals: Energy Efficiency Geekout – Anatomy of Windows and Doors Part I

This article by Clarke Snell was originally published in the New Life Journal.

If you ask 10 kids to draw a picture of a house, I can almost guarantee that they’ll all include a door and at least one big window. Ask those same kids 25 years later to describe their dream houses and I predict they will all be crammed full of windows. What I’m saying here is that in my experience, we all love windows. What’s wrong with that? Well, if our goal is to create an energy efficient building, typical glass-filled openings are actually a real pain in the astragal because compared to modern wall systems they perform horribly. In this month’s column, I’ll explain the basics of why this is true. Then next month, I’ll tell you what you can do about it.

Sidebar: R-value vs. U-value

Resistance to heat flow in building materials is usually quantified as R-value. The higher the R, the better the insulation. Just to confuse us, the insulation value of windows is expressed as U-value which is the inverse of R. To find out the R-value of a window, divide 1 by its U-value. For example, U= .4; 1÷.4 = R2.5

Heat Loss

Other than keeping rain and snow out of your bed, perhaps the most pivotal function of your house is its ability to create a different temperature inside than the temperature outside. This is accomplished by wrapping the interior space with insulation, a generic term for a material designed to resist the flow of heat. To oversimplify for our purposes, the better this insulation cocoon functions, the less heating or cooling the building will need. Since heating and cooling both cost money and usually involve global warming creating carbon emissions (our buildings are responsible for about 50% of our collective carbon footprint), improving insulation has been a focus of the green building movement. In recent years, we’ve made incredible strides and now have access to insulation systems that can produce walls systems with R-values (see sidebar) in the 20’s, 30’s, and even 40’s. Typical new windows, however, have R-values of only 2 or 3, 10 or more times worse than the wall itself. This is almost equivalent to a thermal hole in the wall. Therefore, the main performance flop for windows is their inadequate resistance to the flow of heat.

Mean Radiant Temperature

Mean radiant temperature is basically the average temperature of the surfaces of everything in the vicinity of your body. In a house, that means the surface of windows, walls, furniture, dusty knickknacks, and everything else. All of these surfaces radiate heat outward toward your skin, and your skin in turn radiates toward them. Since windows are so bad at slowing heat movement, their surface temperature will tend to be very different than that of other surfaces in your house. If the surface temperature of an object near you is considerably less or more than that of your body, you feel it as cold or warmth. This is why on a cold winter day, the thermostat can read 70F and you’ll still feel cold standing by a window. Low surface temperature, then, is another way windows drag down the overall thermal performance of our wall system.

Air Leakage

Doors and operable windows are basically huge holes that can be opened and closed. By definition, though, that closure is never perfect. The hole always leaks. Gaps and cracks in our wall will allow air to bypass insulation resulting in the movement of heat in or out of our building. Therefore, another strike against windows and doors is their contribution to this air leakage.

Solar Heat Gain

Responsible energy efficient designs incorporate a basically infinite, free source of energy: the sun. In our climate this means letting the sun in during the winter.  We need glass-filled openings to accomplish this. Different glass types and configurations let in more or less of the sunlight that hits them. This is quantified as a number called the solar heat gain coefficient (SHGC) which is basically the percentage of potential solar heat that glass lets into the building. For example, a SHCG of .5 means that 50% of the potential solar heat is making it through the glass. There are situations where we want solar heat gain and others where we don’t, so the wrong glass type in the wrong place can be a major detriment to building performance.


The point I’m making here is that windows and doors are typically VERY weak spots in the performance of a modern building. Next month, I’ll give you the skinny on how to choose the right windows and doors for new construction and remodeling or how to spiff up the performance of your existing underachieving glass units.

Building Fundamentals: Energy Efficiency Geekout – Anatomy of Windows and Doors Part 2

This article by Clarke Snell was first published in the New Life Journal.

Last month I ragged on windows and doors, pointing out that they are generally a very weak spot  in the performance of a modern, environmentally conscious building. To summarize: they don’t insulate very well, are a source of air leakage, can cause perceived discomfort, and can either let in too much solar heat when it’s not wanted or block too much solar heat when it is wanted. The obvious question is, “What can we do about it?”

Luckily, a lot of really smart people have been working on window technology in recent years and they are making big strides. If you are looking to build a new house, there are good choices to be made to improve the energy efficiency of your doors and windows. Similarly, if you want to increase the performance of your existing house, replacing windows and doors is a good place to start.

Sidebar: R-value vs. U-value

Resistance to heat flow in building materials is usually quantified as R-value. The higher the R, the better the insulation. Just to confuse us, the insulation value of windows is expressed as U-value which is the inverse of R. To find out the R-value of a window, divide 1 by its U-value. For example, U= .4; 1÷.4 = R-2.5

If you want to understand the mechanics, there’s a lot to learn. For example, most windows have two glass panes separated by a space filled with air or another gas, but triple pane windows with much lower U-values (see sidebar) are becoming more common. Then there’s the issue of low-e coatings, basically coatings that increase efficiency by reflecting heat energy. Windows can have different numbers and types of coatings configured to reflect heat in or out. Frame type is also important with choices ranging from metal to vinyl to wood to fiberglass. Glazing spacers, thermally broken frames, gas fills, closure mechanisms…the list goes on.

You really don’t need to worry about most of that stuff because all of this technology is synopsized in three quantifiable performance characteristics: U-value, solar heat gain coefficient, and air leakage rate. The National Fenestration Rating Council has created a standardized rating system that requires computer modeling and lab testing for verification of these variables. The results of these tests are prominently displayed on a label you’ll find on any new window or door. If it’s not labeled, don’t buy it. If you are talking with any professional, be sure to reference these numbers and make clear that you want values for the whole window or door unit, not just the glass. Armed with this basic knowledge, I can now offer you some simple rules of thumb summarized in the following chart:

Wind or Door Facing

U-value (BTU/hr-sf-F)


Air Leakage (CFM/sf)







East, West, North1














* My advice is for you not to go below these performance ratings

1East, west, and north facing openings. In terms of winter solar heat gain, these windows will be a net loss. No matter how much sunlight you can let in, the energy gained won’t be enough to offset the energy lost when the sun isn’t shining through the glass. Therefore, choose windows and doors with the lowest SHGC, U-value, and air leakage rates that you can afford.

2South facing openings. For glass that faces south AND gets full sun at least between 10:00am and 2:00pm all winter, choose windows and doors with the lowest U-value and air leakage but highest SHGC. NOTE: There is a new building code in effect setting a maximum SHGC for windows which is well below the desirable SHGC for south-facing windows that get full winter sun. There are ways around this glitch that are too involved to describe in this column. Just be sure to get this worked out with your builder and code officials before ordering windows.

As you start to shop for windows and doors, you may think that some of my chart numbers are wrong. According to NFRC specs, they aren’t. Right now, there are a huge range of performance levels and corresponding prices for windows and doors. Windows made in Europe, such as by the German manufacturer Optiwin, are the best, but they can cost more than $100/square foot. (Compare this to perhaps $15-20/sf for a decent off the shelf window in the US.) Canadian and US manufacturers are catching up in the performance category, so you just have to look around.

On the other hand, if you can’t afford the premium windows, there are other low-budget strategies. Covering glass openings with thick curtains anytime you aren’t in a room will increase window efficiency. If you live in an old drafty house, you can buy shrink wrap plastic to cover your single pane windows in the winter probably for less than $20. You’ll most likely immediately experience an increase in comfort due to higher radiant surface temperature (see last month’s column) and reduced air infiltration.

Regardless of the specifics of your situation, my point is simple. If you want to reduce your heating and cooling bills, improve interior comfort, and reach carbon reduction nirvana, don’t neglect your doors and windows.

A sample NFRC window label

Building Fundamentals: Certifiably Green

This article by Clarke Snell was originally published in the New Life Journal.

People are always asking me to define “green building”. It’s a good question and one that continues to elicit collective head scratching from us aficionados. How do you define “green” and once you define it how do you really know if a building matches the description? One of many trajectories spawned by this question has been the creation of certification programs designed to define and then guarantee the relative “greenness” of buildings. Some have worked, others not so well, some are still developing. We are lucky enough to live in a region that has a success story, the HealthyBuilt Home (HBH) program. For this month’s column, I talked about HBH with Maggie Leslie of the Western North Carolina Green Building Council.

[Note for readers in Georgia: While HBH is a North Carolina program, there is a similar program in Georgia called EarthCraft House. Though there are differences between the two, this article can serve as a general introduction to both programs. For specific information on EarthCraft, check out the links listed at the end of this column.]

What is a Healthy Built Home and Why Should We Care?

The HBH program was developed as a tool to educate people about green building and to improve the quality of new construction from an environmental and health perspective. It’s a statewide North Carolina initiative that is funded through the North Carolina State Energy Office. Our program here at the WNC Green Building Council was the first in the state and a large part of the development committee was from WNC. The pilot project was Prospect Terrace right here in Asheville.

There are three reasons why you’re better off with a HBH certified home: comfort, durability, and energy efficiency. HBH homes are more comfortable for a variety of reasons. First of all, they are “tighter”, which means that insulation is carefully installed to create a cocoon of 100% coverage around the living space and leaks are carefully sealed to prevent drafts and improve indoor air quality. In addition, heating and cooling systems are designed so that they heat and cool as they should. Durability is increased because moisture is carefully considered with a focus on a variety of construction details to keep both sensitive buildings materials and the building’s interior drier. Credit is given for higher quality materials, such as those with longer warranties. Also, third party certification allows for a fresh eye to catch mistakes and problems that builders under time crunches and other pressures sometimes miss. As for energy efficiency, HBH is built on top of the federal Energy Star program. All HBH homes are Energy Star certified. This means that they are a minimum of 15% more efficient than code requires. This is accomplished through improved insulation, lighting, heating/cooling system design and installation, use of renewable energy sources, and passive solar design.

How do you go about getting your house HBH certified?

The program is based on a checklist. In addition to a number of prerequisites, there are seven categories dealing with the building site, water use, building envelope, comfort systems, electrical consumption, indoor air quality, and materials with a bonus section for miscellaneous features and innovation. By complying with checklist requirements points are earned toward four levels of certification: Certified, Bronze, Silver, and Gold.

The first step is to contact the certifying organization in your area. In WNC, for example, it’s the Green Building Council. We hold HBH orientation classes every other month for builders, designers, homeowners, and anyone else interested in learning about the program. The idea here is for the project to be conceived in the context of HBH from the beginning. At this stage, the checklist is basically a design aide. Once a project is far enough along in the design process, the architect or builder meets with us to go over the checklist and register the project. We review the plans, makes suggestions, and help in any way we can. The next step is to hire a certified home energy rater. The rater will perform a computer energy model to determine the theoretical performance of the planned building. This step is designed not only to determine where the building will fall within the rating system but to identify possible changes to the design that will allow improvements in the building’s efficiency. Once the house is under construction, the energy rater will perform three onsite inspections (framing/HVAC, insulation, and final). After the inspections, project documentation is turned in to us. We check over it and then send it to the state for final certification. The homeowner then receives official certification and a variety of documentation including a list of their house’s “green” features, performance statistics including energy efficiency, money savings, and pollution averted, all in comparison to the present norm.

Personally, I think the real stroke of genius in the HBH program is that it is built on Energy Star, an inspection-based federal program. The Energy Star inspector was already going to the site to inspect for a variety of thermal efficiency issues, so why not get them to check on other building features at the same time? The result is a robust program that produces real building improvement at a very reasonable price.

Of course I agree. Our fees for administering a project are very low and are based on the size of the building. The fee for a building less than 1,200 square feet is only $100 and it goes up from there to $500 for anything over 6,000 square feet. Energy raters usually charge something like 30 cents per square foot of building with a minimum charge. The whole process runs between$750 and $1,500.

From my point of view, though, tabulating fees isn’t a good measure of the cost of certification. Since many of the HBH improvements will save you money over time, the question really is can you afford not to get certified. Increased energy efficiency means lower energy bills, less maintenance means fewer repair bills, and better indoor air quality means fewer doctor bills. In fact, some power companies offer discounts on your monthly bill for HBH certification, so the payback can start immediately

I know that you’re biased, but do you think the program is a success? How would you improve it?

We’ve worked hard on this program and accomplished a lot in a short time. The number of certified and registered buildings is growing at an impressive rate. One thing that I’ve noticed that really excites me is that first time HBH contractors almost always improve their certification level on their second project. For example, from certified on the first home, to bronze or silver on the second. Since we see our role primarily as educational, that statistic alone seems to me like a great measure of success. Our goal isn’t simply to certify homes, we want to be part of building a sustainable industry. We are setting up a system and then letting it loose for market driven businesses to take it where it needs to go. I think it’s working. Of course, we can always improve. I’d like for us to update the checklist even more often. I’d like to increase our educational outreach. I really think that every new home should be enrolled in the program. It just makes sense. I think that the strength of the green building movement is that there is something in it for everyone. Environmentalism is often perceived as forcing people to give something up. Involvement in HBH creates the opposite result. The homeowner gets a better house, the builder gets a certified product that is easier to sell, and we all get the benefits of reduced pollution and better natural resource management. It’s win, win, and win some more.

To learn more about the Healthy Built Home program, contact the WNCGBC:

Phone: 828.254.1995



For more info on EarthCraft, contact South Face Energy Institute:

Phone: 404.872.3549



Building Fundamentals: Engineering Fundamentals

This interview by Clarke Snell was originally published in the New Life Journal.

I moved to this region about 15 years ago because I thought it would be a better place to set up a homestead. I was looking for mountain spring water and milder temperatures than my Texas home. I found both, but the longer I’ve been here, the more I’m amazed by the people who live here, especially the ones I meet in my work in the world of “green building”. For my next few columns, I’m going to interview one of these local founts of wisdom on some aspect of all things green. This month, I talked with local mechanical engineer Jeff Buscher:

You and I are old enough to remember that ancient time before “green building” was a household word. How did you first get involved in the field?

I was studying architecture and engineering at Kansas State University when I read the book “Ecotopia” in an elective philosophy class. I remember it as a turning point for me. I started focusing on energy efficient technologies and sustainable practices in whatever way I could. After graduation, I worked for a large commercial engineering firm in Dallas for a number of years. It was frustrating because I kept pushing for sensible energy efficiency measures, putting them into designs only invariably to have them taken out at some point due to shortsighted reasoning, such as short-term construction cost reductions over long-term operating cost savings, let alone considering the additional environmental benefits. I finally decided to put my money where my mouth was and move to a smaller firm identified with green principles.

You and I have been working together for a while and I’ve come to really value your perspective. You’re unique in my experience because you combine an expansive knowledge of complex technology and technical methods with an interest in simple technologies, such as those commonly referred to as “natural building”. Given that novel perspective, what do you see as the important issues for “green building” enthusiasts to focus on?

First of all, we’ve got to face reality. The conventional construction world is in the grip of two dangerous forces: ignorance and inertia. Ignorance because efficiency has only been a concern for one generation.  We’re all still learning the best way to do this, but frankly, many building professionals aren’t educated as to even the most basic, common sense issues of building science. Inertia because to make money and avoid getting sued it makes sense to keep doing the thing that worked the last time. In other words, the construction industry is wary of innovation and slow to change. Real innovations tend to come from small companies that are light on their feet and driven through passion to do interesting things. Even in the “green building” industry most people are content to build to code. Forget codes. Building to code is the bare minimum acceptable to avoid being fined for breaking the law. To get where we need to be, we should be building at least two times in excess of current code mandated insulation levels. By achieving that level of performance we can significantly downsize or eliminate heating and cooling systems and make zero net energy buildings financially feasible. [Note: Zero Energy Design (ZED) can be defined as designing buildings that produce as much or more energy than they use.] ZED has been possible and achieved for decades. It’s not technically all that difficult to do.  It’s rare because it requires more design effort, and with current solar prices it costs a little more up front.  However,  the long-term benefits are huge. The question today is whether we can afford not to do it.

ZED is just barely starting to make it onto the mainstream radar. I think to a lot of people it sounds like something out of a science fiction novel. Can you shed a little light on the steps to move from conventional construction practices to ZED?

Well, it’s true that there is some high-tech involved, but many of the steps are old school. These concepts have been around for millennia.  First, we start with the land. Maximize what you can get from the building site and the surrounding area. Work with the sun for passive solar heating and cooling. Collect water on the site. Use as many materials from as close to the site as possible. Next, we need to stop building these light, expendable, giant boxes that pass for houses, office buildings, malls, what have you. We need more insulation and more mass. Insulation is a common concept for most people, but mass not so much. Adding heavy, dense materials (mass) adds to temperature stability and longevity of a building. This is a common approach in Europe, but we’ve missed the boat here.

In our climate, by creating a highly insulated building, you can drastically reduce the heating load, and by using a lot of mass you can potentially avoid mechanical cooling to keep the building comfortable. When compared to complex mechanical systems, insulation and mass are inexpensive and, once installed, they don’t require any additional input of energy to do their job. Past a certain threshold of load reduction, current “alternatives” such as solar electricity (PV), wind generators, solar hot water, and waste heat recovery start to become the sensible default solution rather than a luxury. This is where engineering becomes pivotal. Through energy modeling and integrating systems design with passive aspects of the building’s performance (insulation, mass, solar heating and cooling), we can create buildings that require only a fraction of the energy and resources to build and run compared to present common practice in this country.

The single variable that has the most effect on a building’s energy and resource efficiency is it’s size, so another major component of this strategy is to build smaller. Finally, we have to stop looking at our buildings as islands and start seeing them in their social context. A small, energy efficient eco-cottage is still missing the point if it’s part of a lifestyle that requires a two hour daily commute. Mixed use. Co-housing. Go local.  Live where you work.  Eat where you live. We should be designing to make driving less convenient and walking, and biking more convenient. I’m a big fan of the New Urbanism movement and recommend that people read up on it.

I’m with you on all of this, but one thing that makes me a bit nervous is our increasing dependence on complex technology. I’ve always been a do-it-yourselfer, but now I find myself spending more and more time in front of a computer whose inner workings are a complete mystery to me. That makes me fundamentally uneasy. What’s your take on the possibility of taking technology too far?

Obviously, that’s a danger. However, my personal feeling is that we need to find a way to solve our environmental problems while maintaining some level of the “comfort zone” that modern humans have become accustomed to. Technology can be a very useful tool in that context.  For example, in our climate, humidity is extreme. Around here, there is no way to create stable indoor humidity levels without some level of mechanical equipment. For me, the fun is in finding ways to limit and simplify the technology required to solve problems like this. I’m working on it, and I know others are too, so stay tuned.

To find out more about what Jeff thinks about, check out his blog at and check out these sources of information that he recommends:

  • Walkable towns:
  • Andrés Duany’s talk about how to avoid suburban sprawl:
  • ZED Architects in the UK:
  • Passive House Institute:
  • The Living Building Standard (No credits, just prerequisites.  It’s about what you did good, rather than being about what you did less bad.):

Footloose and Carbon Free: The Passive House Standard

This article by Clarke Snell was originally published in the New Life Journal.

Okay, by now everyone has gotten the “human induced global climate change” memo, right? If not, here’s the executive summary: We burn a lot of fuel for heating, cooling, manufacturing, generating electricity, and driving stuff around. That burning releases carbon dioxide (CO2). As CO2 levels increase, the atmosphere basically traps more solar heat, causing temperatures to rise. The dynamics of all this are pretty complicated and the details are debated, but there is a frighteningly solid majority of climate scientists who agree that we need to drastically reduce emissions of CO2 (and other “greenhouse gases”) if we are to avoid catastrophic climate change.

In the US, our buildings are responsible for about 50% of our carbon footprint. Therefore, if we take this somber warning seriously, we need to do a major overhaul of how we build…and fast. Luckily, since carbon emissions come from energy use, the solution is simply to use less energy, something that saves money, reduces pollution, and makes us more self-reliant. That’s right, it’s patriotic, baby!

The concept is really pretty simple. First, we greatly improve the efficiency of the building itself. We do that by reducing heating and cooling demand by increasing insulation levels and carefully sealing up air leaks. We then install a nifty device called an energy recovery ventilator which allows us to bring in fresh air with only minimum energy loss. Next, we focus on the sun, letting it in the winter for heat and blocking it in the summer for cooling. We also add  interior thermal mass to help store this energy. Finally we choose the most efficient systems, including mechanicals, appliances, lights, and anything else that uses energy.

If we do all of this right, we can reduce heating and cooling loads by 90% over the norm and cut electrical consumption by at least 70%. At this point, we’ve significantly reduced the carbon emissions associated with our building. However, to reach carbon reduction benchmarks based on climate science predictions (translation: to save the world as we know it, yeah!!) we need to go even further. We have to make all of the energy our building needs without releasing carbon, which basically means without burning fossil fuels (coal and petroleum). No big deal. Solar, wind, and hydro electric power are all available options. What’s more, our energy demand is so low now, these systems can be much smaller and therefore more affordable.

To go all the way, we need to make enough surplus renewable, non-carbon emitting energy to offset the carbon emissions produced to build the building, even to make the solar panels and other renewable systems we have installed. If we do all of this, we have reached carbon neutrality. In other words, our building is not involved in carbon emissions and is therefore doing its part to avert “human induced climate change” (see memo…you did get the memo didn’t you?) What’s more, the building will cost almost nothing to run and will have wonderful indoor air quality.

What’s the catch? Well, though the concept is simple, the application isn’t. First of all, when we get to this level of energy efficiency, some of our typical building components are woefully inadequate. For example, conventional windows and doors are just sieves for heat and air loss. Though high performance fenestration is available, it’s very expensive. In addition, the tiny air leakage allowable to make this work is simply outside the experience of US builders. Very careful attention to a variety of construction details is required, often using tapes and gaskets that are hard to find for sale in this country. There are other difficulties, all of which have to do with money. Though these buildings cost considerably less in a lifecycle analysis, the fact is that it simply costs more money upfront to save money, energy, and carbon emissions in the long wrong.

Luckily, if we want to move in the direction of carbon neutral construction, and I feel we have to, there are sensible, proven methodologies already in existence. The one I like the best is a certification program called Passive House. There are many thousands of buildings that have been built to this standard and performance monitored throughout Europe, mostly in Germany, though almost none to date in the US. The Passive House standard is laughably simple to grasp. You are allowed a given amount of heating and cooling energy per square foot of building as well as a defined rate of allowable air leakage. You then have to design a building envelope (basically insulation and air leakage strategy) and mechanical system that will perform at that level regardless of the climate in which you live. In other words, you can’t take a common “out” popular in the US green building movement: build a low efficiency building then attach a huge, expensive solar electric system that provides 25% of a large household energy demand and call it efficient.

The Passive House standard is administered in the US by the Passive House Institute US. These wonderful folks are hard at work training consultants, certifying buildings, helping to import or develop requisite materials, and educating the public. For more information, visit their web site at . If you want to see the process up close, we are hoping to build a Passive House certified building in West Asheville starting later this spring. To find out more, go to our project website at

Eco-Panels Installed

Eco-Panels came out on Tuesday and Wednesday and installed the S.I.P. roof.  The finished roof system for the Nauhaus Prototype will have an insulation value of about R80 when completed, because the spaces between the 8″ rafters will be packed with cellulose.

Some information about Eco-Panels, from their website:

For a truly superior building envelope Eco-Panels manufactures the only R60 panel on the market today coming in at just 8.5″ in thickness.  This panel, designed specifically for use in arctic regions, is perfect for the passive house or net zero energy designs where most modeling software calls for an R40 wall and R60 roof (of course this will vary based on region).  This roof panel will perform at better than R60 at 20deg F (-7deg C) using LTTP (long term thermal profile) and temperature vs k-factor performance data provided by the foam component manufacturer.

  • 8 1/2″(21.6 cm) = R60+
  • Maximum panel length is 12′-0″ (360 cm) although this can be increased to 16′-0″ for large opportunities
  • Maximum panel width is 4′-0″ (120 cm)
  • The insulation is high-R-value polyurethane foam injected at a density of 2.5 pounds per cubic foot.

Click here to view the entire Nauhaus Prototype Construction Chronology.

Garnet Igneous delivers supplies.
Garnet Igneous delivers supplies.
The framing is ready to receive the Eco Panels S.I.P.s.
The framing is ready to receive the Eco Panels S.I.P.s.

Chris Cashman
Chris Cashman
Eco Panels Truck
Eco-Panels Truck
Matt, Mike and Tim
Matt, Mike and Tim
The Eco Panels S.I.P.s are attached to a special bracket and lifted with a crane.
The Eco-Panels S.I.P.s are attached to a special bracket and lifted with a crane.
Craig Payne
Matt and Elijah install panels.
Matt and Elijah install panels.
Matt prepares for an Eco Panel.
Matt prepares for an Eco Panel.
Matt and Elijah attach panels to the North side of the roof.
Matt and Elijah attach panels to the North side of the roof.
8.5" R-60 Eco Panel on Rafter
8.5" R60 Eco-Panel S.I.P. on 8" Rafter
Eco Panels being installed on the South side of the roof
Eco-Panels being installed on the South side of the roof
Northeast Corner
Northeast Corner

West Gable
West Gable
All of the Eco Panels are installed.
All of the Eco-Panels are installed. Next we will add the overhangs and metal roofing.