Category Archives: Building Materials

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 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.

We've Got Windows

A quadruple pane window from Serious installed in a hempcrete wall in the Nauhaus Prototype
A quadruple pane window from Serious installed in a hempcrete wall in the Nauhaus Prototype

Well, we finally got the windows and doors installed. Okay, let me vent for a sec: prototypes are a bitch. We had to do a lot of head scratching and trial and error to figure out the best way to insure airtightness in our installation. The hempcrete is awesome, but it create its own set of challenges, especially since our truly wonderful Serious windows aren’t really designed to be installed in the middle of thick walls. (Serious is a partner with us on this project and we’re working with them to make things easier when you decide to replicate what we’re doing.)

First, let’s sing the praises of these windows. Though a number of German companies make windows in this category, Serious Materials is the only US company that can meet the required specs for a Passive House. All window and door units on the project have fiberglass frames and quadruple pane glazing. Southern glazing has a center of glass insulation value of R-7 with an impressive solar heat gain coefficient (the percentage of solar heat that passes through the glass, 1.0 would be 100%) of about 0.7. This allows for heat gain from the low southern winter sun, a strategy integral to the Passive House integrated design system.

North, east, and west glazings weigh in at an amazing center of glass rating of R-11, a rating equal to the fiberglass insulation in some conventional stick frame walls! This is compared to R-2 for a typical double pane window found on most US projects. Unlike the heavier European windows, Serious reaches this performance level with two pieces of glass and two pieces of plastic allowing for a thinner profile more like conventional windows typically available in the US.

Why all the fuss? Well, I’ll tell you. In a Passive House in our climate region, walls need to be about R-40.  Sticking an R-2 hole in an R-40 wall just doesn’t make sense.  In a Passive House, the idea is to spend money on passive elements, extra insulation and really good windows for example, that don’t require energy inputs to do their job once installed, unlike heating, cooling, and ventilation equipment. In the right configuration, these passive elements combine to allow for a much simpler and less expensive mechanical system, thus saving money in construction and afterwards with much lower energy bills.

Anyway, we’ve got video footage that we’ll eventually compile into a bunch of great educational how-to videos on the ins and outs of all this nifty construction detailing. If anyone out there is getting antsy for the goods, getting us a grant to fund collation of the documentation footage would really speed things up. Until then, wet your chops on these few photos:

Here you see our custom plastic lumber sill piece with groove for backer rod and space for spray foam, the edge of the bituthane sill pan (green stuff), and the poured in place concrete exterior sill
Here you see our custom plastic lumber sill piece with groove for backer rod and space for spray foam, the edge of the bituthane sill pan (green stuff), and the poured in place concrete exterior sill.
All windows had to be pre-drilled through the fiberglass frames...
All windows had to be pre-drilled through the fiberglass frames...
...then screwed to the stud framing in the middle of the hempcrete wall.
...then screwed to the stud framing in the middle of the hempcrete wall.
Jeff installs backer rod as part of a multi-step installation process to insure maximum airtightness
Jeff puts his engineering degree to work installing a backer rod as part of a multi-step installation process to insure maximum airtightness
The plastic lumber sills were filled with foam after installation through a series of pre-drilled holes...ingenious!
The plastic lumber sills were filled with foam after installation through a series of pre-drilled holes...ingenious!
Southwest view showing all the windows installed. Doesn't look like any big deal, does it?
Southwest view showing windows installed. Doesn't look like any big deal, does it?
Installing the doors was a whole different story...don't get me started!
Master carpenter and benevolent genius Tim working on a door. Installing the doors was a whole different story...don't get me started!

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.

Conclusion

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)

SHGC

Air Leakage (CFM/sf)

Good*

Best

Good*

Best

Good*

Best

East, West, North1

.3

.15

.4

.25

.3

.01

South2

.35

.15

.5

.6

.3

.01

* 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

This Week in Prototype News

The big blizzard of ’09 temporarily put the kibosh on construction, but we’re back up and running.  The Hemcrete forms have come off of the first floor, Serious Materials windows have arrived, and the roof is moving forward, with horse drawn, local, sustainably harvested hemlock fascia boards from Mountain Works installed this week.

If you’re interested in volunteering for the Nauhaus Prototype Project, please contact Billy.

Click here to view the entire Nauhaus Prototype Construction Chronology.

Wall with Custom Hemcrete Forms
Wall with Custom Hemcrete Forms
Wall after Hemcrete Forms are Removed
Wall after Hemcrete Forms are Removed
Serious Materials Windows Have Arrived
Serious Materials Windows Have Arrived
Serious Materials Windows Waiting for Installation
Serious Materials Windows Waiting for Installation
Head and Jamb of Hemcrete Window Opening
Head and Jamb of Hemcrete Window Opening
Jamb and Sill of Hemcrete Window Opening
Jamb and Sill of Hemcrete Window Opening

Sustainably Harvested Hemlock Fascia
Sustainably Harvested Hemlock Fascia

Closeup of Future Patio Connection at West Wall
Closeup of Future Patio Connection at West Wall
Nauhaus Prototype as of December 31, 2009
Nauhaus Prototype as of December 31, 2009

Hemcrete Installation Continues/ Mountain Works Stops By

The Hemcrete installation continued today in the freezing weather, and is up to the second floor.  Ian Snider from Mountain Works dropped by yesterday to discuss some of the sustainably harvested wood he will be supplying to the project. Ian’s company uses horses to remove the trees that they selectively cull as part of a forest stewardship process.

If you’re interested in volunteering for the Nauhaus Prototype Project, please contact Billy.

Click here to view the entire Nauhaus Prototype Construction Chronology.

Ian Snyder and Jeff Buscher
Ian Snider and Jeff Buscher


House with forms on the South side.
House with forms on the South side.
elisha measures
Elisha measures.
Shutter being attached.
Shutter being attached.
elisha
Elisha
Sarah tamps the Hemcrete.
Sarah tamps the Hemcrete.


mixing
Hemcrete in Mixer
madera-mixing
Nauhaus Building Systems mixes Hemcrete.
interior forms
Shutters line the interior South wall.
Interior of South and West Hemcrete walls with no forms.
Interior of West and North walls without forms.
Electrical Box in Hemcrete
Electrical Box in Hemcrete


Hemcrete Installation/ LEED Consultation

Yesterday, the full-on Hemcrete installation was started.  Thanks to the volunteers who continue to come out and shovel hemp in this wet, cold weather!  If you’re interested in volunteering for the Nauhaus Prototype Project, please contact Billy.

Click here to view the entire Nauhaus Prototype Construction Chronology.

Bucket of Hemp
Buckets of Hemp

Custom forms were built out of plywood to supplement the plastic shutters provided by Lime Technology.
Custom forms on Completed Framing
Exterior Bracing at Plywood Forms
Exterior Bracing at Plywood Forms
Custom window forms were built so that the jambs could flare out and let in more light.
Custom window forms were built so that the jambs could flare out and let in more light.
Horizontal form supports are painted orange, as they will be removed after the the Hemcrete is packed in.
Horizontal form supports are painted orange, as they will be removed after the the Hemcrete is packed in.

Matt pours hemp into the mixer.
Matt pours hemp into the mixer.
Nauhaus Team and Volunteers Installing Hemcrete
Nauhaus Team and Volunteers Installing Hemcrete
A volunteer tamps down Hemcrete around the studs to ensure a tight seal.
A volunteer tamps down Hemcrete around the studs to ensure a tight seal.
Sarah Brinker tamps Hemcrete.  At this point, the forms are 4' high because the first lift is completed.
Sarah tamps Hemcrete. At this point, the forms are 4' high because the first 2' layer is completed.

Today, as the Hemcrete installation continued, Amy Musser of Vandemusser Design came out to give us a LEED consultation.  The Prototype is still on track to receive LEED Platinum certification.

Amy Musser, Luly Gonzalez and Chris Cashman discuss LEED.
Amy Musser, Luly Gonzalez and Chris Cashman discuss LEED.

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
Jeffrey
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.