Category Archives: Roof Systems

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.

Electrical Completed, Lime Technology Pays a Visit

Click here to view the entire Nauhaus Prototype Construction Chronology.

We were excited to have Ian Pritchett and Mario Machnicki from Lime Technology, makers of Hemcrete, come by to check out our building for the first time.  We had some great discussions about Hemcrete, earthen blocks, construction details and more.  The electrical work has been completed, and the walls are ready for the hemp installation.

Jeff Buscher, Tim Callahan, Ian Pritchett, Mario Machnicki
Jeff Buscher, Tim Callahan, Ian Pritchett, Mario Machnicki
Ian Pritchett and Jeff Buscher talk about earthen blocks.
Ian Pritchett and Jeff Buscher talk about earthen blocks.
Southeast View
Southeast view of the nearly-completed framing of the Nauhaus Prototype
Electrical Box Installation
Electrical Box Installation
The electrical boxes are mounted on blocking so that they will be flush to the inside of the 12" walls.
The electrical boxes are mounted on blocking so that they will be flush to the inside of the 12" walls.

Asheville GO Helps Out

Today, the folks from Asheville Green Opportunities came to help out.  In the meantime, Matt and his crew started putting up rafters.

Click here to view the entire Nauhaus Prototype Construction Chronology.

Asheville GO
Asheville GO
asheville go 2
Asheville GO Volunteers
Installing Blocking for Electrical
Installing Blocking for Electrical
Tony Beurskens Directs Asheville GO Volunteers
Tony Beurskens Directs Asheville GO Volunteers
Elijah and Chris
Elijah and Chris

Finished Scaffolding
Finished Scaffolding
Matt Installing Rafter
Matt Installing Rafter
East Gable
East Gable

Chameleon Roof Tiles

These Thermeleon tiles are white when it’s hot and black when it’s not. When they’re white they only absorb 20% of incident sunlight, but when they’re black they can capture 70% of it.

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They use a polymer suspended in water with a dark background layer. When it’s cool the polymer stays dissolved, and the dark background is exposed. When heated, the polymer condenses into tiny droplets which appear white because scatter and reflect the radiation.

The Thermeleon project won the 2009 MIT Making and Designing Materials Engineering Contest. They need to find out if their tile is durable enough to stand up to the harsh conditions on a real roof before they have a real product, but they say the ingredients are all cheap and readily available.

:: Thermeleon.com

Passive Solar Design


This is the second article in a series originally written for New Life Journal.


By: Clarke Snell


Let’s not beat around the bush. In this day and age, heating and cooling our houses amounts to spending a lot of money to create a lot of pollution. That’s because most of the energy we use for this purpose comes from burning fossil fuels. What’s worse, as a society our response to skyrocketing oil and gas prices has been to keep making the skies dirtier. The weird thing about this whole scenario is that everything we’re burning is just stored solar energy.

Here’s the process: Plants turn sunlight into energy which is turned into living tissue. Animals eat the plants. Plants and animals die. Wait several hundred million years. Drill deep wells and dig big holes to access resultant oil, gas, and coal. Transport all over the planet and burn copiously until supply begins to get scarce. Fight wars and panic until lights go out and heat goes off.

I don’t know, wouldn’t it make better business sense to skip the “middle man” and go directly to the source, i.e. the sun? Duh. The technique is called passive solar design: the conscious manipulation of the sun’s direct energy to affect the temperature inside a building. It is clean burning, runs for free after installation, has no moving parts, comes with a lifetime guarantee, isn’t susceptible to power outages or unexpected supply shortages, requires no special maintenance, and can be accomplished by simply rearranging the materials used in a conventional modern house at little or no extra expense.

Though its most effective real world implementation is a beautiful dance between science and art, the concept behind passive solar design is elegantly simple: if you want heat, let the sun in; if you want cool, don’t let the sun in.

Our loving star has made the process so much easier by methodically changing its path through the sky throughout the year. In our region, the winter sun rises to the southeast, stays low in the sky to the south, and sets to the southwest. The summer sun rises to northeast, stays high in the sky most of the day, and sets to the northwest. This is an amazing stroke of luck because it means the sun is low in the sky when it’s cold outside and high in the sky when it’s hot outside. Low sun is easy to let into a building, while high sun tends to be blocked by the roof and other protrusions of the building itself. Perfect!

With this basic observation under our belts, we’re ready to realize a passive solar masterpiece. First, we need to find the right place to build. In our region, that means a site that will give us unobstructed access to the low southern winter sun. Some trees or other obstructions to the east and especially the west would be great to block the hot rising and setting summer sun. (A ridge or evergreens to the north might block some winter winds, but wind is very site specific so we’d have to spend some time on site to make that call.)

Next, we’ll design our building to let in a lot of winter sun and block a lot of summer sun. Building shape is the most basic parameter. In our area, the best shape is longer on the east-west axis, creating more wall surface on the south and less on the east and west.

The main avenue for sun to enter the building will be through glass. From a heating point of view, only south-facing glass will create a net solar heat gain, so other glass should be minimized. However, north, east, and west glass are an important part of our natural ventilation cooling and daylighting strategies. This is where the delicate interplay of science and art comes in, in other words we’ll find beautiful compromises.

The heating equation, in any case, is straightforward, we simply have to carefully match the square footage of our southern glass windows and doors to the amount of “thermal mass” we place in the building. Thermal mass simply means something that stores heat, so technically everything is a thermal mass. Dense heavy materials usually store heat well. Water, concrete, stone, and earth are good examples. A great place to put mass in a building is in a concrete or earthen floor. Sun flows in through glass covered openings and is stored in the mass of the floor. The mass sucks up heat, thus preventing the house from overheating during the day, then slowly releases the heat after the sun goes down keeping the house warm at night. The trick is creating the right balance. Science to the rescue! We have everything from rule of thumb glass to mass ratios to computer assisted thermal modeling at our disposal.

Next, we’ll need to design our roof overhangs and other protuberances so that they follow our mantra: block sun when it’s hot, let in sun when its cold. The poster child for this is the southern trellis covered with deciduous vines (grapes and hops are two options for you vintners and brewers out there). Thick leaf cover that blocks the sun in spring and summer dies back in fall and winter to let the sun through. Since we know where the cooperative sun will be in the sky at any time of year, roof and window overhangs can be sized to interact with the sun exactly as we like.  We’ll add covered patios on the east and west, again to block low hot sun, and one on the north to create an outdoor room that will be shaded all summer long.

Finally, we’ll work with the surrounding landscape to heighten our design. In tandem with our patios, we’ll add shade trees, especially to the west and north. Plants not only create shade, but evaporative cooling which is the natural technology mimicked by your refrigerator and clanking, polluting window A/C or HVAC unit. We’ll also create a focus to the south, perhaps placing an outdoor kitchen under the trellis with a kitchen garden in front of it. We’ll place doors and windows that encourage cross-ventilation and allow effortless transitions to outdoor rooms. Don’t forget that in our climate a little tweaking back and forth between sun and shade makes the outside comfortable for most of the year. Outdoor rooms are inexpensive access to the mansion of nature. Of course, we’ll also design a unified insulation strategy that includes measures to slow convective, conductive, and radiant heat loss through the building, but that’s another story.

Ta-da! A passive solar masterpiece that will supply a baseline of heat and cool at the right time of year which can then be enhanced to create the specific indoor environment of your choosing. Though you may not get the picture from this frantic overview, none of these design features need to control the look or feel of the building. Passive solar is flexible if you are. It’s a pivotal design concept, not an architectural gestalt.

Disagreement abounds even on some of the basics. For example, some people feel that our climate is too wet to allow for natural ventilation as a cooling strategy because open windows plus humidity can result in mold. In the end (here’s where you refer back to that lovingly pawed copy of my column from last month that’s taped to the fridge), the right approach to passive solar is going to have to match the specifics of who you are with the specifics of the place your house will sit.

I will however be unequivocal about one thing: you are going to heat and cool your house with solar energy one way or another. The only question is if you want it free and clean or expensive and dirty. This may sound like a laughably obvious choice, but a cursory glance at any cityscape or subdivision will show that the sun is presently laughing at us, not with us.

Site Cast Concrete Tile Roof

At the Passive House class Katrin said that the house where she lived in Germany had a very old concrete tile roof. The tiles were cast at the site using a mold. She said that traditionally, the builder would cast a stack of extra tiles and put them in the attic along with a mold so that future owners could cast replacements.

We also watched a movie of a new passivhaus being built there. They used concrete tiles with lugs underneath. The lugs rested on 2×2 nailing strips attached to the roof sheathing. There weren’t any fasteners. She said the tiles interlocked some how, but other than that, gravity was all that kept them in place.

I found an aluminum mold supplier in California: Kinetic Die Casting

Roof Materials for Rainwater Harvesting

Texas Rainwater Harvesting Manual:

For potable systems, a plain galvanized
roof or a metal roof with epoxy or latex
paint is recommended. Composite or
asphalt shingles are not advisable, as
toxic components can be leached out by
rainwater. See Chapter 2 for more
information on roofing material.

On the other hand, this research makes me question galvanized because of metals in the water: Link

The Texas Manual also has costs starting on page 50.