Tuesday, August 31, 2010

In the Beginning There was a Hill

We purchased the property in May 2008 and shortly thereafter had a rough idea where our earth sheltered house would be located.

Part of the Hillside Where the Earth Sheltered House Would be Located
Before we could finalize our house design, we needed to know how the land was laid out so the house would fit into the hillside and not interfere with the surrounding trees. Our daughter Jennifer and I took our rod and level out to the hillside in June and July 2008. Then we waded through weeds and brush over our heads, and swatted mosquitoes and bees to get an elevation profile on a 10' by 10' grid.

Elevation Profile with Top View of Earth Sheltered House Superimposed
This image shows the hill's elevation profile obtained from the rod and level measurements. North is to the right and about 42.5° above horizontal. We took the elevation measurements from right to left, starting at the top of the surveyed area, and then we worked our way down the hill. We assigned zero elevation to the upper-right corner. The hill drops about 37' to the lower-right corner. Each line represents a one foot change in elevation. The elevation numbers are negative, so the hill slopes downward from top to bottom in the image.

The elevation profile shows that the hill slopes downward roughly toward the southeast. We wanted a relatively narrow, rectangular house with its long side facing south so that we could take maximum advantage of solar heating. But this meant that the house would not fit very well into the hillside. As a compromise we split the house into two overlapping rectangular pieces and rotated the second part counter clockwise 45°. When we laid the modified drawing out on the surveyed profile, it wouldn't fit within the trees that we wanted to keep. In the end we had to rotate the second part of the house counter clockwise 55° as shown in the drawing above. The modified house fit better into the hillside as well.

The above drawing also shows a bunch of tubes and two junction boxes. They are part of the Passive Annual Heat Storage (PAHS) air movement system, which I will describe in another post.

Patricia and I at the Base of the Hill the Day Before Excavation Begins
Here we are, standing at the base of the hill that will never be the same starting tomorrow. Excavation for the earth sheltered house began September 8, 2009. The weather was clear and dry for the few days it took to move the many, many cubic yards of dirt. And then it rained and/or snowed for the next ten months (well, just about every day, it seems.)

This Sad-Looking Hillside is Ready for Our House
This is what the hillside looked like on September 11, 2009. I took the photo from about 30' east of where the northeast corner of the garage will be. The view is roughly to the west. On the far right of the image is where the root cellar will be located. To the left of that will be the garage and entryway portions of the house. And beyond the dozer and around the 55° corner will be the rest of the house.

Monday, August 30, 2010

Connecting a PAHS Air Tube

Today I hooked up one of the upper air tubes for the Passive Annual Heat Storage system. The PAHS system uses eight 6" diameter tubes to bring in fresh air and remove stale air. Four lower tubes enter through the back walls at floor level, and four upper tubes enter through the roof.

March 19, 2010, Shortly After the Roof Was Poured.

This image shows all the tubes protruding through the roof. The four smallest and shortest vertical green tubes protruding through the roof (some are hard to see) are part of the upper PAHS air tube system. Each of the short vertical tubes will be connected by a horizontal tube to one of the long green vertical tubes coming up from the ground behind the back walls. The two sets of vertical tubes could not be connected by horizontal tubes until after the backfill was put in place and settled, because the moving soil might distort and break them. (In the photo only three long tubes are visible; two of the tubes are adjacent to each other at the interior corner.) For example, the long tube closest to the viewer will be connected to the short tube to the right of the closest large tube. These are the two tubes I connected today.

Cleaning Wet Clay Off the Tubes and Elbows

Finally we've had no rain for the past ten days or so, and the top three-inch layer of backfill clay is dry. But below that, it is a wet muck from the continuous rains we've had all spring and summer. A couple hours of digging around the two tubes and between them with a round shovel, and I was ready to measure and fit the tubes and elbows together. The last step was to clean all the connections and glue them together.

Connected Tubes Ready to be Covered

Now the air-tube circuit is complete. The closer vertical tube is coming up through the roof. The bottom of the horizontal tube is about 18" above the top of the roof. (It's hard to imagine that there's an office below this tube.) The outside of the back wall lies just to this side of the back connecting elbow and the long buried vertical tube.

The PAHS insulated umbrella will run about two to four inches above the top of the horizontal tubes. Over the roof of the house, the insulated umbrella will consist of two layers of 2.5" styrofoam sandwiched between three layers of 6 mil clear plastic vinyl.

Saturday, August 28, 2010

Welcome to the House in the Hill

Dear Visitors,

As I find the time, I will post descriptions of our earth sheltered house and keep you updated as the construction progresses.

I designed the house using VectorWorks 2008 and its predecessor.

Approximate Top View of the Earth Sheltered House

Here is a rough top view of the 2400 square foot earth sheltered house. The north arrow points to the right at about 20° above horizontal. The structure's reinforced concrete ceiling is 11'-0" high. Suspended 10'-6" and 9'-6" ceilings will be installed in most of the rooms as indicated in the drawing.

Southeast View of the Earth Sheltered House Under Construction

The earth sheltered house is nestled into the southeast-facing hillside. A Mansard-type roof hides a 5' high parapet wall along the south and east sides of the house that retains the soil covering the roof. The final graded terrain will be about a foot below the top edge of the 6' tall Mansard roof.

North View of the Earth Sheltered House Under Construction

Numerous tubes and a masonry stove chimney can be seen protruding through the soil in this top view of the earth sheltered house.  An insulated umbrella and two additional feet of soil must be added to this image before the final grading is completed. Except for the tubes and narrow Mansard roof, the house will have a green footprint of grass, flowers, and garden.

Rough-In Window Openings in the South Side of the Earth Sheltered House

Taken in April, 2010, this image shows the rough-in window openings along the south side of the earth sheltered house. The net window glazing area will be more than 20% of the floor space. Marvin windows, with low U value and high solar heat gain, will maximize solar heating in the colder months. Deployable awnings will block direct sunlight from the windows in the warmer months. These windows do not qualify for an energy efficiency tax rebate, even though they will save more energy than those that do; this earth sheltered house has no conventional furnace, but uses a masonry stove for supplemental heat.

View of the Kitchen and Away Room From the Southeast

This photo was taken from the southeast corner of the Great Room (standing in the Living Room area.) An 18" high curved soffit divides the Kitchen and Away Room from the Great Room. Suspended ceilings in the Great Room will be 10'-6" to accommodate the high transom windows. Suspended ceilings in the Kitchen and Away Room will be 9'-6" to allow for ductwork. The glow of a light tube can be seen in the middle of the kitchen, even though the sun was already below the tree-line. A 10" by 10" support column stands at the end of the Kitchen/Away Room wall. One of two 14" diameter support columns, defining the corners of the Foyer, can be seen in the right edge of the image.

Temp-Cast Corner Masonry Stove with Bake Oven

The Masonry Stove is located in the Entry Room at the north end of the earth sheltered house. It is primarily a backup to the Passive Annual Heat Storage (PAHS) system. A plenum, containing a 3-ton air conditioning coil, is installed behind the brick wall to the left of the stove. Ductwork, running the full length of the house, will evenly distribute heat from the stove when needed. The air conditioning coil, although not connected to anything at the moment, may be used as a backup to the PAHS system, which will have its own natural air conditioning capability. The PAHS air conditioning feature, based on a suggestion in John Hait's book, "Passive Annual Heat Storage, Improving the Design of Earth Shelters," will be described in a later post.