The Hobbitat: An Earth Sheltered House in North Carolina

1 / 7
The Hobbitat is an earth-sheltered house that is also partially solar heated.
2 / 7
Earth berming protects the home's west side.
3 / 7
View down the length of the solar attic. 
4 / 7
A wood/coal stove supplements heat the home's heat pump.
5 / 7
Natural light enters through solar attic.
6 / 7
Diagram shows the left half of the house.
7 / 7
Diagram shows the right half of the house.

Nearly a decade ago–when the general public had yet
to be convinced that an earth-sheltered house could be
a sound investment–about the only people who bothered
with underground structures were either progressive
architects who often had to “overdo” their designs (and
hence raise construction costs) in order to suit the tastes
of their usually affluent clients, or truly versatile folk
who [a] more than likely couldn’t afford a
contractor, let alone an architect, but who [b] likewise
realized the advantages of subterranean living, and so went
ahead and built their own shelters on a “learn
as you go” basis.

These days, however, earth-covered residences are becoming
more popular. It’s not unusual for the informed
“average citizen” to consider building an underground
abode.

One such person is Lloyd Remington, a professor of
chemistry at the University of North Carolina’s Asheville
campus. Dr. Remington began building his home (he calls it “The Hobbitat”) back in
October of 1977, and moved in during May of the following
year. Admittedly, the house was never intended to be either
a public showplace or a demonstration of the latest in
gadgetry, but the doctor feels that he has accomplished his
goals: He built a pragmatically unconventional
home which could nonetheless boast such traditional
features as affordability, security, and soundness.

A Successful “Experiment” …

Dr. Remington knew all the time what sort of “return” he
wanted to realize from the time and resources invested in
his project, and felt that “going underground” was the
simplest and least expensive way to achieve his aims. Put
directly, he figured it would be sheer insanity to lay out
money to build a home, only to continue
spending substantial sums– year after year–to
maintain the structure and its interior comfort level.

All told, the professor based his decision to “dig” on four
factors:

[1] The earth provides a stabilized energy “sink” to help
buffer the extremes of seasonal climate.

[2] An “in-ground” dwelling affords the ultimate protection
from what might be the least recognized variety of thermal
“drain” in existence: the wind chill factor. (This
element affects buildings as well as people and is
a basic part of the heat flow principle within any
structure.)

[3] Insurance premiums on an underground house are usually
lower than those for more orthodox residences, because
there’s much less danger of damage to the structure from
fire, storms, vandals, or even fallen trees. In fact, the
underwriters of Lloyd Remington’s policy gave the house a
“Triple A” rating … a designation that’s
shared–according to the doctor–by only one
other home in his area.

[4] An earth-covered structure can furnish adequate shelter
in the unlikely event of a nuclear crisis. Even though
Professor Remington (who taught a survival course as part
of the Civil Defense program years ago) points out that his
home wasn’t primarily designed as a fallout
shelter, he and his family could “make do” in it if
necessary … and will always enjoy the “bonus” thermal
protection provided by the building, while remaining secure
in the knowledge that they are relatively safe from any
intentional or accidental dispersion of radiation .

… at a Conventional Price

Since Dr. Remington planned to keep his overall costs as
low as possible, he essentially acted as his own contractor. Which, practically speaking, meant that he chose (and
later paid) his own subcontractors and coordinated their
work schedules. He also retained the services of a local
architect, who provided the engineering and design skills
necessary to assure that the final product was safe and
aesthetically pleasing.

Then, when much of the “homework” was done, he approached
the community’s financial institutions–armed with
realistic figures and professional blueprints–and was
immediately successful in obtaining the promise of funds:
“I didn’t run into any banks that weren’t
interested. In fact, some were very partial to the
project, and willing to bend a few rules in order
to see it completed.”

And Lloyd Remington feels he got more than his
money’s worth when it came to the job performed by his
building contractor. That individual and his crew
were enthusiastic about the venture they were involved in,
and put in a lot of extra time to see that the job
was done correctly.

The bottom line–as close as the professor can
estimate it–on the two-bedroom, 1,927-square-foot
house came to a bit over $80,000, or about $43 a square
foot … a high figure for the western North Carolina area,
but not out of line in many other parts of the country,
especially when one realizes that the structure is
essentially “overbuilt” throughout.

A Live-In Thermos Bottle

For the most part, the Remington home was constructed along
lines common to many subsurface dwellings, but it
has some interesting variations. The building site sloped
toward the southwest, so the designer took advantage of the
natural lay of the land and positioned the structure to
face due south … eliminating the need for backfill
berming except for that done on the west end of the
dwelling. Then the main excavation was made to a maximum
depth of 15 feet, and the driveway was graded to meet that
level.

Rather than pour the foundation and footing as one, the
builders chose to go with a “floating slab” design, in
which the walls are supported on a stout perimetrical
footing and the foundation itself rests within, on top of a layer of gravel-over-polyethylene.

The 2′ X 4′ footing holds up block walls with filled,
reinforced cores (except for those in the non-load-bearing
rear wall, which have alternating poured and
vermiculite-packed centers), and the roof panels are
pre-stressed concrete … laid east-to-west, half-lapped
1/4″ and caulked at their lateral joints, and covered with
a poured, 2 to 6″ graded slab which is tied into the walls
by means of 3/4″ reinforcing bar all around. (All told,
there are over 200 tons of concrete in the structure!)

In order to guarantee a comfortable, moisture-free
environment, Dr. Remington virtually enshrouded his house
in a combination of rubber, styrofoam, and a locally made
foundation drainage material. First, the completed walls
and roof were covered with a 1/10″-thick layer of
cured-in-place butyl rubber waterproofing. Next, panels of
2″ and 3″ styrofoam insulation were fastened to the
structure’s sides and top, respectively. Then a seepage pad
(Enka-drain, made by the American Enka Company) was placed over all of
the insulation board and the drainpipe which rests against
the exterior face of the footing. Finally, the entire
structure–and its insulated “raincoat”–was
covered with earth, to a depth of 30″ in the front and 48″
at the rear.

Partially Solar-Heated and Earth-Cooled, Too

Because the Asheville area isn’t known for its temperature
extremes, Professor Remington chose an air-to-air heat pump
to function as the backup system in his all-electric
dwelling … partially because such a unit can be
inexpensive to operate if used intelligently, but
mainly because it included an ideal forced-air handling
network that allows the distribution of naturally
tempered currents.

The Tar Heel Stater, you see, has incorporated a solar
attic
into the upper part of his home’s south-facing
wall and entranceway. Originally, the plan called for the
installation of 18 parabolic collectors to provide space
heating and domestic hot water… but such “luxury” wasn’t
within the final budget. Instead, Remington covered the
exposed side of the attic with corrugated Filon glazing,
framed out its lower surface with 1 X 6 “ribs” which
support flat sheets of Kalwall, then tied the huge “hotbox”
into his air handling system, using a thermostatically
controlled fan. Not only does the massive collector provide
a fair amount of heat–usually enough to supply the
entire home during the daylight hours after 10:00 a.m. or
so on a winter day–but it’s also the source of plenty
of more-than-welcome light for the living area below. (The
professor soon plans to set up one or two solar panels in
the enclosure to furnish hot water.)

Additionally, to supplement the other two heat sources, the
Remington family uses a combination wood-and-coal stove…
usually only when the outside temperature dips below
20°F, which is beyond the heat pump’s operational range
of efficiency. Furthermore, a manually controlled damper,
built into the bottom of the air distribution duct and
located at the top of a “channeling” shaft just above the
woodburner, allows normally stagnant ceiling warmth to
collect–for later use–in the insulated air
supply chamber.

During the warmer months, the Remingtons usually enjoy a
comfortable environment simply because they’re essentially
living “in the earth” … but, should temperatures within
the home creep upward, a louvered fan installed at each end
of the solar attic can “sweep” that area clean of heat (the
blowers can also be left closed, and just the air
delivery system of the heat pump activated, with the house
windows open, an alternative that has proved to be
reasonably cost-effective). But if the ambient air is
uncomfortably warm, the Remingtons also have the option of
utilizing an earth-cooled air duct (merely a 20-foot length
of 18″-diameter culvert pipe buried in the soil), which
feeds into the home’s ventilation system to provide supplementary cooling.

Well Worth the Investment

Admittedly, it would be pretty hard for many folks to
justify spending the amount of money that the Remingtons
did … especially if the people had their sights set on a
similar-sized conventional dwelling, which might
cost one-half to two-thirds as much. But when you consider
the energy savings to be had, it appears that the professor
made a good investment. He has kept accurate temperature
and utility bill records for most of the house’s history,
and calculates the minimum total power usage to be
below 1,000 KWH per month, and the maximum 2,300 KWH. The
average consumption for any “heated” or “cooled” month
figured out to about 1,500 KWH, and the most spent
on conventional heating alone was about $38 for a 30-day
period. Remington’s total heating costs for the
first winter–for electricity, wood, and coal–came to
a scant $180.

Thus the monthly savings–added to the reduced price of
maintenance and insurance–could make the long-term ownership
of such a subterranean dwelling quite attractive. If
you’re considering the construction of an
earth-sheltered home, there probably isn’t a better time to
“get with it” than right now!