Colorado Formworks Home for Sale

Link to Photo's of the House

General description

There's nothing like it. Though Asterisk the house is made of conventional materials, and its architectural elements have been familiar since antiquity, the combination used in its construction plus the realization of its design goals makes it dramatically different.

Structurally, Asterisk is a monolithic thin-shell concrete building. Its exterior surfaces are of wood, stone, stucco, glass, and earth. Its interior surfaces are mostly of wood, tile, plaster, and glass.

Architecturally, the main portion of Asterisk is made by joining six barrel-vaulted branches at a central intersection. Its floor plan resembles the symmetric character "*"; hence, the name Asterisk. Its roof lies under at least three feet of earth. It is an underground dwelling.

Asterisk is a successful passive solar design.

Design goals

There are many goals which jostled for position in the design of Asterisk:

Make a house suited to its particular site, its region, its climate
Make a house that relates to the environment outdoors and gives easy access to it
Make a house that is airy, light, quiet, comfortable, and a joy to live in
Make a house that will last a very long time and require little maintenance
Make a house that is fire resistant
Make a house conducive to health
Make a house that will stay warm in the winter and cool in the summer using little or no fuel and electrical energy
Make a house that largely runs itself without complex control equipment

Once I settled on an underground design for Asterisk another goal became apparent: Make a house that violates the common expectations for underground structures--that they are dark, damp, cool, closed in, in short, basementy. Given the previous goals, this one would be realized without further effort.

Detailed Description

Passive Solar
Passive solar design requires two things: windows which permit heat from the sun to enter the structure and thermal mass within to store that heat. Three of the six branches of Asterisk end in window walls with as much glass area as possible. One glass wall faces due south. The other two face sixty degrees to either side of south. Because the house is located at more than 7300 feet above sea level, excessive solar gain in the summer is not a problem. This means that the windows can be designed for maximum solar gain along with a good R-value. The doors in all three walls are glass, too, and are subject to the same considerations. Because the shell is concrete and the floor is tile over concrete, there is enough thermal mass around the living area to store heat for many days. Its thermal mass is equivalent to more than 200,000 lbs of water.

Connection to Outside
Of the building’s six branches, five communicate with the outside. There are the three window walls, each with glass doors, in the two bedrooms and the living room. A fourth branch goes into the tower where the main entrance is located. A fifth branch holds the kitchen where there is a door into the garage. Only the sixth branch, which is the study, has no direct path to the exterior, though it has many indirect ones. The tower also has a roof deck, and it may be accessed through stairs and a weatherproof hatch.

Bedrooms
There are two bedrooms, one facing 60 degrees east of south and one facing 60 degrees west of south. Each looks out onto its own landscaped courtyard.

Study
The study is a large room divided into two parts, a fore part with a translucent false ceiling and a main part with a full height fifteen foot ceiling that ends in an apse.

Lofts
There are two lofts, one over each bedroom. A bridge over the central living area under the cupola connects them. You get to the east loft by means of an unusual set of stairs with alternating treads and only one stringer. It also serves as a sculpture. The lofts and stairs are protected by powdercoated steel railings.

Ceilings
The ceilings in the public areas of the house are barrel vaults which rise to fifteen feet above the tile floor. The ceilings in the bedrooms are divided into square coffers and are at normal height. The ceilings in the bathrooms, closets, kitchen pantry, and part of the study are translucent false ceilings at eight feet, which allow these rooms without windows to be day lit.

Tower
The tower serves several functions. It is the visual signature of the building. An underground house, by its nature, tends to be unobtrusive. A tower calls attention to itself and provides a striking main entrance. The tower also provides an excellent view platform. The view gets progressively more dramatic as you ascend from room to room. The top room has a dozen windows around it that divide the view into narrow slices. This is an unusual and beautiful way to look at a panorama. For unobstructed views, continue up to the roof deck. There you will see the circle of the horizon and the dome of the sky, two major mountain ranges, and layers of ridges and mesas to the south fading into New Mexico.

Asterisk Meridian Observatory
The tower is also the enclosure and mount for the meridian transit instrument of the Asterisk Meridian Observatory. This instrument is a camera obscura armillary device for observing transits of the sun and moon. In the seventeenth and eighteenth centuries comparable instruments were used to determine basic parameters of the earth’s orbitThe Sun in the Church by J. L. Heilbron. The meridian arc, which is the screen that the sun’s image is projected onto, hangs in the entry of the tower, and, when it is not on scientific duty, serves to puzzle visitors. Each sunny day around noon, it can tell time to within a few seconds.

Ventilation
For a number of reasons, all the windows are fixed: Solar gain is higher; air infiltration is nearly eliminated; screens are unnecessary; bears and bugs are less likely to come in. So, ventilation must be provided some other way. At Asterisk, filtered fresh air is normally provided through oversized ducts, which go deep below the floor slab to oversized registers flush with the floor, by means of large quiet fans in the garage. All fans are operated on demand or by timers and move air quietly and insensibly. They cost very little to run, and the incoming air is tempered as it travels through the ducts.

Thermal comfort
A big part of the reason for thermal comfort in winter is the lack of drafts. Another part is the low emissivity windows which feel warmer since they reflect most of the infra-red back which the occupants and interior are radiating to them. Also floors, walls, and ceilings are all at almost the same temperature, which is about the same as the air's. The thermal uniformity is not perfect: The areas near the window walls, which get a lot of direct sun, stay slightly warmer than the northern areas, which get little direct sun. In winter almost every place in Asterisk gets some direct sun, if only for a few minutes. The earth surrounding the building’s shell has reached equilibrium temperature after several years. That temperature varies little from season to season and at depth is in the low sixties.

The hydronic in-floor heating system is no longer used because it is not needed. Even so, the average indoor temperatures range from the low sixties to the mid seventies over the entire heating season.
In the heat of summer Asterisk temperatures average in the mid seventies. The building is ventilated with cool night air to avoid cumulative heat gain from day to day.

Landscaping
The landscaping is entirely xeric and is meant to suggest a heightened form of the landscape in which Asterisk is set, even including weathered stumps and logs set into the earth covering the house as if to suggest that the house, too, was logged over, a long time ago. The landscaped berms radiating from Asterisk freely quote the nearby skyline. The berms also create private courtyards outside the bedrooms and the living room.

Astronomic Alignment
By happy accident, which depends on the basic geometry of Asterisk, its accurate north-south alignment, and its location at about 37 degrees north latitude, the sun at winter solstice rises directly on the axis of the SE-NW branches and fully illuminates the back wall of the kitchen. Later in the winter solstice day the sun sets on the axis of the SW-NE branches, and the back wall of the study is fully illuminated. Future archeologists may think this alignment was deliberate. They will be wrong.

Indigenous Traditions
Asterisk reflects to some extent traditions of the region, in particular those associated with the Anasazi, who used to live nearby and built masonry structures above and below ground. Underground pit houses and later their ceremonial successors, kivas, were familiar to Pueblo Indians, both modern and ancestral. The Anasazi were not familiar with barrel vaults or concrete, however.
The stone tower of Asterisk is consciously modeled on the much earlier Anasazi work. In particular, the peephole windows and tapered cylindrical shape of the tower, found generally throughout Anasaziland, are quoted. The color-banded masonry was suggested by one of the late masonry styles of the Chaco Canyon Culture.

Repetitive design motifs
Several simple motifs repeat themselves at different scales throughout the project. Some of these are based on circles and semi-circles and their 3D elaborations. Others are based on hexagons and their 3D elaborations. You will find countless examples of these motifs inside and outside Asterisk.
The skyline southwest of Asterisk is a motif that is echoed on the three landscaped berms near the window walls.

Embodied Energy and Energy Cost
At first glance the embodied energy of a building made of heavily reinforced concrete might seem excessive. Portland cement is quite energy intensive, and steel is much more so. However, it is important to consider more than just the initial investment of energy in a structure. The energy accounting should include its materials, construction, operation, and maintenance over the building's entire expected lifetime. In the case of a building like Asterisk the expected costs of operation and maintenance are very low, but the expected lifetime is extremely high (possibly several thousand years). This means that the high initial energy investment is to be amortized over a much longer period than would be reasonable for a conventional building, and consequently the annual energy cost considered over its expected lifetime is most favorable.