Florida 34′ Dome Home High Profile Entryway faces south
The above 34′ American Ingenuity dome located in Central Florida has no furnace. January has average minimum temperature of 50 degrees Fahrenheit with winter temperatures reaching 32 degrees. The south facing entryway produces all the heat needed to warm the dome during the winter months.
Any of American Ingenuity’s domes can be designed to have solar gain through its windows if during the site plan phase of design, you orient the dome and its entryways to face the sun in the winter months. The site plan determines the location of your dome on your property and which directions your doors and windows face. Under the entryways (eye brows) your framer builds a wall and installs large pieces of glass or large windows that you purchase locally. These large windows and or glass let the sunlight into the dome to heat the dome in the winter.
Bear in mind if the sun comes in during the winter through this glass; then it can come in during the summer and heat up your dome when you are needing to air condition; thus causing your AC costs to rise. Because the American Ingenuity dome has such a thickly insulated wall it costs so little to heat or cool the dome, we do not recommend large glass areas be installed within the entryways for passive solar gain…simply install enough glass and or windows to allow for the proper amount of sunlight that you want into your dome.
Just to clarify on the first floor of our 30’ and larger domes there can be five entryways. Within each entryway there is enough space to install from two to four French doors or huge pieces of glass. When we have had clients select floor plans that included five entryways their window and door budget sometimes exceeds the cost of the building kit. Windows and large pieces of glass can be quite expensive! If a window or glass area is double paned its R-Value is around four…the wall of our dome is an R-28. So besides our clients spending an exorbitant amount for large windows or glass areas, this decreases the R-Value of the walls and will raise their heating and air conditioning costs. Usually three entryways and a few solar tubes (items you purchase and install in the prefab panels) can supply plenty of light within the dome.
The owners of American Ingenuity built their second home at 3,400 feet elevation in the mountains of North Carolina. To receive the winter sun, they oriented one of the high profile entryways to the south and installed two four foot wide glass sliding doors with an 18” by 6’ long piece of glass above the doors. During the winter enough sun comes through the glass to heat the first floor of the 34’ dome. During the summer, blinds are closed to keep the sunlight out.
As far as solar panels: Anchors or bolts can be installed in the concrete seams or the tops of the entryways. The dome is very strong and can easily bear the weight of solar panels. During the assembly of the dome shell, bolts can be buried in the concrete to later anchor the panels. Tops of entryways, passageways are ideal, although solar panels can be placed on the triangular panels as well. Grooves are cut in the EPS insulation to lay the pipes in and the water pipe(s) are inserted through the entryway EPS before the entryway is concreted.
Solar Hot Water panels can be designed to set on top of the entryways or link. Anchors are buried into the entryway concrete on site. Grooves are cut in the EPS insulation to lay the pipes in and the water pipe(s) are inserted through the entryway EPS before the entryway is concreted. I have a solar hot water panel mounted on my dome link. It sits on the link and lies against the side of the dome. To hide the ends of the solar panel, we filled in the ends with foam and stuccoed over the foam so it matches the dome.
Each dome owner decides what utility hook ups they want for their home……solar or electric or natural gas or propane, etc. All of these are personal preferences. If you can install the service in a conventional house then you can install it in the dome. For example my personal 34′ in diameter dome home has a solar hot water panel setting on the top of one standard entryway with the top edge propped onto the dome. Water pipes for the solar panel, come through the seams or a hole is drilled in the thin concrete of the panel to run the pipes through. The rest of the house is powered with electricity. When we design your building plans, Michael, the plans supervisor will let you know which items need to be shown on the plans.
The following five elements constitute a complete passive solar home design. Each performs a separate function, but all five must work together for the design to be successful. Any of these elements can be incorporated into American Ingenuity’s geodesic dome.
The following information came from the U.S. Department of Energy’s web site:
Aperture (Collector)
The large glass (window) area through which sunlight enters the building. Typically, the aperture(s) should face within 30 degrees of true south and should not be shaded by other buildings or trees from 9 a.m. to 3 p.m. each day during the heating season.
Absorber
The hard, darkened surface of the storage element. This surface—which could be that of a masonry wall, floor, or partition (phase change material), or that of a water container—sits in the direct path of sunlight. Sunlight hits the surface and is absorbed as heat.
Thermal mass
The materials that retain or store the heat produced by sunlight. The difference between the absorber and thermal mass, although they often form the same wall or floor, is that the absorber is an exposed surface whereas thermal mass is the material below or behind that surface.
Distribution
The method by which solar heat circulates from the collection and storage points to different areas of the house. A strictly passive design will use the three natural heat transfer modes—conduction, convection, and radiation—exclusively. In some applications, however, fans, ducts, and blowers may help with the distribution of heat through the house.
Control
Roof Overhangs can be used to shade the aperture area during summer months. Other elements that control under- and/or overheating include electronic sensing devices, such as a differential thermostat that signals a fan to turn on; operable vents and dampers that allow or restrict heat flow; low-emissivity blinds and awnings.
A Consumer’s Guide to Energy Efficiency and Renewable Energy
from the U.S. Department of Energy’s web site:
How a Passive Solar Home Design Works
To understand how a passive solar home design works, you need to understand how heat moves and how it can be stored.
As a fundamental law, heat moves from warmer materials to cooler ones until there is no longer a temperature difference between the two. To distribute heat throughout the living space, a passive solar home design makes use of this law through the following heat-movement and heat-storage mechanisms:
Conduction
Conduction is the way heat moves through materials, traveling from molecule to molecule. Heat causes molecules close to the heat source to vibrate vigorously, and these vibrations spread to neighboring molecules, thus transferring heat energy. For example, a spoon placed into a hot cup of coffee conducts heat through its handle and into the hand that grasps it.
Convection
Convection is the way heat circulates through liquids and gases. Lighter, warmer fluid rises, and cooler, denser fluid sinks. For instance, warm air rises because it is lighter than cold air, which sinks. This is why warmer air accumulates on the second floor of a house, while the basement stays cool. Some passive solar homes use air convection to carry solar heat from a south wall into the building’s interior.
Radiation
Radiant heat moves through the air from warmer objects to cooler ones. There are two types of radiation important to passive solar design: solar radiation and infrared radiation. When radiation strikes an object, it is absorbed, reflected, or transmitted, depending on certain properties of that object.
Opaque objects absorb 40%–95% of incoming solar radiation from the sun, depending on their color—darker colors typically absorb a greater percentage than lighter colors. This is why solar-absorber surfaces tend to be dark colored. Bright-white materials or objects reflect 80%–98% of incoming solar energy.
Inside a home, infrared radiation occurs when warmed surfaces radiate heat towards cooler surfaces. For example, your body can radiate infrared heat to a cold surface, possibly causing you discomfort. These surfaces can include walls, windows, or ceilings in the home.
Clear glass transmits 80%–90% of solar radiation, absorbing or reflecting only 10%–20%. After solar radiation is transmitted through the glass and absorbed by the home, it is radiated again from the interior surfaces as infrared radiation. Although glass allows solar radiation to pass through, it absorbs the infrared radiation. The glass then radiates part of that heat back to the home’s interior. In this way, glass traps solar heat entering the home.
Thermal capacitance
Thermal capacitance refers to the ability of materials to store heat. Thermal mass refers to the materials that store heat. Thermal mass stores heat by changing its temperature, which can be done by storing heat from a warm room or by converting direct solar radiation into heat. The more thermal mass, the more heat can be stored for each degree rise in temperature. Masonry materials, like concrete, stones, brick, and tile, are commonly used as thermal mass in passive solar homes. Water also has been successfully used.
Reading List
- Crosbie, M.J., ed. (1997). The Passive Solar Design and Construction Handbook. New York: John Wiley & Sons, Inc.
- Passive Solar Design (December 2000). DOE/GO102000-0790. Work Performed by the NAHB Research Center, Southface Energy Institute, and Oak Ridge National Laboratory. Washington, D.C.: U.S. Department of Energy.
- Kachadorian, J. (1997). The Passive Solar House. White River Jct., VT: Chelsea Green Publishing Co.
- Van Dresser, P. (1996). Passive Solar House Basics. Santa Fe, NM: Ancient City Press.
