What makes these homes better?
It's the Mass. The " Thermal Mass" created with thick earthen walls make the entire home a storage/transmission medium for radiant heating and cooling. Temperatures are stabilized and constant with little difference in temperature from floor to ceiling thereby maximizing comfort.
Scientific principles as well as testimonials support the thermal mass home's (Earth Home's) superiority in efficiency and comfort. Lets start with some scientific facts:
- Dense or massive solid objects (like concrete and soil) are good conductors and storers of heat; (high "K value"= heat storage capacity). They also are good absorbers and emitters of radiant heat.
- Low density and porous objects (like wood, air and styrofoam) are poor conductors and storers of heat, but make good insulators because of their poor conductivity (high " R Value" = resistance to heat flow).
- All bodies (objects) are continually radiating energy. All bodies are also continually absorbing radiant energy. When radiant energy strikes an object it is transformed into heat. Heat does not rise - hot air rises. Heat energy is transferred by radiation, convection and conduction. Note: Radiation as in invisible heat waves - not to be confused with nuclear radiation!
- A body (object) that is warmer that it's surroundings emits more energy than it receives while a body colder than it's surroundings is a net gainer of energy. ( Refer to last fact if confused.)
Heating and cooling in an Earth Home is primarily achieved by "radiant heating". The thermal mass of the solid walls (and the floor mass) transfer their heat by radiation. Since the house walls (mass) are isolated from extreme outside temperatures with insulation the inside temperature remains relatively stable.
To illustrate this stability I have this great story. During the winter construction of one Earth Home, we had the home closed in but not heated. Through body heat and solar gain the house had risen to 54 degrees inside when we experienced a 4 day cold spell with no sun and temps in the low teens. The temperature inside fell by 1 degree per day without heat or solar gain! By contrast an unheated conventional home would have been as cold as outside by the fourth day (frozen pipes as well).
Heating an Earth Home - " Dampening Effect"
Supplemental heat consists of hydronic radiant floor heat (hot water in tubes imbedded in floor) supplied by a conventional boiler or hot water heater. These homes make excellent passive solar homes. Heat gained through properly placed (and shaded) window glazing is absorbed into the mass of the home ( see above scientific fact). The absorption by the massive masses helps prevent wide temperature fluctuations (overheating) which are common in conventional homes. In fact research has shown that temperature fluctuations from solar gain in a conventional frame structure is 200% higher than the same structure built with thermal mass walls and floors. This " Dampening Effect" is another benefit of an Earth Home.
How Cooling Takes Place
In accordance with the above scientific facts a person emits radiant heat. If this person is in an Earth Home with a mass which is cooler than their body temperature; cooling through radiant heat takes place (the person is doing the radiating; the mass is doing the heat absorption). A person surrounded by this mass receives energy if his body temperature is lower than that of the mass. To cool down the mass/house open the windows at night (or on a cool day) and keep them closed during the heat of the day. If the house is getting too much solar gain close your window shades. Although the air inside the house is also heated through radiation and conduction; convection, (causing floor to ceiling temperature differentials) is minimized because if the air gets warmer than the mass it loses it's heat to the mass in accordance with the scientific facts.
Temps change slowly
Temperatures change slowly inside an Earth Home. Earth Homes are not like the conventional home where you merely turn the thermostat up or down for instantaneous sensory gratification. Although hydronic radiant floor heating has an instantaneous like effect, it's need is minimized by the stored heat. Consideration must be given to the stored heat. For instance if you leave your windows open on subsequent 90 degree days - it may not happen for days or weeks but at some point the mass ( your home) will also be 90 degrees and it will stay that way!
- Energy Efficient
- Aesthetically Appealing
- Strong, Solid, Durable
-Sustainable/ Long Life
- Benefits Environment
- Saves Timber
- Fire, Termite and even Bullet Proof Walls
- Subjective Pleasing "Homey Feeling"
- Good use of Available Resources
- Utility $ Savings- 20% to 60% over 2x4 Conventional home
- Relatively Competitive with Conventional