Thermal Mass, Passive Solar Heating, Convection Cooling
Keep the building warm in the winter and cool in the summer
with little to no utility bills / fossil fuels. This increases both psychological and physiological comfort.
Both the International Building Code and the International Residential Code have requirements for maintaining a minimum temperature in buildings. They do not have requirements for a maximum temperature in buildings though there are ventilation system requirements and there are reasonable standards for comfort.
“All design projects should engage the environment in a way that dramatically reduces or eliminates the need for fossil fuel.” The 2010 Imperative, Edward Mazria,AIA, Founder of Architecture 2030
Passive solar technologies absorb heat from the sun via thermal mass (water, rock, stone, mud, etc.), cause ventilation via cooling tubes and operable windows with little use of any electrical energy.
Every south-facing window creates a direct-gain system, while windows facing east, west, and north lose more heat than they gain in the winter. The greenhouse effect, acts as a one-way heat valve. It lets the short-wave solar energy enter but blocks the heat from escaping. The thermal mass inside the building then absorbs this heat, both to prevent daytime overheating and to store it for nighttime. The proper ratio of mass to south-facing glazing is important.
Since in direct gain the building is the collector, all contents, such as the drywall, furniture, and books, act as thermal mass. However, the contents are usually not sufficient to store an adequate amount of heat without additional thermal mass. When there is no concrete floor or when even more thermal mass is desired, it can be provided in the walls, water containers, floors, or phase-change materials.
Although solar heat can be supplied by convection to the rooms on the north side of a building, it is much better to supply solar radiation directly by means of south-facing clear-story windows. Besides bringing warming sunlight further into the building, clear-stories also provide excellent day- lighting, because light from above is best.
Most direct-gain systems consist of straight walls facing due south or as close to south as possible. Direct gain is the most efficient when energy collection and first costs are the main concerns.
A Passive House / Building is a building standard that is energy efficient, comfortable, affordable and ecological ALL at the same time.
Passive House / Building is not a brand name, but a construction concept that can be applied by anyone and that has stood the test of practice and literally thousands of years of time. These are modern, beautiful, high-value homes.
Passive Buildings allow for heating and cooling related energy savings of up to 90% compared with typical building stock and over 75% compared with average new builds. In terms of heating oil, Passive Houses use less than 1.5 litres per square meter of living space per year – far less than typical low- energy buildings. Similar energy savings have been demonstrated in warm climates where buildings require more energy for cooling than for heating (thermal mass).
Passive Houses are also praised for their high level of comfort. They use energy sources inside the building such as using the heat from an oven or solar heat entering the building – making heating a lot easier.
Appropriate windows with good insulation and a building shell consisting of good insulated exterior thermal mass walls, roof and floor slab keep the heat during winter in the house – and keep it out during summer.
Ventilation consistently supplies fresh air making for superior air quality without causing any unpleasant draughts. This is a guarantee for low Radon levels and improves health conditions.
Earthships collect all of their water from rain and snowmelt on the roof, storing this water in cisterns. (Each inch of rain collected from a square foot of roof equals 2/3 of a gallon of water. Multiply that by the total square footage of the roof and number of inches of rain per year, and you get your total possible collection.) Water from the cistern feeds a pump and filter system that cleans the water and sends it to a solar hot water heater and also to a pressure tank. From there, water is used for bathing, washing dishes, and laundry.
Every building has its own renewable “power plant” with photovoltaic panels, batteries, charge controller, and inverter. The key step in making these systems affordable for residential use is to “design down” the electrical requirements of the home before the solar system is sized. Super efficient lighting, pumps, and refrigeration help lower the load, as does the lack of any need for electric heat or air conditioning. Add in daylight from the windows and skylights and a keen awareness of trickle drains and phantom loads, and an Earthship’s electrical needs are about 25 percent of that of a conventional home. Most residents can meet their demand with one kilowatt or less of energy from solar panels. Some also opt to add a small windmill to the system for gray, stormy climates.
Interior, in-home, organic food production is the most recent design principle added to the Earthship concept. Earthship Biotecture employs a plant specialist who has experimented with the best plants for the interior gray-water botanical cells. She has also designed mini-hydroponic planters in suspended buckets that have added vertical growing space in the greenhouses and have tremendous yields of herbs, peppers, tomatoes, kale, beets, cucumbers, and more. The Earthship Visitor Center features all of these food-producing plants, and staff members regularly enjoy fresh produce straight off the vine. Aqua-botanical systems in the newest Earthship enhance food production capabilities with fish and nutrients from their waste.
The used gray water flows to interior botanical cells, where plants utilize and act as a primary filter for the water until it’s clean enough to be collected and pumped, on demand, to the toilet tank for flushing. (Forty percent of water used in a conventional home is for toilet flushing.) The toilet water then goes to a conventional septic tank, which overflows into an exterior rubber-lined botanical cell filled with exterior landscaping plants. Every drop of water that lands on an Earthship roof is used four times, so homes can subsist and even thrive without taking water from the ground or municipal sources.
Earthships incorporate many natural and reclaimed materials in their construction. Tires are the perfect form for a rammed-earth brick. There’s no shortage of used tires—at least 2.5 billion are currently stockpiled in the United States, with 2.5 million more discarded every year. Tires can be seen as a globally available “natural resource.” Other materials such as cans and bottles are optional, although bottle brick walls have become an iconic decorative feature of many Earthships. All interior walls are packed out between the tires and plastered with adobe mud. Mud can also be used for floors, and reclaimed wood and metal are often used.
LINK: This is an extensive study by the University of Wisconsin-Madison that was presented to us by the state of New Mexico.
We are dedicated to high quality, super efficient and skilled craftsmanship. Our primary goal is to provide buildings that are as sustainable as possible and as affordable as possible. We value the opportunity to work with you.
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