natural+heating+and+ventilation

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[] - solar angle program

Natural ventilation Natural cooling [] - determines benefits or not of natural ventilation systems according to local climate.

Compost heating - [] Passive solar

[] - concentrating solar [] Solar air heating Solar water heating Solar heating Solar cooking Solar drying

Thermal chimneys

Solar greenhouses The ventilation requirement to dilute body odor is the adopted threshold of air quality as if body odor is not discernible then the air exchange provided is sufficiently healthy. This is dependent on the density of bodies - 7 cfm of air is required at 500 cu ft per person but 25 cfm at 100 cu ft per person. [|http://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_201102/index.php#/44]

For many homeowners, building an attached solar greenhouse is very appealing. They believe that they can extend their garden's growing season while reducing their home heating bills. Unfortunately, there is a contradiction between the use of a greenhouse to grow plants and the use of it as a solar collector for heating the house.( [|9], [|28] )

• To provide heat for a home, a solar collector needs to be able to collect heat in excess of what plants can tolerate.

• Much of the heat that enters into a greenhouse is used for evaporating water from the soil and from plant leaves, resulting in little storage of heat for home use.

• A home heat collector should be sealed to minimize the amount of heat loss. Greenhouses, however, require some ventilation to maintain adequate levels of carbon dioxide for plant respiration and to prevent moisture build-up that favors plant diseases. pit greenhouse The Pit or Subterranean Greenhouse



Attached Solar Greenhouse Trombe walls are an innovative method for heat absorption and storage. These are low walls placed inside the greenhouse near the south-facing windows. They absorb heat on the front (south-facing) side of the wall and then radiate this heat into the greenhouse through the back (north-facing) side of the wall. A Trombe wall consists of an 8- to 16-inch thick masonry wall coated with a dark, heat-absorbing material and faced with a single or double layer of glass placed from 3/4" to 6" away from the masonry wall to create a small airspace. Solar heat passes through the glass and is absorbed by the dark surface. This heat is stored in the wall, where it is conducted slowly inward through the masonry. If you apply a sheet of metal foil or other reflective surface to the outer face of the wall, you can increase solar heat absorption by 30-60% (depending on your climate) while decreasing the potential for heat loss through outward radiation.( [|10], [|18] ) Trombe wall. Photo: Australian Center for Renewable Energy || //Water walls// are a variation of the Trombe wall. Instead of a masonry wall, water-filled containers are placed in line with the sun's rays between the glazing and the greenhouse working space. The water can be in hard, plastic tubes or other sturdy containers, and the top of the wall can serve as a bench. The //Solviva// solar greenhouse water wall consists of two 2x4 stud walls, with the studs placed two feet on center. A one-foot spacer connects the two walls. Plastic-covered horse fence wire was then fastened to each stud wall, and heavy-duty, dark-colored plastic water bags were inserted into the space between the two walls. The stud walls were positioned vertically in line with the sun's rays prior to the bags being filled with water.( [|19] ) Both the [|Solviva] and [|Three Sisters Farm] Web pages provide designs for constructing solar greenhouses using water walls. You can use rocks instead of water for heat storage. The rocks should be ½ to 1½ inches in diameter to provide high surface area for heat absorption.( [|5] ) They can be piled in wire-mesh cages to keep them contained. Since rocks have a much lower BTU storage value than water (35 BTU/sq.ft/°F for rocks versus 63 for water) ( [|13] ), you will need three times the volume of rocks to provide the same amount of heat storage. Rocks also have more resistance to air flow than water, resulting in less efficient heat transfer.( [|20] ) Whichever material you choose to use for heat storage, it should be placed where it will collect and absorb the most heat, while losing the least heat to the surrounding air. Do not place the thermal mass so that it touches any exterior walls or glazing, since this will quickly draw the heat away. [|http://www.nxtbook.com/nxtbooks/ashrae/pubcatalog_2011summer/#/6]
 * [[image:https://attra.ncat.org/images/solar-gh/trombe_wall.jpg width="410" height="175" caption="Trombe wall"]]