Re:지열관--여러가지 다른 해법들

[구름치기]

PDF화일로 된 위 3개의 문서는 지열관에 대한아주 자세한 설계와 데이터들을 바탕으로 서술되어 있다.

그러나 HTML문서에는 지열관의 내부 냉매를 공기가 아닌 물을 사용할 경우 이슬현상을 원천적으로 차단할 수 있는 방법이 아래  나와있다. 다만 아래 문서는 물을 순환하는데 들어가는 전력이 더 많이 소모된다는 단점이 있다.

Earth tube and solar chimney ISEC2004-65093r.pdf

--------------------------------------------------------

Earth Tubes2003-01-07GirjaSharan.pdf

---------------------------------------------------------

  REHAU_AWADUKT_Thermo_342100_UK.pdf

--------------------------------------------------------

Earthtubes (earthtubing) non-electric heating, passive geothermal
low-tech solar heating & solar cooling systems for sustainable architecture

home page » passive solar design chapter » earth tube detail page... you are here

Earthtubes (earthtubing) are, in a word, low-tech, sustainable, non-electric, zero-energy passive geothermal solar heating and solar cooling systems. Earthtubing utilizes conventional, thin wall plastic sewer/drain/vent pipe to passively (zero-energy) pre-heat your home's fresh air intake. Filtered fresh air enters a series of non-porous pipes embedded around the interior of your home's foundation, absorbing energy from the surrounding soil, moderating the temperature of fresh air intake. When done correctly, air drafts naturally through your earthtubes for a truly sustainble, non-electric, zero-energy, passive geothermal system that nicely supplements a high thermal mass HTM home's back-up heating and cooling system. Please be careful with earth tube details though... while "Green" architects are warming-up to the idea, they are making very elementary mistakes, such as using large diameter concrete (cement) culvert pipe for the earth tube air inlet pipe. Concrete is nearly impossible to clean and question-able to coat with chemical sealants to make it clean-able.

Limiting your home Fresh Air Intake to a set of four inch plastic pipe makes for very cost effective systems. Easy junction-box-filtration is possible with commonly available activated charcoal furnace filters. Staight-forward return air systems have been common commercial construction for years. Schools, for instance, require a certain number of full air interchanges every hour and use tempering sytems (just like earth tubing) to meet that standard without completely wasting all that energy it took to heat/cool the air. In a commercial building, incoming fresh air is drafted through a series of ducts, allowing outside air to cool/warm a bit before mixing through heating/cooling system with inside air. Indoor environmental health is a critical design issue and should not be taken lightly by architects and engineers in their search for energy conservation. Modern passive solar design must be holistic in its approach or it will suffer the same fate as early attempts at earth sheltered housing that failed to address water transference in unsealed concrete foundation walls and no wing insulation. Poor earthtubing designs must be highlighted and critiqued to avoid repeat errors or the entire concept of earthtubing, and passive solar design in general, is negatively affected. The ultimate goal is to encourage wise passive solar construction, thus moving towards energy independence for all.

Conventional homes are typically High R value and Airtight, so all of the heating and cooling effect is stored within the air temperature (convection). If you let the air escape, you lose all your comfort. High thermal mass building materials allow the heating and cooling effect to be stored within the home's walls and floor (radiant). This allows you to vent the inside air of an HTM without "losing" all your heating or air conditioning comfort. Constant venting in the winter is common to HTMs, with fresh air being pre-heated or pre-cooled before it enters the home. Please note that earthtubing is not meant as a summer cooling system in hot, humid climates where moisture would reach dewpoint and collect in the tubes. Weep holes are drilled in the bottom of corner fittings, but these drains can be quickly overwhelmed in a very humid climate. If you must alter your indoor climate in the summer for personal comfort level, you will need mechanical means. There really is no truly healthy passive method to de-humidify. But there is a new generation of central de-humidifying systems and heat pump water heaters HPWH. Central air conditioning systems that install inside the home, not outside where the heat removed is wasted. In effect, HPWH extract heat from inside the home and use it to warm the hot water tank. James Dulley's website provides research details and manufacturer listings on such mechanical systems. Please see our Research Links page, where this columnist's page is first up.

click here for the main chapter of our free Passive Solar Design eBook

The drawing above illustrates a set of four earth tube ventialtion pipes as they're installed with a monolithic slab. Please note the use of 45 degree fittings which help accentuate airflow and make alignment and spacing easier. Greater spacing between pipes (see below) allows for more surface contact with thermal mass and thus better heating and cooling qualities. Monolithic slabs are confined in terms of space available to separate pipes, but their being imbedded in solid concrete helps make up for the design loss. Please note that this drawing shows insulation under the interior floor slab. With sloped glass, this layer of insulation is typically not installed (see wing insulation detail at end of page). The typical number of earthtubes is four, which is enough to supply average household air volume. One pipe is generally considered to carry enough air for one room. In theory, you could have as many earthtubes as you wish, but the slower the draw-time, the warmer the air moving through it (or cooler in the summer).

Cleaning earth tubes is an easy matter - simply lay nylon cord in the pipes while constructing and use it to pull a bleach, peroxide, alcohol or disinfecting solution soaked towel through the tubes. Tie a second cord to the towel so that you leave a cord in the pipes after the towel has been pulled through. We suggest installing a standard furnace filter at the earthtubing inlet grate to prevent dust and insects from entering the pipes. Keep in mind that mold only grows on surfaces with fuel to support it - clean pipes will not support mold growths. Many people worry about keeping the earth tubes clean, but you rarely see folks cleaning their home heating and cooling ducts. Earth tubes are nothing more that air intake pipes - and round pipes are much, much easier to clean than rectangular duct work. Earthtubing is a very simple and cost-effective means to temper air intake for any home. They are especially important for high thermal mass homes, which can be very aggressively vented, ensuring quality indoor air (versus air-tight conventional construction).

The photo above shows a set of four passive geothermal earthtube pipes being installed around the HTM's foundation. Shown below, are these four earthtubes going around an inside corner of the home's frostwall. Later, these pipes will be backfilled with fill dirt and covered with a concrete floor slab. Earthtubing technology is not geothermal heat pumping. Earthtubes are sustainable, non-electric, passive heating and cooling systems. Unlike geothermal heat pumps, earthtubes do not involve any exotic machinery or special type of pipe that we are trying to sell you. Earthtubing pipe can be installed outside the home foundation, but that is generally only done for cooling purposes in a hot, dry climate. Exterior pipe installation is relatively expensive since you are digging long, deep gravel filled trenches for the pipe. Runs of at least 20 feet, if not up to 100 feet, are needed to get a noticeable cooling (tempering) effect. Moisture in return/intake air will condense on pipe walls at some point in a more humid climate. With exterior earthtubing, the technique involves dropping the inlet end of pipe in yard, down as deep as possible/practical, and then angling up towards the home foundation. You always make a straight run uphill at slight slope (1/4 inch per foot very bare minimum). Bed your pipe well in 3/4 inch nominal crushed gravel to prevent chance of cracking during backfill and to promote better energy transfer. With slope running downhill towards inlet, accumulated condensation can at least be dealt with by drilling weep holes. Cleaning of these long runs in a hot humid climate can be a chore unless you are located on a sloping hillside, where the pipe inlet can level out to grade.

The waterproofing treatment shown above is a simple mop-on coating. If you have the money in your budget, we highly recommend using vertically applied, roll-on roofing underlayment, such as Grace? Ice and Water Shield™, for the exterior of your foundation walls. Don't forget to use their primer first, though! In the picture at right, we have left the earthtubes exposed for better illustration (normally they are hidden in wall or floor). The two pipes seen at right (top of photo below log) are entering from outside. They drop down to the base of the frostwall and encircle the home giving fresh air plenty of time to warm up or cool down before it vents into the HTM. In the lower right corner shadows you’ll see the two grated pipes where air finally enters. These two pipes originated at the opposite end of the planterbed. Earthtubes are a very simple, low-tech system without any moving parts. Passive solar at its best. And see how well the Cannas are blooming in the middle of the winter.

The question of earth tubing layout is never a simple one, but it does boil down to installing as much pipe as is practical. Avoid 90 degree bends (using two 45s) and don't create patterns that you can not clean (like manifolds). Keep in perspective that eleven (11) lineal feet of 4 inch diameter pipe has a volume of One (1) cubic foot. If your building is air tight, the exhaust fan dictates air movement/speed through the earth tubes. For instance: 35 cubic feet per minute of stale air out of the building is clearing almost 400 lineal feet of pipe every minute. Ideally, your slab temperature is elevated by excess solar energy for optimal earth tube tempering effect.

The most important factor to successful earthtubing is warm DRY EARTH. As the wing insulation sketch below outlines, we stress the need for waterproofing and insulating up to a 20 foot perimeter around the home. Wet earth acts as a constant heat sink pulling energy away from your foundation walls. Dry earth under and around an HTM stores an amazing amount of energy. Earthtubes utilize this energy by allowing fresh, incoming ventilation air to passively gain or lose heat energy before it enters your home. This sustainable ventilation system exchanges indoor air more often, keeping your home's environment fresh without the drawback of "losing all that energy".

With any earth tube system, it is key to note:

the earthtubes enter wherever and drop down to bottom of footers

after entering, they encircle the interior of the frostwalls

routing pipe through indoor planterbed soil is very effective

a small amount of slope in the earthtubes is not vital, but nice

drill 1/8th inch weep holes in corners to drain condensation

use 45's in the corners and not 90's to allow easier cleaning

separate pipes by 4 inch minimum to ensure maximum energy transfer

use thin wall SCH2729 four inch diameter sewer pipe (thinner than SDR35)

drag several nylon cords through AFTER the glue sets with a wire fish

cover inlets and outlets ALL THE TIME during installation to keep clean

protect inlet and outlet grates from water/dust intrusion with furnace filters

It is common to bring all earthtubes into the central utility room. Terminate the pipes in a small junction box, if you wish to filter the ventilation air and/or add a fan to power draft and/or use as fresh air intake for HVAC system. The junction box can be a simple wooden cabinet sized for the filter being used. We have seen distribution D Boxes, like those used for septic systems, used to create a very effective interior junction/filter box. It is also possible to simply terminate the pipes in a wooden framed "wet" wall and install standard galvanized grate/vent duct box (cold air return) for each individual room.

The outlet ends of your earth tube vent pipes can be spread out around the home or clustered in a single room. Using tempered air tubes as the "cold air return" for boiler or furnace is common commercial construction practice. A common upgrade to any earth tube system is powered venting to assist passive draft. Your home is constantly venting out through open windows, bathroom vents, furnace, water heater, dryer and range hood. This air is coming in from somewhere - the earth tube pipes (cold air return system). Earth tubes can end in a central terminus box (plenum) and be fan powered (air handler) or you can individually fan assist each earth tube pipe (shown below). We commonly suggest installing a 4 inch axial fan (12 VDC computer cooling fan) in the end of each earth tube pipe and covering with a protective vent grate. Common 80mm computer fans fit nicely into a four inch pipe coupler fitting, as pictured, and can be run on a small solar panel, car battery, or just use a transformer (standard 110 volt AC). A nice touch is pulling cheesecloth across pipe end for filtration and aromatherapy (drip oils onto cheesecloth).