what is the irr

Earth shelter house : 

Earth shelter house OH YOUN SEOK

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What is an earth sheltered house?

What is an earth sheltered house? : 

What is an earth sheltered house? An earth sheltered house is quite simply a building that uses earth (dirt) to protect it from the outside elements. Fallout shelters built during the Cold War era are in fact earth sheltered houses, or buildings. The focus of this website is however a somewhat more optimistic application of earth sheltering, and that is as an aid to building more energy efficient dwellings for now and into the future.

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Why earth sheltered?

Why earth sheltered? : 

Why earth sheltered? Energy Consumption Noise Reduction Aesthetics and Land use $$ Cost $$ Safety

Energy Consumption : 

Energy Consumption No reasonable intelligent person can deny that the world is heading towards a turning point with regard to its relationship with the environment. One aspect of this issue is western society's current reliance on fossil fuels and, at current rates of consumption, their projected exhaustion sometime next century. A large proportion of the fossil fuels currently consumed go towards the production of electricity which is then used for many purposes, one of which is regulating the climate inside man-made dwellings. The search for alternative energy sources is of paramount importance and must be pursued despite pressure from powerful groups (e.g. Coal Industry) with vested interests in the current system. However, regardless of how our electricity is produced we are still using it inefficiently in our buildings. This is largely due to energy inefficient building designs that demand heating in the winter and cooling in the summer. A good example of this are the glass walled sky-scrapers that are present in most major cities; they may look good but they are extremely susceptible to external fluctuations in temperature. Earth sheltering used in conjunction with passive solar design can cause a dramatic decrease in the temperature fluctuations inside a building and consequently dramatic effects on electricity consumption.

Noise Reduction : 

Noise Reduction There are many advantages to living in an earth sheltered home, one of which is savings in energy use. Yet another is the reduction in noise from external sources inside the building. This leads to a more serene environment inside the stucture and makes it possible to build earth sheltered dwellings in places where conventional structures would be virtually unlivable e.g. next to major roads or in airline flight paths. As well as these extreme cases the use of earth sheltering will make nearly any building perceptibly quieter than its conventional neighbour, and the sound of said neighbour mowing his lawn at 7:00 am will be that much less irritating.

Aesthetics and Land use : 

Aesthetics and Land use One of the more common motivations for building an earth sheltered structure is to blend the building in with its natural surroundings. This is often the case on rural sites where the owner wishes to build a dwelling but also retain the 'untouched' beauty of the natural landscape. Although retaining the beauty of a suburban block is not often of much importance, once the earth shelter has been built the area of land available for growing plants is greatly increased over that of a block with a conventional building on it. e.g. This double use of the land, house underneath, garden on top, means earth sheltered houses can be built on smaller blocks than conventional houses and still have sufficient space for outdoor living. This makes earth sheltered housing particulary useful for medium-density housing developments, an area of construction that will no doubt increase in the future as the world population grows and cities become larger and larger.

$$ Cost $$ : 

$$ Cost $$ Reduced Energy Costs This is the main area where cost is reduced in an earth sheltered house when compared with a conventional home. As mentioned earlier one of the key advantages to earth sheltering is a stabilisation of temperature inside the building. Because of this, depending on the climate and the design of the building, some earth shelters can be lived in perfectly comfortably all year without any need for heating or cooling. This may not apply in your particular case however it is certain that the amount of heating/cooling required in an earth sheltered building will be reduced. This obviously leads to a reduction in electricity costs. Reduced Maintenance Costs Because an earth sheltered house has a large proportion of its walls covered with dirt, they do not need to be painted or otherwise maintained. Earth sheltered houses are also usually built with concrete or masonry which tends to be less expensive to maintain than a house constructed with a wooden frame and plasterboard internal walls. e.g. termites, rot.

Safety : 

Safety Something that is truly universally desired is personal safety. Earth sheltered houses, especially those entirely below ground level, offer increased protection from outside events in comparison to conventional homes. This is particularly relevant to people who live in places prone to either tornadoes or cyclones, other severe storms, bush fires, etc. Earth sheltered houses, usually built with concrete or masonry, are much less likely to burn from the inside than a conventional home. Internal furnishings are likely to be combustible however and smoke alarms etc. should still be used. Even if the contents are entirely burnt there is still a good chance that the structure will remain intact and be safe to move back into.

Different Types of Earth Sheltered Housing : 

Different Types of Earth Sheltered Housing Types A1, A2, A3 and A4 These all have their floors located at ground level, or above the ground at the lowest entrance point or door. Because these type A buildings are not recessed into the earth where temperatures are more stable they are potentially less energy-efficient than type B. This type of construction is used when excavation should be kept to a minimum because of rock, or where a watertable exists near the ground surface. Should extra rooms be needed in the future, type A buildings are more easily adapted than type B buildings.

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A1 Chamber This type of house has an earth-covered roof and berms around all its sides with no windows. Although such a house would have quite good insulation properties, the conditions inside would be unlikely to please most people, ie. no natural night.

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A2 Atrium In Roman times, urban dwellings in particular gained privacy by having their open space located centrally in relation to the house as a courtyard (atrium) surrounded by rooms. Consequently, the atrium-type earth-covered building has the spatial characteristics of the Roman atrium house (combined with those of the A1 chamber type.)

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A3 Elevational This is similar to a chamber-type earth-covered building except that it has one wall exposed. This wall has windows, probably to a view, and preferably to the sun for passive-solar purposes for which this type is ideal. Side walls may have small areas of windows with earth-berms up to sill level.

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A4 Penetrational This type of building has windows to more than one elevation of the building. Of all the types of earth-covered buildings, this is the least energy-efficient unless special provisions such as double glazing to doors and windows, or shutters, are used to conserve thermal energy. However, if windows are used all around, the internal rooms would not need any skylights, and future extensions would be easier than for other types. This type has good potential for catching cool breezes in summer. Out of all the types of earth-covered building this is the closest to a conventional

Different Types of Earth Sheltered Housing : 

Types B1, B2, B3 and B4 All these types have their floor levels below the ground surface level at the lowest entrance point or door of the building. Hence, cool air will 'pool' at floor level to a height equal to the height of the steps necessary for access from floor level up to the door threshold. Different Types of Earth Sheltered Housing

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B1 Basement Chamber This term is used to describe a building completely enclosed by earth, except for the entrance/exit. It is the type used for cyclone or tornado shelters. If correctly designed, it is suitable for nuclear blast and fallout shelters. For various reasons, complete shopping complexes have been built totally underground (e.g. Japan, Paris and Montreal). Elsewhere in the world, this type is used for transit networks, defence complexes and explosives stores. (Again, Not very pleasant to live in.)

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B2 Recessed Court As explained, the Roman atrium house contained an internal courtyard surrounded by rooms. In an atrium house (described as 'recessed court' to distinguish it from type A2) one can stand in the atrium and not be conscious that the house is below ground level. One normally enters through the atrium, although direct access into the house is possible. While sometimes awkward to plan, this type is highly energy efficient due to the large amount of earth insulation and minimal door and wall openings to the atrium. In very cold climates, the atrium can be covered, while still permitting the entry of light into the rooms off the atrium.

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B3 Wall Exposed This type is totally buried beneath earth from the front of the roof to its back edge. The front is usually the longest edge of the roof. The rear wall is fully earth insulated and often so are the side walls. This type with an elongated rectangular plan, can balance good insulation of three walls, floor and roof with an exposed front wall. This provides all front rooms with a view, and approaches the appearance of a conventional home. However, solar gain and thermal losses all need careful design consideration when complete wall areas are exposed.

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B4 Recessed Penetrational This type of building, constructed in a previously prepared excavation, has windows and/or doors to the back and front elevations. This type represents only a slight increase in energy efficiency over type A4 and is thus potentially one of the least energy efficient possibilities.

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Site Considerations

Energy Efficiency –Relationship to the sun : 

Energy Efficiency –Relationship to the sun When considering a site for building an earth sheltered house the preferred orientation for passive solar design should be taken into account. On some sites it may be impractical or even impossible to face the house in the 'right' direction. There are several reasons why this may be the case: Site is located on a hill side facing the 'wrong' way (ie. facing towards one of the poles). There are fantastic views in certain directions. There are appalling views in certain directions. The site's relationship to surrounding buildings. The direction of prevailing winds. Miscellaneous others particular to the site in question. If this is the case all is not lost, skylights or other alternatives may be used to collect passive solar energy despite the imperfect orientation of the house. However these alternatives are almost certain to be less efficient than if the house was facing in the preferred direction, to what degree this is the case needs to be considered for each particular site.

Energy Efficiency - The Wind : 

Energy Efficiency - The Wind As mentioned above the direction of prevailing winds can have an effect on the choice of orientation of an earth sheltered home. Direct exposure to cold winter winds increases the loss of heat from the building, this is due to cold air leaking into the house as well as the wind chill effect. A house that is fully earth-covered in the direction of prevailing winds will be very well sheltered. This will be the case if the wind is coming from behind an elevational type house, if this house is also facing in its preferred direction (passive solar) then it represents extremely good energy efficiency. An atrium style house is also well sheltered from wind in any direction, however, depending on the specifics of the courtyard, wind turbulence may result inside it. In summer it is preferable for breezes to flow through the house in order to cool it. On some sites these two orientations, shelter in winter, catching breezes in summer, may be different or indeed they may be exact opposites. In this case the climate of the region needs to be considered and it decided whether shelter in winter is more important or vice versa. Once again there may be reasons why you can not, or would rather not, face the house in this direction. This can be accommodated; however it will reduce energy efficiency. If the site you are considering does not allow either orientation towards the sun or preferable orientation with regard to the wind then perhaps another site should be found, otherwise it must be accepted that the house that is built will not be nearly as energy efficient as it could be. Having said this, such a house may still be more efficient than any conventional house. It should be mentioned that vegetation, grasses, shrubs and trees, can significantly reduce the wind speed on the ground and can therefore help in protecting an earth sheltered house from the cooling effects of the wind.

Siting: Soil and Groundwater : 

Siting: Soil and Groundwater It should come as no suprise that when building an earth sheltered home the type of soil on (or in if you like) which it is to be built is of importance. The type of soil on site can affect the structural design of the house depending on certain characteristics that the soil may or may not possess. The level of the water table will also have an effect on the structure and also the water proofing techniques used. A qualified person, preferably with earth sheltered experience, should take a soil sample at the site in question and consult with your engineer on the results. "Generally ... most types of soil will not greatly affect the design of the house. The groundwater and drainage characteristics of the site can have a larger impact on the design." Underground Space Center, Earth Sheltered Housing Design p27.

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This is a table showing basic soil types and their suitability to earth sheltered applications. This table is only meant to be a very basic guide and actual soil types will probably not fall into these simple categories. Table taken from Underground Space Center, Earth Sheltered Housing Design p103.

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Design Considerations

Passive Solar Design : 

Passive Solar Design To take full advantage of earth sheltering it is necessary to design the house with an eye to increasing the passive solar gain of the house. Minus the jargon this basically means that the house should be oriented such that it receives the maximum possible winter sun and as little as possible summer sun (this depends somewhat on the particular climate). An elevational type design (A3, B3) is ideal from this point of view because all (or most) exposed surfaces face in one direction. The direction in which the house should be 'pointed' varies with latitude, but fundamentally houses in the southern hemisphere should face north and houses in the northern hemisphere should face south. The reason this is the case is because although the sun never changes which direction it comes from (basically north or south) the angle at which it hits the earth sheltered home changes throughout the year. In winter the sun is low in the sky and thus hits the sunside of the house at a low angle. In summer the sun is high in the sky and hits the house from more like directly above. e.g.

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The angles in this diagram are not accurate and are intended for illustrative purposes only, actual angles depend on the location of the house in question.

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As the above diagram hopefully illustrates,the angle at which the sun hits the house in winter allows sunlight and heat to penetrate deep into the house. Conversely, in summer the overhang of the roof blocks all sun from entering the house and thus keeps the house cooler. All this heat entering the house during winter days is great, but what about winter nights which are surely colder than winter days? The crucial part of passive solar design is trapping the sun's heat once it has entered the house, and this is where earth sheltered homes stand out above conventional houses. Objects with high mass, such as rocks have a much greater capacity for storing heat than objects with low mass. In an earth sheltered house all or most of the external walls are directly connected to earth which has a very good capacity for storing heat, the internal walls are also likely to be made of poured concrete or masonry which also has a considerable capacity for heat storage. In addition to this the floor and ceiling are both often (always in the case of the floor) in contact with the earth and are also made of heavy materials. All in all an earth sheltered house has a considerable capacity to store heat which it receives from the sun. In contrast a conventional home, even one built on a concrete slab, has much less mass and therefore much less capacity to store heat. The end result of this stored heat is that come winter night in an earth sheltered house, heat actually radiates from the walls, floor and ceiling and warms the house. This has been a very basic overview of passive solar design. Passive solar design is an energy efficient style of building construction in its own right, and therefore before you build any new home you should seek more information on this very important topic.

Surface Area : 

Surface Area Something that should be briefly mentioned is the exterior surface area of a building. The following diagram shows two floor plans, Plan A. and Plan B. which both enclose the same floor space but have a differing amount of wall area in contact with the outside world.

Derived from Underground Space Center, Earth Sheltered Housing Design, p35 Fig.2-1 : 

Derived from Underground Space Center, Earth Sheltered Housing Design, p35 Fig.2-1

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The units here are irrelevant, what is relevant is the fact that Plan B. has a larger wall area while enclosing the same floor area. This demonstrates the fact that a compact design can reduce the amount of surface area which a building has in contact with the outside. (N.B. This principle also works in three dimensions.) The more surface area a house has in contact with the outside, the more heat it will lose through these surfaces. This leaching of heat is reduced in an earth sheltered house but is still worth consideration. In cold climates it will be desirable to reduce the surface area of the walls, floor and roof in order to minimise heat loss. However, in hot climates, it will aid the cooling of the house if the surface area is increased. In both cases the 'compactness' of the design should be noted and adjusted to suit the conditions if this is acceptable to those who will live in the house.

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Examples of earth sheltered houses

Burnsville House : 

Burnsville House Type : The Burnsville house is primarily a subgrade elevational type of house. However the house is not very deeply recessed into the hill on which it is situated. There is also an entry on the northern side of the house which means that it isn't strictly an elevational type but more of an elevational/penetrational mixture. Location: Suburban Minneapolis, Minnesota Architect: John Carmody, Tom Ellison Structural Engineer: Martin Lunde Mechanical Engineer: Teryy Tillman Contractor: Ellison Design & Construction Earth Cover: 100% on roof, 60% on walls

driveway and entry : 

driveway and entry

view from the south : 

view from the south

roof from the east : 

roof from the east

Clark House : 

Clark House Type : All the photos of the Clark House are either from the west or from inside the house, however there is an exposed wall of windows on the east side of the house. The house is therefore an atrium type mixed with an elevational type. Location: Suburban Portland, Oregon Architect: Norm Clark Contractor: Norm Clark and Haldors Construction Company Earth Cover: 80% on roof, 88% on walls

Roof view : 

Roof view

Roof view #2 : 

Roof view #2

Roof view #3 : 

Roof view #3

Sticks and Stones House : 

Sticks and Stones House Type : This house is a good example of where the simple types defined previously fall down. This home has aspects of the atrium type as well as aspects of the elevational type, and some aspects of the penetrational type also. There is no category into which we can conveniently slot this design. Location: Suburban Minneapolis, Minnesota Architect: Froehle, Saphir, Joos-Sticks & Stones Design Engineer: Fowler, Hanley Contractor: Sticks and Stones Design Earth Cover: 90% on roof, 80% on walls

Sunken patio : 

Sunken patio

View from the street : 

View from the street

Entry, solarium and patio : 

Entry, solarium and patio

House in winter : 

House in winter

View from the footpath : 

View from the footpath

Bibliography : 

Bibliography Baggs,Sydney A., Baggs, Joan C. & Baggs, David W., Australian Earth-covered Building, New South Wales University Press, NSW Aus, 1991 Hollo, Nick, Warm House Cool House, Choice Books, NSW Aus, 1995 Ritchie, James, Successful Alternate Energy Methods, Structures Publishing Co., USA, 1980 Terman, Max R., Earth Sheltered Housing: Principles in Practice, Van Nostrand Reinhold Company Inc., New York, 1985 Underground Space Center, Earth Sheltered Homes, Van Nostrand Reinhold Company Inc., New York, 1981 Underground Space Center, Earth Sheltered Housing Design, Van Nostrand Reinhold Company Inc., New York, 1979 http://members.tripod.com/ellerman79/oldbrowser/index.html

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?!

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Thanks