Энергияны үнемдейтін ландшафтты жобалау

Energy efficient landscaping is a type of landscaping designed for the purpose of conserving energy. There is a distinction between the embedded energy of materials and constructing the landscape, and the energy consumed by the maintenance and operations of a landscape.

Landscaping often refers to the practice of landscape design and gardening, which traditionally concern with designing sites with vegetation and craft for aesthetic, cultural, social, and religious purposes. Landscape architecture and landscape engineering, on the other hand, are multi disciplinary and interdisciplinary professions that integrate technical considerations, such as geography, ecology, biology, and engineering, into the design of landscape and the actualization of it. Energy efficient landscaping falls into the categories of the latter, and it stresses the energy conservation in site operation or the creation of the site. Among its various term usage, energy efficient landscaping can refer to the reduction of energy usage in maintenance and operation of the landscape narrowly for the user/owner of the site, or broadly for the energy conservation of the global environment, such as mitigating urban heat island effect with reflective surface (increase albedo) or reducing the need of water treatment and sewage by using pervious pavement. Common methods of energy efficient landscaping include reducing heat or cooling load of a building through shade, wind blocking, and insulation; management of water; and using plants or construction material that cost less energy.

Planting trees for the purpose of providing shade, which reduces cooling costs. The mature height of the trees and their canopy shape need to be well studied. The location of the trees should be designed based on their height and the height of the building. Also, when trees are plant closer to the windows or walls, they will provide shade for greater portion of the day as the Sun keep changing its relative position to the window and the trees. Planting the trees too close to the building, however, is also not desirable, as it might cause the danger of touching above ground or underground utility lines.

Planting or building windbreaks to slow winds near buildings, which reduces heat loss. Homes loses heat through infiltration in the Winter. Windbreaks should be designed to intercept and redirect the Winter winds before they reach the house and outdoor areas with playgrounds or sensitive plants. The windbreak in the Winter should also be designed so that they would not block the sunlight in the Winder or block the wind in the Summer. In a study of simulating a structure with varying depth submerged in the ground to understand the insulating effect of natural wall and ground in cold climate, it was found that the thermal transmittance of the earth sheltered walls and floor is 16% 45% lower than that of the structure totally above ground. Other than Earth Sheltering, a simpler way of taking advantage of natural landform is using geology, such as mountains, for shade.

Often, landscape design and architecture refers to the design in ground surface; in many contexts, specifically, the design guidance and topics are for a typical residential landscape in suburban housing, where there is a yard (garden), a driveway, and a house. In the crowded urban area, however, there is not abundant ground surface for landscape design. Green roofs, then, become an appealing option to add some aesthetics and green to the crowded cities. Not limited to the cities, green roofs can be applied to wherever it will fit. Most of times, actually, the decision to build Green roofs is based on local climate and policy. It is because other than its aesthetics, green roofs are used often for their ability to conserve energy, such as increasing insulation of the building roof, retaining and infiltrating rainwater, and potentially reducing urban heat island effect when it was installed to a certain scale. In Germany, for example, partly because of EU's regulation, 17% of the new roof construction are green roofs. In Washington DC, green roofs are used as an alternative storm water retention technique.

Reducing building energy consumption by increasing the roof insulation: In total energy consumption reduction, green roof would have the best performance relative to a bare roof in a colder climate, which require nighttime heating. The reduction in heating load of the building increase as the soil depth of the green roof increase, though an increased soil depth would mean heavier roof. On the other hand, if a building is cooling dominated, leaf area index is more important. In peak energy consumption reduction, green roof also has a notable effect, and the leaf area index and soil depth are both positively related to its performance. Rainwater retention and evapotranspiration: a 3 4 inch of soil can retain about 1 inch of rainwater. That is about 75% of precipitation in most areas in United States. By retaining the rainwater in soil, the water would not become runoff, instead they would result in evapotranspiration.

Water runoff quality: When green roof is not able to hold the amount of the precipitation, the excessive rainwater will become runoff. In a field experiment where contaminated water are dripped into a green roof section to mimic rainfall in the green roof, the exfiltrate water was studied and analyzed. It was found that since the average level of suspended solid, nitrogen, and phosphorus concentrations in Green roof water outflow is significantly higher than those in conventional roof outflow, extensive green roofs will become a source of nutrient contamination in urban water environment. Fire Hazard: Green roofs can be more easily ignited than conventional roofs; it is a concern that when the green roof caught fire, the high temperature would damage the roof structure itself. Not only the idea of damaging the roof is contradictory to energy conservation and sustainability, the fire and the roof damage could cause safety issue to the residents. It remains a matter of debate as to whether a green roof will exacerbate or mitigate the effects of a fire. Some argue that, because vegetation is about 95% water, the green roof actually reduces chances of a fire. On the other hand, some argue that during autumn and winter, when the vegetation is dry, fire hazard is increased. A recent study has found, through mathematical modelling, that when the vegetation itself caught fire, heat does penetrate downward (rather slowly as the thermal conductivity of soil is low), eventually damaging the roof itself. Thus the key to whether ignited vegetation will damage the roof or not depends on the thickness of the soil. The study also found that by installing a gypsum layer beneath the soil layer, the possibility of damaging the roof can be greatly reduced. Additional structural load: Most old buildings were not designed for the extra roof dead load of the green roofs. If more energy is consumed in building the additional load bearing structure for the green roofs than the energy saved through insulation enhancement and water retention, it would be contradictory to the idea of energy conservation. By study, common green roofs types in the market would increase the load on the rood by 1.2 to 2.43 kilo newton per square meter.

Energy efficient landscaping techniques include using local materials, on site composting and chipping to reduce green waste hauling, hand tools instead of gasoline powered, and also may involve using drought resistant plantings in arid areas, buying stock from local growers to avoid energy in transportation, and similar techniques.