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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, [1] [2] 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.
Design techniques include:
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. [2]
The type of leaves of the trees is also important. Broad-leaf evergreens like Southern magnolia can be used to provide dense year-round shade. However, needle-leaf evergreens like pines and cedars can provide more air circulation though their shade is sparser and more open. [2]
Not only can tree shade be used to reduce the cooling load in building, it can also be used in parking lot, driveways, and playgrounds. [3]
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. [3]
Planting shrubs near the wall creates an insulating air space around the wall. This is a similar idea to the use of a tree windbreak. Shrubs should be planted at least 2 feet (0.61 m) from the wall to prevent moisture and insect problems. [2]
Earth sheltering is an example of using natural landform and geological condition to save energy in building a structure. It is believed to save energy in multiple ways: by using the rock or strong
soil as wall and ground as the floor, construction cost is greatly reduced, because the structure will need less load bearing material and there is no need for excavation and foundation construction; the wall and the floor made of natural material likely will have better insulation than artificial wall and floors; Natural walls and floors can also reduce fire hazard, because they are hard to be ignited thus reduce the need for flame retardants. [4]
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, [5] 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. [6]
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. [7]
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. [8] 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. [9]
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 [10] 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. [11]
Many pavement in the urban and suburban area are impervious, this likely would result the contaminated stormwater runoff. In pre-development area, averagely 50% of storm-water would result in evapotranspiration, 5% in runoff, and 45% in infiltration, whereas in post-development area, only 35% storm-water result in evapotranspiration, and 50% in runoff, and 15% in infiltration. This change has caused various problem, such as flooding, infrastructural damage due to rapid movement of water, and water contamination. [12]
By using pervious paving, however, the amount of infiltrated storm-water will be increased in post-development area, and the pollutants in the filtrated water can be reduced; thus the problem can be mitigated. In Low Impact Development 2008 Conference, ASCE performed two bench-scale study to examine the effectiveness of permeable interlocking concrete pavement in terms of water flow rate and the role of microbial colonies in pollutant removal in the micro-environment of porous pavement. [13] The experiment shows 84% relative total suspended solids (TSS) removal on average, yet the increased relative removal over time suggests there is potentially solid buildup, and that may result system clogging and system failure. The evidence in pollutant removal proved the conclusion of the previous study that the annual pollutant runoff from the driveways was 86% lower for pervious driveways than impervious driveways.
Types of Pervious pavement include: [12]
Advantage: Relatively low cost; Easy access to the material; Workers are experienced with it
Disadvantage: Susceptible to water damage; Usually used for short-term only; Low relative strength
Advantage: High structural strength; Easy access to the material
Disadvantage: Slow construction process; High initial cost
Advantage: Ease of Construction, Aesthetics, Ease of maintenance and repair
Disadvantage: High Cost; Only can be used for low speed road way
Advantage: Wide variety of products; Relatively inexpensive; Ease of maintenance and repair
Disadvantage: Typically limited to parking areas
The decision among different permeable pavement types depends on the need of the project, available material and equipment, and budget.
Site lighting with full cut off fixtures, light level sensors, and high efficiency fixtures.
Sun rises from East, moves toward South, and sets in the West. Thus, a rule of thumb for design is to avoid south-facing window when trying to decrease cooling load of the building and increase south-facing window when trying to decrease heating load of the building. The reality, however, is more complicated. Sun rises from East and sets in West perfectly only on the autumnal and vernal equinoxes, and during the vast majority of the year, Sun travels slightly southward and eastward depending on whether it is summer or winter and on whether the observer is in Northern Hemisphere or Southern Hemisphere. [14]
To design for the best performance of the site, the designer needs to well understand the local climate and the site's location relative to equator.
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.
In agreement with the city to build a resilient and sustainable landscape, Massachusetts Institute of Technology has initiated several energy efficiency upgrade projects, these projects include:
An earth shelter, also called an earth house, earth bermed house, or underground house, is a structure with earth (soil) against the walls, on the roof, or that is entirely buried underground.
A green roof or living roof is a roof of a building that is partially or completely covered with vegetation and a growing medium, planted over a waterproofing membrane. It may also include additional layers such as a root barrier and drainage and irrigation systems. Container gardens on roofs, where plants are maintained in pots, are not generally considered to be true green roofs, although this is debated. Rooftop ponds are another form of green roofs which are used to treat greywater. Vegetation, soil, drainage layer, roof barrier and irrigation system constitute green roof.
A green wall is a vertical built structure intentionally covered by vegetation. Green walls include a vertically applied growth medium such as soil, substitute substrate, or hydroculture felt; as well as an integrated hydration and fertigation delivery system. They are also referred to as living walls or vertical gardens, and widely associated with the delivery of many beneficial ecosystem services.
Permeable paving surfaces are made of either a porous material that enables stormwater to flow through it or nonporous blocks spaced so that water can flow between the gaps. Permeable paving can also include a variety of surfacing techniques for roads, parking lots, and pedestrian walkways. Permeable pavement surfaces may be composed of; pervious concrete, porous asphalt, paving stones, or interlocking pavers. Unlike traditional impervious paving materials such as concrete and asphalt, permeable paving systems allow stormwater to percolate and infiltrate through the pavement and into the aggregate layers and/or soil below. In addition to reducing surface runoff, permeable paving systems can trap suspended solids, thereby filtering pollutants from stormwater.
A living street is a street designed with the interests of pedestrians and cyclists in mind by providing enriching and experiential spaces. Living streets also act as social spaces, allowing children to play and encouraging social interactions on a human scale, safely and legally. Living streets consider all pedestrians granting equal access to elders and those who are disabled. These roads are still available for use by motor vehicles; however, their design aims to reduce both the speed and dominance of motorized transport. The reduction of motor vehicle dominance creates more opportunities for public transportation.
Impervious surfaces are mainly artificial structures—such as pavements that are covered by water-resistant materials such as asphalt, concrete, brick, stone—and rooftops. Soils compacted by urban development are also highly impervious.
The United States Environmental Protection Agency (EPA) Storm Water Management Model (SWMM) is a dynamic rainfall–runoff–subsurface runoff simulation model used for single-event to long-term (continuous) simulation of the surface/subsurface hydrology quantity and quality from primarily urban/suburban areas.
Rain gardens, also called bioretention facilities, are one of a variety of practices designed to increase rain runoff reabsorption by the soil. They can also be used to treat polluted stormwater runoff. Rain gardens are designed landscape sites that reduce the flow rate, total quantity, and pollutant load of runoff from impervious urban areas like roofs, driveways, walkways, parking lots, and compacted lawn areas. Rain gardens rely on plants and natural or engineered soil medium to retain stormwater and increase the lag time of infiltration, while remediating and filtering pollutants carried by urban runoff. Rain gardens provide a method to reuse and optimize any rain that falls, reducing or avoiding the need for additional irrigation. A benefit of planting rain gardens is the consequential decrease in ambient air and water temperature, a mitigation that is especially effective in urban areas containing an abundance of impervious surfaces that absorb heat in a phenomenon known as the heat-island effect.
Sustainable drainage systems are a collection of water management practices that aim to align modern drainage systems with natural water processes and are part of a larger green infrastructure strategy. SuDS efforts make urban drainage systems more compatible with components of the natural water cycle such as storm surge overflows, soil percolation, and bio-filtration. These efforts hope to mitigate the effect human development has had or may have on the natural water cycle, particularly surface runoff and water pollution trends.
Pervious concrete is a special type of concrete with a high porosity used for concrete flatwork applications that allows water from precipitation and other sources to pass directly through, thereby reducing the runoff from a site and allowing groundwater recharge.
Green infrastructure or blue-green infrastructure refers to a network that provides the “ingredients” for solving urban and climatic challenges by building with nature. The main components of this approach include stormwater management, climate adaptation, the reduction of heat stress, increasing biodiversity, food production, better air quality, sustainable energy production, clean water, and healthy soils, as well as more anthropocentric functions, such as increased quality of life through recreation and the provision of shade and shelter in and around towns and cities. Green infrastructure also serves to provide an ecological framework for social, economic, and environmental health of the surroundings. More recently scholars and activists have also called for green infrastructure that promotes social inclusion and equity rather than reinforcing pre-existing structures of unequal access to nature-based services.
Xeriscaping is the process of landscaping, or gardening, that reduces or eliminates the need for irrigation. It is promoted in regions that do not have accessible, plentiful, or reliable supplies of fresh water and has gained acceptance in other regions as access to irrigation water has become limited, though it is not limited to such climates. Xeriscaping may be an alternative to various types of traditional gardening.
Sustainable landscaping is a modern type of gardening or landscaping that takes the environmental issue of sustainability into account. According to Loehrlein in 2009 this includes design, construction and management of residential and commercial gardens and incorporates organic lawn management and organic gardening techniques.
Desert greening is the process of afforestation or revegetation of deserts for ecological restoration (biodiversity), sustainable farming and forestry, but also for reclamation of natural water systems and other ecological systems that support life. The term "desert greening" is intended to apply to both cold and hot arid and semi-arid deserts. It does not apply to ice capped or permafrost regions. It pertains to roughly 32 million square kilometres of land. Deserts span all seven continents of the Earth and make up nearly a fifth of the Earth's landmass, areas that recently have been increasing in size.
An Eco-house (or Eco-home) is an environmentally low-impact home designed and built using materials and technology that reduces its carbon footprint and lowers its energy needs. Eco-homes are measured in multiple ways meeting sustainability needs such as water conservation, reducing wastes through reusing and recycling materials, controlling pollution to limit global warming, energy generation and conservation, and decreasing CO2 emissions.
A subtropical climate vegetated roof is a type of green building practice that employs a planted soil media installed above a waterproof roof deck to obtain environmental benefits and address sustainability concerns, similar to traditional green roofs located in northern continental United States. Soil media, plant palettes, and green roof systems that can adapt to the adverse weather conditions and physical characteristics of the humid, subtropical regions of the United States are utilized in the construction and design of subtropical climate vegetated roofs.
The Gies College of Business Instructional Facility (BIF) is a state-of-the-art business facility designed by Pelli Clarke Pelli Architects located on the Champaign campus at the University of Illinois Urbana–Champaign (UIUC).
Water-sensitive urban design (WSUD) is a land planning and engineering design approach which integrates the urban water cycle, including stormwater, groundwater, and wastewater management and water supply, into urban design to minimise environmental degradation and improve aesthetic and recreational appeal. WSUD is a term used in the Middle East and Australia and is similar to low-impact development (LID), a term used in the United States; and Sustainable Drainage System (SuDS), a term used in the United Kingdom.
Low-impact development (LID) is a term used in Canada and the United States to describe a land planning and engineering design approach to manage stormwater runoff as part of green infrastructure. LID emphasizes conservation and use of on-site natural features to protect water quality. This approach implements engineered small-scale hydrologic controls to replicate the pre-development hydrologic regime of watersheds through infiltrating, filtering, storing, evaporating, and detaining runoff close to its source. Green infrastructure investments are one approach that often yields multiple benefits and builds city resilience.
Indira Paryavaran Bhawan is India's first on-site net-zero building located in New Delhi, India. The building houses the Ministry of Environment, Forest and Climate Change (MoEFCC) accommodating three ministers and their offices along with about 600 officials. The building, designed and constructed by the Central Public Works Department (CPWD), was completed in 2013 at a cost of INR 209 Crore.
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