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Site Design and Planning

Both site selection and site planning have a major impact on the relative "greenness" of any facility being planned. Site selection includes such issues as transportation and travel distances for building occupants, impacts on wildlife corridors, and impacts on the hydrology (storm water flows, wetlands, etc.). Decisions made during site planning will impact the immediate natural community as well as the building energy consumption and occupant comfort. Good site planning minimizes site-clearing (saving money), and preservation of existing vegetation may provide a low-maintenance landscape that avoids supplemental irrigation and fertilizer. Mature stands of native vegetation often provide the desired energy-conserving shade and wind control that would otherwise require years to develop from expensive new plantings. Thoughtful placement of a building on a site promotes energy conservation by taking advantage of natural site features such as topography, sunlight, shade, and breezes.

This section addresses the following siting topics:

• Rehabilitation or in-fill versus an undeveloped site
• Site planning
• Design to minimize impacts to site
• Parking and pavement
• Exterior water management
• Water efficiency

Rehabilitation or In-Fill vs. Undeveloped Site

In the big picture of sustainable land use, it is better to renovate or build-out an existing building than to construct a new building. Interiors projects located within existing buildings are truly an environmental choice in that they are not disturbing the natural environment or creating new infrastructure. Existing transportation systems can be used. Adding parking spaces and altering the site are usually unnecessary. There is, however, a lack of ability to control mechanical systems and building envelope. The focus shifts to the parts of an interiors project that can be controlled: the plan layout effectiveness, material selections, lighting efficiency, furniture, views to the outside, and availability of natural light. If renovating an existing building, the funds saved from construction can be put toward energy-efficient features. If demolition of a previous build-out is necessary, establish a construction waste management program to recycle or reuse demolition material. For example, gypsum board, metal framing, ceiling grid, wood, carpet, light fixtures, and doors can be salvaged or recycled.

It is also better to build on previously developed sites while improving or restoring natural site features, than to develop undisturbed land. Consider whether redevelopment of an existing site is feasible. When planning site design for a previously disturbed site, consider allocating the funds saved from infrastructure development to enhanced landscape restoration.

If the chosen site has a building that will be demolished, consider deconstruction and reuse of building materials instead of demolition and sending materials to the landfill. Deconstruction is an innovative tool intended to contribute to a community's revitalization. Deconstruction is actually a new term to describe an old process—the selective dismantling or removal of materials from buildings before or instead of demolition. What is innovative and exciting is how communities can potentially use this process—deconstruction-to support and complement other community objectives. Deconstruction has the potential to (1) create job training and job opportunities for unskilled and unemployed workers, (2) foster the creation and expansion of small businesses to handle the salvaged material from deconstruction projects, and (3) benefit the environment by diverting valuable resources from crowded landfills into profitable uses, which in turn would enable deconstruction to pay for itself by generating revenues and reducing landfill and disposal costs.

Site Planning

Sustainable design practices assess both the site and the building requirements to determine the site's capacity to support the building without degrading vital systems or requiring extraordinary development expenditures.

The most effective opportunities for creating greener facilities arise throughout the site selection and site planning stages of design. Address site planning and building siting as part of the overall building design.

Carefully planned building placement should:

• Minimize storm water runoff
• Minimize habitat disturbance
• Protect open space
• Reduce the risk of erosion
• Save energy by providing for passive solar, natural ventilation, and daylighting

Opportunities to maximize sustainability should be acted on as early as possible in the site selection and site planning process to ensure that site issues and features are integrated into the design process. Some opportunities continue through design and, to a more limited extent, through construction and landscaping.

The natural and existing characteristics of a site influence site and building design elements including shape, massing, materials, surface-to-volume ratio, structural systems, mechanical systems, access and service, solar orientation, and provisions for security and fire safety.

Inventory the existing boundaries and features of the site. Once the site inventory is complete, further analysis will contribute to the most appropriate ecological and physical fit between the building and the site constraints.

Design to Minimize Impacts to Site

After completing the site inventory and analysis, look at the overall building footprint's compatibility with the site. Identify alternative site design concepts to minimize resource costs and site disruption. As the schematic design is developed, follow these guidelines:

Natural Site Features

• Preserve natural drainage systems. Site buildings, roadways, and parking so that water flowing off the developed site during extreme storm events will not cause environmental damage. Also, consider how drainage systems will be affected during construction, and avoid sites where impacts will be excessive.
• Locate driveways, parking, entrances, and loading docks on the building's south side. Desirable locations of driveways and parking in snowy climates are generally on south-facing slopes or the south sides of buildings to help avoid snow and ice build-up. Balance these needs with other priorities for infrastructure and landscape.
• Orient the building with the long side in line with the east-west axis. This orientation allows for the highest winter solar gains and lowest summer solar gains. Mitigate excessive summer solar heat and minimize the cooling load through optimum orientation of the building. Orienting a building to true south, as opposed to 45 degrees off true south, makes it easier to manage solar gains.
• Minimize ground-level wind loads. Localized build-up of snow, especially at doors and loading docks requires much effort and energy for snow removal. Control wind at the ground level through use of vegetation, walls and fences acting as windbreaks. An area exposed to wind can also be minimized through berming and earth sheltering.

Vegetation

• Minimize native vegetation disruption. Locate and size facilities to avoid cutting mature vegetation and to minimize disruption to, or disassociation with, other natural features. Balance this strategy with the fire risk reduction guidelines.
• Minimize visual impacts. Use natural vegetation and adjust the building plan to diminish the visual impact of facilities and to minimize imposition on environmental context.

Hydrology

• Minimize erosion. Locate and design facilities to minimize erosion and impacts on natural hydrological systems.
• Avoid hydrological system contamination. Safeguard the hydrological system from contamination by construction activities and building operation.
• Allow precipitation to naturally recharge groundwater.

Geology/Soils

• Minimize excavation and disturbance to groundcover.
• Minimize erosion. Avoid large impervious surface areas and building footprints that collect rain and create concentrated runoff onto site.

Heat Island Effect

• Use trees for shade, use less pavement, reduce or avoid air conditioning use and use reflective coatings on pavement and roofs to help reduce a building's contribution to the heat island effect. On warm summer days, the air in urban areas can be 6 to 8 degrees F hotter than surrounding areas. Scientists call these cities "urban heat islands." They contribute to smog and higher energy use.

Parking and Pavement

Parking can be the single biggest use of land area at a facility. Anything that can reduce the area devoted to parking results in:

• Less polluted surface runoff (stormwater)
• Greater groundwater recharge
• More green area for employee enjoyment
• Improved air quality from more oxygen-producing plants

Strive to increase the habitat for nature and decrease the habitat for cars. However, to successfully reduce the demand for parking spaces, alternative transportation options and incentives must be available to the building occupants. Another issue is visual glare that often accompanies parking areas adjacent to buildings. Abate this glare by screening or shading the parking lot with vegetation. If significant parking areas must be included on the building site, then design bioretention areas into the parking lot landscaping as part of the exterior water management strategy and to provide shading.

Exterior Water Management

Sustainable site development can help solve regional watershed problems at the source. Good site design and water management practices address water issues by:

• Increasing the permeability of constructed pavements
• Capturing and treating excess runoff by means of natural soil and biological processes
• Minimizing or eliminating potable water usage in the landscape
• Maintaining or restoring the infiltrating, cleansing, and storing functions of soils, plants, and groundwater with natural landscape systems

Stormwater is precipitation that does not soak into the ground or evaporate but flows along the surface of the ground as runoff. Conventional practice for stormwater management—concentrating runoff and carrying it off a site as quickly as possible through storm sewers—causes various environmental problems, including erosion and downstream flooding, pollution loading of surface waters, and reduced groundwater recharge.

There are two basic principles to stormwater management:

(1) Drainage and flood control is based on managing the quantity of stormwater runoff potentially generated during a design-basis storm event (a storm event likely to occur only once in a specified time period). The major contributors to stormwater runoff are impervious surfaces such as rooftops and parking lots.

(2) Water quality control is based on managing the on-site sources of pollutants in stormwater and, if needed, treating these pollutants. Pollutants entering stormwater are primarily caused by erosion of soil (creating sediment pollution) or contacting surfaces that have accumulated pollutants since the last storm event. Rooftop surfaces typically accumulate pollutants that are deposited from the atmosphere or blown on during adverse weather, while parking lot surfaces collect a variety of pollutants leaked from vehicles.

The primary goal of sustainable stormwater management is to generate no additional runoff from the existing site as compared to undeveloped conditions. The intent of this design goal is to utilize an integrated approach that minimizes the generation of stormwater runoff and promotes infiltration of the generated stormwater into the subsurface. This approach limits runoff (and potential pollutants) from leaving the site. An integrated design approach involves configuring the location and placement of impervious surfaces, specifying land-based structural practices (stormwater storage and treatment) for stormwater pollution control, and integrating native landscaping into the overall site development.

Stormwater Management Strategies

Investigate the feasibility of applying stormwater management strategies to treat and retain stormwater on the site. Each of these strategies requires specific maintenance practices for proper operation.

Bioretention Areas

• Parking lot island landscaping features adapted to treat stormwater runoff.
• Surface runoff is directed into shallow, landscaped depressions with pollutant removal layers.
• Typically, the filtered runoff is collected in a perforated underdrain and returned to the storm drain system, but the system can be enhanced for partial exfiltration.
• The system should be sized between 5 and 10 percent of the impervious draining area.
• These areas can be designed to hold plowed snow.

Dry Extended Detention Pond

• Vegetated, open channel management practice.
• May be an option as a snow storage facility to promote treatment of plowed snow.
• Swale with engineered soil matrix and underdrains to promote filtration.
• Recommended for sites with a minimum drainage of 10 acres.
• Least expensive stormwater treatment practice, on a cost per unit area treated.
• Best long-term performance track record (least clogging problems).

Infiltration Trench (narrow and deep)

• Generally applied to sites less than five acres with relatively high impervious cover.
• Soil infiltration rate ranges between 0.5 and 3 inches per hour.
• Best applied to drainage areas less than 10 acres.
• Soil infiltration rate should range between 0.5 and 3 inches per hour.
• Can be optimized for seasonal operation and to accommodate snow melt.

Note: Design all stormwater detention areas to be "dry" for most of the year. Stormwater retention areas should not be designed to be wet year round, as that may encourage development of wetlands or breeding areas.

Water Efficiency

Water efficiency is the planned management of potable water to prevent waste, overuse, and exploitation of the resource. Effective water-efficiency planning seeks to "do more with less," without sacrificing environmental performance. There are two basic approaches to potable water efficiency in the landscape:

Water Efficiency in the Landscape

• Reduce water use associated with irrigation and landscaping.
• Recycle or use water with gray water or process recycling systems.

Reduce water use associated with irrigation and landscaping. This can be accomplished to varying degrees by one or a combination of the following:

• Preserve, encourage or reintroduce native or drought-tolerant vegetation that is already optimized for naturally occurring precipitation levels.
• If plants are desired that need water, group them by similar watering and soil type needs.
• Irrigate efficiently (see irrigation tips).

Recycle or use water with graywater or process recycling systems. Reclaimed wastewater, sometimes called irrigation quality or IQ water, is another possible source for irrigation water. Reclaimed water is from a wastewater treatment plant that has been treated and can be used for nonpotable uses such as landscape irrigation, cooling tower, industrial process uses, toilet flushing, and fire protection. It must be scrupulously isolated from potable water distribution, and all IQ hose bibs must be clearly marked as "nonpotable."

Graywater is untreated wastewater generated within the facility from shower and bath, laundry, and bathroom sinks (not from toilets, urinals, kitchen sinks, or dishwashers). Graywater can be used for below-ground irrigation, but it is not recommended for above-ground irrigation.

Efficient Irrigation Tips

• Use ultra-low-volume distribution devices.
• Irrigate after on-site inspection or electronic sensing of moisture requirements, rather than just by a timeclock.
• Water requirements vary greatly by season, and as the landscape matures, less irrigation is required.
• Automatic irrigation controllers should have rain switches that override the "on" signal hen sufficient rain has fallen or soils are moist.
• Use rainwater harvested from building roofs for irrigation.