It focuses on green site-planning strategies and practices that specifically relate to assessing and selecting a site for uses such as office buildings and parks, institutional and research structures, retail businesses and industrial facilities. The purpose of sustainable site planning is to integrate design and construction strategies by modifying both site and building to achieve greater human comfort and operational efficiencies. Sound site planning is prescriptive and strategic. It charts appropriate patterns of use for a site while incorporating construction methods that minimize site disruption and the expenditure of financial and building resources.
Site planning assesses a particular landscape to determine its appropriate use and then maps the area’s most suitable for accommodating specific activities associated with that use. The process is based upon the premise that any landscape setting can be analyzed and studied as a series of interconnected geological, hydrological, topographic, ecological, climatological and cultural features and systems. An ideal site plan is one in which the arrangement of roads, buildings and associated uses is developed using site data and information from the larger macro-environment, including existing historical and cultural patterns of the community.
Selecting a building site begins the process of calculating the degree of resource use and the degree of disturbance of existing natural systems that will be required to support a building’s development. The most environmentally sound development is one that disturbs as little of the existing site as possible. Therefore, sites suitable for commercial building should ideally be located within or adjacent to existing commercial environments. Building projects also require connections to mass transit, vehicular infrastructure, utility and telecommunication networks. Sound site planning and building design should consider locating building-support services in common corridors or siting a building to take advantage of existing service networks. This consolidation can minimize site disruption and facilitate building repair and inspection. The use, scale and structural systems of a building affect its particular site requirements and associated environmental impacts. Building characteristics, orientation and placement should be considered in relation to the site so that proper drainage systems, circulation patterns, landscape design and other site-development features can be determined.
Site Analysis and Assessment
The purpose of a site analysis is to break down the site into basic parts, to isolate areas and systems requiring protection and to identify both off-site and on-site factors that may require mitigation. Site assessment is a process that examines the data gathered and identified in the site analysis, assigns specific site factors to hierarchies of importance and identifies interactive relationships. For example, an analysis may identify specific soils and their properties, vegetation types and their distribution or various slope and slope-orientation conditions to name a few site factors. An assessment applies evaluation criteria that allow the comparison of various sites’ suitability for a specific use.
Sustainable design practices assess both site and building program to determine the site’s capacity to support the program without degrading vital systems, or requiring extraordinary development expenditures. The result of analysis and assessment is a blueprint for the most appropriate ecological and physical fit between site, building and the resulting cultural landscape.
1) Data Collection
- Perform a site analysis to determine site characteristics that influence building design. The following site characteristics influence building design elements, including form, shape, bulk, materials, skin-to-volume ratio, structural systems, mechanical systems, access and service, solar orientation and finished floor elevation.
- Geographical latitude (solar altitude) and microclimate factors, such as wind loads — Affect building layout, including solar orientation and location of entrances, windows and loading docks.
- Topography and adjacent land forms — Influence building proportions, wind loads, drainage strategies, floor elevations and key gravity-fed sewer-line corridors.
- Groundwater and surface runoff characteristics — Determine building locations as well as natural channels for diverting storm runoff and locations of runoff detention ponds.
- Solar access — Determines position of building to take maximum advantage of natural solar resources for passive solar heating, daylighting and photovoltaics.
- Air remove patterns, both annual and diurnal — Particularly influence siting of multiple structures to avoid damming cold moisture air or blocking favorable cooling breezes during periods of overheating.
- Properly measured wind loads and pressure differentials are essential for designing interior air-handling systems or use of passive solar cooling strategies.
- Soil texture and its load-bearing capacity — Determine building location on the site and the type of footing required.
- Identify site-grading processes by the soil’s potential for erosion by wind, water and machine disturbance.
- Parcel shape and access — Affect a site’s capacity to accommodate a proposed development, even if its size and environmental factors are favorable. Potential access points should not burden lower-density or less compatible adjacent land use. Zoning setbacks and easements can also affect development potential.
- Neighboring developments and proposed future developments — Affect proposed project and may lead to requisite design changes.
2) Analyze Specific Characteristics of Climate Zones
Climate zones (hot-humid, hot-arid, temperate and cold) have specific characteristics requiring mitigation, augmentation and exploitation. Each climate zone suggests historically amenable siting and building practices.
3) Analyze the Site’s Existing Air Quality
Most state and federal projects require an Environmental Impact Statement (EIS) outlining the potential negative impacts of a proposed development and how they might be alleviated. Site planning requires two kinds of air-quality analysis regarding: (1) assessment of the existing air quality of the site to determine the presence of noxious chemicals and suspended particulates, and (2) projection of the negative consequences (if any) of the proposed development on existing air quality. In primarily commercial or industrial areas, poor air quality should be a key factor in determining site suitability and use, especially for such facilities as schools, parks or housing for seniors. Testing should anticipate seasonal or diurnal wind patterns to make certain that the worst possible case is tested. Certified labs should perform testing to determine both chemical and particulate pollution.
4) Perform Soil and Groundwater Testing
Perform soil tests to identify the presence of chemical residues from past agricultural activities (arsenic, pesticides and lead); past industrial activities (dumps, heavy metals, carcinogenic compounds and minerals and hydrocarbons) and any other possible contamination both on and in the vicinity of the subject site. Also, the possibility of water contamination, in areas where the native rock and substrata deserves specific attention. These tests are crucial to determine both site feasibility and/or the construction methods required to either mitigate or remove contaminants.
5) Test Soil Suitability for Backfills, Slope Structures, Infiltration
The native soil should be tested to determine bearing, compactability and infiltration rates and in turn, structural suitability and the best method for mechanical compaction (i.e., clay soils require non-vibrating compaction and non-erosive angles of repose for cut-and-fill slopes).
6) Evaluate Site Ecosystem for Existence of Wetlands and Endangered Species
In addition to wetland regulations governing vegetative-cover removal, grading, drainage alterations, building siting and storm water runoff mitigation, there are endangered species regulations designed to preserve specific plant and animal species. Preservation and restoration strategies require thorough economic analysis, specialized expertise and sound baseline data gathered through both remote and on-site sensing methods.
7) Examine Existing Vegetation to Inventory Significant Plant Populations
This will enable the developer or owner to later specify vegetation that is susceptible to damage during construction, so that protective measures can be developed and implemented.
8) Map All Natural Hazard Potentials (Such as Winds, Floods and Mudslides)
Historic flood data, wind-damage data and subsidence data should be mapped along with current annual wind and precipitation data. It is important to indicate if the proposed development is within a statistically significant probability of sustaining impacts within the near future. Often, evidence of past occurrences is not visible. Subsurface investigation may yield data on surface rock strata or uncharted previous excavations. Such evidence may require that a different site be selected or an architectural modification be made.
9) Diagram Existing Pedestrian and Vehicular Movement and Parking to Identify Patterns
Existing traffic and parking patterns in areas which are adjacent to or near the site may need consideration in relation to proposed building design and site circulation patterns.
10) Review the Potential of Utilizing Existing Local Transportation Resources
Explore the sharing of existing transportation facilities and other resources, such as parking and shuttles, with existing institutions. This can lead to greater site efficiencies.
11) Identify Construction Restraints and Requirements
Special construction methods may be required because of local soil condition, geology, earth-moving constraints and other site-specific factors and constraints.
Cultural and Historical Data
1) Review Site’s Cultural Resources for Possible Restoration
Historical sites and features can be incorporated as part of the project site, thereby increasing ties with the community and preserving the area’s cultural heritage.
2) Review Architectural Style of the Area for Incorporation into Building
If desirable, the architectural style that is historically predominant in an area can be reflected in the building and landscape design, enhancing community integration.
3) Explore Use of Historically Compatible Building Types
There may be building types that are historically matched to the region. Consider integrating such types into building development.
Data Assessment
1) Identify Topographic and Hydrological Impacts of Proposed Design and Building Use
Measure cut-and-fill potential and assess potential for erosion, siltation, and groundwater pollution.
2) Develop General Area Takeoff and Overall Building Footprint Compatibility with Site
For example, measure total site coverage of impermeable surfaces to determine thresholds of run-off pollution potential (i.e., over 20 percent impermeable coverage of gross site requires mitigation to clean storm water before it enters drainage system off-site). Footprint should also maximize site efficiencies with regard to required road, utility and service access.
3) Identify Alternative Site Design Concepts to Minimize Resource Costs and Disruption
Develop several alternatives to explore optimal pattern with regard to factors such as grading and tree-clearing consequences and resulting infrastructure costs.
4) Review Financial Implications of Site Development, Building and Projected Maintenance Costs
Total cost of the project must factor in ongoing costs associated with the site design, development, and operations, as well as hidden embodied energy costs associated with specific materials.
5) Develop Matrix of Use and Site Compatibility Index
Each site may be assessed to reveal its development compatibility index with regard to a specific type of development. This index may reveal a pattern of incompatibilities, suggesting that either a different site be chosen or specific appropriate mitigation measures be undertaken.
Site Development and Layout
After the site has been selected on the basis of a thorough analysis and assessment, ideal diagrammatic concepts are laid out on the topographic survey with the objective of organizing all proposed built elements to achieve an efficient and effective site and development fit. The main goal of the concepts should be to minimize resource consumption during construction and after human occupation. It should be noted that during reclamation of disturbed sites, initial expenditures may be higher than normal and should be balanced by ongoing landscape management strategies. The following practices serve to guide the initial concept diagramming process.
Infrastructure
Utility Corridors
1) Design the site plan to minimize road length, building footprint, and the actual ground area required for intended improvements. Such planning decreases the length of utility connections. Consult local codes regarding separation requirements for water, sewer, electrical and gas lines.
2) Use Gravity Sewer Systems Wherever Possible
Avoid pumped sewer systems because of ongoing power consumption.
3) Reuse Chemical-Waste Tanks and Lines
Existing chemical-waste tanks and lines should be inspected, protected and reused to avoid creation of additional hazardous-materials problems.
4) Aggregate Utility Corridors When Feasible
Where possible, common site utility corridors should be consolidated along previously disturbed areas or along new road or walk construction, both to minimize unnecessary clearing and trenching and to ensure ease of access for ongoing repairs.
Transportation
1) Support Reduction of Vehicle Miles Traveled (VMT) to the Site
Where applicable, existing mass-transit infrastructure and shuttle buses should be supported, or a new line developed. Carpooling strategies should be encouraged in addition to mass-transit use. To foster the use of bicycles, showers and lockers should be considered. All of these transportation methods reduce parking and transportation costs for employees.
2) Use Existing Vehicular Transportation Networks to Minimize the Need for New Infrastructure
This practice can increase site efficiencies associated with reduced ground coverage, parking requirements, and related costs.
3) Consider Increased Use of Telecommuting Strategies
Telecommuting and teleconferencing can reduce commute time and VMT to and from worksites.
4) Consolidate Service, Pedestrian and Automobile Paths
To minimize pavement costs, improve efficiency, and centralize runoff, the pattern of roads, walkways, and parking should be compact. This not only is a less expensive way to build, it also helps to reduce the ratio of impermeable surfaces to the gross site area.
Building and Site Requirements
Land Features
1) Develop Previously Disturbed Sites Such as Unused Urban Lots and Commercial Sites
These sites may already be affecting the environmental quality of neighboring properties, the watersheds, and other features, therefore redevelopment requires minimal disturbance of natural systems. Furthermore, redevelopment is likely to improve the immediate community, potentially create jobs, and increase land values that have been affected by the abandoned or blighted property.
2) Avoid Stream Channels, Flood Plains, Wetlands, Steep Erodible Slopes, and Mature Vegetation
To avoid high site-preparation costs, and to preserve important visual and ecological features, development activity should be configured to occupy “interstitial site space,” or those spaces between critical resources.
Building and Site Orientation
1) Plan Site Clearing and Planting to Take Advantage of Solar and Topographic Conditions
Solar orientation, sky conditions (cloudy versus clear), and topography are interrelated. A site’s latitude determines the sun’s altitude and associated azimuth for any given time of day, each day of the year. Site-clearing and planting strategies, which partially determine solar access, are influenced by those requirements.
2) Orient Building to Take Advantage of Solar Energy for Passive and Active Solar Systems
The building should be oriented to take advantage of shade and airflows for cooling in summer, and of passive solar energy for heating and wind protection in winter. If solar collectors or photovoltaic systems are proposed, orientation should allow maximum access to sunlight.
3) Minimize Solar Shadows
Landscaped areas, open spaces, parking, and septic fields should be aggregated to provide the least solar shadow for southern orientations of the building project and adjoining buildings. Calculating total site shadow can prevent the creation solar voids and cold-air-drainage dams. This is especially helpful in cold and temperate climates.
4) Minimize earthwork and clearing by aligning long buildings and parking lots with landscape contours; take up excess slope with half-basements and staggered floor levels.
5) Provide a North-Wall Design that Minimizes Heat Loss
Provide entrances with airlocks and limit glass to prevent heat loss in human-occupied areas. Large buildings in cold or temperate climates require air-handling system compensation for balancing interior building pressure in such circumstances.
6) Provide a Building-Entrance Orientation That Maximizes Safety and Ease of Access
The building should be positioned on the site so that its entrance provides maximum safety and ease of access, as well as protection from the elements.
Landscaping and Use of Natural Resources
1) Harness solar energy, airflow patterns, natural water sources, and the insulating quality of land forms for building temperature control. Existing water sources and landforms can be used to create winter heat sinks in cold climates, and temperature differentials for cooling air movement in hot climates. Existing streams or other water sources can contribute to radiant cooling for the site. Colour and surface orientation may be used to favorably absorb or reflect solar energy.
2) Use existing vegetation to moderate weather conditions and provide protection for native wildlife. Vegetation can be used to provide shade and transpiration in the summer and wind protection in the winter. Additionally, vegetation can provide a natural connection for wildlife corridors.
3) Design access roads, landscaping, and ancillary structures to channel wind toward main buildings for cooling, or away from them to reduce heat loss.
Public Amenities
1) Modify microclimates to maximize human comfort in the use of outdoor public amenities such as plazas, sitting areas, and rest areas.. In planning outdoor public amenities, the designer needs to consider seasonal weather patterns and climate variables such as vapor pressure in hot-humid zones, desiccating winds and diurnal extremes in hot-arid zones, and annual temperature extremes in temperate and cold zones.
Introduce structures and plantings that provide shelter from harsh elements and highlight desirable features. Modulation of tree-canopy heights and inclusion of water fountains and other built structures can fine-tune an exterior site by accelerating or decelerating site winds, casting shadows, or cooling by evapotranspiration or evaporative cooling.
2) Consider sustainable site materials for public amenities. Materials should be recycled, if possible, and have a low life-cycle cost. Albido (solar reflectance index attributed to color) should also be considered when choosing site materials.
Construction Methods
1) Specify Sustainable Site Construction Methods
The construction methods employed should ensure that each step of the building process is focused on eliminating unnecessary site disruption (e.g., excessive grading, blasting, clearing) and resource degradation (e.g., stream siltation, groundwater contamination, air-quality loss). The strategies can harness features such as ventilating breezes, solar gain, and microclimates, and can mitigate unfavorable features such as cold, moist air drainage; desiccating winds; and increased stormwater runoff.
2) Develop Sequential Staging to Minimize Site Disruption
The building process should be strategically charted in stages to avoid unnecessary site disruption, and to achieve an orderly construction sequence from site clearing to site finish. Such a strategy reduces costs and damage to the site. It requires close coordination between all sub-contractors.
