PPP Notes - Environmental Factors

(These notes are compiled from Spreiregen's Exam Review)

CHAPTER EIGHT - ENVIRONMENTAL FACTORS

CLIMATE

THE INFLUENCE OF CLIMATE

Climate is one of the most important influences on site development.  Climate analysis and its impact on site development can be examined at two levels: macroclimate and microclimate.  Macroclimate is the general climate of a region and is defined by National Weather Service statistics, such as maximum and minimum temperatures, wind velocity and direction, precipitation, cloudiness, hours and days of sunshine, etc.  Microclimate is the local modification of the macroclimate by the features peculiar to a site:  type of vegetation, elevation, slope, the presence or absence of water, wind velocity and direction, and manmade structures.  While there is a general awareness of the effects of macroclimate, commonly referred to as "the weather," there is generally far less appreciation of microclimate and its effects on a particular site or building.

In site planning and design, information on both macro- and microclimate, for all seasons, should be obtained and analyzed.  This information helps determine the orientation of buildings, their protection from (or exposure to) sun and wind, fenestration, building materials, heating and cooling systems, and the location and selection of plant materials.  Aesthetics and appearance are also influenced, to a considerable degree, by the characteristics and quality of natural light and its daily and seasonal variations.  Natural light establishes the conditions under which a building's mass, profile, colors, details, and materials are seen.  For example, "warm" colors are best seen in bright sunlight, and "cool" colors in overcast light, or northern light, which contains more blue.  However, we are primarily concerned with the practical considerations of climate and its influence on design.

MACROCLIMATE

The macroclimate of an area depends primarily on its latitude, elevation, and proximity to bodies of water.  All weather phenomena - indeed all life -  depend on the sun.  Thus, a primary determinant of the climate in a particular location is the amount of solar energy that it receives.  That, in turn, depends on latitude, the distance from the equator.  In the United States (excluding Alaska and Hawaii) the latitude varies from about 49 degrees north at the northern tip of Minnesota to about 25 degrees north in southern Florida.

Of course, there are several other factors which influence climate.  As the elevation increases temperature decreases, about 1 degree Fahrenheit for each 300 ft.  This is because the thinner air of the higher altitudes is not able to hold as much heat as the denser air of lower altitudes.  Even near the equator, the climate at high altitudes may be very cold.  

The proximity of bodies of water, rivers, bays, or lakes - also affect climate; water is much slower to rise or fall in temperature than land, and does not reach the extreme high or low temperatures that are recorded on land.  Consequently, the effect of bodies of water on nearby land areas is to reduce temperature extremes, both daily and seasonal.

This moderating influence increases as the size of the body of water increases.  Thus, islands and coastal areas usually have a more constant and moderate climate than do inland areas at the same latitude.  Compare the pleasant climate of Hawaii to that of central Africa, which is at about the same latitude; or the Pacific Northwest, with its mild winters and pleasantly warm summers, to Minnesota or North Dakota, where the extremes of temperature are far greater.

Even at a small geographical scale, a house located alongside a river or lake is apt to be more comfortable than one located far from water.

Prevailing winds also influence climate.  The prevailing southerly winds (winds from the south) of the southeastern part of the country carry moisture and warm air from the Gulf of Mexico into the plains states, altering their climates considerably, particularly in the summer, when these areas are quite humid.  Similarly, during the winter, cold Arctic air from the north makes the same central plains states quite cold.  Such air is cold, dry and clear.

Climate is also influenced by ocean currents.  Areas warmed by the Gulf Stream (London, England) enjoy a warmer climate than those cooled by the Labrador Current (St. Johns, Newfoundland).

Mountain barriers influence climate by forcing prevailing winds to rise.  The air cools as it rises, clouds form, and rain falls.  This phenomenon has several interesting and important variations, depending on a number of factors, such as the strength and regularity of the winds, altitude, sunlight, soil and vegetation combinations, etc.  For example, the western (windward) slopes of the Sierra Nevada and Coast Ranges are relatively humid, and the areas leeward of the mountains are hot, these being the dry regions of Nevada and Arizona.  A somewhat different pattern is found in the Hawaiian Islands.  The steady and uniformly flowing ocean breezes from the southwest, colliding with the mountain barriers of the islands, are forced to rise suddenly.  The humid air, suddenly forced upwards and cooled, condenses into clouds and then rain.  In this case, however, the rain generally occurs on the leeward side of the mountains.

The range of daily and seasonal temperatures is also dependent on whether the sky is clear or cloudy.  Clouds act as a blanket; less solar radiation is received during the day and less is lost at night than on clear days.  As a result, there is a narrow temperature range on cloudy days.  Similarly, clear winter nights are colder than cloudy winter nights and clear summer days are warmer than cloudy summer days.

Arid regions, with generally low humidity levels, experience great variation in temperature range, since humid air retains more heat energy than does dry air.  Thus, desert areas and high mountainous areas, which also have dry air, experience great extremes of daytime and nighttime temperatures.

MICROCLIMATE

In analyzing a site, the designer should obtain data on the macroclimate of the area.  This is available from the National Oceanic and Atmospheric Administration (NOAA).  The data is available in many forms, from simple climatological summaries to detailed computerized information programs.  Familiarity with an area comprises a useful source of information as well.  To learn about the microclimate, a site designer should "walk the site," studying the indigenous plant material, as well as those features that are inherent to the particular site - elevation, land forms, slope orientation, bodies of water, and structures.  One of the best ways to survey a site is "through the soles of one's feet."  But it is not an exclusive way.  A designer may learn much about an area by studying the climate-influenced details of indigenous architecture, such as roof slopes and overhangs, window orientation, planting, etc.  For example, the old farm houses located in the eastern United States are characteristically sited atop hills, surrounded by trees.  This simultaneously provides for positive drainage away from the house, exposes the house to summer breezes from all directions, and shades it from the hot summer sun.  In winter, when the trees are bare of leaves, the southern sun warms the house through its south-facing windows.

The amount of solar radiation received on a site is a function of the angle between the ground surface and the direction of the sun's rays.  The closer the rays are to being perpendicular to the surface, the greater the amount of solar radiation received.  This is the reason for seasonal variations.  The angle between the sun and the horizon, referred to as the altitude, is greater in the summer than in the winter.  This also explains why the more southerly latitudes are warmer than those more northerly; the sun's angle with the horizon is higher in the south.  

Added to this is the obvious factor of duration of exposure.  In the northern hemisphere, the hours of sunlight are greater in the summer than in the winter.  The day that has the maximum hours of sunlight exposure is referred to as the winter solstice; this occurs on December 21 or 22.  Midway between these two extremes is a day when the hours of sunlight equal the hours of darkness.  This is referred to as the equinox and occurs about March 21 (vernal equinox) and September 21 (autumnal equinox).

The slope of a site also affects the amount of solar energy that it receives.  Since the sun's path is inclined southerly in the northern hemisphere, the angle between the ground surface and the direction of the sun's rays is greater if the ground slopes to the south than if it is level.  Hence, south-sloping sites receive more solar radiation that level or north-sloping sites.

At the same latitude, the sprouting of plants in spring occurs earlier and more rapidly on south-facing slopes than on level or north-facing slopes.  Indeed, the advantage of a south-facing slope for agriculture is great enough to justify modifying its topography, to accelerate and increase agricultural output.

Topography affects the microclimate in a number of other ways.  In hilly country, the wind velocity at the crest of a hill may be 20 percent greater than on the flat, while the wind velocity on the hill's surface is influenced by the steepness of the slope and the wind direction.  At night, the layer of air along the ground is cooled by the ground.  This cool air, being heavier flows downhill and forms a pocket of stable, cold air in the valley.  The midslope remains relatively warm, while the top of the hill is cold and windy.  

On the windward side of hills, wind speeds are greater and more turbulent near the crest, while the leeward slope experiences less turbulent winds.  On the leeward side of the hill, bottom wind velocity is minimal, in the so-called "wind shadow."  Strong winds on the windward side of a hill may carry precipitation, either rain or snow, over the hill, where it falls on the leeward side, as previously described for the Hawaiian Islands.

Winds, whether an element of the macroclimate or the microclimate, are an important characteristic of a site.  Winter winds can make a site very unpleasant; a 30 mph wind with the air at 30 degrees F has six times the cooling effect of still air at 10 degrees F.  This is referred to as the "wind chill factor."

This effect of wind chill on building energy consumption for heating is quite significant.  The fuel consumption needed to heat an enclosed space in freezing temperatures will double as the wind increases in velocity from 3 to 12 miles per hour.  In the summer, of course, the cooling effect of the wind is highly desirable.  In developing a site plan, it is very important to study the direction of the prevailing winds during the different seasons.  Since the wind direction often changes seasonally, it is wise to plan site developments to admit cooling summer breezes while blocking undesirable winter winds.

Before the advent of modern heating and cooling technology, buildings, entire villages, even cities, were oriented to the climate.  An outstanding example is the ancient city of Peking, China, in which houses faced south, to receive winter sun.  Overhangs kept the sun out of rooms in summer, while courtyards admitted and directed cooling summer breezes into interior spaces.  Northern exposures were blocked by blank northern facades.  Similar examples were found in American Pueblo Indian settlements and other types of indigenous architecture, such as the ranch houses of the American Southwest.

Air movement also affects heat transfer.  Turbulent air disperses heat, while a steady flow tends to contain it.  Wind velocity and direction can vary significantly, depending on height.  Wind speed generally increases with height because of the surface friction of the ground.  At the ground surface, the wind speed decreases to almost zero.

A body of water is usually warmer at night and cooler during the day than land adjacent to it.  Similarly, it is normally cooler in summer and warmer in winter, than adjacent land.  Thus, the effect of a water body on the land adjacent to it is to moderate the microclimate, just as oceans moderate the macroclimate.

Where land is adjacent to a large body of water, the difference in temperature between the two causes an almost constant breeze.  Such locations generally have desirable climatic conditions.  Other locations that enjoy desirable conditions include south and southeast slopes and upper or middle slopes, in contrast to those at the base or crest of a hill.

The microclimate is also affected by ground surface materials.  To examine this phenomenon two terms should be identified.  One is albedo, the other is conductivity.  Albedo is that fraction of the radiant energy received on a surface that is reflected, expressed on a scale of zero to 1.0.  Zero corresponds to a flat black surface that absorbs all the heat it receives and reflects none, while 1.0 corresponds to a perfectly reflecting surface, such as a mirror, which reflects all the energy directed to it, absorbing none.  Materials such as grass and forest trees have low values of albedo, varying from about 0.05 to 0.30.  Pavements have high albedo.

Conductivity refers to the speed with which heat passes through a material.  Metals have high conductivity, while materials such as sand and soil have low conductivity.

Ground surfaces having low albedo and high conductivity moderate the microclimate considerably.  Heat energy is absorbed and released later when the temperature drops.  Consequently, grass surfaces are cooler in hot weather and warmer in cold weather than nearby paved surfaces.  Grass areas are also less dusty, have less glare, and are more sound-absorbent than paved surfaces.  It is apparent why urban areas, with few grassy areas and great concentrations of structures and pavements, become hotter in the summer than corresponding rural areas.

Trees have a variety of microclimatic effects, all of which tend to moderate the microclimate.  Rows of trees act as effective windbreaks, reducing wind speeds within and downwind of the trees to be at least one-half or more.  The distance in which wind speeds are reduced is many times greater than the height of the trees, with certain configurations of trees being more effective than others.  By carefully siting structures to take advantage of this reduction of wind in winter, the wind chill factor can be dramatically reduced, resulting in a more comfortable microclimate and less fuel consumption.

Trees block the direct radiation of the sun, as well as light and glare from secondary sources such as the sky and the ground surface.  Deciduous trees provide an excellent example of nature's grand plan: they block the summer sun and glare, while allowing most of the winter sun and light to come through.  Evergreens, on the other hand, have the same blocking effect all year round.  A beneficial effect of evergreens in winter is that they help reduce snow glare.  

Another desirable effect that trees, as well as other plants, have on the microclimate is that they filter the air by absorbing dust, dirt, and other pollutants.  In addition, all plants absorb carbon dioxide and release oxygen in photosynthesis.  The air of the forest has a natural freshness that man cannot easily duplicate.  Trees and other plants also evaporate water vapor into the air through transpiration, which cools and humidifies the air.

Trees, therefore, not only satisfy our instinctive desire for protection, but also help to maintain a stable, pleasant microclimate, clean air, and a naturally pleasing environment virtually free of maintenance.

If we think of "conditioned air" as air whose temperature, humidity, velocity, and freshness are within the parameters of human comfort, then trees are among nature's most effective air conditioners.

Thus far we have discussed the local modifications of the macroclimate by natural features, such as topography, water, wind, and trees.  Manmade structures also modify climate.  In urban areas they may be the predominant microclimatic factor.

Structures alter air movement.  They block, divert, and channel winds, sometimes in unpredictable ways.  When wind strikes a large surface, the opposite face of the surface becomes a low pressure area, in which the air is relatively quiet but moves erratically, in a whirling flow.  The thicker the surface in the direction of the air flow, the less significant is the leeward low pressure area.  On large projects, scale models are sometimes tested in wind tunnels so that wind flow can be predicted more accurately.

We have mentioned how manmade structures and pavements in urban areas reflect solar radiation, elevating temperatures.  Urban areas may be 10 degrees warmer than comparable rural areas both day and night, winter and summer.  In general, urban areas are not only warmer, but also noisier, drier, dustier, and more polluted than non-urban areas.  They may also have more rain, clouds, fog, and glare.  Urban wind velocities are generally lower, and the frequency and severity of flooding in urban areas is greater than in rural areas.

CLIMATIC CONSIDERATIONS

The human comfort zone is that range of temperature and relative humidity in which the average person is comfortable wearing light clothing.  The comfort zone ranges between 63 and 71 degrees F in winter, and 66 and 75 degrees F in summer, within a relative humidity range of 30 to 60 percent.   As the humidity increases, discomfort is experienced at increasingly lower temperatures, until the relative humidity reaches 75 percent, at which point discomfort results regardless of the temperature.

At temperatures above the comfort zone, air movement makes people feel more comfortable.  For example, if an individual is sitting in a light breeze of at least 200 feet per minute, temperatures of approximately 85 degrees F may be quite comfortable in the 20 to 50 percent humidity range.  When humidity levels are low, additional moisture must be introduced in order to maintain the sense of comfort.  At temperature levels below the comfort zone, additional radiation from the sun is needed to maintain the sense of comfort.  And when humidity levels are high, moisture must be removed to avoid discomfort.

Air movement causes a cooling sensation because of heat loss from the body by convection and evaporation.  The greater the speed of air movement, the greater the cooling effect.  Air movement less than 50 feet per minute is generally not noticed, 50 to 100 feet per minute is pleasant, 100 to 200 feet per minute is pleasant and noticeable, 200 to 300 feet per minute is felt to be drafty, and more than 300 feet per minute is uncomfortable.  

Physical well-being as well as mental health are also related to climate.  The closer the microclimate is to the comfort zone, the higher the level of health and energy.  Consequently, in the temperate zone of the United States, this level is highest in autumn, drops to a low point in winter, rises again in the spring, dropping once again during the hot summer.  The seasonal variation may differ in other climates, but it is always directly related to the comfort zone.

This does not mean that uniformity is desirable.  Variation is conducive to change of mood and pace, and consequently, a healthful stimulus.  One of the tasks of the designer, then, is to try to temper the climate so it falls within the comfort zone, both indoors and outdoors.  Obviously, this is not always possible.  But if the designer is aware of the factors influencing human comfort - temperature, humidity, air movement, and solar radiation - as well as all the variables that make up the microclimate, he or she can produce a most effective design within a particular microclimate, and modify it where necessary.  Winter winds can be intercepted and summer winds admitted.  Summer sun can be shaded, but advantage can be taken of winter sun.  Structures can be placed on desirable sites and optimally oriented.

Conversely, undesirable situations can be avoided, such as steep north-facing slopes with cold drafts, west slopes that face a body of water with uncomfortably strong glare, windy hilltops, frost pockets with low temperatures, bare dry ground subject to flash flooding, and areas with polluted air or noise.  All such undesirable sites can simply be avoided for habitation, and used for activities serving few or no people, such as warehousing.  Desirable microclimatic conditions, such as southeast to southwest slopes, locations close to water, and well-planted or forested sites, can be used to great advantage in site planning.  By designing for sun, shade, breeze, and air quality we can improve the microclimate and hence the comfort of potential inhabitants.

Sustainable design planning is a design philosophy that tries to work with the virtues of the natural conditions, rather than forcing a solution that requires imported energy to overcome natural conditions.  For example, by designing with minimal interference with the existing topography and existing drainage ways, the final design may be less costly, less homogenous, and have a unique quality reflective of local natural ecosystems.

Whenever the landscape is altered the microclimate is affected - sometimes improved, sometimes harmed.  By changing the natural drainage flow, clearing forests, plowing, planting, or grading, we alter the environment.  With the creation of the urban habitat, with its extensive paving, dense buildings, blocked air movement, noise and air pollution, we have also created a somewhat hostile environment in regard to climate.  As a result, we have become more sensitive to the conditions of the urban climate and its sometimes deleterious effects upon the health and well-being of people.  A sensitive and intelligent designer, however, may manipulate surfaces and structures, in addition to using modern mechanical means, to produce a climate as desirable as one found in nature.

AIR POLLUTION

The envelope of air surrounding our planet sustains all life - plant, animal, and man.  Therefore, air quality is of vital concern.  Is air ever absolutely pure?  By definition, being itself a mixture, it cannot be.  The question of air quality is a question of the balance or imbalance of its constituent ingredients, and of the presence of undesirable, deleterious substances.  These include certain dusts, particles, industrial gases, ozone, etc.

Man is not alone in harming air quality.  Occasionally, acts of nature create air pollution.  Sandstorms fill the air with whirling grit.  Ash erupting volcanoes and smoke from forest fires blanket huge areas.  But such occurrences are relatively rare and, in any event, largely uncontrollable by man.

Of far greater concern is the air pollution caused by our own actions and practices.  Over the years, the burning of coal, oil, and gas, and the exhausts of millions of automobiles have discharged enormous quantities of gaseous and solid matter into the atmosphere.  Noticeable and sometimes dangerous concentrations of air pollutants occur, principally in industrialized areas, such as the United States, Western Europe, and Japan.  Under some circumstances, the extreme effects of air pollution are lessened by natural weather action such as wind, rain, and air currents.

But natural weather action can also magnify the effects of manmade pollution.  Such an action is the temperature inversion phenomenon.  This occurs because the air temperature at the ground level is lower than at some elevation above the ground.  It becomes warmer as we go higher.  At some point, this increase changes and the air then becomes cooler as we go still higher.  The cooler air at the ground surface is heavier than the air above it and therefore cannot move upward.  The air becomes trapped and any pollutants discharged into it cannot escape into the upper atmosphere.  They linger over the city in the form of smog (smoke and gases) until a strong current of new air displaces the lingering layers, and the inversion disappears.  Air pollution is damaging to plants, animals, and man.

An increased public awareness of the effects of air pollution has resulted in the enactment of federal and state legislation designed to restrict noxious emissions from both vehicles and industry.  Even with these measures air pollution will not disappear entirely.  Therefore the process of site selection and design must take this modern problem of man and nature, and their coexistence, into consideration.

NOISE

Noise is unwanted sound.  The sound (sonic) environment within a building is a primary concern of design.  Through careful acoustic design, absorptive insulation, and isolation devices, internal noise can be confined to its place of origin.  External noise, however, is more difficult to control.  Noise is created  and aggravated by airplanes, automobiles, buses, rail systems, construction equipment, and the many activities of urban life.  As cities and suburbs increase in area and population, more noise is generated.  The increase in mechanization both indoors and outdoors results in an increase of noise.  As you read this, you can probably hear vehicle noise in the street, ringing telephones, clacking typewriters, the sounds of radio or television.  For some persons, noise-induced hearing loss can be an occupational hazard.  Many workers are exposed each day to noise levels that are detrimental to their health.

Sound levels are measured in decibels, on a logarithmic scale that has a value of 1 at the threshold of hearing and 140 at the threshold of pain.  One decibel is the smallest difference between two sounds that the human ear can detect.  Each increase of 10 decibels represents a tenfold increase of sound energy, which the human ear perceives as approximately twice as loud.  A noise 30 decibels higher than another has one thousand times the sound energy of the latter (10 X 10 X 10).  Some typical sources and their approximate values are shown in Table 8.1

Decibels Source

10 Normal breathing

20 to 30 Soft whisper

40 Hum of small electric motor

50 Typical kitchen

60 Normal conversation

70 Normal office

90-100 Rock band

100 Subway train

160 Jet airplane

A comfortable noise level for the average person is in the range of 50 to 60 decibels.  No more than 30 decibels is recommended for sleep or study areas.  85 decibels is considered the safety threshold; exposure to higher noise levels over a prolonged period may cause hearing impairment.

Sound pitch is determined by frequency, which is the number of oscillations, or cycles, per second.  Sound audible to humans generally ranges from 20 to about 20,000 cycles per second.  The pitch of sound can be a major factor in causing discomfort: high-pitched sounds that contrast with background sounds can be irritating even if they are relatively soft.

Noise can contribute to stress, particularly when it disrupts sleep or rest.  Apartment dwellers are especially subject to "noise invasion" from outside sources, such as traffic, as well as noises from nearby apartments and corridors.

Normal city noises can affect the heart and blood pressure, and severe noises may damage the auditory system permanently.  Many sounds are attenuated (weakened) before they reach us.  For example, doubling the distance between the source and receiver diminishes the sound level six decibels.  Since sound intensity decreases in proportion to the square of the distance from a point source, doubling the distance reduces the sound intensity to one-quarter.  This does not apply to linear sources, such as freeways, where the sound level drops only three decibels for each doubling of distance, and the sound intensity drops to one-half.

Gusty winds reduce the effect of sounds by adding a "white noise," a blend of all sound frequencies, which tends to blur a noise of a specific frequency.  Thus, wind sound minimizes the effects of traffic noise.

Trees "thin out" high-frequency noises, but solid barriers, such as earth, walls, and structures, are more effective in reducing noise.  A high wall close to the source of the sound reduces high-frequency noise.  However, a low wall midway between source and receiver has little effect on low-frequency sound.  Water movement, such as a fountain, helps to mask unpleasant sounds, while ground covers help to absorb noises.  An example is the Freeway Park in Seattle, designed by landscape architect Lawrence Halprin.  The "white noise" generated by its cascading fountain literally and figuratively drowns out the sound of the nearby interstate highway.

Thus, noise may be controlled either by locating activities at some distance from the noise source, or by placing physical barriers between the noise source and the planned activity.

GLARE

Glare is a common environmental problem that can be controlled by careful planning.  Glare occurs when there are two sources of illumination of extremely different intensities, such as very light against very dark.  Glare is not a result of too much light, but rather of too much contrast.  In the natural landscape, glare can be eliminated from natural landscapes by such simple means as planting grass.

Some structures create problems of glare.  Buildings that are located to take advantage of solar heating during wintertime may cause glare problems.  Visual discomfort caused by glare can be severe.  Looking out of a south-facing window into the low winter sun can be very uncomfortable.  If the ground is covered with snow, or if windows face a lake, the glare problem can be even more severe.  While consideration must be given to the desirable aspects of solar radiation, the objectionable problems of glare must also be dealt with.

Glare may be alleviated by certain wall treatments, such as blinds, drapes, and nonglare glass.  In very warm climates, however, additional protection from the sun is needed.  Such locations require buildings that continually shield windows from the sun.  In tropical climates, sun screens can help reduce both construction and cooling costs.

Exterior sun control devices such as overhangs, fins or louvers are very effective in reducing heat and glare.  Natural landscape elements, such as trees, can also control glare.

ECOLOGY

BACKGROUND

Although the term ecology is relatively new in environmental planning, an ecological approach to planning goes back well into history.  The Old Testament, for example, contains admonishments that may be regarded as ecological principles, such as allowing land to rest periodically, not destroying trees in a conquered territory, and the consideration and care of animals.

In fact, all through history, societies have had to practice land and resource husbandry for their own survival.  Present day ecology, as a science, was introduced in the late 19th century, by an American named George Perkins Marsh.  His book, Man in Nature, published in 1875, is the landmark introduction to the study of ecology.  It was the product of his reflections on mankind's historical experience in land settlement and development, some of which proved disastrous, and some highly responsible and consequently successful.  Another pioneer in this field, who linked ecology to regional and urban planning, was the Scottish biologist Patrick Geddes.  His work dates from World War I, and his influence was worldwide.

In the 1920s, a group of American environmentalists formed the Regional Planning Association of America to explore and expand the possibilities for large-scale comprehensive planning in the United States.  That group included the American philosopher and environmental writer Lewis Mumford, as well as Benton Mackaye, a forester, who proposed the Appalachian Trail in 1922.  Mackaye's writings include The New Exploration: A Philosophy of Regional Planning and From Geography to  Geotecture.  In 1926 two members of this group, Clarence Stein and Henry Wright, drafted a landmark ecologically-based plan for the entire state of New York.  In essence, that plan identified the critical and vital natural resources of the state - water, forest, soil, and topography - and then determined the land uses or activities appropriate to those resources.  From that derived a brilliant plan of appropriate uses.  Natural and human activities were thus brought together in harmony.  Larger applications of the same methods were made for the entire United States in the 1930s, many under the direction of a federal agency eventually known as the Natural Resources Planning Board (NRPB).  Though operated under the federal government, much of its work was done by diverse and comprehensive groups of experts in various local regions.  NRPB was a system of democratic planning, based on scientific knowledge and American values.

Among the notable regional planning efforts of the 1930s were the creation of the Tennessee Valley Authority and the development of the Columbia River.  NRPB's work made it possible for the nation to mobilize rationally and rapidly for World War II.  However, the war interrupted the nation's work in regional planning, and the post-war years were too occupied with rapid growth to pay much attention to it.  In retrospect, that proved to be a tragic oversight, for regional planning, based on ecology, would have resulted in far more workable and livable metropolitan areas.

Our rapid growth, without sound regionally scaled ecological planning, resulted in many errors in urbanization.  And that led to the realization that we had acted irresponsibly, giving rise to a renewal of interest in ecological planning.  Landscape architects deserve the most credit for reformulating and, indeed, advancing ecologically based planning.

Two outstanding spokesmen in this field are Professor Ian McHarg, of the University of Pennsylvania, who authored Design with Nature, and Professor Philip H. Lewis, Jr., of the University of Wisconsin, whose plan, "Recreation in Wisconsin," is a landmark in method, wisdom, and common sense.  The method is, simply, to survey a natural or man-transformed landscape, and to assess the possibilities or constraints for potential activities or uses according to the inherent capability of the landscape components.  With that knowledge, it is possible to determine - in the words of the late American planner, S.B. Zisman - where to build, where not to build, and consequently to a large degree, what to build, and how much to build.  Thus natural landscape and humankind's settlements become partners in a continuing enterprise, and ecological statements in this regard are the writings of the later Dr. René Dubos, a microbiologist.  Particularly helpful is his insightful book, So Human an Animal.  Ecological planning is the foundation of all successful design.

ECOLOGICAL CONSIDERATIONS

Ecology is the science of the pattern of relations between a community of organisms and its environment, the community comprising all the living animals and plants occupying a given area.  The community and its physical environment form an ecological system, or ecosystem.  An ecosystem may be a forest, a desert, a pond, a laboratory culture, or a manned space vehicle.  The organisms in an ecosystem compete as well as cooperate with each other to achieve a dynamic balance with the earth, air, and water that form their physical environment.

Ecosystems are constantly changing.  As an ecosystem changes, it approaches a stable condition in which the diversity of its constituent species reaches a maximum.  If a particular species in a complex ecosystem, such as a forest, is destroyed, the system itself will form new relationships.

In contrast, simple, uniform ecosystems tend to be unstable.  They are vulnerable to the destabilizing introduction of a single "foreign" element.  The constituent elements of a fragile ecosystem are few in number.  If, in such an ecosystem, one constituent element is destroyed, that entire ecosystem is likely to collapse.

In a broader sense, ecology refers to the independence of man, plants, animals, and the physical environment.  The scale of the ecological approach to planning ranges from a single urban site to the entire planet.  To the designer, it means understanding the complex web of relations existing on a site, and between the site and its surroundings.

In urban areas, the pre-existing natural ecology has been largely supplanted by a manmade ecology: a interdependence of people, institutions, circulation systems, etc.  Site analysis must consider the effect of a given site development on the environment.  Are existing circulation systems (streets, highways, public transportation) adequate?  Are existing utilities, sewers, and storm drains adequate?  How will the planned development affect the microclimate by modifying prevailing winds or creating glare?  Will the development be harmonious with the neighborhood in appearance, use, and scale?  Will the development produce noise, smoke, or other undesirable effects?

In rural areas, where the ecology may be such that the natural processes predominate, considerations may differ.  In general, the environment should be altered as little as possible.  Grading should be minimal, natural drainage patterns left intact, and points of interest, such as rock outcroppings, left undisturbed.

Obviously, whether the setting is rural or urban, a balance of objectives must be sought.  Good judgment must be exercised in choosing alternatives, and in establishing priorities.  With careful planning and continuing management, the development of a site can be accomplished while preserving its basic resources of air, water, and soil.  At the same time it is possible to protect plant and animal life, while still solving the basic architectural problems.

AHWAHNEE PRINCIPLES

In 1991, in the Ahwahnee Hotel in Yosemite National Park, a group of architects, planners, and community leaders got together to present community principles that express new, sustainable planning ideas.  These principles are summarized below:

PREAMBLE:

Existing patterns of urban and suburban development seriously impair our quality of life.  The symptoms are: more congestion and air pollution resulting from our increased dependence on automobiles, the loss of precious open space, the need for costly improvements to roads and public services, the inequitable distribution of economic resources, and the loss of a sense of community.  By drawing upon the best from the past and the present, we can plan communities that will more successfully serve the needs of those who live and work within them.  Such planning should adhere to certain fundamental principles.

COMMUNITY PRINCIPLES:

1. All planning should be in the form of complete and integrated communities containing housing, shops, workplaces, schools, parks, and civic facilities, essential to the daily life of the residents.

2. Community size should be designed so that housing, jobs, daily needs, and other activities are within easy walking distance of each other.

3. As many activities as possible should be located within easy walking distance of transit stops.

4. A community should contain a diversity of housing types to enable citizens from a wide range of economic levels and age groups to live within its boundaries.

5. Business within the community should provide a range of job types for the community's residents.

6. The location and character of the community should be consistent with a larger transit network.

7. The community should have a center focus that combines commercial, civic cultural, and recreational uses.

8. The community should contain an ample supply of specialized open space in the form of squares, greens, and parks, whose frequent use is encouraged through placement and design.

9. Public spaces should be designed to encourage the attention and presence of people at all hours of the day and night.

10. Each community or cluster of communities should have a well-defined edge, such as agricultural greenbelts or wildlife corridors, permanently protected from development.

11. Streets, pedestrian paths, and bike paths should contribute to a system of fully-connected and interesting routes to all destinations.  Their design should encourage pedestrian and bicycle use by being small and spatially defined by buildings, trees, and lighting, and by discouraging high speed traffic.

12. Wherever possible, the natural terrain, drainage, and vegetation of the community should be preserved with superior examples contained within parks or greenbelts.

13. The community design should help conserve resources and minimize waste.

14. Communities should provide for the efficient use of water through the use of natural drainage, drought tolerant landscaping, and recycling.

15. The street orientation, the placement of buildings, and the use of shading should contribute to the energy efficiency of the community.

REGIONAL PRINCIPLES:

1. The regional land-use planning structure should be integrated within a larger transportation within a larger transportation network built around transit rather than freeways.

2. Regions should be bounded by and provide a continuous system of greenbelt/wildlife corridors to be determined by natural conditions.

3. Regional institutions and services (government, stadiums, museums, etc.) should be located in the urban core.

4. Materials and methods of construction should be specific to the region, exhibiting a continuity of history and culture and compatibility with the climate to encourage the development of local character and community identity.

IMPLEMENTATION PRINCIPLES:

1. The general plan should be updated to incorporate the above principles.

2. Rather than allowing developer-initiated, piecemeal development, local governments should take charge of the planning process.  General plans should designate where new growth, in-fill, or redevelopment will be allowed to occur.

3. Prior to any development, a specific plan should be prepared based on these planning principles.

4. Plans should be developed through an open process and participants in the process should be provided visual models of all planning principles.

Source: Local Government Commission's Center for Livable Communities, http://lgc.org/center.

SUSTAINABLE DESIGN

HISTORY OF SUSTAINABLE DESIGN

What is sustainable design and how is it different from the ordinary process that architects have used for thousands of years?

In early human history, builders of human habitats used materials that occurred naturally in the earth, such as stone, wood, mud, adobe bricks, and grasses.  With nomadic tribes and early civilizations, the built environment made little impact on the balance of natural elements.  When abandoned, the grass roof, adobe brick, or timber beam would slowly disintegrate and return to the natural ecosystem.   Small human populations and the use of natural materials had very little impact on a balanced natural ecosystem.

But as human populations expanded and settlements moved into more demanding climates, natural materials were altered to become more durable and less natural.  In fact, it is the remnants of archeology that demonstrate some of the human creations that are not easily recycled into the earth; fired clay, smelted ore for jewelry, and tools are examples of designs that will not easily reintegrate into the natural ecosystem.  These materials may be represented (grinding, melting, or reworking) into other human creations, but they will never be natural materials again.

As human populations expanded, there is strong evidence that some civilizations outgrew their natural ecosystems.  When overused, land became less fertile and less able to supports crops, timber, and domesticated animals necessary for human life.  The ancient solution was to move to a more desirable location and use new natural resources in the new location, abandoning the ecologically ruined home site.

The realization that global natural resources are limited is an age old concept.  The term conservation, which came into existence in the late 19th century, referred to the economic management of natural resources such as fish, timber, topsoil, minerals, and game.  In the United States, at the beginning of the 20th century, President Theodore Roosevelt and his chief forester, Gifford Pinchot, introduced the concept of conservation as a philosophy of natural resource management.  The impetus of this movement created several pieces of natural legislation to promote conservation and increased appreciation of America's natural resources.

In the middle of the 1960s, Rachel Carson published Silent Spring, a literary alarm that revealed the reality of an emerging ecological disaster - the gross misunderstanding of the value and hazards of pesticides.  The pesticide DDT and its impact on the entire natural ecosystem was dramatic; clearly, some human inventions were destructive and could spread harm throughout the ecosystem with alarming speed and virulence.  Birds in North America died from DDT used to control malaria in Africa.  Human creations were influenced by the necessities of the natural cycles of the ecosystem.  Human toxic efforts could no longer be absorbed by the cycles of nature.  Human activities became so pervasive and potentially intrusive that there needed to be a higher level of world wide ecological understanding of the risk of disrupting the ecosystem.

Architects, as designers of the built environment, realize the ecological impact of their choices of architectural components, such as site selection, landscaping, infrastructure, building materials, and mechanical systems.  The philosophy of sustainable design encourages a new, more environmentally sensitive, approach to architectural design and construction.

There are many credos for the approach to a new, sustainable design.  Some architectural historians maintain that the best architects (Vitruvius, Ruskin, Wright, Alexander) have always discussed design in terms of empathy with nature and the natural systems.  Now it is evident that all architects should include the principles of sustainable design as part of their palette of architectural best practices.

PRINCIPLES OF SUSTAINABLE DESIGN

Why is sustainable design necessary?

PRINCIPLES OF THE SCIENTIFIC LAWS OF NATURE

1.1 In the earth's ecosystem (the area of the earth's crust and atmosphere approximately five miles high and five miles deep) there is a finite amount of natural resources.  Mankind has become dependent on elements such as fresh water, timber, plants, soil, and ore, which we process into necessary pieces of our human environment.

1.2 Given the laws of thermodynamics, matter cannot be created nor destroyed.  The resources that we have been allotted to manage our existence are contained in our ecosystem.

1.3 All forms of energy tend to seek equilibrium and therefore disperse.  For example, water falls from the sky, settles on plants, and then percolates into the soil to reach the subterranean aquifer.  Toxic liquids, released by humans, and exposed to the soil, will equally disperse and eventually reach the same underground reservoir.  The fresh water aquifer, now contaminated, is no longer a useful natural resource.

These laws of science indicate why it is necessary to maintain the delicate balance of natural ecosystems.  There is a need to focus on the preservation of beneficial natural elements and diminish or extinguish natural resources contaminated with toxins and our destructive practices.

There are many credos for environmental responsibility.  One, The Natural Step, was organized by scientists, designers, and environmentalists in 1996.

There were concerned with the preservation of the thin layer that supports human life in a small zone on the earth's surface: the ecosphere (five miles of the earth's crust) and the biosphere (five miles into the troposphere of the atmosphere).

Their principles are summarized as follows:

1. Substance from the earth's crust must not systematically increase in the ecosphere.  Elements from the earth such as fossil fuel, ores, timber, etc., must not be extracted from the earth at a greater rate than they can be replenished.

2. Substances that are manmade must not systematically increase in the ecosphere.  Manmade materials cannot be produced at a faster rate than they can be integrated back into nature.

3. The productivity and diversity of nature must not be systematically diminished.  This means that we must protect and preserve the variety of living organisms that now exist.

4. In recognition of the first three conditions, there must be a fair and efficient use of resources to meet human needs.  This means that human needs must be met in the most environmentally sensitive way possible.

5. Buildings consume at least 40% of the world's energy.  Thus they account for about a third of the world's emissions of heat-trapping carbon dioxide from fossil fuel burning, and two-fifths of acid rain-causing carbon dioxide and nitrogen oxides.

The built environment has a monumental impact on the use of materials and fuels to create shelter for human beings.  The decisions about the amount and type of materials and systems that are employed in the building process have an enormous impact on the future use of natural resources.  Architects can affect and guide those decisions of design to influence the needs of sustainability and environmental sensitivity.

It is not a quick process.  Like moving a boat in a new direction, it must be done gradually and with awareness of the many natural forces that are acting on it.  But, the process has started and architects should be aware of the philosophy of sustainable design in order to influence the results.

SUSTAINABLE MATERIALS AND PRODUCTS

As demonstrated in the previous section, sustainable design should be extended through the entire project, from conception to final construction details.  Designers developing an environmentally responsible plan need to pay attention to these principles in every stage of the project.  The materials and products specified carry an ecological responsibility, from the way they are manufactured to the manner in which they are transported to the job site.  Materials and products should follow the same sustainable principles of waste reduction, increased use of recycled content, and maximized reuse of existing materials.

Most product manufacturers today are very familiar with the environmental concerns of the design community and have developed many alternatives to commonly used products.  Most follow one or more of these guidelines:

1. Use a high percent of recycled content

2. Use local or regional materials that reduce environmental impact from transport

3. Use products containing rapidly renewable natural materials such as bamboo and cork

4. Use certified wood to ensure environmentally responsible forest management

5. Reuse existing materials

6. Use products free of toxic ingredients

7. Offer recycling or reuse programs

With increasing demand for more environmentally responsible product choices, designers today have a better selection than ever of materials that can be quite beautiful as well as more economically feasible.

Since this list is meant to be comprehensive for the purposes of this lesson only, candidates are encouraged to become familiar with Leadership in Energy and Environmental Design (LEED) and its green building rating system, the leading green building guidelines in the United States since their inception in 1995.

SUSTAINABLE SITE PLANNING AND DESIGN

Most architectural projects involve the understanding of the design within the context of the larger scale neighborhood, community, or urban context in which the project is placed.

If the building will be influenced by sustainable design principles, its context and site should be equally sensitive to environmental planning principles.

Sustainable design encourages a re-examination of the principles of planning to include a more environmentally sensitive approach.  Whether it is called Smart Grow, sustainable design, or environmentally sensitive development practice, these planning approaches have several principles in common.

1.0 SITE SELECTION

The architect and planner may assist the client in developing the criteria for site selection that reflects the proposed environmental goals of the complex of buildings.

The selection of a site is influenced by many factors including cost, adjacency to utilities, transportation, building types, zoning, and neighborhood compatibility.  But, in addition to these factors, there are sustainable design standards that should be added to the matrix of site selection decisions:

ADJACENCY TO PUBLIC TRANSPORTATION

If possible, projects that allow residents or employees access to public transportation are preferred.  Allowing the building occupants the option of traveling by public transit may decrease the parking requirements, increase the pool of potential employees and remove the stress and expense of commuting by car.

FLOOD PLAINS

In general, local and national governments hope to remove buildings from the level of the 100-year flood plain.  This can be accomplished by either raising the building at least one foot above the 100-year elevation or locating the project entirely out of the 100-year flood plain.  This approach reduces the possibility of damage from flood waters, and possible damage to downstream structures hit by the overfilled capacity of the floodplain.

EROSION, FIRE, AND LANDSLIDES

Some ecosystems are naturally prone to fire and erosion cycles.  Areas such as high slope, chaparral ecologies are prone to fires and mud slides.  Building in such zones is hazardous and damaging to the ecosystem and should be avoided.

SITES WITH HIGH SLOPE OR AGRICULTURAL USE

Sites with high slopes are difficult building sites and may disturb ecosystems, which may lead to erosion and topsoil loss.  Similarly, sites with fertile topsoil conditions - prime agricultural sites - should be preserved for crops, wildlife, and plant material, not building development.

SOLAR ORIENTATION, WIND PATTERNS

Orienting the building with the long axis generally east west and fenestration primarily facing south may have a strong impact on solar harvesting potential.  In addition, protecting the building with earth forms and tree lines may reduce the heat loss in the winter and diminish summer heat gain.

LANDSCAPE SITE CONDITIONS

The location of dense, coniferous trees on the elevation against the prevailing wind (usually west or northwest) may decrease heat loss due to infiltration and wind chill factor.  Sites with deciduous shade trees can reduce summer solar gain if positioned properly on the south and west elevations of the buildings.

2.0 ALTERNATIVE TRANSPORTATION

Sites that are near facilities that allow several transportation options should be encouraged.  Alternate transportation includes public transportation (trains, buses, and vans); bicycling amenities (bike paths, shelters, ramps, and overpasses); carpool opportunities that may also connect with mass transit; and provisions for alternate, more environmentally sensitive fuel options such as electricity or hydrogen.

3.0 REDUCE SITE DISTURBANCE

Site selection should conserve natural areas, and restore wildlife habitat and ecologically damaged areas.  In some areas of the United States, less than 2 percent of the original vegetation remains.  Natural areas provide a visual and physical barrier between high activity zones.  Additionally, these natural areas are aesthetic and psychological refuges for humans and wildlife.

4.0 STORM WATER MANAGEMENT

Reduced disruption of natural water courses (rivers, streams and natural drainage swales) may be achieved by:

1. Providing on-site infiltration of contaminants (especially petrochemicals) from entering the main waterways.  Drainage designs that use swales filled with wetland vegetation is a natural filtration technique especially useful in parking and large grass areas.  

2. Reducing impermeable surface and allowing local aquifer recharge instead of runoff to waterways.

3. Encouraging groundwater recharge.

ECOLOGICALLY SENSITIVE LANDSCAPING

The selection of indigenous plant material, contouring the land, and proper positioning of shade trees may have a positive effect on the landscape appearance, maintenance cost, and ecological balance.  The following are some basic sustainable landscape techniques:

1. Install indigenous plant material, which is usually less expensive, to ensure durability (being originally intended for that climate) and lower maintenance (usually less watering and fertilizer).

2. Locate shade trees and plants over dark surfaces to reduce the "heat island effect" of surfaces (such as parking lots, cars, walkways) that will otherwise absorb direct solar radiation and retransmit it to the atmosphere.

3. Replace lawns with natural grasses.  Lawns require heavy maintenance including watering, fertilizer, and mowing.  Sustainable design encourages indigenous plant material that is aesthetically compelling but far less ecologically disruptive.

4. In dry climates, encourage xeriscaping (plant materials adapted to dry and desert climates); encourage higher efficiency irrigation, rainwater recapture and gray water reuse.  High efficiency irrigation uses less water because it supplies directly to the plant's root areas.

5.0 REDUCE LIGHT POLLUTION

Lighting of site conditions, either the buildings or landscaping, should not transgress the property and not shine into the atmosphere.  Such practice is wasteful and irritating to the inhabitants of surrounding properties.  All site lighting should be directed downward to avoid "light pollution."

6.0 OPEN SPACE PRESERVATION

The quality of residential and commercial life benefits from opportunities to recreate and experience open-space areas.  These parks, wildlife refuges, easements, bike paths, wetlands, or play lots are amenities that are necessary for any development.

In addition to the aforementioned water management principles, the following are principles of design and planning that will help increase open-space preservation:

6.1 PROMOTE IN-FILL DEVELOPMENT that is compact and contiguous to existing infrastructure and public transportation opportunities.

In-fill development may take advantage of already disturbed land without impinging on existing natural and agricultural land.

In certain cases, in-fill or redevelopment may take advantage of existing rather than new infrastructure.

6.2 PROMOTE DEVELOPMENT THAT PROTECTS NATURAL RESOURCES and provides buffers between natural and intensive use areas.

First, identify the natural areas (wetlands, wildlife habitats, water bodies, or flood plains) in the community in which the design is planned.

Second, the architect and planners should provide a design that protects and enhances the natural area.  The areas may be used partly for recreation, parks, natural habitats, and environmental education.

Third, the design should provide natural buffers (such as woodlands and grasslands) between sensitive natural areas and areas of intense use (factories, commercial districts, housing).  These buffers may be both visual, olfactory, and auditory protection between areas of differing intensity.

Fourth, provide linkages between natural areas.  Isolated islands of natural open space violate habitat boundaries and make the natural zones feel like captive preserves, not a restoration or preservation of natural conditions.

Fifth, the links between natural areas may be used for walking, hiking, or biking, but should be constructed of permeable and biodegradable material.  In addition, the links may augment natural systems such as water flow and drainage, habitat migration patterns, or flood plain conditions.

6.3 ESTABLISH PROCEDURES THAT ENSURE THE ONGOING MANAGEMENT OF THE NATURAL AREAS as part of a strategy of sustainable development.

Without human intervention, natural lands are completely sustainable.  Cycles of growth and change including destruction by fire, wind, or flood have been occurring for millions of years.  The plants and wildlife have adapted to these cycles to create a balanced ecosystem.

Human intervention has changed the balance of the ecosystem.  With the relatively recent introduction of nearby human activities, the natural cycle of an ecosystem's growth, destruction, and rebirth is not possible.

Human settlement will not tolerate a fire that destroys thousands of acres only to liberate plant material that re-blooms into another natural cycle.

The co-existence of human and natural ecosystems demands a different approach to design.  This is the essence of sustainable design practices, a new approach that understands and reflects the needs of both natural and human communities.

SUMMARY

Each site has a unique combination of physical characteristics that distinguishes it from other sites.  This lesson has dealt with the physical factors that the planner must evaluate in site planning and design: climate, air pollution, noise, glare, and ecology.

Although we have considerable control over the effects of climate and other natural factors, we must be fully respectful as well as understanding of nature as we analyze a site and design the structures to be placed upon it.  Nature's patterns must be considered, along with man's if we are to achieve harmonious and functional design.