I

PROJECT

DEVELOPMENT

1

Assessing Project Needs

Walking the site with the Landscape Architectural team from Rees Roberts in NYC, we started identifying the scope and the direction for the landscape lighting. Photograph: George Gruel.

As with all architectural design processes, lighting design is based on creativity and responding to project needs. The development of a responsive design concept results from collecting information about the project. Some information will be gained during the initial interview for the job, but the bulk of it is gathered once a contract has been signed and the project has begun. This chapter addresses the information-gathering stage of the project, which includes:

Interviewing the client(s) and other design team members to establish the scope and design direction of the project

Reviewing the plans to gain an understanding of the landscape design concepts

Visiting the site to gain a visual understanding of the project

Synthesizing the information to create a base from which design ideas will develop

INTERVIEWING CLIENTS AND THE DESIGN TEAM

Interviews present an opportunity to start collecting valuable information about the project and develop a working communication channel between members of the design team. The lighting designer can learn how various team members feel about light and their desires for the lighting approach or its effects on the project. Interviewing other consultants, such as the irrigation or soils engineers, provides the link to valuable technical information.

Clients

Many clients have limited understanding of the design process involved in lighting or what can be done with light to create an atmosphere. They often have preferences about the atmosphere, but no idea how to achieve it. Interviewing the client or end user builds the foundation for successful landscape lighting. The interview can open a strong communication channel between client and designer, which will help throughout the project. It can develop a trust between the client and the designer that encourages the client to rely on the designer for guidance throughout all phases of the project.

In interviewing clients, ask questions that allow clients to provide information regarding their design needs and desires. Then, listen carefully to the information they provide. Discuss the client’s personal feelings about light, the anticipated use(s) of the landscape at night, the anticipated maintenance of both the garden and the lighting, budget constraints, and deadlines. Break the discussion into three distinct categories: information retrieval, information dissemination, and client commitment.¹ During each area of discussion, ask questions to retrieve needed information, then provide the client with choices or guidance, and finalize the discussion with an understanding between client and designer.

Consider showing a portfolio. This presents the designer’s experience and introduces lighting ideas to a client. The designer can lead the client through past projects, discussing how the lighting effects and techniques shown in the photographs relate to this project. It provides a time for client feedback and discussion of their lighting goals. This is the time for the designer to show strengths that relate to this client’s project. The strengths can be creativity, technical knowledge, construction experience, or simply a history of quick project completion.

Offer to take the client and other design team members on a tour of local projects. This experience clearly shows clients what lighting can do for a landscape and showcases the designer’s skills and abilities. These visits often stimulate clients’ thinking about lighting, triggering new feelings or ideas about lighting their property.

Clients’ Expectations

Ask clients their feelings about light and their expectations of lighting in their landscape. People want landscape lighting for various reasons: view out from inside a room, use of the space for one or more activities, identification of the property, safety of people in the landscape, and security of people and property on the site or inside buildings. They often do not even have a clear idea of what they want. The designer must have a clear idea of the client’s expectations before embarking on a design concept. When interviewing a client, be sure to cover the following points:

Understand the client’s basic likes and dislikes about landscape lighting. Some clients want to see beautiful fixtures; others may want fixtures totally hidden. The client may want a dramatic scene with high contrast (see Figures 1.1 & 1.2) and limited areas lit, or the client may be sensitive to glare and prefer less contrast (see Figure 3.12).

Determine what the client dislikes about the existing lighting (or other landscape lighting that the client has seen). Ask about lighting the client has seen and likes, including specifically what attracted the client’s attention to that lighting. It may be a neighbor’s lighting or something the client saw in a magazine. Understand the client’s light level requirements. What does the client mean by a little or soft lighting? How much light is a lot of light?

Discuss what impelled the client to install landscape lighting. This will give the designer information about the client’s perspective on landscape lighting. Often, a specific event or issue sparked the client’s interest. It may be safety, the need to see the way from a door to a parking garage, or a desire to see the landscape at night.

Talk about the atmosphere or appearance the client would like to create. Encourage the client to use adjectives to describe the scene. Words such as dramatic and theatrical present a different image than simple and subtle.

Inquire about the impression the client would like visitors to experience. Answers will vary from drawing attention to the site to impressing visitors to welcoming guests.

Next, discuss space use issues. Often clients will not know how they will use their outdoor spaces once they have lighting. Ask specific questions about the kind of entertaining or daily/family use the client might envision. Ask about the type, size, and frequency of events the client might want to plan. This starts to define a client’s goals for the project.

Discuss what activities will take place in the landscape after dark. In many areas, there may not be any activities outside at night (due to climate) during certain times of the year.

Consider activities that occur inside buildings and the importance of view out to the landscape.

Determine specific lighting needs or expectations. When several needs surface, this may indicate that flexibility will be required in the lighting system controls.

Explore safety and security issues.

Discuss who will be using the space(s). Older people or people with any visual disabilities have special lighting needs that must be considered in planning the lighting.

Maintenance

Two kinds of maintenance issues should be discussed: landscape maintenance and lighting maintenance.

Landscape Maintenance

Consider changes that could occur to the landscape over time—decks, pathways, patios, structures, or sculptures that may be modified, added, moved, or removed.

Inquire who provides normal maintenance.

Ask what services are included in normal maintenance.

Ask about the maintenance schedule.

Discuss whether the basic planting design will develop further over time.

Determine if seasonal planting occurs in certain areas. This may mean not installing lighting fixtures in that planting area. Working around fixtures while maintaining the planting can be cumbersome and fixtures can be knocked out of adjustment.

Ask who makes the planting decisions. This decision maker might be the landscape architect or designer together with the owner or the head gardener. This person(s) should be included in the discussion of the lighting design and briefed on the required maintenance of the lighting.

Inquire about fertilization, including both schedule and materials used. Due to corrosion implications, this fertilizer information may affect the lighting equipment selection.

Ask about plant pruning. Hedges may be cut to keep at a certain size – or may be planned to keep to a certain size as they grow. Specimens may be shaped or groomed for various reasons including allowing good air movement through branches, keeping or creating a specific shape or form. This may affect a designer’s approach to the lighting concept.

All these issues indicate how careful the designer will need to be in the selection and placement of fixtures. Unless the owner maintains the grounds, few people working at the site understand the necessity of not moving the fixtures and coordinating the maintenance of the landscape with the lighting to preserve the lighting effects.

Lighting Maintenance

Prompt the client to think about the future. Successful lighting depends on long-term functionality of the system. This requires proper maintenance and the ability of the lighting system to grow and change with the landscape.

Any discussion of lighting maintenance requires educating the client. As with the landscape, maintenance of the lighting system requires continuous design input. Landscapes continually change due to hardscape revisions or use changes, as well as plant growth and death. Changes require lighting adjustments to maintain desired effects, such as adding or deleting fixtures, moving fixtures to retain effects as plants grow, and changing lamps to different wattages or beamspreads as plants mature. Also, lamps burn out and must be replaced over time. Identify who will be the appropriate person to provide the lighting maintenance. After the design has been installed, familiarize this person and the owner with the operation of the fixtures.

Maintenance of lighting can be part of the lighting designer’s contract with the owner. An effective approach includes an annual site review by the designer. After surveying the existing conditions, the designer can recommend what maintenance, if any, should be done.

The timing for this site review will vary based on the garden maturity when the lighting is installed. A newly planted garden will need lighting maintenance sooner and more frequently than will a mature garden. This concept must be discussed with the client at the beginning of the project for the client to understand fully the implications of landscape lighting.

Budget

One of the most critical factors to an owner is budget. Clients unfamiliar with lighting costs may have no idea what to expect or have an unrealistic expenditure in mind. Bringing up this issue during the initial interview prevents wasted design time, avoids introducing the client to ideas or equipment inappropriate for the project, and maintains good relations throughout the project.

Determine the anticipated life cycle for commercial landscapes or how long an owner plans to live at a residence.

Ask what budget, if any, has been planned.

Provide the owner with basic cost information to help develop a preliminary budget.

When the budget is limited but the owner wants thorough lighting, consider planning the project in phases. This stretches the budget over a longer time frame and eliminates inconveniences at a later date. For example, plan a complete lighting design, install conduit throughout the landscape for future power distribution, but limit the initial fixture installation to areas directly around the building. In this case, always budget the total installation and plan a schedule for installing the remainder of the design to ensure that it happens.

Deadlines

The last area to cover, in questioning the client, involves time. Whether the project is a large public commercial project or a small private residential project, involving only lighting installation, deadlines exist. One or more of the following six deadlines may be involved:

Design

Installation bids

General construction

Preliminary wiring

Installation completion

Aiming/adjusting the lighting system

The lighting designer should be brought in to start planning the landscape lighting after the landscape design has been substantially completed but before final construction documents are completed. Lighting ideas may affect other areas of design, such as structural details or planting layout, and need to be addressed while changes can still be made. A schedule needs to be agreed upon by all parties (including the owner, other design team members, and the lighting designer), allowing the lighting designer time to evaluate and plan the lighting while still fitting into the overall project schedule. Take care not to let unrealistic deadlines push the lighting design too quickly. The time required for conceptual design, design development, and construction drawings will vary from project to project, based on the project size, complexity, number of people involved in the design process, and the lighting designer’s workload.

The most crucial deadline is completion date. Bank loans for construction may be involved, as may scheduled use of the landscape. Commercial projects may be working toward the opening of a public park or a major public appearance of a political, religious, or entertainment figure. Residential projects often need to function for a special party.

In collecting all this information about the project, conflicts may arise between scope and budget. Possible solutions include phasing the project, using less expensive equipment to retain the overall design intent, simplifying the design intent to retain high-quality fixtures, or discussing increasing the budget with a client who has the means. In some cases, a chunk of the budget can be saved by having the client tackle the installation. This requires experience in electrical installation. Discussing all these issues at the start may avoid potential conflicts from occurring during the planning stage of the project.

Other Design Team Members

Most projects consist of a group of design professionals—landscape architects, interior designers, engineers (including structural, mechanical, electrical, and soils), fountain designers, and other specialists (including geologists and lighting designers). Consider how each member affects the lighting design and coordinate with them.

Start talking with the landscape architects, as it is their design that the lighting complements. Discuss the atmosphere envisioned for the night appearance of the garden. Listen carefully for clues about their approach to the project and solutions to the design issues. The landscape architects may have in mind a clear view of the lighting but not know how to achieve it. Or they may not have developed any concept and want to discuss all the options. Discuss how the site relates to neighboring properties. Should the lighting relate to them visually or remain visually separate?

Ask the landscape architects to walk through the project, either on plan or at the site, and discuss their design concepts for the landscape. Together, identify any special lighting needs. For example:

Traffic patterns for new sites

Changes of traffic patterns on an existing site

Areas with specific uses requiring specific lighting, such as sports areas, gathering places for parties, or other functions

A particular vista or focal area requiring special attention

A specimen plant, sculpture, or architectural feature meant as a prime focal point

Grade changes such as stairs or berms that lighting should address for safety

The client may also supply some of this information. In case of conflict between the client’s vision of the landscape and the landscape architects’ vision, be sure to clarify the design direction in the most diplomatic way as quickly as possible.

REVIEWING ARCHITECTURAL AND LANDSCAPE PLANS

Thoroughly understanding a landscape design helps the designer plan lighting that responds to all the project needs. Drawings build a picture of the competed landscape in the designer’s mind. Before starting to develop a lighting concept, gather and study all the available drawings on the project.

Figure 1.1. Photo of pool garden immediately after construction. Look at figures 1.8 and 1.9 to see how the landscape designers’ sketches gave valuable visual information to help in design. Landscape Design: Magrane Latker Landscape Design; Photograph: Janet Lennox Moyer.

With new construction, procure both architectural and interior design drawings of the buildings on the site, including building layouts and furniture layouts, along with sections, elevations (see Figure 1.2), lighting plans, and details. The architectural drawings show how the building(s) fit into the landscape and the views from the interior to the exterior, and vice versa. The physical appearance of the building itself is an element to consider in the landscape lighting. Locations of windows identify view areas within buildings. Furniture arrangements further clarify how people will view the landscape through the windows. Elevations show window size and positioning in a space that helps direct fixture location and aiming to accommodate night views.

Procure these drawings from the landscape architect:

Site plan

Demolition plan

Grading plan

Hardscape plan

Elevations

Irrigation/plumbing plan

Electrical plan

Planting plan

Construction details

Sections

Perspective drawings

Each of these drawings helps build the lighting designer’s understanding of the project and represents a strong communication tool between the two designers. Sometimes the landscape architect does not realize how these drawings help the lighting designer. The following list identifies the importance of each for the lighting designer:

Figure 1.2. Comparing day (Figure 1.2) and the night lighting shows how lighting can transform a landscape. The bench at the end of the pool is the focal point (20 watts in the 1980s); the line of lighting mounted under the pool coping visually expands the garden’s depth; and theground plane is lit to the brightest level making the space human-friendly. Lighting Design: Janet Lennox Moyer, MSH Visual Planners: Photograph: Michael McKinley; Landscape Design: Magrane Latker Landscape Design

The site plan provides orientation to the landscape on the site and an overview of all areas comprising the project.

The demolition plan identifies what is being removed from the existing layout of the landscape.

The grading plan shows changes in elevationthroughout the site..

The hardscape plan introduces the organization of the garden as well as traffic paths, stairs, decks, patios, pergolas, and other structures, such as retaining walls. It shows the juxtaposition of living areas, work areas, view areas, focal points, parking areas, equipment rooms, and other visual or activity areas included in the landscape design (see Figure 1.3).

Elevations and sections provide details not evident on any plan. They show the effect of natural or modified grading on elements within the landscape (see Figures 1.3 & 1.4). These often provide information as to how and where to mount lighting equipment.

The irrigation plan shows where new ditches will be dug and water conduit installed, as well as the location of irrigation heads and other irrigation equipment.

The electrical plan, done early in the project development, locates the main electrical service for the landscape, locates the equipment room(s), and ensures that sleeves for electrical distribution are installed under hardscape in the early phases of construction. This plan may be produced before the lighting designer gets involved in the project. It may be done by the electrical engineer on large projects. At other times the landscape architect includes the information provided by the lighting designer on an electrical sheet.

The planting plan adds a new layer of information about the landscape design. It is part of the decoration of the space. Planting plans may be simple or complex. Landscape architects vary in the way they present planting plans. Often, they use a symbol for each plant type with an identification line leading from the symbol to the margin of the drawing where the plant name is listed. For typical trees and ground covers, a symbols list may be provided on the drawing. Sometimes a separate list of plant identification is produced and not printed on the drawing. In this case, be sure to procure that list (see Figures 1.5 & 1.6).

Construction and/or structural details give added information about the seating, stairs, trellises, pergolas, sculpture bases, tree wells, stages, and buildings. These details further clarify the design and provide information regarding potential fixture mounting locations.

Perspectives provide a realistic view of the completed project. Look at the before and after landscape photographs, along with perspective drawings, of a residential project in northern California in Figures 1.2 & 1.7 to 1.9. This series of views show how much a garden can change during landscape development. They also show how clearly the perspective drawings show the final design. This information completes the picture of the landscape, helping the lighting designer fully understand the landscape design.

Sometimes no landscape drawings exist, limited drawings exist, or the drawings are under development. The type of available drawings influences the way a lighting project develops. When no drawings exist on completed, mature landscapes, the lighting designer has three options. Each of these approaches has drawbacks:

To develop landscape drawings

To draw rough sketches of the landscape

To work without producing lighting drawing

Developing landscape drawings adds significantly to the project cost and requires hiring a landscape architect. Working with rough sketches requires close coordination between the lighting designer and the electrical contractor. Small projects can be done without producing lighting plans, but again increases the designer’s on-site involvement and coordination effort with the electrical contractor. All fixtures, wiring trenches, and transformers must be field-located and noted in some way — either in a sketch/drawing or a photo or both for future maintenance reference.

Models help in visualizing complex structures and understanding the landscape construction opportunities. Borrow the model (when possible) while developing the lighting concepts and photograph the model for future reference. If the landscape architects are seriously debating whether or not to build a model, your explaining how it could help on the project may be all the impetus they need to produce one.

VISITING THE SITE

Visiting the site is imperative. It helps the designer understand how the property fits into the neighborhood. It shows existing elements (plants, structures, etc.) important to the final design. Vistas will become apparent, including views:

Within the landscape (from one area to another)

From the garden to other properties

From the landscape into buildings on the site

From buildings out into the landscape

Figure 1.3. Hardscape plan and elevation at garden entry — Thornton residence in San Francisco, CA. The hardscape plan shows the changes to the street access and the new planting and entrance structure. Elevations and sections show style and detailing. This decorative information never shows on plans. Landscape Design: Magrane Latker Landscape Design; Drawing: Lezlie Johannessen.

Figure 1.4. Elevation showing grading effect on a garden/private residence in San Francisco, CA. This elevation shows the drop in grade through the site and the relationship between areas that the grade change presents. Also, mounting locations for light fixtures or auxiliary electrical equipment can be identified. Design and Drawing: Gary Millar.

Look at all these views to help build a mental image of the scene. Include glimpses around corners or from one area to another. Take care to light juxtaposing areas, as this will be important to the success of the lighting. Provide a visual destination at the end of a walkway or a view and outside windows. Study views of the landscape from streets or adjacent properties. This helps determine how the initial view of the garden should appear and how to avoid light pollution or glare going into neighboring properties. Also, make note of any lighting on adjacent properties that may affect the project.

Documenting Site Conditions

Note any existing conditions that may affect design decisions for the lighting:

Roof overhangs for potential recessed or surface-mounted fixtures.

Existing hardscape that will remain.

Location(s) of existing power in the landscape.

Location of the existing power supply panel. When a panel does exist, inspect it for overall capacity, capacity currently used, and total spare capacity. Be sure to assess how much of the currently used capacity will remain used and the amount that will be freed up for new lighting use. Early evaluation of potential total wattage will show whether the electrical service is large enough or needs to be upgraded.

Any existing or potential safety hazards that will or might need lighting attention. This would include the edges of pools, fountains, streams, or other waterways; changes in elevation and stairways; and paths or walkways through the site.

The relationship of adjacent properties. Surrounding properties should be included in the designer’s thinking to ensure that no light trespass or annoying glare affects these neighbors or inadvertently lights their building. Learn about the owner’s relationship with neighbors. Neighbors may be able to help during the project, such as providing access for equipment to the site or other unforeseen issues. Understanding their sensitivities may allow the lighting designer to allay any client/neighbor tensions that could develop over the new lighting.

Make notes and sketches about impressions of the site and lighting ideas. Try to visualize the proposed landscape improvements as well as absorbing existing conditions.

Photograph every view and every detail of the site. The photographs help recall the site while working on the design. A project that is close by allows the designer to revisit the site. If the site is not near enough to revisit easily, take more photographs than seems necessary. The one view critical to finalize a detail always seems to be missing. Again, make notes about impressions or lighting ideas. These can easily be forgotten by the time when design actually starts.

Soil Considerations

Soil information can prove to be critical. Soil penetration and soil stability varies radically from one soil type to another. The mounting detail for light poles will therefore vary from one soil type to another. Clay soils may be difficult to penetrate and will affect construction cost due to additional trenching time required for conduit and additional time required to mount fixtures. Clay soils do not drain well, potentially discouraging ground-recessed equipment or light fixtures. Sandy soils may not support electrical equipment or light fixtures properly, requiring special mounting details. The inherent moisture content of a soil layer or the added content due to irrigation affects potential fixture corrosion. This in turn affects the selection of fixtures based on construction materials, methods, and finishes.

The arrangement of soil layers provides important information. Movement can occur at the juncture of two soil layers. This movement can nick the fixture surface allowing moisture or dirt to contact the metal. This may cause pitting on the fixture surface. Movement also causes soil instability, which may affect fixture selection or installation methods. (See Chapter 8 for more information on the corrosion potential of fixtures.)

Figure 1.5. Planting Plan. The planting plan provides information about plant types and locations in the landscape. Understanding each plant’s characteristics, as well as, the integration of each individual into the overall landscape design, helps the lighting designer develope a lighting concept. Landscape Design: Magrane Latker Landscape Design; Drawing: Lezlie Johannessen.

Figure 1.6. Plant List: The plant list can take several forms. It may simply be a list with the Latin or botanical name and the common name or it may be the Latin name only, as shown here. It may list the names and have symbols for easy recognition of each plant on the plan. Sometimes there will be a combination of lists and symbols or just an arrow pointing to the plant with the name printed outsite the drawing boundary. Landscape Design: Magrane Latker Landscape Design.

Evaluate the soil on the project. Soils are graded based on three types of materials: clay, silt, and sand (see Figures 1.10 & 1.11).²,³ The percentage of each determines the makeup of that particular soil. Soil makeup will affect the ease of installation for wiring, lighting poles, junction boxes, and stake-mounted and recessed fixtures.

Figure 1.7. Perspective of the trellis structure. This drawing of the end of the pool area shows the construction intent for the trellis. Mounting locations for fixtures can be identified with a drawing like this. Landscape Design and Drawing: Magrane Latker Landscape Design.

Figure 1.8. Before view of a landscape. Visiting the site provides an understanding of the project scale and the relationship between one area and another. It identifies or reinforces an understanding of dominant views within the landscape, from interior spaces out into the landscape, and from adjacent properties into the landscape. Photograph: Janet Lennox Moyer.

Figure 1.9. Perspective sketch of the pool garden. Three- dimensional views provide information that may not be evident by studying two-dimensional plans. It clarifies relationships between areas and design elements, as well as the overall landscape composition. Note how similar this sketch is to the photograph of the garden after construction (see Figure 1.2). Landscape Design and Drawing: Magrane Latker Landscape Design.

Figure 1.10. Soil structure triangle. Soil classification is based on the amount of three particle types that occur in the soil: clay, silt, and sand. Other factors influence the classification: the number and kind of layers, the kinds and amounts of minerals, the presence or absence of salts, the amount of organic matter, and the drainage characteristics. From Kermit Berger, Introductory Soils (New York: Macmillan, 1968). Drawing: Lezlie Johannessenn.

Soils are identified by different types of characteristics and existing conditions:⁴

Amount of clay, silt, and sand (see Figure 1.10)

Types and quantities of minerals

Presence or absence of salts

Amount of organic material

Drainage characteristics

Inherent moisture content

Number and types of layers (see Figure 1.11)

A site survey may have been done on a large project by a soils engineer. The report may not be readily interpreted by a lighting designer, but a discussion with the soils engineer will explain the soil conditions. Sometimes the landscape architect may be familiar with the soil condition and can provide this information. Soils survey maps are available from the Department of Agriculture (USDA) or local Soils Conservation Services. These have limited use, as they cover large areas and do not offer detailed information. They do provide clues about the overall site soil type. Be aware that the soil makeup may vary throughout a site.

Perhaps the most useful information for the lighting designer can be gained by digging holes and checking the conditions at several areas in the site. A handheld auger or sampling tube shows the soil consistency and texture. This does not provide information about the chemical makeup of the soil. The landscape architect may have contracted a soils engineer to perform a soils test. If not, contact a soils analysis lab. Ask them to test for soil pH (see Chapter 8) and identify any salts or other corrosive elements in the soil.

SYNTHESIZING THE INFORMATION

After all this initial information has been gathered, allow time to think about it. Study the plans and try to visualize the landscape design. This may be the most critical time of the project. Conscious and subconscious analysis of this information leads to the core direction for the lighting design.

Look again at traffic patterns, views, and vistas, and identify all focal areas or points. Keep in mind the use of the space. One of the most important aspects of this study phase is to become familiar with the plant materials. Refer to the plant list supplied on or with the planting plan. (See Chapter 14 for information on plant material.) Research each plant listed. Recognize that this list will be revised up to the day that all plants are installed in the ground.

Many factors influence these planting changes. The landscape architect may determine at some point in the project that another plant is more appropriate. In procuring the plant material, some of the desired plants may not be available, requiring a change in plant type. In other cases, the plant material may exist, but not be of acceptable quality or the right size. Many times the landscape architect, while locating plants on the site, determines that plant locations need to be shifted to create the desired massing effects. Also, the quantity of a specific plant may change due to site relationships. Sometimes more plants are installed, sometimes fewer. This means that the lighting plan needs to stay flexible until all the plant material has been installed.

Figure 1.11. Soil classification chart. The height of the bar shows various percentages of sand, silt, and clay materials in the various textural classes of soil. Clay particles are extremely fine and are the active portion of the soil. In addition to these mineral components, soils will have varying amounts of organic material. From Kermit Berger, Introductory Soils (New York: Macmillan, 1968). Drawing: Lezlie Johannessenn.

Other elements of the project can also change. Deck or patio sizes and shapes can change or they may be moved to another location. Structures may be added, deleted, or moved. Keep in contact with the landscape architects and other designers working on the project. Impress upon them the importance of communicating changes and developments as they occur.

As the lighting designer assimilates this information, the lighting concept starts to formulate. The daytime view can be retained, reinforcing the fundamental landscape design, or changed to sculpt a new view at night (see Figures 1.1 & 1.2). The most complete information regarding the lighting desires of the owner, the physical layout of the site, the juxtaposition of buildings with the landscape, and the landscape design concept provides the best opportunity to develop a successful lighting system.

REFERENCES

1. Robert B. Miller and Stephen E. Heiman, Conceptual Selling, Miller-Heiman, Inc., Walnut Creek, California, 1987, pp. 63–104.

2. S. W. Boul, F. S. Hole, and R. J. McCracken, Soil Genesis and Classification, Iowa State University Press, Ames, Iowa, 1973, p. 27.

3. Kermit C. Berger, Introductory Soils, Macmillan, New York, 1968, p. 106.

4. Ibid., p. 105.

2

Vision and Perception of Light

Looking from a remote garden, a sculpture in a contrasting color, lit slightly brighter than the surrounding, beckons a person back to the main garden. Downlighting from trees lights most of the path, while two completely shielded path lights make sure that the bottom of the stairs are visible. Lighting the garden plantings surrounding the walk and the stairs fills in the boundaries and details of the space. This provides vertical surface lighting along the path aiding psychological comfort.

The human mind continually tries to create meaning or order out of the external stimuli received through the eye. To design with light, the designer needs to understand how the two organs (eye and brain) work and the interaction between them. The process of seeing starts with the eye receiving stimuli and culminates with the brain interpreting information, translating it into shape, size, texture, depth, motion, and position.

Light functions as a stimulus. The light pattern in a space creates a response from a viewer. If the light changes in the space, a person’s feeling or reaction to the space will change. Human beings are dynamic—continually responding. This applies to the sensitivity of both the eye and the brain to light. Under differing lighting circumstances, the human interpretation of a space will change.

The brain organizes the information continuously arriving through the eye in an attempt to produce order and meaning from the jumble of sensory data received. During the interpretation process, the brain constructs a view for the person. While the actual functioning of the brain is not clearly understood, scientists know that the brain has a memory capability that provides both expectations and a storehouse of previous experiences that allow people to interpret familiar objects in low light levels.

At times, the brain corrects information to fit a best or simplest interpretation. For example, in the dark, the eye cannot distinguish color easily, but the brain remembers that the brick in a wall is red. This phenomenon is called color constancy. Phenomena of this type occurring in the brain help people cope with their surrounds. The seeing process provides valuable information to the designer that helps guide what could or should be done with landscape lighting.

Human vision is selective due to the physical structure of the eye. Designers need to be aware of how the eye deals with stimuli, which is called brightness, and, equally important, how the mind steps in when the eye cannot cope with the stimuli presented. This chapter will look at both the physical and psychological aspects of the seeing process. Since landscape lighting involves primarily low light levels, this discussion will emphasize the way the eye functions in dark environments and how light cues can direct people. For further information about the functioning of the eye or the seeing process, see the list of reference books in the Bibliography.

HOW THE EYE WORKS

The eye sees images of brightness. Light enters the eye and strikes the retina, a layer of light-sensitive cells along the back wall of the eye (see Figure 2.1). The retina has two types of photo receptors: cones, high-light-level receptors, and rods, low-light-level receptors. These receptors generate photochemical reactions that travel along the optic nerve to the brain. The brain collects these signals and translates them into pictures.

The eye reacts to light levels by involuntary action of the iris, a kind of shutter mechanism. In bright light, the iris protects the eye by closing over the pupil, the black, circular opening that allows light to pass to the retina (see Figure 2.1). In dim light, the iris opens to expose more pupil and allow more light into the eye. Adjusting to bright light is called photopic vision, and to dim light, scotopic vision (see Figure 2.2).

The change between photopic light level and scotopic is called the Purkinje effect. Depending on the light level around a person outside at night, they may be experiencing the range in between these two which is called mesopic vision. Exterior lighting levels tend to be lower than the photopic level, so as one leaves an interior space to go outdoors, their eyes start adjusting. The range of mesopic vision straddles the range of capabilities of the other two. For example at the low end of mesopic vision the eye is at the threshold of cones. At the high end, rod saturation begins. As the eye shifts, its response to color shifts from warmer to cooler and it’s normal functioning shifts from foveal to peripheral. This becomes critical in an situation where safety is involved. In the lighting world most research has been done on driving, but, in landscape lighting it would apply more to a persons concern about physical safety — is there a threat nearby? ⁷,⁸,⁹

In light levels approximately equal to or greater than 1 footcandle, images of brightness impinge primarily on the fovea, a spot on the retina directly behind the pupil containing the highest concentration of cones. The fovea, due to acute light sensitivity, allows us to discern variations of color, details, and shape. Natural lighting levels drop significantly from day to night. Moonlight produces only a fraction of the level produced by the sun (see Figure 2.3). As the light level drops below 1 footcandle,1 or 3 cd/sq.m ⁷ perception switches to the rod receptors. They provide peripheral vision, consisting of the perception of brightness contrast and movement. This occurs because they line the retinal wall with greatest concentration at the side of the eye, gradually decreasing in number as they approach the fovea.

Figure 2.1. Parts of the eye. Drawing: Lezlie Johannessen.

The eye perceives an object based on the amount o

f light reflecting off it. Three factors influence the amount of light that will reflect off the object to the eye: color, texture, and finish. Light colors reflect more than dark colors (see Figure 2.4). Smooth textures reflect more than rough surfaces (see Figure 3.4). Shiny surfaces reflect more than matte surfaces. The apparent brightness of an object also depends on the brightness of the surrounding area or brightness contrast from one to the other.

Changes in brightness level within the field of view trigger two involuntary adaptation responses in the eye: expansion or contraction of the iris and a photochemical change. Although the eye adapts to a wide range of levels, it does not respond as well to large changes of brightness in the field of view. The iris opens and closes as the eye moves from one brightness to another controlling the amount of light allowed to enter into the eye. This causes no long-term effect on the eye, but during extended viewing muscle fatigue can cause eye discomfort when several brightly lit focal points have no fill light between them to act as a brightness bridge. (Refer to Figure 2.5 for recommended brightness relationships [luminance ratios] for various lighting situations).

Both cones and rods have compounds that respond to light and send signals to the brain. Rhodopsin or visual purple, located in rods, permits dark adaptation. Exposure to high light levels bleaches rhodopsin, impeding the rods’ ability to respond. Darkness starts the regeneration of rhodopsin, permitting the eye to begin responding as a person moves from a brightly lit space to a dark space. However, it takes several minutes for a view to start appearing. Complete adaptation takes 20 to 30 minutes. The eye adapts more quickly when shifting from low to high light levels. Initial response occurs within a minute, and full adaptation between 7 and 12 minutes.²,³

The dark-adapted eye can recover quickly when exposed to a flash of light (10 seconds’ exposure to a dim light requires roughly 60 seconds’ recovery time).¹ However, extreme shifts in brightness level cause momentary disorientation.⁴ Minimize this problem by providing a transition level of light between areas with a sharp contrast in brightness level.

Current research suggests that the eye continually adjusts to changes in spectrum of light, quantity of light, location of response in the retina, and length of exposure. Due to this dynamic response, scientists have difficulty in clearly identifying how vision works. Sensitivity to light includes functions in the eye, in pathways to the brain, and in the brain. Research into brain functions, including memory and expectations, may change our understanding of vision in the near future.

Figure 2.2. As the light level varies, the eye’s response to color shifts. In high light levels, the eye sees color according to the solid line on the graph. As the light level drops, the way the eye sees color shifts to the dashed line on the graph. This tells designers that the eye has less sensitivity in the warm end of the visible spectrum. Cool colors are more easily discernible.Based on material from The IES Fundamentals Course Manual, 1976, Illumination Engineering Society of North America, New York.

DESIGNING FOR THE EYE

Plan for eye response in dark environments. Since brightness attracts the eye, a contrast between dark and light causes the eye to attempt to adapt to both brightnesses. When a viewer focuses on the light object for several seconds to several minutes, dark adaptation may be broken. Then, when shifting view to a dark area, the eye will have to start adapting again. Understanding how the eye works helps direct landscape lighting decisions:

Use dramatic changes in brightness level cautiously to minimize or eliminate eye discomfort.

Provide transition light levels in border areas between interior and exterior spaces to soften brightness contrast.

Layer light into the landscape to provide a brightness-level balance, which allows the eye to move through the space without a continual shift of the iris opening.

Provide even light level along walkways to aid in human comfort and minimize fatigue. Pools of light confuse the eye and cause shifts of the iris opening size.

Control the brightness of light-fixture lenses or openings. This minimizes uncomfortable contrast and directs attention to the intended lighting effects rather than to the fixture.

Eye defects and physical deterioration of the eye due to aging affect the eyesight of many people. These disorders include the inability of the eye to accommodate. Accommodation refers to the ability of the eye to locate and focus on an object in the visual field. Ciliary muscles and suspensory ligaments change the shape of the lens from flattened for long distances to spherical for short distances. The pupil size changes, becoming larger for distant objects and smaller for near objects.

Figure 2.3. Light level chart

Figure 2.4. Typical reflectances based on material from the IES Lighting Handbook, Reference Volume, Illuminating Engineering Society of North America, New York, 1984.

Figure 2.5. Luminance ratio chart

Figure 2.6. The electromagnetic spectrum shows the continuum of all electric and magnetic radiation. The portion visible to the human eye is the small portion roughly in the middle, called the visible spectrum. The expanded portion showing the visible spectrum shows how it encompasses all colors of the rainbow, from violet to red. Drawing: Lezlie Johannessen.

As people age, the lens becomes less elastic, preventing it from changing shape to focus on objects at differing distances from the eye. This aging process begins at approximately 30 and accelerates past 40.⁵ Other aging problems include:

Yellowing of the lens and other eye components, which affects color perception, primarily in the blue end of the visual spectrum.

Clouding of the lens, which obscures detail and affects perception of brightness. To compensate, raise the light levels and reduce brightness contrast.

Shrinkage of many eye components, due to reduced fluids in the eye, which limits the range of pupil opening size and therefore the amount of light entering the eye. This causes exaggerated brightness contrast to the eye, requiring careful brightness control.

Hardening of the lens, which limits its ability to change size. This affects focusing on close objects.

Reduced coordination and loss of elasticity of muscles and ligaments, which control many eye functions. This restricts adaptation, requiring more careful brightness contrast control.

Color perception also plays a part in night vision, but to a lesser extent than during day vision. The color response of the eye shifts in low light levels toward the blue end of the visible spectrum (see Figure 2.6). Although this suggests that cool light sources may be seen more easily, a balanced or white light offers the best approach. The eye, familiar with the relatively balanced white light from the sun and the warm color of incandescent light in residences at night, favors white light sources. While inconclusive, preliminary research shows a better visual response to light from a continuous wide band across the visible spectrum.6 Light sources with discontinuous spectral output may make focusing difficult.

PERCEPTION

The combination of the eye admitting light and the brain interpreting this visual information provides cues and direction to people at night. One phenomenon of light is that the human eye is always attracted to the brightest light in the field of view. Designers can use this to build a composition by planning which area or object in a landscape should be brightest. This can work against a design when the brightness of a fixture lens is not controlled, distracting the eye from a more important element in the composition.

Designers can direct how people see a space by controlling the brightnesses introduced into the space. A soft light level in the front of a space with a more brightly lit object or area farther into the space draws the eye through the space to the distant object. Controlling brightnesses can also direct people’s movement through a space. Walking through a dimly lit area will feel comfortable as long as the person is heading toward an area with a higher light level visible to the viewer from the outset. This acts like a visual destination, especially if the lit area includes a vertical surface. Humans are vertical animals. We see vertical surfaces before we see horizontal surfaces. This affects us when walking through dark areas and changes our perception of a space when the walls of the space have been lit.

When a designer plans to vary the level of light from one area to another or one object to another, care must be taken not to create too high a brightness contrast. A large difference in light level from one object to another introduces confusion to a space. Many landscapes will have multiple areas of interest, requiring several areas with high light levels and areas of less interest that do not require accent lighting. Uneven numbers will produce a more stable effect in a lighting composition. Three represents the most stable number of objects lit to the same level. This creates a triangle of interest, allowing the eye to move from one area to another in a continuous motion. When two objects are lit as focal objects the eye bounces from one to another. To avoid a spotty effect when highlighting multiple objects, introduce a lower fill light level between the objects, providing a bridge from one object to the next.

People feel comfortable when they can see the boundaries of a space. It does not matter whether the light is soft or strong (this is directed by design intent), just that the edges of the space are identified. In large landscapes, the designer or owner does not always want to treat the entire property with light. A decision should be made as to what should be the visual boundary.

When planning the lighting for a project, the designer can direct the viewer’s eye through a space. Introduce light that creates a path through the darkness, taking the eye to an area intended for use or viewing (see Figures 17.17 & Color Plate 60). The manipulation of light to make a