Ecostructure Glossary

The following definitions are not necessarily accepted throughout the professions of those who plan, design, construct, manage, maintain, and use infrastructure. I have drafed some of these to resolve ambiguities in common usage or to address particular considerations regarding the interactions of people, infrastructure, and environment. Components of definitions shown in italics are themselves defined in this glossary.

This is a work-in-process. I welcome your suggestions for additions or corrections.


ACCESSIBLE SERVICE AREA Space within a facility designed to facilitate maintenance and repair of equipment; accessible in the sense that personnel and equipment can in fact gain access and complete required tasks.

ADAPTIVE REUSE Conversion of a facility or part of a facility to a use significantly different from that for which it was originally designed; e.g., converting a railroad station to a shopping mall or post office to a rail station.

BENCHMARK A basis for comparison derived from past behavior or characteristics of a system or comparable systems, against which current behavior or characteristics may be judged; not a standard, although standards may be adopted from benchmarks

BENEFITS The delivery of services, shelter, and other support a facility provides to its owners and users throughout the facility’s lifetime; may be positive or negative, but generally assumed to be positive (see disbenefits); may be valued in monetary or other terms.

BUILDING Type of constructed facility; generally intended to provide shelter from inclement conditions.

CANYON Vertical service bays in a building‘s structure, designed to house communications, electrical, and mechanical service distribution equipment in a readily accessible way; a type of accessible service area.

COMMISSIONING An activity commenced at completion of construction and often including initial user occupancy, intended to allow designers and managers to check functional subsystems, to determine that the facility is functioning properly, and to undertake any necessary remedial action. Commissioning typically spans a period of 6 to 12 months.

COMPONENT A part or product specified for use in a constructed facility (e.g., air chiller units, pavement, turbines); also an element. See specifications.

CONSTRUCTED FACILITY A facility, the physical product of construction activities; an assemblage of relatively distinct functional systems, sub-systems, elements, and components.

CONSTRUCTION The process of creating facilities, typically according the designers’ plans and specifications.

CONTRACTOR The organization responsible for construction of a facility, typically under contract to an owner.

COSTS Expenditures of funds or the fungible equivalent, at a particular time, required to obtain the benefits of a facility; valued in monetary terms; not the same as disbenefits.

COSTS OF OWNERSHIP The total of all costs, generally incurred by the owners but also possibly by the users, necessary to obtain the full benefits of a facility during the period of ownership.



DESIGNERS Architects, engineers, and other professionals responsible for making technical recommendations about a facility‘s configuration, materials, mechanical systems, and other characteristics that determine future performance and cost.

DESIGN LIFETIME Also design service life; the period of time over which a facility, subsystem, or component (e.g., the pavement, roof, pipeline, or generators) is designed to provide at least an acceptable minimum level of service, as defined by the designer or owner; typically depends on assumptions, sometimes implicit, regarding satisfactory completion of normal maintenance activities. An idealized service life.

DESIGN SERVICE LIFE See design lifetime.

DISBENEFITS. Undesirable results obtained by infrastructure’s owners, users, or neighbors as a result of the facilities’ performance; negative benefits; not the same as costs, although the terms are sometimes used interchangeably.

DISCOUNT RATE A measure of the economic time value of money, the opportunity cost of having funds or benefits available now versus at some future date; may include allowance for inflation (nominal discount rate); generally expressed as an annual percentage rate; not the same as interest rate.

ECONOMIC LIFE An assumed period of time over which costs and benefits of infrastructure are assessed for purposes of making decisions about design and management; see design lifetime. The economic life is sometimes established by tax regulations or other legal requirements or accounting standards and is not necessarily related to the likely service life of a facility or subsystem.

EFFECTIVENESS The degree to which a system accomplishes the tasks set for it by owners, users, neighbors, and society-at-large.

ELEMENT See component.

EQUIVALENT ANNUAL VALUE The net amount of costs and benefits that, if received as a uniform annual amount for the duration of the economic life, would have a present value equal to all costs and benefits anticipated; computed using the discount rate; see present value.

FACILITY A physical element of infrastructure; intended to provide support, shelter, or otherwise to facilitate economic or social activities and thereby accrue benefits for humanity.

FACILITY PORTFOLIO A collection of buildings or other constructed facilities managed by a single agency or other owner.

FINANCIAL COSTS Costs expressed in terms of monetary value at the time incurred; see discount rate and inflation.

GREEN INFRASTRUCTURE Infrastructure that uses natural processes and features (such as wetlands, stream basins, and the biological and chemical functions they support) to provide services..



HVAC. Heating, ventilation, and air conditioning.

INFLATION A rise in the general price level, typically expressed as an annual percentage increase; also described as a general decrease in purchasing power of a given amount of funds.

INFRASTRUCTURE The supporting structure of society; a complex socio-technical system comprised of facilities and other physical components (e.g., bridges, roads, reservoirs, cables, pipes, rails, schools, health-care, and public safety facilities, parks and open space) and the institutional and management relationships among these components and the society that uses them; society’s skeleton, sinews, and nerves. Infrastructure delivers a varied range of valuable and essential services and is a storehouse of resources and wealth that each generation inherits, uses, and passes on to succeeding generations.

INTEGRATED BUILDING SYSTEMS Functional systems designed specifically to fit and work together as a larger system; intended to provide better performance than systems not designed for integration.

INTEREST RATE The percentage cost incurred for use of funds (typically borrowed) over some period of time; typically expressed on an annual basis; typically includes amounts to account for expected inflation, time value of money (see discount rate), and compensation for risk and administrative effort of the lender who provides funds.

INTRINSIC REMEDIATION (BIOREMEDIATION) The reduction of an environmental hazard through the action of organisms or processes indigenous to the media or setting in which the hazard is found; e.g., naturally-occurring soil micro-organisms converting groundwater contaminants to harmless substances.

LEVEL OF SERVICE A standardized measure of infrastructure operating conditions, e.g., traffic flow on a highway; generally defined with reference to a benchmark; a measure of effectiveness.

LIFE CYCLE. The sequence of events in planning, design, construction, use, and abandonment or disposal (e.g., through sale, demolition, substantial renovation) during the economic or service life of a facility; may include changes in use and reconstruction.

LIFE-CYCLE COST The present value of all anticipated costs to be incurred during a facility’s economic life; the sum total of direct, indirect, recurring, nonrecurring, and other related costs incurred or estimated to be incurred in the design, development, production, operation, maintenance, support, and final disposition of a major system over its anticipated useful life span.



MEASURE OF EFFECTIVENESS A sign, symbol, or statistic (typically numeric) that people understand to convey information about how well infrastructure is accomplishing its tasks; may be defined relative to a generally-used scale (e.g., water flow rates), a benchmark (e.g., the 100-year flood), or a standard (e.g., above or below the minimum standard).

MODULARITY In a building, the separation of major user areas into zones served by independent mechanical and electrical components; also a characteristic of integrated building systems, in which repetitive use of components and subsystems facilitates facility maintenance and repair.

NET PRESENT VALUE The sum of the present values of all costs and monetary-valued benefits of a facility over its economic life.

NONMONETARY COSTS Disbenefits not readily measurable in monetary terms, such as air pollution emissions or worker absenteeism.

NONRECURRING COSTS Costs incurred once, infrequently, or on an irregular basis during a facility’s economic life, typically for repair or replacement of components or subsystems.

NONQUANTIFIABLE COSTS Disbenefits not readily measurable but attributed to a facility’s performance, such as worker dissatisfaction or dissolution of a community.

OBSOLESCENCE. The condition of being antiquated, old fashioned, or out of date, resulting when there is a change in the requirements or expectations regarding the shelter, comfort, profitability, or other dimension of performance that a facility or subsystem is expected to provide. Obsolescence may occur because of functional, economic, technical, or social and cultural change.

OPENING CONFIGURATION. A term used by some designers; the specifics of use dictated by the facility owner and initial users during the earliest stages of project development; the spatial and systems configuration that should be considered as simply the first of many uses for which the facility should be planned if its service life is anticipated to exceed its economic life.

PERFORMANCE. The degree to which a facility or system fulfills the purposes for which it was built or acquired, or which it is now expected to fulfill; a function of effectiveness, reliability, and cost.

PERIODIC RENEWALS. Regular changes of elements, e.g. replacing seats, painting structure, overhauling mechanical equipment, to maintain acceptable performance.

PHYSICAL LIFE The time it takes for a facility, subsystem, or component to wear out or fail to perform its intended functions because of physical deterioration; typically differs from service life.

PLANNED SHORT SERVICE LIFE A design lifetime assumption that the service life of a facility will be shorter than might typically be expected; implies selection of components that have low first cost and low durability; similar to the term “planned obsolescence” used in the automobile and consumer-products industries.

PLANS AND SPECIFICATIONS The means by which designers convey what is to be constructed and contractors bid for the construction assignment; see specifications.

PORTFOLIO. A collection of buildings or other constructed facilities managed by a single agency or other owner.

POSTOCCUPANCY EVALUATION Collection and analysis of information, particularly from users, to assess how well a building’s performance matches design intent and user needs.

PREDESIGN ANALYSIS. Analysis involved in developing conceptual design alternatives and working out a variety of design details before the actual detailed design begins.

PRESENT VALUE A concept in economics reflecting the time-value of money, in which costs and revenues of future years are expressed in terms of their equivalent amounts if incurred in the present year; sometimes termed “discounted value;” may be computed for costs or benefits using the discount rate; see economic cost.

PROGRAMMING Activities that lead to determination of the specific scale, scope, and timing of facility construction; typically precedes consideration of spatial configurations, but when used in the architectural sense, includes determination of required capacities, floor areas, adjacencies of various uses, and functional connections among subsystems.

PUBLIC WORKS Facilities constructed by or for government and quasi-governmental agencies; often used in conjunction or interchangeably with the broader term infrastructure



RAISED ACCESS FLOOR In a building, a platform built several inches above the structural floor, creating a space to house communication, electrical, and mechanical distribution equipment; a type of accessible service area.

RECURRING COSTS Costs incurred on a recurring and generally regular basis throughout a facility’s economic life, typically for operation, normal maintenance, and anticipated repair or replacement of components or subsystems.

RELIABILITY The likelihood that a system‘s effectiveness will be sustained over a defined time horizon; may be measured as a probability.

RENEWAL Substantial repairs and improvements in a facility or subsystem that returns its performance to levels approaching or exceeding those of a newly constructed facility.

RETROFIT The redesign and reconstruction of an existing facility or subsystem to incorporate new technology, to meet new requirements, or to otherwise provide performance not foreseen in the original design.

SERVICE LIFE The period of time over which a facility, component, or subsystem actually provides adequate performance; a technical parameter that depends on design, construction quality, operations and maintenance practices, use, environmental factors, and users’ and owners’ expectations; may differ from economic life, physical life, or design lifetime.

SHELL SPACE In a building, space for which the structural system and typically the exterior envelope are complete but in which other functional subsystems are left for completion at some future time.

SPECIFICATIONS An explicit description of the characteristics required of a facility or a component, or of the performance to be delivered; typically a part of the plans and specifications.

STANDARD A basis for comparison and assessment of the behavior or characteristics of a system, established by law, regulation, consensus, or common practice. See benchmark.

SUBSYSTEM Functional part of a system, and often used interchangeably with that term (e.g., the guideway and controls of a rail transit system, the heating subsystem of the HVAC system).

SYSTEM Collection of subsystems, components, or elements that work together, e.g., to provide some major aspect of infrastructure‘s services (e.g., water distribution system, building electrical system); the value of the assemblage is greater than the sum of its part. Also, a set of building components specifically designed to work together to facilitate construction (e.g., modular building system).

TIME HORIZON The period of time considered by an analyst or decision maker in choosing among alternative designs or management strategies; typically the economic life for such facilities decisions as lease or purchase, build or buy, and renew or replace.

VALUE ENGINEERING Currently defined by many government agencies as an organized effort directed at analyzing the function of construction operations, systems, equipment, facilities, procedures, methods, and supplies to determine if anticipated costs are consistent with the requirements for performance, quality, safety, and maintainability.

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