Cost is a critical component of any project to be predicted, monitored and controlled.  It is the one metric that everyone understands, at least on a superficial level.  Deeper understanding of project costs requires insight into the sources, benefits, and alternatives available.  Various tools are available to document and compare lighting system designs.
            Basic methods often lack accuracy, but are useful for preliminary screening purposes.  More-sophisticated methods capture greater detail, facilitating assessment of the impacts of design decisions and assumptions on project costs.  In this installment, common cost analysis methods are presented, from the simple to the complex.

            Light that does not contribute to its intended purpose, i.e. visual performance in a defined area, is wasted.  When it detracts from the experience of surrounding areas, light is obtrusive.  Wasted light is often obtrusive, but need not be to contribute to nuisance.  Systems that produce little wasted light also contribute to nuisance.  The existence of nuisance light is bothersome irrespective of its impact on visual performance, though it can be significant.
            Several aspects of nuisance light, also known as “light pollution,” are considered in this installment of the “Workplace Illumination” series.  Many parallels are evident between light pollution and “noise pollution.”  Review “Occupational Soundscapes – Part 15:  Community Noise” [15May2024] for a presentation of the latter; read on for a discussion of the former.

            Superficially, lighting for safety, security, and emergency situations may seem redundant.  While there is overlap among these lighting scenarios, they are differentiated by their primary purposes, operating conditions, and characteristic requirements.  There is also an interdependence among these lighting scenarios, despite independent operation in the majority of circumstances.
            In this installment of the “Workplace Illumination” series, the characteristics of safety, security, and emergency lighting are explored.  What separates them and what unites them in a cohesive lighting system design is discussed to enhance understanding of each lighting scenario and recognition of their interdependencies to support effective installation and maintenance.