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I agree with Mr. DiLouie that occupancy sensors save energy. EverGlow believes there are significant savings to be realized with all lighting controls and systems and, if installed and maintained properly, do not compromise occupant comfort or safety.
Our concern is with lighting controls - occupancy sensors and dimmers - that are installed in egress pathways. Although Mr. DiLouie does not specifically mention egress and occupant safety, he does suggest that occupancy sensors are appropriate for use in corridors.
When does a corridor become an egress path (or, how do occupants move from offices or conference rooms to the building exits)? Are lighting controls appropriate for use in exit stairs (exit stairs are clearly a part of the safety egress system in a multi-floor building)?
Consider that more than 90% of emergency evacuations occur in normal lighting. Emergency lighting, significantly dimmer than normal lighting, activates only after electrical failure or if it is switched on by the emergency alarm.
Normal lighting is the type of lighting that lighting control systems attempt to adjust automatically. It is against all building, fire and life safety codes to install lighting controls on emergency lighting that might compromise the ability of emergency lighting to provide minimum required lighting levels.
We prefer automatic dimmers better than automatic off lighting control systems in corridors and exits. For most lighting installations, it is far easier to control lighting on or off. And, for offices and conference rooms where the adjoining corridors are lighted to a dimmed level, there is certainly never any loss of occupant safety.
What lighting levels are safe and acceptable. Well, that depends on building codes and occupant demands. Most jurisdictions maintain that only 1-2 ft-candles of illumination at floor level is adequate (1 ft-candle of lighting at floor level is approximately that level of lighting that is needed to recognize a one dollar bill placed on the floor). Most occupants feel minimally comfortable in a minimum of 5-10 ft-candles of illumination (5 ft-candles of lighting is approximately that level of lighting that enables a person with normal eyesight to read a newspaper held a arm length). For most office work, normal lighting levels is approximately 10 times higher; for retail occupancies the lighting level is higher still.
EverGlow manufactures (non-electrical) photoluminescent emergency lighting and I am the operations manager. Code approved photoluminescent exit signs and exit path markings require room lighting to charge properly. For more information, please visit our website - www.everglow.us.