tishman construction: developer of 2′ x 4′ ceilings and occupancy sensors?

Ever wonder where 2′ x 4′ ceilings come from?  Or occupancy sensors?

I just read an interesting biography called “Building Tall” by John L. Tishman.  John Tishman led the construction division of his family’s real estate company for many decades.  Tishman Construction racked up a most impressive list of buildings for which they acted as professional construction managers, including the Hancock Tower in Chicago, both the original and the rebuilt World Trade Centers, and EPCOT Center at Walt Disney World, among countless others.

In the biography, I found two gems of history relating to the lighting industry:  Tishman helped develop the first ceiling system based on 24″ square dimensions, and also developed one of the earliest uses for infrared occupancy sensors.

Here’s the section where Tishman describes the process in which they developed 24″ ceiling systems instead of the earlier 12″ grids:

Light from the Ceilings

Developers of office buildings in that era would provide prospective tenants with certain “building standard improvements,” typically the floor covering, ceiling system, and light fixtures. We would guarantee an illumination level of a certain number of watts per square foot, and then go about spacing the lighting fixtures to provide that level. We would also offer several variations of such configurations for a single price. Innovative interiors and tenant installations were a selling point for our firm’s office buildings. One such innovation involved changing the module for office space ceiling tiles. Prior to this time the standard ceiling tile modular size was 1×1 foot, but the standard for fluorescent lighting fixtures was 1×4 feet. That meant four fluorescent lamps had to be squeezed into a one-foot wide metal shell, and this crowding created so much heat that the bulbs were literally fried and their efficiency and life expectancy dramatically reduced. The crowded space was also a magnet for dust and all sorts of insects attracted by the bright lights. This made for high operating costs, since the bulbs had to be replaced frequently and the fixtures cleaned often to produce the expected light levels. The logical solution, it seemed to me, was to increase the space between the bulbs so that the heat they put out was more easily dissipated, allowing the bulbs to last substantially longer. My former math student Fred Shure joined me in trying to solve the problem. We increased the size of the ceiling tiles that had been traditionally 1×4 foot, to 2×4 feet. This simple change allowed the four fluorescent light bulbs to be spread apart within a 24-inch-wide fixture, instead of within the smaller space that had been the previous standard throughout the industry. In this way the fluorescent bulbs were no longer fried by the others’ proximity, and there was no decrease in the light available at desk height. We worked with the manufacturers to fabricate these larger ceiling panels and light fixtures, and installed them as the “tenant standard” throughout the 99 Park Avenue building. Not only did the fixtures allow the bulbs to last much longer, but because the acoustic panels and lighting fixtures were wider and removable, the spaces above the hung ceiling were easier to get at for cleaning and alterations. Additionally, the quality of light at desktop height was far superior to the older configuration, since it was spread more evenly. The 2×4 fluorescents then became the standard throughout the industry, and the ceiling module became pretty much the standard throughout the country. Neither Fred nor I was able to make any money from this innovation because it was so easily copied, but we had the satisfaction of having created a nationwide standard. Fred went on to my alma mater, Michigan, for his undergraduate work and then to Harvard, where he earned a Ph.D. in physics. I was energized by this innovation, and went looking for other nationwide standards that we could upgrade.

Here’s the section where Tishman describes the process of developing infrared occupancy sensors:


Innovation doesn’t always have to entail inventing something yourself; sometimes, you innovate by making it possible to use another person’s breakthrough that otherwise might have sat unused. That’s what happened with us in regard to a device that we named Infracon. During the 1973 Middle East War, the oil-producing nations embargoed the sale of oil from that region to the United States, making oil scarce and expensive to American consumers, and as a consequence, spurring research into energy conservation. Tishman Research worked with federal and state agencies, and industrial companies, to come up with new ways for buildings to conserve more energy. The cost of electricity, which had gone up as a consequence of rising oil prices, was a significant factor in the operating costs of all buildings, and we looked for ways to lower that. We worked jointly with United Technologies to cut electricity use. One obvious target was lights that were usually left on all night so that cleaning crews could work in office buildings. Was it necessary to have the lights on during all the night hours, a period when most employees were not working in their offices? Of course not. So if we could figure out a way to douse the lights whenever no one was in the office for a stretch of time, that would save money and also conserve energy. Infrared sensors are able to detect the presence of small heat changes. We reasoned that a device that used an infrared sensor could be affected by very small temperature changes, and might be able to detect the sort of changes that are inevitably produced by human beings as they move within a room. We further reasoned that the absence of movement in a room for a given number of seconds or minutes would denote a lack of need for lights to be on in that room, and provide an opportunity for a relay to switch off the lights in that space. We purchased a sensor system that an inventor had not previously found a use for. We boxed it with relays to control high voltage and called it Infracon. United Technologies manufactured it for us. We installed the new heat-and-motion sensors in buildings that we built for ourselves, particularly in the conference and meeting rooms of our hotels, and in several instances, in areas within buildings that we built for others. Beyond saving money in use of electricity, Infracon provided benefits in terms of building security. The sensors functioned as a back-up security system, able to signal to guards at the front desk when someone was in an office upstairs—someone other than an authorized cleaning crew; for example, a burglar. We ultimately sold our rights in Infracon to an electrical contractor who in turn resold it to Minneapolis Honeywell. I am delighted whenever I see Infracon technology incorporated into other devices in which even minor heat variations in the air are used to trigger protective action, particularly if this usage results, as it is supposed to, in saving energy.

So now you know!  It is amazing sometimes to remember that fundamental “application standards” we take for granted today were very tightly linked to technologies of the time.  The question is:  What new standards will LED lighting generate?


About Brad Koerner

Venture Manager - Luminous Patterns Philips Lighting
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