Cooling people, not buildings
Entering the manufacturing plant in Penang, Malaysia, we breathed a sigh of relief from the oppressive conditions outside to bask in the cool, dry air in the lobby. After a greeting, we walked toward a conference room for our meeting. Our host opened the door and we immediately felt the heat and humidity in the room, which was a surprise because the lobby had been so comfortable.
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Entering the manufacturing plant in Penang, Malaysia, we breathed a sigh of relief from the oppressive conditions outside to bask in the cool, dry air in the lobby. After a greeting, we walked toward a conference room for our meeting. Our host opened the door and we immediately felt the heat and humidity in the room, which was a surprise because the lobby had been so comfortable. Of immediate concern was whether the conference room was air conditioned. It was tempting to suggest that we meet in the lobby instead.
That concern vanished as soon as our host turned on the lights. He also turned on the air conditioner and, much to our relief, cool air immediately began to flow. In minutes, temperature was no longer an issue and the high heat and humidity faded to a distant memory while the meeting continued and we were absorbed in our discussion.
In Malaysia, the weather is fairly consistent year-round—hot and humid. Located just a few degrees north of the equator at almost the opposite side of the planet from my home in Minnesota, it takes about a day of travel to get there.
Walking through the manufacturing plant in Penang was intriguing in itself considering the many cultures that made up the workforce. But it was how the air conditioning worked that really left an impression—it must be the effect of a working lifetime in the HVAC business.
The experience started opening my mind to accepting different ways to create comfort in our buildings. Having more efficient system options will be important in the face of our growing and urgent need to reduce energy use in buildings.
What are we cooling?
Reflecting on that experience later, and at the time, traveling outside the United States, a couple of things stood out:
People were being cooled, not necessarily the buildings
A beginning of an understanding toward why alternatives to central chilled water systems evolved outside the United States.
Not just cooling buildings, but cooling people, was a revelation. If a room is not in use, why cool it? Our expectation in the United States tends to be that any room should be comfortable at any moment in time, whether or not it is being used.
Turning on a light is OK, but we are not conditioned to turning on comfort. Saving energy by turning off lights was a frequent reminder back in the 1970s when we first dealt with energy conservation. Some of you may remember the signs adorning light switches in public buildings, urging us to save energy by turning out the lights when we left the room.
Having cut my teeth on chillers and central systems, it was difficult to accept the ideas of not using them. After all, what could be better than a central system if you could afford it? But now, after years of being exposed to many applications that use non-central systems, what has evolved is an appreciation of another tool in our arsenal to create comfort in our buildings at minimal energy usage.
I was able to witness a group of experienced U.S. commercial sales engineers tour large buildings in Belgium. The buildings use variable refrigerant volume systems, which also opened my mind to the possibilities of these systems being used in addition to or in lieu of central systems in commercial buildings. Why is that?
Space saving: more rentable area by freeing up floor space
Less structure on the roof
Extremely quiet operations that should be witnessed to appreciate
System backup in case of failure
Easy retrofit for air conditioning buildings with no existing ductwork
Less required ductwork and less shaft space: the only ductwork required is floor-by-floor
Very good zone control
Flexibility to move condensing units in an elevator
Floor-by-floor investment as tenants occupy space
Single supplier of the system, including controls
The interior space can look the same as what is used to with a wide choice of diffusers
No operating engineers required due to the modular size of the system.
What stands out is the zoned philosophy of these non-central systems, which include ductless and variable refrigerant volume designs. Sure, buildings in the United States are constructed so occupants can turn zones on and off in a variety of ways, but realistically, we often do not. We expect invisible comfort, it should always be there and we don’t want to think about it, see it, or have to manage it on a daily basis. But outside the United States, energy costs also have been much higher for a long time and air conditioning often is considered more of a luxury. Using air conditioning more sparingly and, when it is used, using it efficiently, became design foundations. Cool people, not buildings.
Think outside the chiller box
Recently, I toured a building in Shanghai that is familiar to those of us in the United States. It uses a chilled water system consisting of centrifugals and direct-fired absorption chillers supplying chilled/hot water with four air handlers per floor and VAV boxes in each zone.
The purpose of the visit was to demonstrate a large, applied chilled-water system to a group not familiar with such systems. It was impressive to see a huge equipment room in the subbasement with an intricate set of large pipes, many sets of large pumps, and multiple air handlers on each floor with ductwork streaming out of them to a number of VAV boxes.
On the obligatory tour of the roof to see the cooling towers, we were surprised to find a multitude of small condensing units quietly tucked in and around the cooling towers and the other roof equipment. Evidently, due to additional cooling loads that were added after the building was occupied, variable refrigerant volume units had been easily retrofitted to provide cooling. It was intriguing to see central and variable refrigerant volume systems working in harmony on the same building.
But what was most intriguing about this was the perspective of first showing the large equipment room for the chillers, space on each floor for the air handlers, and multiple large cooling towers on the roof to people who were not familiar with those systems. Then we saw, placed around the multiple cooling towers, a number of small, very quietly running air-cooled condensing units for a variable refrigerant volume system. It was quite a contrast in systems, size, and complexity.
The point? It’s not that one particular system is better than any other, but that there are definitely applications that are suited toward certain system types or combinations of types. Our responsibility is to keep an open mind for the best solutions for particular buildings and how they’re used.
It’s widely known that chilled water is one answer, but rooftop, self-contained, water-source heat pumps, split systems, air-cooled, water-cooled, and variable refrigerant volume systems that have been in use for more than 25 years all over the world are all good options. Properly designed, they are options that can give the owner, the building, and its occupants a comfort solution that is ideal for their application. It’s eye-opening and mind-broadening to see a multitude of applications where chilled water is mixed with variable refrigerant volume systems, or where standalone variable refrigerant volume systems are installed in buildings that looked like applications where you would find “conventional systems.”
As we further address energy conservation in our buildings to respond to the rising cost of energy and reduce their environmental impact, it is comforting to know we have options, which had their origins in countries where energy has been more expensive for a longer time than the United States. Cooling people, not buildings, may be the way we choose in the future and using variable refrigerant volume systems is one way to achieve that objective.
|Suzukida is president of Lanex Consulting LLC, Shoreview, Minn. He is a member of CSE’s editorial advisory board.|
Not sure how these systems operate? It’s like a chiller system that circulates refrigerant instead of water to ducted or non-ducted fan-coil units. The compressor and condenser are located outside the building and the evaporator and expansion valve are inside. In a majority of the systems, the heat pump mode is used because it is a natural system, moving the heat around the building where it is needed and removing it where it is not. Because refrigerant piping is used instead of ductwork or water pipes, the amount of space required to move the same amount of energy is significantly reduced, as illustrated in the diagram.