In a large building with centralized air conditioning, a chiller or condenser pumps “chilled” water through a system of tubes running the ceiling. This is generally efficient and effective, but requires a lot of land and has a high up-front cost. In buildings with many disjointed rooms, installers have been shown to prefer the flexible PTAC for heating and cooling.
You have most likely seen one of these small all-in-one air conditioning boxes in buildings before. They are often wall mounted and can be controlled by a remote or manual controls on the outside of the box. They became popular because of their low price point and ease of deployability. Why spend tens of thousands on a central chilling system when you can cool each room with a machine that can cost as low as $150?
If it ain’t broke, don’t fix it has been the common theme when building owners have considered their AC systems. Nursing homes, hospitals, hotels, and homes are littered with outdated and inefficient PTAC systems which burn through energy much quicker than modern systems. According to the U.S Department of Energy, even systems 10 years old are 20%-40% less efficient than their modern counterparts. The SEER rating organization recommends a system with a rating of at least 14 and warns that most older PTAC systems have a rating around 6. When trying to save, modern technology is there to help.
Unless controlled by an energy optimizer such as Zero Energy Solutions OAK (zero.energy hyperlinked), PTAC systems have the weakness of each being manually controlled. Without centralization, waste is common and users often leave the devices on when not needed and blast the air conditioning to a temperature that is lower than what would be sufficiently comfortable. Psychology has shown that people tend to be loyal to a specific temperature and not a zone of comfort. Their energy bill suffers.
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