By Bud Hammer
HVAC systems are designed to provide indoor comfort, based on extreme weather conditions; therefore, they are inherently oversized for most days. The challenge we have is to adjust the system capacity for all the days the weather is between 0 and 100 degrees. There are many strategies to accomplish this feat, however, most systems react slowly to a change in weather; ergo, we have another challenge to deal with. In-between seasons has always been a tough time to make buildings comfortable on the inside. Outdoor temperature swings, humidity, sun shining, etc. present a challenge for many systems to overcome.
“Old School” conventional systems that use water as a medium for heating/cooling have traditionally been the toughest to manage. If a building needs heat in the morning and cooling in the afternoon, it’s almost impossible to accomplish with a water system that is either hot or cold. Newer systems have better reaction times. However, the ones that work best are smaller in capacity, and a building may require several of these “unitary” systems throughout, thereby making the installation and maintenance more expensive and burdensome.
Heat pumps are the current hot topic in our industry and make sense for quick reaction. Instead of water, they use refrigerants as a heating/cooling medium and have the ability to react quickly to a change in demand. Variable refrigerant flow (VRF) systems are gaining popularity and offer zoning applications so many occupants can set their own temperature range. The more advanced systems actually operate to “recover” heat and can be very efficient as they work to keep everyone inside as comfortable as possible.
As technology and building energy codes advance, we are getting better at matching conditions that change rapidly in buildings. Remember that air conditioning is still a new technology, and the industry needs to mature to learn what works well and what doesn’t. Many new buildings being built today do not use the “old school” method of heating/cooling due to improved efficiency with newer technology. However, the older buildings that have these water-based systems won’t be able to adapt since the same challenges exist. Water takes a while to change temperature, and the more water in a system, the longer it takes to adjust.
Suppose it’s time to consider updating your building’s HVAC systems. In that case, new technology should be regarded to improve indoor comfort under all outdoor conditions and improve operating efficiency. Hence, the building works better for less expense. And remember, professional maintenance is critical to keep systems running at peak performance.