HVAC (Heating, Ventilating and Air Conditioning) systems have evolved and gotten better with technology.  Matching system requirements with the need and with quality will always trump the bells and whistles. Over the years I have worked with a number of HVAC subcontractors and a few thoughts come to mind that might be useful:

SYSTEM ENERGY EFFICIENCY
Depending on the application and occupancy, a higher SEER (Seasonal Energy Efficiency Rating) for equipment is preferable most of the time. A higher the SEER means more expensive equipment, but the lower operating cost is a win for energy and your occupants.

SYSTEM MAINTENANCE
When selecting the right HVAC system, keep in mind the occupancy type vs. the long-term cost of maintenance. Chilled water/boiler systems will require preventive maintenance for a chiller, cooling tower, boiler, heat exchanger, etc to a greater extent than a DX (direct expansion) unitary system. A DX split or packaged system will be a handful of components that are readily available and replaced at a minimal cost.

INSTALLATION COST
Most of the HVAC system cost is in the equipment and control system. Both are important to system sustainability. Duct systems normally require little maintenance if quality materials, closure systems, sealants and higher “R” value insulation are used. Providing the correct type of air distribution is just as vital as selecting the equipment and will maximize coverage, eliminate the draft effect on occupants as well as air noise transmitted from the device due to a high velocity (fpm) of air.

BUILDING AUTOMATION

There’s a big debate over whether to use programmable thermostats or fully automated systems. Most projects perform well with proper zoning and programmable thermostats as opposed to extensive control systems that require increased up front cost and service for the life of the system.

Each control system has a place in the “right choice column.” A commercial building operating from 8 a.m. to 5 p.m. will have different needs than an institutional building or medical facility. The challenge with a fully automated system is it’s almost always proprietary in nature and can only be serviced by the brand vender, leaving the building owner with no other option for value shopping. A stand-alone zoned system with programmable thermostats is fairly user-friendly and can be serviced by any commercial company. This dramatically reduces long-term replacement and/or maintenance cost for the end user.

To me, when it is all said and done, you need a cost-efficient system that will deliver the performance and can be maintained without having to go to the banker every time a failure happens.

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Merrill Stewart is Founder and President of the Stewart Perry Company, a commercial building contractor based in Birmingham, Ala. Contact him via email.
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