Zoning System Design for Light Commercial Buildings

A zoned heating and cooling system provides excellent levels of comfort while allowing building occupants substantial control over the temperatures in their own zone. Zoning systems are frequently used in residential settings, but these practical and efficient HVAC set-ups can be just as useful for a light commercial building, such as an office or small retail establishment. A well-designed zoning system can improve overall HVAC efficiency and indoor comfort levels while reducing your heating and cooling bills by up to 25 percent.

Zoning System Basics

Zoning systems provide adjustable levels of heating and cooling to different areas of an indoor space. They allow a building owner or manager to separate a commercial building into separate areas, or zones, that will each be heated or cooled separately without affecting the temperatures in nearby zones. Zoning systems contain a series of motorized dampers that control the amount of warm or cool air that enters a specific zone. Excess conditioned air is diverted through a bypass system into another zone, into the return air system, or into a common area of the building. Each zone is equipped with its own thermostat, which allows occupants of that zone to set the temperature to their preferred levels.

HVAC Requirements

When planning and designing a zoning system, remember that zoned heating and cooling must provide the same basic functions as a single-zone forced-air or heat-pump based system.

• Heating and cooling: This is the core function of the system, but care must be taken to ensure that the zone system is designed to take advantage of environmental conditions while not affecting temperatures in adjoining areas.
• Filtration of indoor air: The zoning system must provide the same level of indoor air filtration and removal of particulates as a larger single-zone system.
• Humidity control: The zoning equipment should be able to increase or decrease indoor humidity as effectively as single-zone equipment.Zoning System DesignIn general, zoning systems for light commercial buildings are the same as those for residential applications, except that they are usually larger and have more heating and cooling capacity.
• Ensure proper sizing: As with all HVAC systems, a zoning system must be properly sized, with sufficient heating and cooling capacity to meet the demands of the occupants of your commercial space. A load calculation will give you and your HVAC specialist precise information on how much conditioning is needed and the required size of equipment.
• Install appropriate bypass ducts: The system must be able to deliver heated or cooled air quickly and efficiently, with any excess air diverted to a bypass system that either sends excess air to the return system or directs it to another zone or a common area of the building, such as a lobby. A configuration of three or more zones will require a bypass system.
• Restrict individual zones to a single floor: Zoning systems can work well in heating or cooling a single floor of your commercial establishment, but trying to condition anything larger will not work as well. In general, zoning systems work best when they are restricted to smaller zones such as individual rooms or office suites.
• Put the thermostat in the most-used room: If the zone consists of more than one room, put the thermostat in the room that’s used most often. This ensures that the zone will be conditioned according to its most frequent occupancy and function.
• Remember the effects of environmental factors: Zones that have windows that permit heat gain from sunlight, for example, will have different heating and cooling requirements throughout the day. Keep rooms with similar characteristics or conditioning needs within the same zone as much as possible.

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