How a Proper Controls and Integration Design Increase your Building Comfort
Thermal comfort within a building is frequently an afterthought, that is, until the space temperature needs to be adjusted for more heating or cooling. Homeowners understand that the thermostat in their home is the means by which they can make that adjustment, which is typically to a home furnace with or without air conditioning, a home boiler radiant heat system, or even a heating/cooling heat pump system. The same simple adjustment may appear more daunting, complicated, confusing, or even unknown when away from home in a work environment or visiting a building.
Homeowners frequently try to strike a balance between thermal comfort and energy costs. Outside of the home, in commercial buildings, facility owners or managers are frequently tasked with reducing energy costs for providing occupant thermal comfort and the required outdoor ventilation air.
A thermostat or space temperature sensor is associated with a microprocessor-based direct digital control (DDC) controller that is associated with a Heating Ventilating Air Condition (HVAC) system in each temperature-controlled zone within a building. The system may be self-contained in terms of heating and cooling, or it may be linked to a building plant that provides heating and/or cooling to individual HVAC systems. The temperature control system associated with the building equipment employs both occupied and unoccupied control strategies in order to reduce energy costs while maintaining thermal comfort. There are many temperatures display and setpoint options for space sensors depending on the location of zone temperature sensors and building management policies, including the option of having a hands-off blank cover.
A building automation system (BAS) is typically used to network individual equipment controllers and thermostats (if network capable) to provide a management level graphical interface to the entire temperature controls of the building. This enables the scheduling of building occupancy, the adjustment of space temperature setpoints, system monitoring, alarm notifications, and the trending of equipment operations and temperatures. Other systems that can be integrated into the BAS include building lighting, fire alarm system monitoring, security/access, elevator system monitoring, and electrical metering. These systems are typically connected via open communication protocols such as BACnet, LonWorks, and Modbus, which are industry standards. The additional data is intended to improve the operating environment in an energy-efficient manner.
Control Suppliers and Coordination of Installation with Building Owners
Several brands of BAS and controllers have been developed by industry leaders, some of which are considered proprietary and can only be installed and serviced by select area representatives/installers. Other available BAS and controllers are freely distributed and installed by certified installers, providing facility owners with more options for building controls installation and service. For controller network communications and integration, all systems use an open protocol.
There have been numerous successful installations of these systems, each with its own set of advantages and disadvantages. Several owners have successful relationships with control providers, while others are looking for alternatives to take a different path. A Master Systems Integrator is sometimes used by owners with multiple buildings and ongoing construction projects to maintain consistency with their BAS data configurations and graphics.
BAS technology is constantly evolving. Current control systems make use of the owner’s information technology network to provide a good communication channel for owners to monitor and maintain the HVAC systems in their buildings. Controller communications, which were previously wired to a building supervisory controller that served as a router via a single or minimal IP connection, are now taking advantage of ethernet technology. Controllers can now communicate using Cat-6 network cabling, which can handle more data at faster speeds.
Some IT departments accept multiple IP data drops to individual controllers; however, others do not, prompting the controls industry to develop Operational Technology (OT) networks designed specifically for BAS communications with minimal IP drops to the IT system in a secure manner. Networking requirements necessitate collaboration with the owner’s IT departments.
Packaged Controls
More HVAC equipment is being manufactured today, with packaged DDC controls replacing built-up control installations. Owners and construction managers are interested in this delivery method because it can help them save money on control installation costs. In lieu of custom programming, equipment controls have configurable programming and open protocol capability to integrate with the BAS to provide monitoring, operating schedules, and setpoint adjustments to owners. Equipment with self-contained controls is a lower-cost material solution, but it also requires some installation labor. Additional installation labor includes equipment technician time for proper configuration. TC contractor technician time for mapping over logical information to the BAS for the owner’s graphical interface, and more coordination between the installation contractors, design engineers, and, in some cases, a commissioning agent. In the end, the installed cost of the equipment may be lower. However, the owner must understand which service provider, equipment or BAS service representative, may be required for future maintenance and repairs.
Control Strategies
Much care must be taken when selecting and coordinating equipment and controls for a project design to ensure that systems can be programmed or configured to provide overall building thermal comfort while adhering to building energy and building ventilation-related codes and standards. Among the examples of strategies are, but are not limited to:
- Scheduling building occupancy for occupied/unoccupied heating/cooling setpoints,
- During building occupancy, unoccupied standby modes are used to relax space setpoints and reduce outdoor ventilation as needed.
- When large spaces are lightly occupied, demand control ventilation can be used to reduce outdoor air ventilation.
- Water Supply Temperature Setpoint Reset for Hot Water Heating Systems and Chilled Water Systems to save energy at source plants, and Air Handling Equipment Static Pressure Reset to save fan energy when remote zone heating and cooling demands are reduced.
Source: https://blog.peterbassoassociates.com/
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