May 07, 2009
By Carlos Petty, Syska Hennessy Group
Appeared in Building Operating Management/FacilitiesNet
One way facility executives can respond to the economic downturn is finding new ways to increase operating efficiency while reducing energy consumption. Energy management systems (EMS) and building automation systems (BAS) have achieved both goals when properly applied. The challenge is to make the case for EMS/BAS upgrades.
Before proceeding with upgrades to an existing EMS/BAS — or in lieu of an upgrade if the budget does not allow for it — facility executives should make sure existing systems are operating at optimal levels. First, examine the HVAC equipment under EMS/BAS control, using the principles of retro-engineering to audit mechanical and electrical performance. Reevaluating existing mechanical equipment ensures that equipment selected for automation can be controlled by an EMS/BAS in the most energy-efficient manner.
The existing legacy control system equipment also should be reviewed. Technologically outdated control equipment that uses obsolete programming languages and lacks sufficient memory or expansion capabilities should be replaced. Replacement will reduce the time and cost of labor required for troubleshooting and software revision. This also is an opportunity to install electronic metering to gather the data required to verify energy savings from EMS/BAS upgrades on legacy systems (or justify their replacement).
In addition, check facility measuring devices such as temperature, humidity and pressure sensors responsible for maintaining operating parameters for major HVAC equipment. As part of a facilitywide standard, select industry-standard end devices that provide 4-20 ma or 0-10 volt output signals with high measuring accuracy.
BAS Optimization Tips
One way to add credibility to the case for upgrades is to verify that existing systems are at their most productive. Review all active or available energy optimization programs and applications. Consider the following standard strategies, both individually and in conjunction with each other.
- Economizer controls save energy by allowing the use of outdoor air ventilation for cooling. When the enthalpy, or total heat content, of outside air is less than the enthalpy of the recirculating air, using cooler outside air is more energy efficient than mechanically cooling recirculating air. Economizer controls should not be used when outdoor climates are hot and humid.
- Alarming and monitoring of critical equipment allows for early detection and troubleshooting of abnormal conditions. Consider EMS/BAS systems with remote alarming capabilities to PDAs or pagers.
- A start/stop optimization control strategy determines when to start up and setback HVAC equipment operation based on outdoor air temperature and internal building temperature. It’s not unusual for start/stop schedules to fall out of adjustment as building occupancy changes, equipment ages and staff turns over.
- At a minimum, take advantage of basic control functions that schedule the operation of equipment based on time of day.
- Measurement and resetting of supply-air temperature during air handler partial-load conditions can save energy in constant air-volume systems. Measurement and resetting of supply-air static pressure during air handler partial load conditions saves energy and is recommended for variable air volume systems.
- Indoor air quality can be monitored using carbon dioxide, temperature and humidity sensors, and the data trended and stored in the EMS/BAS. Seek opportunities to use demand-controlled ventilation control functions for carbon dioxide monitoring, which adjusts outside air quantities based on actual occupancy via the EMS/BAS. Demand-controlled ventilation saves energy by reducing over-ventilation.
- Electronic metering can collect data on water, gas, steam and electricity use. Once collected, the data interfaces with the facility’s EMS/BAS. The information can subsequently help facility operators control and adjust systems to maximize energy efficiency.
- Use EMS/BAS control functions to automatically shed HVAC or plant equipment to reduce energy consumption while maintaining overall facility environmental conditions.
- Explore use of an EMS/BAS communication interface to an existing lighting control system. A BAS software scheduler can index facility lighting control system “addressable circuit breakers” to occupied and unoccupied modes.
- Occupancy sensors can be connected to the EMS/BAS to reduce mechanical ventilation in conjunction with lighting use.
- Monitor outdoor and indoor airflow via airflow sensors to maintain building envelope pressure. Maintaining proper building differential pressure reduces total building energy consumption.
Making the Case for a BAS Upgrade
If cost reduction is a top priority for an organization and facility executives are faced with shrinking resources, including maintenance and operational staff reductions, it is important to emphasize the potential of EMS/BAS upgrades to reduce energy use, improve operational efficiency and reduce overtime labor costs. Present objective, supporting data concerning the impact of budget cuts on building operations and management. For example, include information about how reductions in funding for timely EMS/BAS maintenance and upgrades will have a direct effect on facility maintenance and operations:
- Reduction in quality of service. Occupants and visitors to the facility are likely to react negatively to the quality of day-to-day building service associated with the use of older, inefficient or poorly maintained EMS/BAS to monitor conditions of their spaces.
- Increase in maintenance costs. A reduction of funding in monitoring equipment often correlates to an increase in equipment maintenance costs. Regular calibration and timely replacement of field devices and sensors are important to maintain the optimum operation of this technology for real-time condition monitoring.
- Increase in overtime labor costs of internal maintenance staff. Reducing the number of staff required to perform maintenance tasks will increase overtime for remaining facility operating staff. Make the case to use EMS/BAS integration to share resources. EMS/BAS integration across facility-based systems such as lighting, power monitoring and security may provide a partial solution to shrinking facility resources.
In this economy, facility executives should identify EMS/BAS upgrades that can be implemented within a short time period while achieving maximum benefits. The typical corporate budget structure will require these projects to be completed within four to six months. Therefore, effective EMS/BAS planning will require facility executives to set priorities for building equipment, systems and facility areas for conversion.
Consideration should be given first to areas in the facility where environmental control is critical to reducing energy consumption. The next consideration should be the age and reliability of existing control equipment and its potential for catastrophic failure.
Discussions about the intrinsic value of maintaining the EMS/BAS budget will ultimately require a balance between what is necessary for the facility to operate given the practical limitations of today’s economy such as reduced staff and leaner operating budgets versus what can be achieved through automation.
In this new economy, successful facility executives should clearly define specific cost-saving goals to maintain in-house corporate support for each EMS/BAS upgrade project. Navigating this process will lead to development of a sound plan that takes advantage of the best EMS/BAS operating strategies to reduce energy consumption and overall facility operating costs.
Carlos Petty is a vice president and group manager in the New York City office of Syska Hennessy Group, a consulting, engineering, technology and construction firm that provides technical solutions in such areas as building automation system design, facilities management, energy management, life safety, technology consulting/engineering, and turnkey design/build services.