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Ensure Indoor Comfort and Energy Efficiency through the Heating Season
With it being heating season in many parts of the country, it’s time to ensure that your building systems will uphold occupant comfort, health, and productivity, while consuming energy efficiently. Facility operators and managers can take steps this winter to ensure optimal building performance regardless of weather conditions.
Keep temperatures comfortable and constant. Throughout the heating season, facility managers need to closely monitor temperatures through their building-control systems. Take measures to avoid temperatures that are too high, too low, or fluctuating. This may involve adjusting thermostat controls and equipment sequencing, or resolving heat-loss problems.
Building temperature swings not only cause occupant discomfort and illness, but also have financial ramifications. Research (such as “Linking Environmental Conditions to Productivity,” the ergonomics study by Alan Hedge of Cornell University) shows that productivity drops when work space temperatures fall outside the thermal comfort zone, which typically lies between 69 to 73 degrees F. In addition to occupant discomfort, temperature fluctuations and uneven distribution of heat also waste energy and increases utility costs.
Besides building-controls technology, one of the best ways to know if you need to adjust the heating system is occupant complaints. Start troubleshooting as soon as people begin to grumble about indoor climate conditions.
Eliminate space temperature variations. Not only should you avoid allowing occupied spaces to reach uncomfortable temperatures, but also eliminate unnecessary temperature differences throughout the facility or within a space. It’s uncomfortable and unhealthy for people to leave a heated room and enter a cold corridor or restroom several times per day.
Often, varying temperature zones are created artificially by dividers, furniture, cold concrete walls, leaky windows, or other factors. Remove objects that block the heat diffusers or obstructed air vents, radiators, or baseboard heating elements. Ensure that thermostat sensors are properly located in the center of the area away from drafts, separation walls, or areas of excessive body heat.
Listen to your system. During the winter, keep your ear to the vents. Rattling in the grills could indicate loose belts or bearings. Make sure to keep fans and air intake and return registers clean of debris with regular vacuuming. Also, consistently check that dampers and valve controls are functioning properly.
Target heat loss with diagnostics. Hiring an expert to conduct an infrared thermography analysis is an inexpensive way to gain useful knowledge about weaknesses in your HVAC system or building envelope.
Infrared can help you detect things such as cold air leaking through windows or doors, or warm spots that may be caused by power irregularities or malfunctioning equipment. An outdoor infrared analysis will also show areas where the structure is poorly insulated or is losing heat, such as through the roof, doors, or windows.
Maintain humidity control. During the heating season, indoor air can dry out. In general, humidity should be held at about 50 percent, though this varies with the facility’s use.
In certain facilities, humidity control is not only important to worker comfort, but also critical to operational performance. For example, in a data center or computer room, ambient relative humidity levels should remain between 45 and 55 percent for equipment performance and reliability. High relative humidity can cause hardware corrosion, while low humidity can cause electrostatic discharge that damages components.
Psychrometer readings provide precise readings of humidity levels. If you detect high static levels or other indicators of low humidity, check that there is proper humidity transfer in the air-handling unit.
Take a proactive approach to maintenance. During the winter, your preventive and predictive maintenance programs are put to the test. Have you been maintaining your systems adequately to ensure indoor comfort levels when outdoor temperatures drop below zero? Has your maintenance schedule ensured that your equipment will meet the facility’s energy consumption targets during the winter? When the cold weather hits, you’ll discover the answers.
Save money through preventive and predictive programs. Preventive maintenance, which involves scheduling maintenance tasks on a periodic basis, achieves cost savings of about 12 to 18 percent over reactive maintenance. Predictive maintenance, which takes the preventive approach even further by considering equipment criticality for overall system function and reliability, can save up to 40 percent over a reactive approach, according to the Federal Energy Management Program (FEMP).
Much of the heating system’s performance depends on whether you’ve taken the right measures in the fall, including inspecting boilers, domestic water heaters, heat exchangers, pumps, insulating piping, checking antifreeze levels, and so on. During the heating season, continue to monitor these things, particularly when there’s the threat of freezing temperatures.
Heating/cooling coils and water pipes are particularly subject to freezing. Sometimes, in extreme conditions, a freeze-up can’t be avoided, so have parts on hand to repair the problem quickly. Regularly check coils that are exposed to the elements and monitor to make sure that the antifreeze levels will hold up at the lowest possible temperatures in your area.
With steam systems, continually monitor your steam traps, condensate return systems and valves, making sure water circulates to the boiler properly and pressures are correct.
As you conduct winter maintenance, document any problem areas that can be prevented the following year.
Conduct cooling system maintenance. You’ve shut down and drained your cooling systems, but don’t neglect them. During the winter, conduct any repairs, improvements, or equipment replacements to avoid high equipment and service costs during the winter.
Keep calibrations in line with operations. In the fall, you validated room thermostats, duct thermostats, humidistats, and temperature and pressure sensors. You have also scheduled lighting changes to reflect the end of daylight savings time. Throughout the winter make sure that heating and lighting system schedules remain on target with occupancy schedules and seasonal daylight conditions.
Control the heating load. Your main target during the winter is to make sure that your heating load adequately meets the heating demand without excess.
Monitor energy consumption regularly and document well for your energy-management program. Also, conduct emissions checks on stacks to make sure you’re not burning excess fuel to achieve space temperatures. Don’t wait until the end of the month to discover that the facility is using too much electric power, gas, or oil.
Review the utility rate schedule for on-peak and off-peak rates, which have a major impact on your utility bills. When possible, adjust set-back times or equipment usage to lower on-peak energy consumption.
Create occupant awareness. When occupants are uncomfortable, they are likely to make their own adjustments to thermostats or plug in space heaters. Inform occupants of the importance of not taking things into their own hands and alerting facility management of any indoor comfort problems.
Make contingency plans. During the winter, facilities face risks of freeze-ups, blackouts, and building shut-downs. Healthcare facilities, schools, and other buildings with strict indoor comfort and air-quality standards must be particularly diligent with maintenance programs to avoid system failures.
If your winter contingency is already in place, be sure to make regular checks on the back-up equipment and generators. Run through tests with the staff to make sure that everyone is clear on his or her role during a winter emergency and that systems and evacuations will operate as planned. Update all phone numbers of emergency service providers, whether that is HVAC service, the utility company, medical response, etc.
The right approach to winter facility management will keep your building and its occupants on top of performance goals.
John W. Conover IV is the president of Trane’s commercial systems business (www.trane.com/commercial) in the Americas region.