Control & Automation
5 key areas to inspect for energy savings
By Colin Plastow
In these tough economic times, it is becoming a requirement for facility managers to pay very close attention to their operation and maintenance budgets. Many are now focusing on energy conservation opportunities that can save thousands of dollars per year with relatively little capital investment. While capital expenditures on equipment may be hard to come by, it’s surprising how much you can free up financial resources through proper maintenance. Following is a helpful checklist of five key areas for inspection and the recommended tools to help you pinpoint potential areas.
By Colin Plastow
There are a number of areas where energy may be wasted with steam systems. For example:
- Insulation – Loose or missing insulation can cost you thousands of dollars in extra fuel costs in the heating season. A thermal imager offers a quick and easy way to inspect system insulation and identify any weak spots.
- Steam traps – These remove condensate from heating and process equipment. If the traps fail to open, valuable steam is lost. Use a non-contact IR thermometer or thermal imager to spot a failed trap by comparing the temperature of the trap to the pipes on either side of it.
- Air temperature in the boiler room – Combustion air should be between the appropriate limits in order to optimize efficiency. Use a digital thermometer to measure ambient air temperatures. Also check the carbon monoxide levels in boiler rooms to ensure safety.
- Others – Additional areas to add to your checklist include feed water temperature and lubricants.
A proper inspection of cooling systems should include the following:
- Electrical – A digital multimeter can be used to check the compressor voltage and amperage to ensure that the motor is operating at the manufacturer-recommended levels.
- Temperature – Use a digital thermometer to look at the temperatures of the inlet and outlet air and water temperatures at heat exchangers to verify that they are operating at their most efficient levels.
- Pressure – Fouling within cooling system tubes leads to lower heat transfer and higher energy consumption at the compressor. Use a digital multimeter with a pressure attachment to take the inlet and outlet pressures of shell and tube heat exchangers. Also check refrigerant and pump pressures to ensure that everything is operating at the appropriate baseline levels.
- Cooling tower – Cooling towers reject heat at a specific rate to the atmosphere. The best tool for this job is a temperature/humidity meter, which can be used to measure the outside air temperature and humidity to analyze cooling tower operation. Also measure the temperature of the condensing water supplied to the chiller.
Your fan system inspection should include the following elements:
- Electrical – Measure the voltage and amperage of the fan motor and compare your reading to the nameplate conditions.
- Temperature – When looking at air handlers, include outside air temperatures, mixed air temperatures, return air temperatures, discharge or supply air temperatures, coil face discharge air temperature, space temperature sensors and economizer and related dampers. Readings should be done with a handheld temperature meter and then compared against those indicated by the control system to ensure accuracy.
- Air pressure – Excessive pressure drops will cause higher than normal energy consumption. Therefore it is important to check pressure drops across filter banks to ensure adequate air flow. Measure air pressure drops across heating and cooling coils to ensure that the coils are clean. Also measure the inlet and outlet air temperatures to ensure that the temperature rise or drop is within an acceptable range.
Lighting systems can offer numerous opportunities for energy savings. Before determining next steps, make sure you check the following:
- Electrical – Use a thermal imaging tool to look for hotspots and compare values with baselines or previous temperature measurements for evaluation.
- Illumination levels – A light meter can be used to measure lumen levels. Where possible, reduce illumination levels to industry standards, especially during seasons where there is more natural light available.
- Operational performance – Set up a recording meter to sample illumination levels during a facility’s unoccupied hours. This will help identify areas where the lights are left on unnecessarily.
Building automation systems
While automation systems are designed to improve energy efficiency, that doesn’t mean they should be overlooked during your energy inspection. Areas to look at include:
- Energy consumption – Use a power quality meter to evaluate your facility’s voltage, current and KWH energy consumption. Ideally you should log energy consumption over time on specific circuits and by specific equipment and areas. Then compare hourly usage rate to your utility fee structure and adjust usage patterns out of high-demand, high-cost times of day. Also check control system supply voltages; as well as controller communication bus values to ensure the integrity of the communication wiring.
- Control system – Check all sensors and indicating thermometers for properly calibrated gauges, as well as valve and damper actuators. Actuator output voltages and current signals can be checked using a regular digital multimeter.
- Temperature – Check the temperatures of inlet and outlet air and water temperatures at heat exchangers to make sure that they are operating at their most efficient levels.
- Operational performance – Log air temperature over time, and over occupied and unoccupied schedules to identify areas that may be in the wrong temperature mode at night or on weekends.
- Setpoints – Check the accuracy of all temperature, pressure and humidity controlled setpoints by logging their values over time. (keep in mind that control inaccuracy can waste 1 % of energy per degree of error.)
A thorough inspection with the right test tools can turn up a surprising number of opportunities to save energy and improve your operation’s bottom line. Following this checklist is an excellent starting point from which to build your energy savings strategy.
Colin Plastow has been with Fluke Electronics Canada since 1987 in various support and product management positions. Today, as Industrial Product Manager for Fluke, he brings his expertise in electronic test and measurement to customers in high-tech and industrial markets. Mr. Plastow continues to share his in-depth industry knowledge through various customer seminars, as well as educational articles written for leading industry publications. He may be contacted at firstname.lastname@example.org.