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Log maximum efficiency: Data loggers offer a low-cost solution to expensive problems

Low-cost data loggers can provide contractors and building managers with information that helps save thousands of dollars in energy costs while ensuring that indoor air quality and occupant comfort are maintained throughout properties.

By monitoring and recording simple variables like temperature, relative humidity, carbon dioxide and light or motor on/off, data loggers can help detect and document whether "too hot or too cold" comfort-complaint conditions are warranted, whether the property is threatened by conditions suitable for mold growth and whether energy savings can be realized through ensuring that lights are off when areas of the building are unoccupied. More sophisticated measurements-such as AC current, AC voltage, power demand (kW), energy consumption (kWh), and pressure and differential air pressures-provide valuable information for troubleshooting HVAC/R systems, submetering, building commissioning, and measurement and verification of energy savings.

Data Logger Basics

Data loggers are battery-operated measurement tools containing a microprocessor, memory and sensors for measuring and recording one or more variables over time. They are typically small, enabling them to be deployed almost anywhere throughout a building or complex, with some packaged to work in outdoor environments.

Some data loggers have internal sensors so measurements are made only at the logger location, while others utilize sensors on external cables that allow for monitoring at some distance from the data logger itself. A logger may offer a combination of internal and external sensors, as well as external channels accepting pulse, 4-20mA or DC voltage inputs from other sensors for even greater flexibility. The loggers operate unattended for hours, days or months at a time. Specialized software configures the logger and offloads the recorded data from the logger to a PC for graphing and analysis.

Temperature is the most common measurement required for most condo environmental monitoring applications, as it is important in monitoring the human environment, as well as equipment operation and efficiency. Relative humidity and CO2 are two other common measurements for indoor air quality and comfort-complaint investigations. Combined temperature and relative humidity measurements are also critical indicators of conditions that may be conducive to mold growth, which is an important concern for today's building managers and occupants.

In addition to standalone data loggers, Web based remote monitoring systems are available, which not only measure and record a range of environmental parameters but also make the data available on the Internet on a 24/7 basis. Typically, these systems incorporate some type of wireless communications technology-including GMS cellular or Wi-Fi-and offer Web-based software that enables all logger management and retrieval functions to happen over the airwaves.

 

HVAC/R Troubleshooting

Airflow pressure, monitored with an external airflow pressure sensor mounted within an air duct or attached to heating coils or pipes, can provide valuable insight into heating distribution or air balance problems. Multiple airflow points may be used to evaluate a larger section of an air distribution system for larger scale analyses along with temperature readings at supply and return vents.In addition, time-of-use data loggers can be used to monitor HVAC/R equipment to detect short cycling of, for example, a compressor or blower or other equipment runtime to evaluate potential failures and schedule repairs or replacements.

Chiller system efficiency is monitored easily by logging outdoor temperatures, water temperatures and flow rates at supply and return vents, as well as when pumps are turning on.

Energy Management

Data loggers can be used to track energy usage in various parts of a building to verify equipment operating efficiencies and identify areas where energy costs can be reduced.

Light Usage Monitoring

Total light usage in a building complex can gobble up a good share of power, especially if left on unnecessarily for long periods of time. Light intensity (loggers which have built-in photo sensors) or state on/off data loggers can be placed as close as possible to individual light sources oron ceilings or walls to record when lights are on over various times. Data should be logged for a period long enough to cover various times of day and night, as well as occupied and unoccupied periods. The data gathered can detect direct light usage and help in deciding whether the expense of permanently installed occupancy light sensor/ switches or some other remediation is justified.

If changes are made to reduce light use, the very same loggers can be redeployed in the same spaces later on to generate data to verify that the changes were successful.

Ultimate Tools

Portable data loggers are inexpensive and easily deployed measurement-recording tools that can have a positive impact on containing building energy costs without sacrificing occupant comfort levels. With so many possible applications in a building-energy usage monitoring and verifying comfort and indoor air quality conditions-they may be the ultimate measurement and recording tools for balancing and managing a building's energy usage and environmental qualities.

Evan Lubofsky is the director of marketing at Onset Computer Corp., Bourne, Mass. For more information, visit www.onsetcomp.com.