Log maximum efficiency:
Data loggers offer a low-cost solution to expensive problems
Evan Lubofsky,
Posted
03/01/2009
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.
www.onsetcomp.com