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With cold winds blowing and blizzards gathering, the winter months for many of us are spent indoors. If ventilated properly, the indoor air quality is favorable and the warmth keeps us comfortable. Yet, many components within the HVAC system at home or in our workplaces can reduce air quality and system efficiency.
The EPA states "duct leakage can cause or exacerbate air quality problems and waste energy."1 From malfunctioning coils to low-efficiency filters to condensation on pipes, systems that are not monitored or maintained well sacrifice efficacy and, ultimately, budget. The online site, Buildings.com2, specifies "routine maintenance can lower utility costs, reduce equipment-replacement costs, and keep tenants or occupants happy." Beyond routine maintenance, an energy audit can detect systemic issues that place a burden on the HVAC system.
According to Fluke3, 32% of common air leakage in homes is found in floors, walls, and ceilings. For larger facilities, the US Bureau of Labor Statistics emphasizes, "Unnecessary energy expenditures can be significant in large buildings or buildings that lack energy-efficient technologies, such as proper insulation or fluorescent light bulbs."4
An energy audit will reveal where leakages are occurring, insulation is inefficient, and system performance is lacking. Used for both homes and commercial buildings, the audit (or assessment) involves a variety of inspection tests. Thermographic inspections examine the interior and exterior walls for temperature changes caused by leaks. An energy analysis of usage within the building, along with equipment performance, will help an auditor determine waste areas and suggest recommendations.
The results can be inspiring. The Department of Energy cites the case of the Athenian Corner restaurant in Lowell, Massachusetts. Experiencing high energy bills, the owners sought solutions with an energy assessment. The assessment indicated the building needed a new boiler, air conditioning and heating system, control for the exhaust fan, and other equipment. The restaurateurs made the upgrades.
"During the first year, the upgrades helped reduce the restaurant’s energy use by 41 percent or almost $4,000—far exceeding the projected savings of 30 percent. Thanks in part to educating their staff on the restaurant’s new temperature controls, the Panagiotopoulos family has been able to increase their energy savings to 51 percent during the second winter since making the upgrades."5 With more consistent temperatures, the diner also increased their business with more customers stopping by.
Energy auditors need precise and effective equipment to complete their assessment. What tools assist auditors in determining the efficiency of an HVAC system?
Air Meters, for airflow measurement, are used to evaluate and adjust ventilation levels and verify HVAC controls. Anemometers (both hot-wire and vane) check the flow and volume of air in ducts and at registers. Capture hoods are used for air balancing. They measure the volumetric flow rate or cubic feet per minute from supply diffusers and return/exhaust grilles.
Power Analyzers or Loggers conduct energy studies by measuring electrical power parameters, harmonics, and voltage events. The analyzer validates the performance of the power system and diagnoses HVAC equipment failure.
Digital Multimeters measure volts, ohms, and amperes, combining several measurement functions in one meter for greater efficiency. These meters are used for troubleshooting
electrical equipment in HVAC.
Clamp Meters combine a digital multimeter with a current sensor for electrical testing. While probes measure voltage, clamp meters measure current. Specifically, HVAC technicians can use a clamp meter to measure resistance, continuity, and, depending on the model, temperature, frequency, capacitance, and more.
Thermal Imagers measure infrared wavelengths to determine temperatures from a safe distance. These units display an image using different colors to represent varying temperatures. For inspection purposes, the imager identifies where heat may be escaping the home or building. It can also pinpoint blockages in pipes, moisture accumulation, and overall system leakage.
Infrared Thermometers scan a variety of items including insulation of structures, pipes, ducts, breakers, wire, connections, and motors to inspect and diagnose temperature differences. Like thermal imagers, they do not come in contact with objects as they measure surface temperature and spot potential energy losses.