Energy efficiency measures can drastically reduce electricity and gas bills in buildings. Many of these measures focus on HVAC and lighting, which represent the largest share of energy consumption in residential and commercial buildings. Some common options are: fuel-efficient boilers and furnaces, air conditioning units with a high energy efficiency ratio, and LED lighting.
While these upgrades can yield attractive savings by themselves, even higher performance is possible if they are automated with electronic controls. Purchasing equipment with a high nameplate efficiency is the first step, but savings are even higher when smart controls optimize operation in real time.
LED lighting has a much lower power consumption than older lamp types, but only natural lighting is completely free of energy costs. An effective strategy to improve lighting efficiency is daylight harvesting, which works as follows:
Lighting systems can also be combined with occupancy sensors, ensuring the lights are turned off when there is nobody in the area. Based on the technology used, occupancy sensors can be classified into infrared, ultrasonic and hybrid.
LED lighting guarantees efficiency, but an automated installation achieves higher savings than manually controlled fixtures. Of course, adequate product selection is very important to achieve satisfactory results. Both LED lamps and their compatible sensors are characterized by variety, and performance may be poor if the products chosen don’t match the application.
HVAC systems can achieve higher efficiency with a similar approach as LED lighting. Equipment with a high nameplate efficiency is deployed as a first step, and smart controls can then optimize its operation. Considering that heating and cooling are the largest energy expenses in residential and commercial buildings, the savings opportunity is huge.
The US Department of Energy does not recommend setting the thermostat at extreme values, even during the hottest or coldest days of the year. Their recommended temperature setting is 68°F during winter and 78°F during summer. When the temperature difference between indoor and outdoor air is increased, HVAC equipment must consume more energy to sustain it.
Smart thermostats can learn usage habits over time, achieving energy efficiency without constant adjustments. They can achieve further savings when the local utility applies time-of-use electricity rates; when the highest kWh prices are applied, the thermostat can ramp down or deactivate the HVAC equipment.
Further efficiency gains are possible if the ventilation system is equipped with occupancy sensors to control airflow, a concept called demand controlled ventilation (DCV). This method not only achieves fan power savings but also heating and cooling savings as less air moves through HVAC equipment.
Electric motors have many uses in homes and businesses, and their applications include air handlers and pumping systems. Traditional control methods for motor-driven equipment are wasteful, and two examples are air dampers for fans and valves for pumping systems. In both cases there is a pressure loss in the fluid being controlled, representing a waste of motor power.
A much more efficient solution is controlling motor speed with a variable frequency drive (VFD). These are solid-state electronic devices that adjust the voltage and frequency of a power supply, modulating the rpm of the motors. This way, VFDs can replace wasteful control devices.
The main drawback of VFDs is affecting the waveforms of voltage and current, producing a phenomenon called harmonic distortion. In addition to overheating the wire, harmonics can damage sensitive equipment. Specially-designed filters can block the propagation of harmonic distortion beyond the VFD itself.
Electronic control systems have various applications in energy efficiency measures. In general, they achieve higher efficiency than what is possible with manual controls only. Having the most efficient LED lamps and HVAC equipment is guaranteed to reduce utility bills, but even better performance is possible with smart controls.
Michael Tobias is the founder and principal of Chicago Engineers, an Inc 5000 Fastest Growing Company in America. He leads a team of 30+ mechanical, electrical, plumbing, and fire protection engineers from the company headquarters in New York City; and has led over 1,000 projects in Chicago, New York, New Jersey, Pennsylvania, Connecticut, Florida, Maryland and California, as well as Singapore and Malaysia.