With the increased adoption of LEDs in commercial buildings, watts per square foot have drastically reduced.
But have we gone far enough with current energy efficiency standards and code compliance to really drive down lighting energy consumption in a building? What about the decarbonization and net zero initiatives proposed by federal and state agencies? Are current lighting and control technologies and strategies getting us closer to achieving these ambitious standards in a timely manner?
Four strategies to fuel a long-term savings plan
1. Investigate energy code compliance
Energy code sets the minimum efficiency requirements for lighting and lighting controls in the building. Compliance with the latest energy code helps reduce lighting levels further than the previous iteration of code. Energy codes set mandatory levels for lighting efficiency in the built environment and each state is encouraged to adopt the latest available version of code. It is important to note:
Lighting power density (lumens per watt) limits vary by building type and space type.
Automatic lighting shut off and setback requirements are mandated by most energy codes to help reduce unnecessary energy use in interior and exterior lighting systems.
The Energy Usage Index (EUI) is a good metric for managing and identifying opportunities for further reduction and increases in energy efficiency in lighting and other areas such as HVAC. Total annual kWh and natural gas usage, for example, is divided by the square footage of the building and can be compared to similar buildings in similar climate zones.
Strategies can be identified and energy saving opportunities can be put into play to reduce a building’s EUI. This is a good way to establish an energy baseline from which to improve.
2. Implement innovative strategies
Advanced lighting controls and building management systems (BMS) can contribute to the overall energy efficiency of a building. These two systems can range in levels of maturity and integration with other building elements. For example, lighting controls generally fall into three different levels:
Component or standalone controls: individual devices that control individual lighting loads in a small setting such as an occupancy sensor on an overhead lamp in a small office
Digital room controls
Networked building controls: a network of devices that tie into a large control system, are programmable, and can be managed remotely
Buildings can implement one or all of these control strategies, depending on the building’s needs.
Utility strategies such as demand response – taking a signal from the energy company to reduce loads during peak time periods to automatically reduce lighting and HVAC power consumption – can complement overall efficiency required by the code and reduce overall consumption in a building. This can also reduce demand charges from the utility company, which can be 30-50% of a building’s electrical bill.
Other energy efficiency strategies such as plug or process load reduction and other sources such as ventilation rates, boiler and steam systems, compressed air systems, and motor loads can also reduce overall building energy use.
However, facility managers cannot identify and manage usage if these systems cannot be measured. Are we lighting and over-ventilating spaces that are not being occupied? Lighting loads can contribute to cooling demands in a building. The key here is to have a BMS in place to monitor the energy consumption in lighting and other systems to help identify areas of high energy usage and waste.
3. Go beyond code
The movement to go beyond code compliance, increase occupant wellness and generate on-site energy via renewables such as solar power is driving the future of how we can design and manage the built environment. Many state and federal government agencies have already set goals and/or initiated decarbonization and net zero energy initiatives. Reducing combustion of utility-generated power and reducing greenhouse gas emissions will continue to drive these initiatives moving forward.
Generating the energy needs of the building on-site and not pulling more energy from the utility is a reality now. Some buildings today are even net positive, which means they are generating more power with renewables than they need to operate and selling the excess back to the utility company. Buildings and construction contribute to almost 40% of energy-related CO2 emissions globally, according to the UN’s 2017 Global Status Report, making energy efficiency a good starting point in achieving these initiatives.
4. Utilize occupant-centric design
Lighting and controls not only contribute to reducing energy but can also positively impact occupant satisfaction. For example, employees having the ability to adjust their lighting based on the task can contribute to increases in job performance and satisfaction. Reducing eye strain due to glare from lighting sources and windows can also contribute to more comfortable and efficient work environments.
Solar heat gain from fenestration can be managed by automated shading systems to help reduce cooling demand and increase worker productivity. Increasing lighting efficiency can also be optimized by using automatic daylighting controls in spaces. Adjusting electrical power down by dimming lighting systems based on ambient lighting entering the space can also achieve significant energy savings.
Most mandated energy codes require a setback of lighting – dimming or switching off all or a portion of the lighting – for side lit and skylight applications based on window head height and width and ceiling height. Energy codes and good design practices require controlling primary and secondary zones separately. With digital lighting controls, closed loop (electric lighting and outdoor lighting) and open loop sensors (outdoor lighting only) easily accomplish this task.
Energy efficiency with lighting systems is truly the low hanging fruit for design teams and energy or facility managers. Energy codes will continue to drive down lighting power requirements and mandate controls and energy metering. Having a BMS in place where facility managers can view lighting loads, plug loads, HVAC and other systems coupled by the ability of these systems to interoperate via a digital open protocol will allow buildings to be truly energy efficient.
Looking beyond simple payback and taking future savings into consideration should drive facility and energy management teams to demand lighting and control systems to deliver energy efficiency now and throughout the life cycle of the building. Productivity improvements, albeit often difficult to quantify, will be an added benefit. Ultimately, balancing good lighting design and control systems with energy savings and efficiency can be a good starting point in the effort toward better buildings.
About the author:
Joseph (Joe) Gohn is National Sales Director, Energy Codes for Legrand, North & Central America. He has more than 30 years of experience in the lighting/lighting controls industry and brings a wealth of knowledge in national energy codes and sustainability issues. At Legrand, Joe works closely with direct and specification sales teams and marketing conducting and developing energy code and sustainability training. He has numerous certifications, including CLCP, CLEP, CLMC, LC, LEED AP, and WELL AP.