FEATURE – Lighting controls play a key role in meeting building energy codes
By Michael Jouaneh
May 9, 2012 - Buildings consume the bulk of the world’s energy (nearly 40%), so the building industry has been focusing on sustainability, efficiency and practical energy-saving solutions for both new construction and retrofits.
By Michael Jouaneh
As the building industry moves (albeit slowly) toward Zero Net Energy—the goal of the Architecture 2030 program—the industry is recognizing that lighting controls play a crucial role in energy conservation. According to the U.S. Department of Energy (DoE), lighting is—by far—the largest user of electricity in commercial buildings. It consumes 38% of a building’s total electricity use—more than space heating, cooling, ventilation, equipment and computers combined.
Lighting controls can drastically reduce that appetite. They can eliminate 60% or more of the wasted lighting energy in buildings while enhancing occupant comfort and productivity. They provide flexible control over the lighting in a space, and support energy savings by reducing the amount of power or amount of time the lighting system is in use.
Energy codes and standards
In the States, the nation’s top three building energy codes and standards—California’s Title 24, the International Energy Conservation Code (IECC) and ASHRAE 90.1— are used by nearly every state as the basis for their local building energy code. They provide the minimum acceptable energy performance requirements for new construction or major renovations of commercial buildings.
These codes/standards reflect the importance of using lighting controls to conserve energy. In fact, they all have similar mandatory lighting control requirements that designers and engineers must meet for their new construction for major renovation projects.
Focus on ASHRAE 90.1 2010
Sometimes referred to as America’s primary commercial energy code, ASHRAE 90.1, “Energy Standard for Buildings Except Low-Rise Residential Buildings” was published in late 2010. The American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) partners with the Illuminating Engineering Society (IES) to produce the standard, which provides the minimum requirements for the energy-efficient design of buildings, excluding low-rise residential buildings. Below are some of the mandatory lighting control requirements contained in the standard:
Each area enclosed by ceiling-height partitions must have an accessible, independent switching or control device (such as an occupancy sensor, manual switch or dimmer) to control the general lighting. Each control device shall be readily accessible and located so the occupants can see the controlled lighting and can only override the automatic lighting shut-off requirement by a maximum of two hours.
Occupancy sensor or timer switches that turn off lighting within 30 minutes of vacancy are required in the following spaces:
1. Classrooms and lecture halls
2. Conference, meeting and training rooms
3. Employee lunch and break rooms
4. Storage and supply rooms between 50 sf and 1000 sf
5. Rooms used for document copying and printing
6. Office spaces up to 250 sf
8. Dressing, locker and fitting rooms
All indoor lighting systems must include a separate automatic shut-off control, such as an occupancy sensor or time switch. An astronomical timeclock that provides a building lighting off-sweep after hours is a common way to comply with this requirement.
An automatic reduction in lighting power in areas where daylight can help illuminate the space will be required in most areas that are side-lighted (with windows) or top-lighted (with skylights). Areas greater than 250 sf for side-lighted areas or greater than 900 sf for top-lighted areas shall have a multi-level photocontrol (including continuous dimming devices) for the general lighting.
Exterior lighting control
Permanently installed outdoor lighting must be controlled by a photocontrol or astronomical time switch that automatically turns off the lighting during daylight hours. In addition, the new standard also requires that facade and landscape lighting be turned off between midnight and 6 a.m., or in conjunction with business opening and closing times.
Other outdoor lighting, such as advertising signage, must operate at 70% power (or lower) between midnight and 6 a.m., or in conjunction with business closing and opening times, or when no activity has been detected for 15 minutes.
All automatic control devices shall not be set to automatically turn the lighting On. This effectively requires manual-On/automatic-Off controls, or up to 50% auto-On capability for automatic controls. These controls already exist, and are referred to as ‘vacancy sensors’ or ‘multi-level’ occupancy sensors. Auto-On is allowed in some spaces, including:
• Public corridors and stairwells
• Primary building entrance areas and lobbies
• Areas where manual-On operation would endanger safety or security
Multi-level lighting control
Most areas must provide at least one light level between 30% and 70% of full lighting power in addition to Off. This can be done by continuous, or stepped, dimming, or stepped/dual switching of luminaires or lamps while maintaining a reasonably uniform level of illuminance throughout the area.
Lighting in enclosed stairwells shall have one or more control devices to automatically reduce lighting power by at least 50% within 30 minutes of all occupants leaving.
The examples above represent a portion of the new ASHRAE 90.1 regulations related to lighting control. Other items include automatic receptacle shutoff (to control task lighting and other plug loads), parking garage lighting control (automatically reduced lighting power when daylight is present and/or during periods of vacancy), and functional testing requirements (to ensure that the lighting controls operate as intended).
Lastly, there are now extra lighting power credits for using additional lighting controls in a space above and beyond the mandatory controls for that space. The additional lighting power credit can be used anywhere in the building, not just in the space with the additional controls.
Stringent energy requirements
All in all, lighting controls are vital components for helping us meet the increasingly stringent energy code requirements; requirements that help us meet our energy conservation goals in an energy-starved world. For more information on building energy codes and standards, visit www.energycodes.gov.
A marketing manager with Lutron, Michael Jouaneh’s primary focus is energy conservation and sustainability. He is active in the development of energy and green building codes/standards, and has authored several articles, white papers and case studies on high-performance green buildings. He frequently presents at industry events, such as Lightfair and Greenbuild.