Colorado Real Estate Journal - August 6, 2014
Nobody likes surprises when it comes to building codes, so it is important to understand the options available to meet new daylighting control requirements, and how these changes benefit your building. Office buildings designed to meet the 2012 International Building Codes must have separate lighting controls for daylighting zones. This might mean a different design approach to ensure compliance with the new energy codes, and a possible increased upfront investment. However, as commissioning of lighting controls is now also required, owners will see a quick return on their investment through increased energy savings because the lighting system will be operating at an optimal level from Day One of occupancy. It is important to understand what “energy code compliance” means before determining your lighting and control design strategy. There are five different compliance options under two different codes. (And who doesn’t love options?) The traditional path uses the 2012 IECC (International Energy Conservation Code). The less utilized approach is to comply with 2012 IECC using ANSI/ ASHRAE/IES 90.1-2010. Each of these energy codes has several choices for lighting controls within daylighting zones. You can either follow the codes to the letter (the “prescriptive” path), or use an energy model to capture some energy trade-offs between systems (the “performance” path). So how do you know which method and which code is right for your project? First, let’s define the daylighting zone near windows; this is the most common scenario in office buildings. The perimeter daylighting zone is the area next to windows and classifies light fixtures that must be controlled separately from the other lights in the space. These zones can be grouped together by orientation. The size and definition of the daylighting zone will vary depending on whether you choose to follow 2012 IECC or ASHRAE 90.1-2010. For 2012 IECC compliance, the daylighting zone depth is 15 feet from a window into the space, or the distance to the nearest ceilingheight partition, whichever is less. The width of the daylight zone equals the width of the window plus two feet on each side. Separate controls are not required for zones that have two or fewer light fixtures. For ASHRAE 90.1-2010 compliance, the daylighting zone depth is equal to the window head height, or the distance to the nearest 5-foot high partition, whichever is less. Also, the control requirements only apply to daylight zones that are 250 square feet and greater, so fewer spaces will require daylighting controls under ASHRAE 90.1-2010. The other major difference between the codes is that ASHRAE 90.1-2010 requires automated controls, while 2012 IECC allows you to choose manual or automatic controls. ASHRAE 90.1-2010 also provides extra credit for going beyond the minimum daylight zone, which makes it possible to demonstrate greater energy savings for LEED and other certifications. This extra energy savings can also be used to balance the efficiency of another building system to manage costs. This attention to daylight is just one of the significant changes in the 2012 International Energy Conservation Code (IECC) versus the 2009 version. The original goal of the code was to reduce energy costs by 30 percent; the final 2012 version achieved an impressive average of roughly 18 percent savings across building types (slightly more for office buildings). So, which code and compliance path is the best for offices? The energy trade-off compliance path within ASHRAE 90.1-2010 gives design teams more flexibility and allows for the most cost-effective choices, especially for larger buildings. Smaller projects will likely prefer the simplicity of following the prescriptive path of the 2012 IECC. Either way, the investment in improved lighting controls will pay off in increased energy savings, decreased utility costs, reduced employee absenteeism, and happier tenants.