Integrating lighting design, building envelope
In this Q&A, the importance of total building integration—including lighting design—is discussed. Engineers must consider not only the lighting, but also building envelope, lighting controls, and daylighting.
Consulting-Specifying Engineer obtained insights from Brent Protzman, manager of energy information and analytics, Lutron Electronics, about lighting design in nonresidential buildings. He discusses building envelope, daylighting, and lighting controls in this Q&A session.
CSE: Can you explain the importance of moving lighting design and interior design to the early stages of a project as part of the building envelope design?
Protzman: Among other factors, building envelope design is strongly influenced by daylight. Daylighting and lighting design are just as essential to space functionality as energy performance, and when incorporated at the beginning of project development, can help meet the illumination needs of the space while minimizing energy cost. If lighting and daylighting are the last systems to be addressed in project design, they tend to get value engineered when cost overruns occur. But, when they are considered in tandem with the building envelope specification, it not only allows for better use of daylighting, it also helps designers avoid unnecessary cost and thus avoid getting value engineered in later stages.
Typically, window size and performance properties are specified early with primary decisions based on view and reduced heat gain. Although these are two important parameters for high-performance buildings, we also need to consider glare control, daylight harvesting potential, and overall indoor environmental quality. Proper design of the lighting and daylighting systems can also help optimize HVAC design by reducing heat loads.
CSE: How do current codes and standards integrate daylight design?
Protzman: The latest versions of building energy standards, such as ASHRAE Standard 90.1-2010, International Energy Conservation Code (IECC) 2012, and California Title 24-2013, all include mandatory provisions for daylight control. Although not all states have adopted these latest standards, they are likely to be adopted in the future and clearly drive industry trends toward daylighting. Perimeter spaces with windows, as well as areas with skylights, are all included in daylight control requirements. Some codes, such as ASHRAE/IES 90.1 and IECC, only require on/off or bi-level control of fixtures in daylighting zones. Full dimming also meets these requirements and is desirable if reduced disruption is a priority. Title 24 essentially requires full dimming in the daylight zones, and as Title 24 requirements trickle into other energy standards, dimming is likely to be included in future versions of other standards.
CSE: Can you speak to the ways in which lighting and daylight control help achieve high-performance building design?
Protzman: Multiple research papers have shown the benefit of controls in lighting and daylighting. Williams et al., in their review paper “Lighting Control in Commercial Buildings” show the benefits of different lighting control strategies. Significant savings can be achieved even when the lighting power density (LPD) is low, especially when advanced control strategies such as multi-zone daylighting and automated shading are implemented. The Energy Center of Wisconsin recently released a daylighting study that highlighted the performance of proper control commissioning, as well as optimized lighting energy savings (as high as 90% in some spaces). These studies identify critical energy considerations, but lighting energy is only one aspect of high-performance building design. We also need to remember that buildings are designed for the people who use the space. Proper daylighting design can reduce or eliminate glare and thermal discomfort while providing the mood and health benefits of daylight and views.
CSE: How can lighting controls integrate with other building systems, including HVAC, window solutions, and plug load control and what are the benefits of integration?
Protzman: Currently, building systems are often designed in silos. This is often due to different specifiers working on their areas of specialty and missing potential areas of integration. For instance, a single occupancy sensor could be used for turning lights on and off, controlling plug loads, operating automated shades, and even for a temperature setback. The obvious benefit of this integration is the need for fewer devices, especially redundant devices, but there is also an opportunity to reduce building energy use without sacrificing the comfort of occupants. In fact, integrated controls can help increase the productivity of occupants, and particularly the facility management team. Integration also allows a facility manager to better manage different systems and track their performance and energy consumption. It can also aid in space planning by shedding light on usage patterns across the building.
CSE: Do you have any examples of how lighting solutions have integrated successfully as a part of a building system?
Protzman: Please refer to this Glumac case study as it combines the use of task/ambient lighting, light room surfaces for maximum penetration, daylighting control, and automated shades with a perimeter buffer zone to allow for abundant redirected daylight to fill the space.