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CATEGORY: Topics » Energy Codes
By Craig DiLouie, on March 19, 2012
 The International Energy Conservation Code (IECC) is a model residential and commercial building energy code produced by the International Code Council. First published in 1998, the IECC was updated in 2000, 2003, 2006, 2009 and, earlier this year, 2012.
The IECC is actually not a code, but instead a template for legal jurisdictions to use to implement an energy code. These jurisdictions may adopt the IECC in whole, in part or modify it based on local needs.
Today, most states have energy codes based on IECC and the ASHRAE/IES 90.1 energy standard. IECC references ASHRAE/IES 90.1, Energy Standard for Buildings Except Low-Rise Residential Buildings, currently the national energy standard, as an alternative standard.
The IECC lists requirements and minimum standards for the design of lighting and other energy-using systems and features of energy-efficient buildings. This article by the Lighting Controls Association describes the basic requirements of the IECC, highlighting major lighting-related changes in the new 2012 version. Note that for each feature described, exceptions may apply; consult IECC 2012 for specific details.
Residential and commercial requirements in the 2012 IECC are more strongly differentiated in two separate sections.
Residential
The residential lighting provisions in the 2012 IECC are relatively simple. Mainly, at least 75% of the lamps in permanent light fixtures must be high-efficacy, defined as T8 or smaller-diameter linear fluorescent lamps, or lamps with a minimum efficacy of 40 lumens/W for <15W, 50 lumens/W for 16-40W, and 60 lumens/W for >40W lamps. In the 2009 IECC, 50% of the lamps were required to be high efficacy.
Commercial
The commercial section of the code contains both mandatory and prescriptive lighting provisions. The mandatory provisions require:
* tandem wiring in certain fluorescent applications;
* maximum wattage for exit signs;
* circuiting for daylight harvesting control; and
automatic shutoff, light level reduction and other controls.
The prescriptive provisions establish limits on lighting power by building and space type, with the designer and owner ultimately deciding how best to accomplish the lighting goals within the power constraint.
Occupancy sensors. Occupancy sensors are now specifically required in a series of spaces, including classrooms, conference/meeting rooms, employee lunch and break rooms, private offices, restrooms, storage rooms, custodial closets, and other enclosed spaces 300 sq.ft. or smaller. The sensor must turn the lights OFF within 30 minutes of vacancy and provide manual-ON or auto-ON-to-<50% operation.
Daylight harvesting. The 2012 IECC follows the 2009 IECC in requiring general lighting in defined daylight zones (areas expected to receive high, consistent daylight levels) to be separately controlled from other general lighting in the space.
While daylight zones define an area of daylight availability and separate control, the system designer then determines on their own how best to zone the lighting for manual or automatic control. IECC 2012 limits the maximum size of these control zones to 2,500 sq.ft. Options for automatic daylight harvesting control include continuous dimming with a 100% to <35% light output range or multilevel controls offering 100%, a step between 50% and 70%, and another step between OFF and 35%.
Additional controls. The 2012 IECC further requires separate control of display and accent lighting from general lighting, supplemental task lighting and others, bringing it more in line with ASHRAE/IES 90.1.
Interior lighting power allowances. The interior lighting power allowances, expressed as W/sq.ft., or lighting power density (LPD), are largely unchanged from the 2009 IECC, with these exceptions:
* 1.0 to 0.9W/sq.ft. for office;
* 1.5 to 1.4W/sq.ft. for retail;
* 0.8 to 0.6W/sq.ft. for warehouse buildings;
* 0.8W/sq.ft. for fire stations, new to the list; and
* reduction from a base of 1000W to 500W for the additional retail lighting power allowance.
With the 2012 version, for the first time, the IECC recognizes the Space by Space Method in addition to the Building Area Method (and Total Building Performance Method, requiring building modeling) as a compliance path, providing greater design flexibility. The IECC Space by Space Method is based on ASHRAE/IES 90.1, but with slight differences in the space types, and with different lighting power allowances for many spaces.
(The Building Area Method specifically requires adding up the installed interior lighting power in an entire building (or major section) and ensuring it is not greater than the single interior lighting power allowance for that building type. The Space by Space Method also compares the total installed lighting wattage in the building, but allows the user to develop the lighting power allowance based on the space type, with each type having its own LPD, and with tradeoffs permitted between spaces.)
Additional energy efficiency measures. Another major change in the IECC is Section C406, Additional Efficiency Package Options, which requires the building to either:
1) optimize HVAC efficiency beyond code;
2) optimize lighting efficiency beyond code; or
3) produce renewable energy onsite.
In this case of lighting, this entails achieving a lower LPD value using the Building Area Method—e.g., 0.99 instead of 1.2W/sq.ft. for school/university buildings, for example.
Readers may obtain a copy of the new 2012 IECC here.
By Lighting Controls Association, on January 25, 2012
 Just as the US Department of Energy (DOE) recognized ANSI/ASHRAE/IESNA Standard 90.1-2010 as the national energy standard, WattStopper launched a new CodeSmart publication designed to guide lighting and building professionals through the intricacies of the many lighting control requirements that debuted in this newest version of the code. The informative booklet available for free download (PDF), Discover lighting control solutions: Energy code compliance, also compares and contrasts multiple versions of today’s most widely adopted building energy codes: ASHRAE 90.1-2004, 2007 and 2010; IECC 2006, 2009 and 2012; and California Title 24-2008, and recommends code compliant control solutions.
This new publication is the latest addition to WattStopper’s well known CodeSmart initiative, and examines requirements for both indoor and outdoor lighting controls. The Code Compliance Guide section is designed as an easy-to-follow table with line by line comparisons of code requirements for performance in different space types and applications. Control Solution sections include best practice recommendations for major control mandates that are designed to meet code while also maximizing return on investment (ROI). Each solution includes a sample floorplan illustrating lighting, room layout and controls as well as a typical equipment list. Finally, the brochure examines tax saving opportunities available by exceeding code requirements as allowed under the Energy Policy Act of 2005 (EPAct), which has been extended through 2013. Get it here.
By Craig DiLouie, on December 19, 2011
 In July 2011, the Department of Energy recognized the ASHRAE/IES 90.1-2007 standard as the new national energy standard, superseding the 2004 version.
In a bold move, on October 19, 2011, DOE recognized the 2010 version of 90.1 as the new national energy standard. By October 18, 2013, all states in the United States must put in place a commercial building energy code at least as stringent as the ASHRAE/IES 90.1-2010 energy standard. This means the 2007 standard is effectively being leapfrogged as the national energy standard. (More than one-half of the states in the USA already have a code in place at least as stringent as the 2007 version.)
(In July 2011, the DOE also issued a rule requiring new Federal buildings, for which construction design begins on or after October 11, 2012, to comply with ASHRAE/IES 90.1-2007. The October 2011 ruling did not change that.)
Below are two articles describing the ASHRAE/IES 90.1-2010 standard:
New administrative requirements in ASHRAE/IES 90.1-2010
New lighting control requirements in ASHRAE/IES 90.1-2010
Part of the new documentation requirements is a lighting control narrative. LCA has published guidance to developing this kind of document.
By Lighting Controls Association, on December 7, 2011
 Consulting-Specifying Engineer has published an article by Brian Baumgartle, PE, LC, LEED AP of CMTA Inc. about lighting and control changes in the ASHRAE/IES 90.1-2010 energy standard, recently recognized by the Department of Energy as the national energy standard effective October 2013. Check it out here.
By Lighting Controls Association, on November 21, 2011
Last month at LightingControlsAssociation.org, we published an article about how to establish daylight zones in sidelighted (windowed) building spaces. We looked at an industry rule of thumb and then how the latest generation of energy codes and standards address it.
In review, when designing an energy-saving daylight harvesting control system, a critical decision is to establish lighting control zones, identifying lighting loads to be separately controlled. Before this decision can be made, however, we must first determine the daylight zones.
A daylight zone, also called the daylight area (expressed in square feet) is defined by the ASHRAE/IES 90.1-2010 energy standard as “the floor area substantially illuminated by daylight.” In other words, it should consistently receive significant quantities of daylight.
By identifying daylight zones, the lighting control system designer identifies areas where daylight harvesting control is appropriate. The designer can then make further decisions about how many control zones are appropriate for the given daylight zone, and their configuration.
In this article, we will examine methods for establishing daylight zones in toplighted building spaces, such as spaces with skylights, roof monitors and clerestories.
Rule of Thumb for Toplighted Daylight Zones
For toplighted spaces, a rule of thumb is that a daylight zone can be established as the skylight length or width plus 1/2 the ceiling height on each side, and a second zone as the skylight length or width plus the ceiling height on each side.
 Image courtesy of the Lighting Research Center. If a space is uniformly lighted using skylights as shown below, with properly spaced skylights covering about 3-5% of the floor area, the entire space may be considered a daylight zone suitable for daylight harvesting control.
 Image courtesy of Acuity Brands Controls. Energy Codes/Standards And Toplighted Daylight Zones
As stated in last month’s article, daylight zones are increasingly being determined by codes and standards, notably the 2009 IECC model energy code, ASHRAE/IES 90.1-2010 model energy code, ASHRAE 189.1-2009 model green building code and California’s Title 24-2008 (state energy code). These codes and standards all require that daylight zones be established around toplighting apertures, and general lighting in these zones be separately controlled from other lighting. The dimensions of the daylight zone are defined and adjusted based on elements in the space that would limit daylight availability, such as tall obstructions (e.g., walls and stacks).
Codes and standards may recognize one or more of the following types of toplighting:
Skylights
Let’s begin with skylights. Below is a short reference to how the latest generation of codes and standards establish daylight zones, or daylight areas, in spaces toplighted using skylights. Note that CH = ceiling height (floor to ceiling), and OH = obstruction height—the height of permanent obstructions (to daylight distribution) such as walls and permanent storage stacks.
The below graphic illustrates the daylight zoning requirements. In each case, a wall restricts the daylight zone in the north because the distance between the skylight and the wall is less than the ceiling height (IECC 2009) or 0.7*CH (ASHRAE 189.1-2009).
ASHRAE/IES 90.1-2010 and Title 24-2008 use a different system that addresses how likely the permanent partition will block the daylight. If the distance between the skylight and the obstruction is less than 0.7*CH and greater than 0.7*(CH–OH), then the front of the partition (facing the skylight) marks that boundary for the daylight zone.
Further, IECC 2009 and ASHRAE 189.1 reduce the given daylight zone dimension to 1/2 the distance to the nearest skylight or vertical fenestration, while the daylight zone in ASHRAE/IES 90.1-2010 and Title 24-2008 is reduced by the outermost boundary of any nearby primary sidelighting zone or roof monitor daylight zone.
Let’s look at a sample problem:
We have 10 skylights that are each 18 ft. from each other, providing illumination in a space with a ceiling height of 20 ft., and bounded on all sides by ceiling-height walls 10 ft. away. Under IECC 2009, what are the dimensions for each skylight daylight zone?
Under IECC 2009, 1/2 distance (D) between skylights (9 ft.) < CH (20 ft.) and D to any nearby partition, so the zone around each skylight would be the skylight length or width + 1/2 D between it and its nearest skylights (9 ft.). The exception is the dimension facing the walls, which would be limited by the distance between the skylight and those walls (10 ft.), as D to these nearby partitions < CH (20 ft.).
Now suppose we added a 15 ft. tall warehouse stack 10 ft. from the edge of a skylight. Under ASHRAE/IES 90.1-2010 and Title 24-2008, would that stack limit that skylight’s daylight zone?
The distance between the skylight and the stack (10 ft.) > [0.7*(CH-OH)] (3.5 ft.) and < 0.7*CH (14 ft.), so the stack would limit the boundary of the daylight zone extending toward the stack to 10 ft. In this scenario, any obstruction over roughly 5 ft. in height would impose a limitation on the dimensions of the daylight zone.
Now suppose the northern row of skylights is 20 ft. from a windowed wall with a primary sidelighted daylight zone of 15 ft. Under IECC 2009 and ASHRAE/IES 90.1-2010, would there be any limitation to the daylighting zone?
Under IECC 2009, the answer would be yes. The windows are 20 ft. away from the skylight, and 10 ft. < CH (20 ft.) and there is no intervening partition, so the daylight zone would be halved to 10 ft.
Under ASHRAE/IES 90.1-2010, the answer is also yes. The windows are 20 ft. away, so the outermost edge of the primary sidelighted daylight zone is 5 ft. away. As 5 ft. < (0.7*CH, or 14 ft.), the northern daylight zone for these skylights would extend 5 ft. toward the windows.
What if, for theoretical purposes, we add a ceiling-height vertical obstruction 2 ft. away from the skylight? Would the daylight zone be limited to 2 or 5 ft.?
Anytime the limitations are in conflict, common sense dictates that the closer one applies, in this case the obstruction 2 ft. away, as it would block any light from extending the extra 3 ft.
Roof Monitors And Clerestories
Now let’s move on to roof monitors and clerestories, which are recognized by ASHRAE/IES 90.1-2010 and ASHRAE189.1-2009.
ASHRAE/IES 90.1-2010 specifically recognizes roof monitors, which it defines as “vertical fenestration integral to the roof.” Below is a summary of the ASHRAE/IES 90.1-2010 requirements:
The below graphic illustrates the daylight zoning requirements.
Let’s look at a sample problem:
We have a roof monitor with a width of 10 ft. and a monitor sill height of 20 ft., meaning the daylight zone would extend 20 ft. from the vertical glazing. A 14-ft.-tall vertical obstruction, placed 15 ft. from the monitor, protrudes into the daylight zone, and the outermost edge of a primary sidelighted daylight zone is 18 ft. away from the glazing. Under ASHRAE/IES 90.1-2010, what are the dimensions for this daylight zone?
The daylight zone would normally be 10 ft. wide and extend from the glazing 20 ft. (the MSH), or an area of 200 sq.ft. However, the primary sidelighted daylight zone is 18 ft. away, which is less than the MSH, so that would limit the zone to a depth of 18 ft. The distance to the vertical obstruction (15 ft.) > MSH – OH (6 ft.) and < MSH (20 ft.), so it too would limit the zone to a depth of 15 ft. along the front face of the obstruction. Basically, in this scenario, any obstruction over 5 ft. in height would impose a limitation on the dimensions of the daylight zone.
Finally, ASHRAE 189.1 recognizes clerestories, roof monitors and clerestory roof monitors. In review, ASHRAE/IES 90.1-2010 defines clerestories as “that part of a building that rises clear of the roofs or other parts and whose walls contain windows for lighting the interior.” Below is a summary of the ASHRAE 189.1 requirements.
The below graphic illustrates the daylight zoning requirements.
Once the daylight zones are established in a space, we can then decide whether daylight harvesting control is warranted, how many control zones we will need (including what loads will be covered by each controller), and what control method or methods—switching, dimming, etc.—we will use. Each of these areas may be covered by separate code/standard requirements.
By Craig DiLouie, on October 12, 2011
When designing an energy-saving daylight harvesting control system, a critical decision is to establish lighting control zones, identifying lighting loads to be separately controlled. Before this decision can be made, however, we must first determine the daylight zones.
A daylight zone, also called the daylight area (expressed in square feet), is defined by the ASHRAE/IES 90.1-2010 energy standard as “the floor area substantially illuminated by daylight.” In other words, it should consistently receive significant quantities of daylight during the day.
By identifying daylight zones, the lighting control system designer identifies areas where daylight harvesting control is appropriate. The designer can then make further decisions about how many control zones are appropriate for the given daylight zone, and their configuration.
In this and a second article to be published next month here at LightingControlsAssociation.org, we will examine methods for establishing daylight zones based on prevailing energy codes and standards. This month, we will cover the most common type of daylighting—sidelighting, or daylight entering a space through vertical fenestration such as windows. Next month, we will cover toplighting (e.g., skylights) applications.
Energy Codes/Standards And Sidelighted Daylight Zones
Daylight zones are increasingly being determined by codes and standards, however, notably the ICC’s 2009 International Energy Conservation Code (IECC) (model energy code), ASHRAE/IES 90.1-2010 (model energy code), ASHRAE 189.1-2009 (model green building code) and California’s Title 24-2008 (state energy code). These codes and standards all require that daylight zones be established adjacent to sidelighting apertures, and general lighting in these zones be separately controlled from other lighting. Regional and national design firms working in multiple jurisdictions and project types may find themselves determining daylight zones using up to four or more definitions that have many similarities but also significant differences.
Basically, each code or standard defines the dimensions of a daylight zone, and then identifies elements in the space that could limit these dimensions, such as tall obstructions (e.g., walls) and other daylight apertures. Additionally, some codes and standards recognize a difference between primary and secondary sidelighted daylight zones, with control in primary zones typically being mandatory, and control in secondary zones being encouraged through power credits.
Below is a short reference to how these codes and standards establish daylight zones in sidelighted spaces (vertical glazing below the ceiling), which, depending on the code or standard, may be called daylight areas. Note that window height (WH, also called window head height) is formally defined in ASHRAE/IES 90.1-2010 and ASHRAE 189.1-2009 as the distance from the floor to the top of the glazing. Also note that the main limitation to the daylight zone is the presence of some type of permanent partition, which may be defined slightly differently across the four codes and standards.
Here we see these rules presented visually in an example space. In each case, the width of the daylight zone is limited by the wall located 1 ft. to the north of the window. In each case, the depth is limited by the wall located southeast of the window, which is located at a distance that is less than one window head height deep into the space.
Some codes and standards, notably the ASHRAE/IES 90.1-2010 energy standard and California’s Title 24-2008 energy code, also establish secondary daylight zones. In the case of sidelighting applications with vertical fenestration such as windows, these are daylight zones extending deeper into the space, controlled separately from primary daylight zones and other general lighting in the space. This level of control is not mandatory but instead encouraged through the use of power credits—that is, a multiplier increasing available watts for the controlled lighting load. If you save energy, the code/standard says, you can have a more power.
As the below graphic illustrates, in each case, the secondary sidelighted daylight zone should be the same width as the primary zone, and another window head height in depth, with the same limitations in regards to 60-inch or taller permanent partitions.
Once the daylight zones are established in a space, we can then decide whether daylight harvesting control is warranted, how many control zones we will need (including what loads will be covered by each controller), and what control method or methods—switching, dimming, etc.—we will use. Each of these areas may be covered by separate code/standard requirements.
Next month, we will examine how to set up daylight zones in toplighted spaces.
By Craig DiLouie, on September 19, 2011
As demand for lighting controls continues to grow, advanced solutions are becoming increasingly specified while also becoming increasingly sophisticated. This increasing sophistication translates to greater owner benefit but can also pose greater risk of design and installation mistakes.
In a perfect world, designers create clear and detailed lighting control requirements that are easily installed by the installer and the owner. In the real world, however, the owner may not have clear expectations about their lighting. Further, the designer may not provide clear design intent, the installer may make errors and, if anything goes wrong, users will complain.
For the designer, the key is to clearly express the design intent, or the basis of design, so as to provide a common roadmap for the functionality of the lighting control system.
The question is: How?
While there is no standard for communicating design intent, designers have a number of tools at their disposal:
The written lighting control narrative describes the lighting controls, including a sequence of operation, or description of system outputs in response to various inputs. Device settings include occupancy sensor time delay and sensitivity adjustments, integrated dimmer presets, time schedules for relays, and other programming and calibration. Control zoning visually reveals what control devices control what loads. One-line wiring diagrams visually reveal how all of the control devices connect and their relationship to each other. Specifications and cut sheets describe the products used and desired baseline levels of performance. Lighting and electrical panel schedules assign loads to specific dimmers or switches in the panel. And performance testing criteria tell the commissioning authority and electrical contractor how and what to test the system for after installation, and criteria for acceptance.
The written control narrative could be considered most important because it informs everything else, and yet it is often missing in project documents. Going beyond what drawings can communicate, it provides a common guide and reference for the project. Specifically, it can be used to support contract document and specification preparation, provide clear direction during bidding to contractors and manufacturers, give the commissioning authority criteria for testing and accepting the control system, and tell the owner how their control system operates.
Designers benefit by accessing a common roadmap describing the lighting control system’s intended functionality, which increases the likelihood of satisfying the owner. Contractors and manufacturers have clear direction for bidding. Installers are less likely to commit costly errors. The commissioning authority knows what to test, how to test it, and criteria for acceptance. And the owner is more likely to receive a quality product, increasing the likelihood of acceptance.
 (Click on the image to enlarge for easier viewing; enlarged image will appear in a new window; click the back button to return to the article.) Problems and fixes matrix illustrating the relative degree of difficulty (and expense) of correcting problems during construction, and whether a controls narrative would likely make an impact on avoiding these problems. Image courtesy of The Weidt Group. This type of documentation may become common in the future as commercial building model energy codes address documentation and commissioning. ASHRAE/IES 90.1-2010 requires the following documentation be delivered to the owner within 90 days after acceptance of the control system: record drawings of the actual installation, submittal data for all controls, recommended schedule for inspection and recalibration, and a complete control narrative showing “how each lighting control system is intended to operate, including recommended settings.”
A basic control narrative might include at least two main elements. First, a general description of the project goals and delivered control strategies deployed to satisfy these goals. Second, a description of the control system and sequence of operations for each space type. The document may change or be fleshed out over time as the project moves from the pre-design (programming) to design (schematic design, design development, construction documentation) to construction and occupancy and operations, with changes reviewed and approved at each step.
 (Click to download as XLS file.) Example of a matrix approach to creating a control narrative. The matrix identifies spaces or space types and control strategies implemented within each; on the far right, number codes reference the wiring diagrams and a detailed sequence of operations for each space or space type. Here is an example of very general project goals, including relevant codes, for a new office building:
“The lighting controls must meet the mandatory control requirements as defined in the ASHRAE/IES 90.1-2007 energy standard. Select control strategies implemented by the lighting systems go beyond these requirements to support LEED certification.”
Ideally, the owner will provide clear direction to inform the project goals. Following is a general description of the control strategies used in the project. Here’s an example:
“The interior lighting controls will enact two primary strategies intended to minimize energy consumption: 1) automatic shutoff via occupancy sensors in small, enclosed spaces and via a timeclock-based low-voltage control system in larger, open spaces, and 2) daylight harvesting in all spaces receiving high, consistent levels of daylight contribution, notably the main lobby and private and open office spaces. In certain spaces lacking daylight and where personal safety is an issue, such as corridors illuminated by electric lighting, select lights will remain ON at all times during normal hours of occupancy. In presentation spaces, notably the meeting and training rooms, flexibility will be provided to enable users to select preset light levels. Lighting controls will also turn exterior lighting ON/OFF using a photocell/timeclock based on curfew (grounds lighting) or dusk-to-dawn operation (security lighting).”
Following the project description is a lighting control system description, including a sequence of operations—a description of what the controls in each space do in response to inputs such as occupancy, time events or daylight levels.
This could take the form of a written description produced in a simple and consistent format; a matrix providing an at-a-glance view for each space type or each individual space (room numbers pulled from the drawings), an approach well suited to complex projects.
Back to our example, we will be deploying manual-ON, timeclock-OFF for general lighting in the open office spaces in our office building, and daylight harvesting dimming in perimeter zones receiving sufficient levels of daylight. The control narrative for the manual-ON and timeclock-OFF switching controls (code 2 under the “sequence of operations” column on the matrix) might read (adapted from the Department of Energy’s Commercial Lighting Solutions webtool):
“ON/OFF control of the general lighting in each open office area will be controlled by a combination of manual wall switches and timeclock schedule functionality residing in a low-voltage relay panel-based control system.
“Users entering the space at the start of business hours will turn the general lighting ON by control zone, with each zone being within 2,500 sq.ft. in area or per the local energy codes.
“At 6:00 PM, the control system will blink several times, warning users that the lights will turn OFF in five minutes. At 6:05 PM, the control system will turn the general lighting OFF. Users working afterhours may keep the lights ON, or turn the lights back ON, by toggling the manual wall switches, which function as a 120-minute override for the timeclock automatic shutoff system.
“After 120 minutes, the system will blink the lights again, and sweep them OFF five minutes later unless the override is again activated.”
Using this basis, we might add even more information—the more detail, the better:
“The control system shall be programmable at a microprocessor-based central processing unit (CPU). The system shall provide weekly routine and annual holiday scheduling and automatically adjust for leap year and daylight savings time. Each program shall not exceed 25,000 sq.ft. or one floor, whichever is smaller. The control system shall have 10-year nonvolatile memory that stores all schedules. The system shall be able to reboot the program and reset the time schedule and current time, without errors, following power outages up to 14 days in duration. The system shall export lighting energy consumption reports by space and zone. The control system shall operate independently of but be capable of communicating with the building automation system, if present.”
From there, we could also add performance testing and criteria for acceptance. For the above low-voltage relay control system, this might include ensuring that the general lighting in each zone turns OFF at the scheduled time, the sweep is properly preceded by a blink or other warning, and the overrides are properly zoned and working.
Finally, we could add references to other pertinent documents, such as wiring diagrams, control zoning and equipment specifications and cut sheets.
Producing a written controls narrative entails more effort at the front end, but can deliver strong project benefits. By providing clear expectations for lighting control system functionality, designers will more likely deliver a quality product, contractors will more likely provide an error-free installation and properly calibrate and program the system, the owner will more likely properly maintain it, and users will more likely accept it.
By Craig DiLouie, on June 13, 2011
 Daylight harvesting is an advanced lighting control strategy used to minimize ongoing owner energy costs. It occurs when a sensor measures daylight levels and signals a control to adjust electric lighting system output to maintain a desired task light level. Variable daylight levels are automatically harvested as energy savings through electric lighting reductions.
Because energy savings will be dependent on factors such as type of available daylight, control response and space and task characteristics, actual savings can be difficult to predict, although studies suggest strong potential. A 2003 study conducted by the National Research Council of Canada discovered 40% energy savings in an open office environment and 50% (with manual blinds) to 70% (manual blinds used optimally, or automatic shading) in private offices. Another 2003 study, conducted by Heschong Mahone Group, found that daylight harvesting strategies can produce 50% energy savings in school classrooms.
LEED 2009 encourages providing daylight and views to users. IEQ, Credit 8.1 awards 1 LEED point for providing a minimum 25 footcandles of daylight in at least 75% of regularly occupied building areas. IEQ, Credit 8.2 awards 1 LEED point for introducing views in at least 90% of regularly occupied building areas—that is, a direct line of sight to the outdoor environment via vision glazing 90 in. above the floor. Because strong daylight availability is essential to daylight harvesting, these buildings are well suited to this control strategy. Daylight harvesting, in fact, is favored in LEED projects, not only because of daylight availability, but because energy points are based on exceeding ASHRAE/IES 90.1-2007, and because daylight harvesting is not required by this standard, its energy savings can be captured as LEED energy points. Further, the Green Interior Design & Construction version of LEED further awards 2 points for introducing daylight harvesting controls in all daylighted areas (1 point) and/or on 50% of the lighting load (1 point).
Because of the strong energy savings potential offered by daylight harvesting, coupled with advancing technology, codes and standards are now beginning to address daylight harvesting—specifically, International Energy Conservation Code (IECC) 2009, ASHRAE/IES 90.1-2010, ASHRAE 189.1 and Title 24-2008. In review, IECC 2009 and ASHRAE/IES 90.1-2010 are energy standards offered as model energy codes for states and other jurisdictions. ASHRAE 189.1 is a green building standard. And Title 24-2008 is California’s unique energy code.
All of these codes and standards are different and yet have similar major themes. First, they define daylight availability as zones around sidelighting (e.g., windows) and toplighting (e.g., skylights and roof monitors) daylight apertures. Second, they require separate control for general lighting in these daylight zones. The standard may also specify whether the control must be manual or automatic, switching or dimming, stepped switching or simple ON/OFF. And the standard may reward aggressive daylight harvesting with power adjustment credits that can be used to acquire greater design flexibility with the controlled load.
Let’s look more closely at the daylight harvesting requirements published in IECC 2009 and ASHRAE/IES 90.1-2010. First, what is the daylight zone? After all, daylight harvesting is entirely dependent on daylight availability in the space. Both IECC 2009 and ASHRAE/IES 90.1-2010 define daylight zones using formulas based on size of aperture and whether there are any obstructions blocking the light, with ASHRAE’s approach being similar to ASHRAE 189.1 and California’s Title 24-2008 code. Sidelighted daylight zones are defined as depth x width adjacent to the aperture, and toplighted daylight zones are defined as length x width under the aperture. ASHRAE/IES 90.1-2010 includes helpful drawings detailing daylight zones.
IECC 2009 offers a basic approach to daylight harvesting control by simply stating that general lighting in these zones must be separately circuited and controlled from other general lighting in the space. The method of control is not specified, so the designer has a choice of switching or dimming. ASHRAE/IES 90.1-2010 goes much farther with an approach that is similar to California’s Title 24-2008 energy code:
Sidelighted spaces: If the sidelighted daylight zone is larger than 250 sq.ft., then the control method must be automatic and multilevel (or continuous dimming), providing one step between 50% and 70% of the design lighting power, and another between OFF and 35%. ASHRAE/IES 90.1-2010 encourages more aggressive daylight harvesting strategies in sidelighted office, meeting, classroom, retail sales and public space types with credits that can be used to increase the power allowance for the controlled lighting load. Recognized strategies include continuous dimming control and automatic control of general lighting in secondary (deeper) daylight zones in sidelighted spaces.
 Energy standards and sidelighting. Toplighted spaces: In toplighted spaces, if the total daylight area under skylights plus the total daylight area under rooftop monitors is larger than 900 sq.ft., the general lighting must be separately controlled using either a stepped switching or continuous dimming controller, with some exceptions. As with sidelighted spaces, more aggressive daylight harvesting control in toplighted areas is rewarded with power adjustment credits.
Additionally, perimeter lighting in parking garages is required to be automatically reduced in response to daylight, with some exceptions.
Demand for daylight harvesting controls has grown dramatically in recent years, driven largely by sustainability initiatives such as LEED. Since 2005, California’s energy code required daylight harvesting in certain spaces. Now the major energy standards—IECC and ASHRAE/IES 90.1—contain significant requirements for daylight harvesting control, signaling widespread acceptance and adoption of this control strategy in the future.
By Lighting Controls Association, on May 16, 2011
Last month, the Lighting Controls Association published a guide to the new ASHRAE/IES 90.1-2010 standard, focusing on its prescriptive lighting power requirements as well as significant changes to its scope and administrative requirements.
In Part 2 of this series on the new standard, we will focus on its extensive new mandatory and optional lighting control requirements. Regarding controls, the changes are nothing short of historic.
“In the past, designers have been able to design project using only the minimum level of control required by code,” says Jeff Park, manager of sustainable market development for WattStopper and a consulting member of the ASHRAE 90.1 Lighting Subcommittee. “With the new additions incorporated into the 2010 revision, designers are being tasked with paying closer attention to lighting controls in general. They will now need to integrate control design into their lighting design in ways not often done in the past.”
Michael Jouaneh, LEED-AP BD+C, marketing manager for Lutron Electronics Co., Inc. and a consulting member of the ASHRAE 90.1 Lighting Subcommittee, says the dramatic lighting control-related changes in ASHRAE/IES 90.1-2010 are a sign of the times and a vote of confidence for the reliability and utility of advanced lighting control technology. “Lighting controls have come a long way,” he says. “Lighting controls are a critical component for saving energy in buildings; they are now a ‘must have’ in buildings instead of a ‘nice to have.’ These controls can eliminate 60% or more of the wasted lighting energy in buildings while enhancing occupant comfort and productivity.”
ASHRAE/IES 90.1-2010 requires:
• automatic shutoff of indoor and outdoor lighting when not in use;
• automatic lighting shutoff now required in buildings <5,000 sq.ft. unless specifically exempted;
• automatic lighting shutoff requirements of code now required for lamp plus ballast retrofits impacting 10+% of the connected lighting load;
• occupancy sensors required for a broader range of applications
• manual-ON or auto-ON to 50% operation required for automatic controls;
• multilevel lighting in spaces using manual space controls;
• automatic multilevel lighting in certain stairwell, parking garage and other spaces;
• automatic daylight harvesting control;
• power credits providing additional lighting power allowances as an incentive for using advanced control strategies;
• functional testing of controls; and
• documentation requirements including a control narrative and maintenance schedule.
Automatic shutoff
ASHRAE/IES 90.1-2010 requires that all lighting systems be turned OFF when not in use, with some exceptions.
Indoor: As with previous versions of the standard, for indoor lighting systems, this could be satisfied through use of a schedule-based control device, occupancy sensor or signal from another control or alarm system indicating the area is unoccupied.
Previous versions of the standard limited its automatic shutoff requirements to buildings larger than 5,000 sq.ft. The 2010 standard requires these controls in all buildings, with exemptions limited to lighting required for 24-hour operation, where patient care is provided, and where they might endanger safety or security.
“This change is a direct result of the realization that with the reduction in cost for controls in general that include building system controls and the options available for compliance—e.g., occupancy sensors—the rationale for application only to larger facilities was no longer compelling,” says Eric Richman, LC, senior research engineer for the Pacific Northwest National Laboratory and chair of the ASHRAE 90.1 Lighting Subcommittee. “Of course, this will increase initial control costs in some smaller facilities, but they should also see energy benefits over the life of the facility.”
Occupancy sensors: In previous versions of ASHRAE/IES 90.1, occupancy sensors began to be required in certain applications. The 2010 version expands this list: Occupancy sensors (or timer switches, per approval by the authority having jurisdiction) that turn the lights OFF within 30 minutes of the space becoming unoccupied are required in:
• classrooms and lecture halls;
• conference, meeting and training rooms;
• employee lunch and break rooms;
• storage and supply rooms between 50 and 1,000 sq.ft. in size;
• rooms used for document copying and printing;
• office spaces up to 250 sq.ft.
• restrooms; and
• dressing, locker and fitting rooms.
“Since the first requirement for this technology in the 2004 standard, the intent has always been to explore the addition of more space types to the list where it can be found to be an effective energy-saving option,” says Richman. “These new additions to the list are based on the latest research and case studies for different space types. Occupancy sensing control is considered one of the most effective methods for reducing lighting energy usage, and supporting its installation in as many spaces as possible—where it is a practical application—will have a large and immediate impact on lighting energy savings.”
Exceptions include shop and laboratory classrooms, spaces with multi-scene (e.g., dimming) control systems, lighting required for 24-hour operation and spaces where automatic shutoff would endanger safety or security of people or property.
Occupancy sensing is also required in guestroom bathrooms in hotels, motels, boarding houses and similar buildings. The sensor must turn OFF the lighting, with the except for night lighting not exceeding 5W, within 60 minutes of the occupant leaving the space. (In addition, bathroom lighting is now exempt from the requirement that all lighting in the guestroom must be controlled by a master control at the entry door.)
Outdoor: The previous version of 90.1 requires outdoor lighting to be controlled by a photosensor (daylight) or astronomical time switch (scheduling) for dusk-to-dawn lighting and either a time switch or combination photosensor/time switch. It also required that building grounds lighting fixtures >100W either use lamps with an efficacy of 60+ lumens/W or be controlled by a motion sensor, with a long list of exceptions.
The new standard simplifies these requirements. First, all outdoor lighting must be controlled by a photosensor. Second, building façade or landscape lighting must also be controlled by an astronomical time switch that turns the lights OFF between midnight or business closing (whichever comes first) and 6AM or business opening (whichever comes first) (or at times designated by the authority having jurisdiction).
Retrofits as trigger: ASHRAE/IES 90.1-2010 now explicitly covers “maintenance-like” lamp plus ballast (lamp/ballast) retrofits in both indoor and outdoor applications, which have traditionally been ignored for the most part by code officials. Specifically, if a building owner replaces lamp/ballast systems representing 10% or more of the connected lighting load in an indoor space or outdoor area, the owner must comply with the standard’s lighting power density limits expressed in watts per square foot and also its automatic shutoff requirements.
Note that in this situation the standard requires automatic shutoff but not space controls. If a panelboard upgrade is undertaken to provide automatic lighting shutoff in an existing building, the designer should take care to ensure that some form of override is provided to users so they are not left in the dark, even though this is not explicitly required in the standard.
Multilevel lighting
Previous versions of ASHRAE/IES 90.1 do not require multilevel lighting; the current version embraces it broadly for indoor and outdoor automatic shutoff and space controls, with special requirements for specific applications.
Manual-ON or auto-ON to 50%: Previous versions of the standard allowed automatic control devices to activate the lighting system as well as turn it OFF. In 90.1-2010, no longer: Automatic shutoff controls must be manual-ON or automatically turn the lighting ON to not more than 50% power. Exceptions include public corridors and stairwells, restrooms, primary building entrance areas and lobbies, and areas where manual-ON would endanger safety or security.
Manual-ON and auto-ON to 50% occupancy sensors, for example, have been demonstrated to save energy compared to auto-ON to full occupancy sensors, while eliminating nuisance false-ON triggering. Allowing auto-ON to 50% also increases flexibility in choice of light levels for users.
Space controls: The lights in each enclosed space in the building must be independently controlled by a conveniently located manual control device or automatic occupancy sensor with manual-ON or auto-ON to 50% operation. Certain enclosed spaces, identified in the previous section of this whitepaper, require occupancy sensors (or timer switches if approved), while designers have a choice of manual control or occupancy sensors in all other spaces. Regardless if using manual controls or occupancy sensors, the lighting must be configured for multiple levels enabling users to select at a minimum OFF, a step between 30% and 70% (inclusive) of full lighting power, and 100% of full lighting power. Exceptions include corridor, electrical/mechanical room, public lobby, restroom, stairway and storage room lighting.
“This change was made primarily to provide users with light level options that have been shown in some studies to have energy-saving benefits,” says Richman. “While the benefits are generally always smaller than automatic controls, the application of bilevel-type manual control has become common practice in a lot of commercial construction, and this requirement encourages the use of occupancy sensors that can be more cost-effective than the wiring needed for bilevel control.”
Stairwell lighting: Stairwell lighting must be controlled so that lighting power can be reduced by at least 50% within 30 minutes of the stairwell space becoming unoccupied.
“While stairwell and egress lighting are critically important for occupant use, the realization is that these areas are often rarely occupied and these are great opportunities for energy savings,” Richman explains. “It is understood that some jurisdictions may have local requirements that may conflict with this requirement but as with all energy code documents, any legislated life, health or safety requirements typically take precedent.”
Parking garages: Parking garages must comply with the standard’s automatic shutoff requirements but also be controlled so that lighting power can be reduced by at least 30% when there is no activity detected for no longer than 30 minutes, with some exceptions. To satisfy this requirement, the lighting must be grouped in zones no larger than 3,600 sq.ft.
“The 2010 version of the standard includes specific parking garage control requirements,” Richman says. “These include reducing lighting power for luminaires by 30% when the area is unoccupied, providing separate control for daylight transition zones—entrance/exit—and daylight-responsive control of luminaires within 20 ft. of effective daylight openings. This is a new area for the 90.1 standard but one where there is typically a lot of lighting use when spaces are unoccupied and therefore ripe for effective controls.”
Daylight harvesting: Daylight harvesting is an important area of the standard and is covered in detail in the next section.
Outdoor lighting: ASHRAE/IES 90.1-2010 requires a reduction of lighting power during times of night when the lighting is required to be ON but is unlikely to be used, or will be used only intermittently. If the lighting is not building façade or landscape lighting, it must be controlled by a device that reduces lighting power by at least 30% for at least one of these conditions:
• from midnight or within 1 hour of the end of business operations (whichever is later) until 6 AM or business opening (whichever is earlier); or
• during any period when no activity has been detected for a time of no longer than 15 minutes.
The standard specifically states this requirement also applies to advertising signage; exceptions include the same as those that apply to automatic shutoff (see previous section of this whitepaper). This requirement would entail using either a time switch or occupancy sensing.
Daylight harvesting
Previous versions of ASHRAE/IES 90.1 do not address daylight harvesting control, an advanced control strategy that has matured due to strong demand in projects requiring high levels of sustainable design, such as LEED projects. The new standard now includes the most aggressive and complex daylight harvesting control requirements in current codes.
The code first distinguishes between primary sidelighted areas directly adjacent to daylight apertures and secondary areas in proximity but not directly adjacent to daylight apertures. These areas are strictly defined by the standard using helpful diagrams and are intended to define zones in which consistent, unblocked, high levels of daylight availability is typically expected.
If the primary sidelighted area (defined in the standard and based on space geometry and window effective aperture characteristics) in an enclosed space is 250 sq.ft. or larger, the general lighting in that area must be separately controlled using either a stepped switching or continuous dimming controller, with some exceptions. More aggressive daylight harvesting in primary and secondary sidelighted areas is rewarded with power adjustment credits described later in this whitepaper.
In toplighted spaces, if the total daylight area under skylights plus the total daylight area under rooftop monitors is larger than 900 sq.ft., the general lighting must be separately controlled using either a stepped switching or continuous dimming controller, with some exceptions. As with sidelighted spaces, more aggressive daylight harvesting control (i.e., automatic continuous dimming) is rewarded with power adjustment credits.
Additionally, perimeter lighting in parking garages is required to be automatically reduced in response to daylight, with some exceptions.
“Daylighting control has been an elusive item for energy codes and standards because of its natural complexity, which makes it very difficult to write a code requirement that is practical and enforceable,” notes Richman. “The requirements in 2010 include control of electric lighting when sufficient sidelighting from windows or top lighting from skylights or roof monitors is present. A second part of the requirements makes the installation of skylights mandatory but only when there is sufficient open area available to make good use of daylighting. The trick with these requirements is the determination of an effective daylight capability.”
While ASHRAE/IES 90.1-2010 endeavors to simplify the process, its approach to daylight harvesting control will increase the complexity involved in compliance. Of particular concern is the fact that daylight harvesting control, particularly zoning, is now treated differently in ASHRAE/IES 90.1-2010, ASHRAE 189.1, IECC 2009 and California’s Title 24-2008.
“This will not be the easiest energy code requirement to apply but the diagrams do a good job of clarifying the requirements,” says Richman. “This is the most aggressive and involved daylighting requirement in current codes and is expected to help increase the use of daylighting control as standard commercial construction.”
Power adjustment credits
When using the Space by Space Method of compliance with the standard’s prescriptive lighting power allowance requirements, ASHRAE/IES 90.1-2010 offers lighting power adjustment credits based on use of advanced lighting control strategies in certain offices, meeting spaces, education spaces, retail sales areas and public spaces. Qualifying technologies range from manual dimming control to automatic continuous daylight harvesting dimming, with power adjustment factors, which are applied to the controlled lighting load, of 5-30%.
“When a lighting control system is installed that is more advanced—higher energy-saving capability—than the controls required in the standard, an incentive in the form of additional lighting power is allowed,” says Richman. “Because the 2010 version of the standard is aggressive in terms of controls, users will find that the controls needed to go beyond the requirements and enable getting the additional allowance will be advanced and more complicated but will also provide additional energy savings.”
For example, in an open office, if workstation-specific fixtures are installed with occupancy sensor-based dim-to-OFF control of the downlight component and occupant manual continuous dimming control of the downlight component, the designer can claim 30% of the wattage of these fixtures as an additional interior lighting power allowance anywhere inside the building.
Functional testing for lighting controls
ASHRAE/IES 90.1-2010 requires functional testing of lighting controls and systems, a service typically provided by the installing electrical contractor in a new construction project, sometimes supervised by the designer or a commissioning agent. The standard requires that the construction documents identify who will conduct and certify the testing.
Specifically, all specified lighting controls and associated software must be calibrated, adjusted, programmed and assured to operate in accordance with construction documents and manufacturer installation instructions. Specific requirements are identified for occupancy sensors, programmable schedule controls and photosensors.
For example, at a minimum, the party conducting the testing must confirm that the placement, sensitivity and time-out settings for any installed occupancy sensors provide acceptable performance—e.g., the lights must turn OFF only after the space is vacated, and must turn ON only when the space is occupied. Time switches and programmable schedule controls must be programmed to turn the lights OFF. And photocontrol systems must reduce light levels produced by the electric lighting based on the amount of usable daylight in the space as specified.
“This new requirement simply recognizes the fact that lighting controls, like any control system, needs to be set up to function properly and therefore achieve the energy savings while maintaining useful function of the lighting,” Richman explains. “The requirements ensure that the systems are running correctly when the facility is turned over to building owners and that provisions are in place to make sure that they are periodically reviewed for correct operation. Too often, well designed systems are eventually overridden or fall out of function, which defeats their ability to affect energy savings.”
Documentation to include control narrative
ASHRAE/IES 90.1-2010 requires that certain documents be turned over to the owner within 90 days of system acceptance, including, for example, as-built drawings of the lighting and control system, operating and maintenance manuals for all lighting equipment, recommended relamping program, schedule for inspecting and recalibrating lighting controls, and a complete narrative of how each lighting control system is supposed to operate, including its recommended settings.
“This documentation requirement is intended to ensure that the new owner and/or operator of the lighting systems has the information needed to understand their operation, plan for future maintenance, and address any configuration concerns,” says Richman. “The requirements are fairly straightforward encompassing the need to provide drawings, operation and maintenance manuals on equipment, and narratives on the operation of each control system. Most of these are standard items that these requirements now ensure will be completed and provided.”
A stronger code standard
The ASHRAE/IES 90.1-2010 standard is far more comprehensive, stringent and complicated than its predecessors. Expect early adoption in states and other jurisdictions that are most progressive towards energy conservation, such as the Northeast and Pacific Northwest. To obtain a copy of the standard, visit the ASHRAE bookstore at www.ashrae.org or the IES bookstore at www.ies.org.
By Craig DiLouie, on April 18, 2011
 ASHRAE/IES 90.1, Energy Standard for Buildings Except Low-Rise Residential Buildings is published every three years to provide states and other jurisdictions with a model commercial building energy code. Today, most states have adopted either 90.1 or the International Energy Conservation Code (IECC), published by the International Code Council (ICC), as their energy code, have a code based on one of them, or publish a state-specific code with similar requirements.
The 2010 version, published November 2010, represents the most dramatic revision of the standard since 1999. Over the past decade, the standard has steadily become more restrictive in terms of allowed lighting power and requirements to install lighting controls. The 2010 version takes both of these trends to a new level with the goal of achieving dramatic energy savings and taking a significant step towards the ultimate goal of net-zero buildings. According to the Department of Energy, commercial buildings designed to ASHRAE/IES 90.1-2010 are expected to achieve 32.6% site energy savings and 30.1% energy cost savings compared to buildings compliant with ASHRAE/IES 90.1-2004, excluding plug loads.
In all, the new ASHRAE/IES 90.1 standard is far more comprehensive, stringent and complicated than its predecessors. Expect early adoption in states and other jurisdictions that are most progressive towards energy conservation, such as the Northeast and Pacific Northwest. To obtain a copy of the standard, visit the ASHRAE bookstore at www.ashrae.org or the IES bookstore at www.ies.org.
“This version of the 90.1 energy standard is definitely aggressive but the developers have taken great care to develop a set of requirement that are fair, practical and effective,” says Eric Richman, LC, senior research engineer for the Pacific Northwest National Laboratory and chair of the ASHRAE 90.1 Lighting Subcommittee. “As with all energy codes, there will be conflicts for some applications and building or space types. It is hoped that when these occur, the building owner and local building officials can follow the intent of the standard and craft an energy-effective yet practical solution.”
In this two-part series of special reports by the Lighting Controls Association, we will examine the new energy standard in detail. Part one, presented here, focuses on changes to the prescriptive lighting power requirements as well as changes to scope and administrative requirements. Part two, to be published next month, will focus on the standard’s extensive list of new mandatory and optional lighting control requirements.
 Lower lighting power allowances
ASHRAE/IES 90.1 imposes limits on the amount of lighting power installed in the building, expressed in watts per square foot (or W/linear ft.), to promote efficient technology and design. These lighting power densities (LPDs) apply to interior and exterior applications. It is the designer’s job to design a lighting system that satisfies the owner’s requirements within the given LPD limit.
The 90.1 standard is considered friendlier to designers than current versions of the IECC code because it provides LPDs for individual space types in addition to whole building types, which provides more flexibility (but is more cumbersome to enforce, which is why IECC, written by code officials, does not include a space by space method). In ASHRAE/IES 90.1, designers have a choice of using the Building Area Method (whole building power allowance) or Space by Space Method (individual spaces, with potential additional and tradable allowances).
In the 2010 version, the majority of whole building and space LPDs are reduced by varying amounts, based on modeling that incorporated the latest off-the-shelf energy-efficient technologies and current IES light level recommendations.
Power adjustment credit for odd room geometries. If using the Space by Space Method for designing lighting systems in interior spaces, a new adjustment credit is available for rooms with odd geometries, increasing flexibility even further.
“The 2010 Standard will now provide a room geometry-based adjustment to interior space type LPDs based on the room cavity ratio (RCR) of the empty room,” says Richman. “This is in recognition of the fact that the current LPDs simply don’t have much play in them, are based on typically expected room geometries, and that not all room geometries for a specific space type are the same.”
In review, RCR is calculated as (2.5 x room cavity height x room perimeter length)/room area, with room cavity height being the distance in feet between the light fixtures and the workplane. The adjustment is allowed when RCR for a given room can be shown to be greater than the threshold RCR that is tied to the LPD allowance as shown in a table provided in the standard. It also applies to corridor/transition spaces that are less than 8 ft. wide regardless of RCR. In these cases, the LPD allowance can be increased by the LPD for the space type x 0.20.
“It won’t be an easy adjustment to get,” says Richman. “The RCR thresholds in the standard are not particularly loose but those spaces that do need extra allowance for their odd geometries will be able to get it.”
Power adjustment credit for advanced lighting controls. Although controls will be covered in more detail in next month’s whitepaper, it is important to point out here that ASHRAE/IES 90.1-2010 offers lighting power adjustment credits based on use of advanced lighting control strategies. Qualifying applications include certain offices, meeting spaces, education spaces, retail sales areas and public spaces. Qualifying technologies range from manual dimming control to automatic continuous daylight harvesting dimming, with power adjustment factors, which are applied to the controlled lighting load, of 5 -30%.
“When a lighting control system is installed that is more advanced—higher energy-saving capability—than the controls required in the standard, an incentive in the form of additional lighting power is allowed,” says Richman. “Because the 2010 version of the standard is aggressive in terms of controls, users will find that the controls needed to go beyond the requirements and enable getting the additional allowance will be advanced and more complicated but will also provide additional energy savings.”
Exterior lighting power allowance section expanded for lighting zones. In recent versions of 90.1, the exterior lighting section has evolved to impose lighting power allowances similarly to the way interior lighting power allowances are treated, effectively creating a Space by Space Method addressing outdoor lighting. A large number of outdoor lighting applications are identified covering virtually all possible applications from building façade to parking lot, with some applications considered “tradable” (you can take wattage savings in one applications and give those watts to another applications) and some “nontradable.”
In ASHRAE/IES 90.1-2010, the evolution continues with the introduction of Lighting Zones 0-4 covering application environments in order of increasing population density (and increasing light level requirements due to assumed higher level of ambient light from other sources in the surrounding environment), from undeveloped areas through high-activity commercial districts. The result is a matrix crossing outdoor application with these lighting zones, resulting in customized power allowances by zone.
“This change is based on the current lighting community understanding that exterior lighting needs are partially based on the level of surrounding light,” Richman explains. “Exterior applications in areas with bright surrounding night need higher light levels to provide appropriate contrast and eye adaptation. The table of allowances has been split into zone sections and the allowances increased or decreased accordingly. With this version of the standard, the exterior allowances will be applied based on the exterior zone type.”
For example, lighting for sales canopies is limited to 0.6W/sq.ft. in developed areas of national and state parks, forest land and rural areas, but this is increased to 1W/sq.ft. in high-activity commercial districts in major metropolitan areas.
“It is expected that most exterior environments will fall in the middle categories of neighborhood districts and light industrial,” Richman adds. “These categories have generally lower allowances than the previous single category, which included major metropolitan high-activity commercial districts and was therefore set high to cover these areas. The expected impact is that each site will have more specific and appropriate allowance with a general reduction in exterior lighting energy use across the country.”
Table 1. ASHRAE/IES 90.1 lighting power allowances using the Building Area Method.
| Building Type |
Maximum Lighting Power Density (W/sq.ft.) Allowed Per Version of the ASHRAE/IES 90.1 Standard |
|
| 1989 |
1999/2001 |
2004/2007 |
2010 |
| Automotive Facility |
0.96 |
1.5 |
0.9 |
0.982 |
| Convention Center |
2.07 |
1.4 |
1.2 |
1.08 |
| Court House |
1.44 |
1.4 |
1.2 |
1.05 |
| Dining: Bar Lounge/Leisure |
1.37 |
1.5 |
1.3 |
0.99 |
| Dining: Cafeteria/Fast Food |
1.37 |
1.8 |
1.4 |
0.90 |
| Dining: Family |
1.37 |
1.9 |
1.6 |
0.89 |
| Dormitory |
1.15 |
1.5 |
1.0 |
0.61 |
| Exercise Center |
2.07 |
1.4 |
1.0 |
0.88 |
| Gymnasium |
2.07 |
1.7 |
1.1 |
1.00 |
| Healthcare Clinic |
1.44 |
1.6 |
1.0 |
0.87 |
| Hospital |
1.44 |
1.6 |
1.2 |
1.21 |
| Hotel |
1.15 |
1.7 |
1.0 |
1.00 |
| Library |
1.29 |
1.5 |
1.3 |
1.18 |
| Manufacturing Facility |
0.96 |
2.2 |
1.3 |
1.11 |
| Motel |
1.15 |
2.0 |
1.0 |
0.88 |
| Motion Picture Theater |
2.07 |
1.6 |
1.2 |
0.83 |
| Multi-Family |
1.15 |
1.0 |
0.7 |
0.60 |
| Museum |
2.07 |
1.6 |
1.1 |
1.06 |
| Office |
1.26 |
1.3 |
1.0 |
0.90 |
| Parking Garage |
1.03 |
0.3 |
0.3 |
0.25 |
| Penitentiary |
1.44 |
1.2 |
1.0 |
0.97 |
| Performing Arts Theatre |
2.07 |
1.5 |
1.6 |
1.39 |
| Police/Fire Station |
1.44 |
1.3 |
1.0 |
0.96 |
| Post Office |
1.44 |
1.6 |
1.1 |
0.87 |
| Religious Building |
2.07 |
2.2 |
1.3 |
1.05 |
| Retail |
2.25 |
1.9 |
1.5 |
1.40 |
| School/University |
1.29 |
1.5 |
1.2 |
0.99 |
| Sports Arena |
2.07 |
1.5 |
1.1 |
0.78 |
| Town Hall |
1.44 |
1.4 |
1.1 |
0.92 |
| Transportation |
2.07 |
1.2 |
1.0 |
0.77 |
| Warehouse |
1.03 |
1.2 |
0.8 |
0.66 |
| Workshop |
0.96 |
1.7 |
1.4 |
1.20 |
Tandem wiring
The mandatory requirement related to tandem wiring in previous versions of the standard is now eliminated. “This requirement was aimed directly at eliminating the use of older standard magnetic ballasts that are designed to drive two T12 lamps and have unnecessary losses when only driving one lamp,” explains Richman. “The current reality is that this older technology is simply not an option anymore for new or retrofit projects, so the language was removed.”
Coverage of lamp/ballast retrofits
Traditionally, 90.1 and IECC have covered new construction and major renovations. Lamp and ballast replacement is typically considered maintenance and not an alteration or repair, resulting in retrofits being traditionally ignored by code officials.
ASHRAE/IES 90.1-2010 now explicitly covers “maintenance-like” lamp plus ballast (lamp/ballast) retrofits in both indoor and outdoor applications. Specifically, if a building owner replaces lamp/ballast systems representing 10% or more of the connected lighting load in an indoor space or outdoor area, the owner must comply with the standard’s lighting power density limits and also its automatic shutoff requirements.
First, the proposed retrofit lighting power will have to be no greater than the maximum allowable lighting power density (LPD, expressed in watts per square foot) for the given building or space. Next, the lighting will have to be turned OFF automatically when it is not being used. Recognized methods include a schedule (e.g., programmable low-voltage relay control system), occupancy sensors that turn the lights OFF within 30 minutes of the space being vacated, and a signal from another control or alarm system that indicates the area is unoccupied (e.g., security or building automation system). Exceptions include lighting that must operate continuously, lighting where care is given to patients, and lighting where automatic shutoff would endanger occupants. (The retrofit does not further trigger the space controls section of the standard, but if a panelboard upgrade were to be undertaken to gain lighting automation capability, some type of manual override control should be provided as a common sense measure ensuring occupant safety.)
The result is some regulation for lamp/ballast retrofits that previously were typically considered not covered by code. Projects may require inspection depending on the authority having jurisdiction. Half-measures will no longer be acceptable for retrofits due to the requirement to achieve lower LPD levels. Again, the retrofit must be lamps plus ballasts, so lamp-only retrofits can presumably still be performed without having to satisfy the code. Requiring controls in retrofits may change the economics of some retrofit projects while requiring that practitioners achieve a high level of proficiency with lighting control application, installation and functional testing.
“This is a major change but is considered important because a majority of lighting efficiency opportunities are found in the large fraction of projects that are retrofit rather than new construction,” says Richman. “These requirements will likely force more thought behind the lamp and ballast retrofit to ensure the right equipment is used to meet the LPD limits. The additional control requirement may seem intrusive, but this is only the simple shutoff requirement that can be met with a whole building system or individual low-cost occupancy sensors or some other system. As with all requirements, there are some exemptions and allowances that will provide relief in appropriate situations.”
Documentation
Finally, there are new documentation requirements. ASHRAE/IES 90.1-2010 requires that a list of documents be turned over to the owner within 90 days of system acceptance, including, for example, as-built drawings of the lighting and control system, recommended relamping program, schedule for inspecting and recalibrating lighting controls, and a complete narrative of how each lighting control system is supposed to operate, including its recommended settings.
“This documentation requirement is intended to ensure that the new owner and/or operator of the lighting systems has the information needed to understand their operation, plan for future maintenance, and address any configuration concerns,” says Richman. “The requirements are fairly straightforward encompassing the need to provide drawings, operation and maintenance manuals on equipment, and narratives on the operation of each control system. Most of these are standard items that these requirements now ensure will be completed and provided.”
Next month: Part 2 of this article, where we will talk about ASHRAE/IES 90.1-2010’s dramatically expanded requirements for lighting controls.
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