Why is this big news?
The Federal stimulus targeted $5 billion to upgrade Federal buildings, with an estimated $1 billion being spent on lighting. The CLS for Office webtool was fast-tracked by DOE to support Federal facility managers who will be looking for solutions. Meanwhile, the Energy Policy Act of 2005 requires all new nonresidential Federal buildings to exceed ASHRAE 90.1-2004 by 30%.
Green construction is growing from about 10% of the current commercial building market to 20-2% by 2013, or $96-$140 billion, according to McGraw-Hill. Public construction at state and local levels benefits from Federal stimulus money as well, and more than 30 states, 35 counties and 135 cities now have laws and policies requiring or encouraging the use of LEED in public construction. These jurisdictions may begin adopting green construction codes based on standards such as ASHRAE’s new Standard 189.1, published in January.
LEED 2009 requires the building to achieve 10% lower energy consumption than ASHRAE 90.1-2007, and assigns LEED points towards different levels of certification based on going above and beyond. The ASHRAE 189.1 green construction code caps maximum allowable lighting power density at 90% of 90.1-2007.
Saving energy is easy. One could find some light fixtures with the highest efficiency possible, for example—say, some industrial open-bottomed strips with T5 or T8 lamps, install them in an open office, and dramatically reduce energy use. The only problem would be the people working in that office would hate being in the space, as that type of light fixture, while highly efficient, is also a “glare bomb” at typical office mounting heights. The employees would come to work wearing baseball caps—or not at all.
Saving energy while providing good lighting quality is hard, particularly when tasked to save lighting energy compared to a building already complying with ASHRAE 90.1-2004. In fact, it is arguable that only design leaders in the field can do it well.
To take on this problem, the Department of Energy launched the Commercial Lighting Solutions (CLS) program at www.lightingsolutions.energy.gov. CLS is a webtool that allows people to customize lighting templates designed to produce 30+% energy savings compared to ASHRAE 90.1-2004, while also providing good lighting, in different building types. The tool includes extensive lighting control templates developed by the author in collaboration with the Lighting Controls Association.
Following the CLS for Retail webtool, which launched at last year’s LIGHTFAIR, CLS for Office launched at LIGHTFAIR 2010 in May.
Here’s how it works.
The user provides information about the building, such as location, operating hours and prevailing energy code. Next, the user selects a typical office space within the building, including private office, open plan, open plan perimeter, corridor, conference room and reception area, and enters information about it, such as total area, ceiling height and whether there is daylight present. If daylight enters the space, additional information is requested, including shading, presence of light shelves, orientation, etc.
The webtool takes this information and produces several lighting options, called lighting vignettes. Suppose we want to meet certain energy-saving and lighting quality goals in the renovation of a series of private offices. After entering some information, we are given a choice of direct/indirect pendant light fixtures or recessed lensed, with lighting power densities (W/sq.ft.) up to 35% lower than the maximum allowed by ASHRAE 90.1-2004/2007 using the Space by Space Method. All lighting vignettes were designed by lighting design firm Horton Lees Brogden.
After selecting the lighting vignette, control options are presented. The control options were developed in an exhaustive process involving members of the Lighting Controls Association and its parent, the NEMA Lighting Controls Section. Due to the multitude of control choices, the user is given a general performance spec and clearly expressed design intent based on their control choices.
In the case of private offices, for example, the user can choose a manual-ON occupancy sensor with either bilevel switching or manual dimming and a photosensor for daylight harvesting.
With both the lighting and control options selected, total energy savings is shown at the bottom. The user can now download an energy summary, implementation instructions for the different spaces/lighting templates, and a light fixture schedule. For the lighting, the implementation instructions include sample lighting layout, light levels, contrast ratios, color rendering, how to integrate the electric lighting with the daylighting and notes on maintenance.
For the controls, the implementation instructions include a strategy description, color-coded control zone drawing revealing the strategy at a glance, performance specifications and notes on maintenance and commissioning.
Using the CLS for Office webtool, construction professionals can achieve lighting designs that maximize both energy efficiency and lighting quality. It’s available free here: www.lightingsolutions.energy.gov.