Tightening energy codes and standards, along with new technology, present lighting designers with opportunities and challenges
Lighting designers can help assure that a project is adequately
illuminated, set the tone of a space or a room, or emphasize
architectural form. But their role is growing increasingly complex, in
part because lighting-related technology is evolving at a breakneck
pace, but also because energy codes are becoming progressively more
stringent.
One illustration is the standard
developed jointly by the American Society of Heating, Refrigerating and
Air-Conditioning Engineers (ASHRAE) and the Illuminating Engineering
Society (IES): 90.1, Energy Standard for Buildings Except Low-Rise Residential Buildings.
The document, updated every three years, is often referred to in
shorthand simply as "90.1." Most state energy codes are based on 90.1 or
the International Energy Conservation Code (IECC) published by the
International Code Council.
The
latest version of 90.1, released in November 2010, is much more
rigorous than its predecessor, says the U.S. Department of Energy (DOE).
When comparing 90.1-2010 to 90.1-2007, DOE found an impressive 18.5
percent savings of site energy (the amount of heat or electricity
consumed by a building as reflected in utility bills). In contrast,
buildings that comply with 90.1-2007 are expected to save about 4.6
percent of site energy when compared with those designed to the 2004
version.
The savings achieved by the
latest iteration of the standard can be attributed to several factors,
including requirements for more efficient mechanical systems and for
better-performing envelopes. However, tougher standards for energy
consumption associated with lighting are also a major contributor.
THE QUALITY ISSUE
The
90.1 sets new limits on the amount of lighting that can be installed
in buildings. For example, the whole building lighting power density
(LPD) allowance for a library in 90.1-2010 is 1.18 watts per square
foot, down from 1.3 in 2007, and from 1.5 in 2004. For an office, the
limit in the most recent standard is 0.90 W/square foot, reduced from
1.0 in 2007, and 1.3 in 2004. With these guidelines in mind, many
prescient lighting-design and daylight consultants aim for the lowest
numbers possible.
For instance, Washington,
D.C.-based MCLA used 90.1-2007 to plan the illumination scheme for the
city's Watha T. Daniel - Shaw Neighborhood Library. But the building is
below the LPD set by the 2010 standard. And for the research areas of
Princeton's Frick Chemistry Laboratory, lighting designers from Arup
devised a scheme with densities well under code limits
Architect: Davis Brody Bond
Project: Watha T. Daniel – Shaw Neighborhood Library
Location: Washington, D.C.
Architect: Hopkins Architects with Payette Associates
Projcet: Frick Chemistry Laboratory
Location: Princeton, New Jersey