Dc Building Power: Economic Factors, Application Drivers, Architecture/technology, Standards And Regulatory Developments

The dc building power market is projected toexist in both new installations and retrofits,
grow significantly over the next several years,according to the EMerge Alliance, 80% of the
and among the driving forces is the need tomarket opportunities are in the updating and
improve efficiency and reduce electricity costs inretrofitting of commercial buildings. Actually, the
several areas. According to the US Environmentalability to distribute low-voltage dc power within
Protection Agency (EPA), in 2006, data centrescommon infrastructures is already present in
and servers in the United States accounted formost commercial interiors
approximately 1.5% of the nation's total electricityLighting presents one of the major opportunities
consumption. To put this in perspective, the EPAfor the further development of dc power.
stated that this total exceeded the electricityAccording to a recent study funded by the U.S.
consumed by the entire nation's colour televisions,Department of Energys Energy Efficiency and
and is similar to the amount of electricityRenewable Energy Office (DOE EERE), lighting
consumed by approximately 5.8 million averageaccounts for 22% of all electricity consumed in
TV households. In addition, energy consumption inthe United States. Commercial businesses
data centres in the US is projected to continue toconsume 20% to 30% of their total energy just
grow, and double every five years.for lighting. And, 50% or more of that
Traditionally, large data centres andlighting-related energy may be wasted by
telecommunications facilities have consumed largeobsolete equipment, inadequate maintenance or
amounts of electricity without much regard forinefficient use. Upgrading lighting systems is one of
energy efficiency. Due to the continuous need forthe best energy efficiency investments available
energy production, it has been an acceptableto a commercial facility. Since linear fluorescent
practice to trade off energy efficiency andlight accounts for the majority of a commercial
operating costs for the sake of system reliability.building's lighting energy use, improving the
However, in recent years a number of factorsefficiency of these systems can save significant
have emerged that may change that practice.amounts of energy and money.
Now, a debate is taking place on how to copeIn addition to advances in dc power for data
with the growing need for electricity to powercentres, new advances in solid-state lighting (SSL)
these facilities. Data centre managers and otherare among the market forces expected to drive
data centre professionals are looking to dc powerthe dc power market over the next several
as an alternative solution to traditional ac power.years. The era SSL will be arriving soon, primarily
Proponents of dc power claim that it has thepowered by ultra-high-efficiency light emitting
potential to eliminate the biggest sources ofdiodes (LEDs) and to a lesser extent by organic
energy loss and waste in traditional ac systems:light emitting diodes (OLEDs). Used in large
the multiple back and forth transformations andhigh-definition signs, architectural lighting, stadiums,
conditioning needed to step voltage down for usebillboards and other applications, modern LEDs
by IT equipment.represent the latest lighting devices based on dc
One of the pressing needs for the furtherpower. In fact, current economic conditions are
expansion of dc power was the establishment ofjust right for the emerging LED replacement
dc voltage standards. In light of this need, twomarket. Several factors cited for this include
new dc power distribution standards for facilities"dramatic" improvements in commercially available
were developed over the past year, one forLED performance, significant cost reduction,
high-voltage (380Vdc) applications and another forgovernment regulations, and energy savings.
low-voltage (24Vdc) applications. The developmentOther applications contributing to the
of theses standards is significant and is expectedadvancement of dc power include common
to contribute to the further expansion of dcconsumer electronics devices, which operate on
power. The 380Vdc standard was developed bydc power and require conversion from dc
the Electric Power Research Institute (EPRI) alongsources. These devices are common in every
with Lawrence Berkeley National Laboratories andhousehold and include televisions, computers, set
is designed for data centres and other criticaltop boxes and many others. (All microprocessors
facilities. EPRI has developed the first dc voltagerequire direct current and many devices operate
tolerance envelope plotting voltage variationson direct power because it can be precisely
versus time for 380-Vdc powered equipment.regulated for sensitive components.) In fact,
The new dc voltage tolerance envelope providesmany of the smaller electronic devices such as
the technical details of the electrical operatingmobile phones, notebook computers and personal
environment, including allowable voltage surges anddigital assistants (PDAs) use ac-dc adapters, which
sags that could enable engineers to design poweralso result in power loss during conversion. In
converters for use with 380-Vdc distributionaggregate, the millions of ac-dc conversions
systems for next-generation data centreperformed for the operation of these electronic
equipment.devices extract a huge loss in energy during
The 24Vdc standard was developed by EMergeconversion.
and is expected to play an important role in theIn addition to the applications and trends driving
expansion of dc power in commercial, industrialthe industry, the market for dc power is strongly
and residential buildings. The new EMerge Allianceinfluenced by a number of technological and
standard is described as the first roadmap for theregulatory factors. These factors vary from
utilization of safe, low-voltage direct currentapplication to application and represent both
power in commercial interiors. The EMerge Allianceopportunities and threats. They include the growth
Standard 1.0 establishes a more efficient meansof dc power used in alternative energy systems,
of powering the rapidly increasing number ofthe availability of UL rated equipment and
digital, dc-powered devices, such as sensors,experienced personnel, the further development
lighting and IT equipment found in today'sof both UPS technology, the expansion and
workplaces. It creates an integrated, opendevelopment of a number of organizations and
platform for power, interior infrastructures,alliances the already-mentioned importance of
controls and a wide variety of peripheral devicesincreased efficiency and the further development
to facilitate the hybrid use of ac and dc powerof regulatory standards and policies.
within buildings.Among the areas examined in this report are the
As the emergence of the EMerge Alliancetechnology and architecture trends affecting the
standard suggests, dc power can be used toindustry, as well as a thorough discussion of new
improve efficiency at the lower-voltage levels.and emerging products and materials, potential
The addition of dc power delivery systems tothreats and the latest regulatory developments
homes, office building and commercial facilitiesand standards. Over 35 tables are presented
offers the potential for significant improvementsdepicting a variety of power system schematics
in energy delivery efficiency, reliability, powerand comparisons, architectural standards, product
quality and cost of operation. Most of theseintroductions, packaging solutions, efficiency
facilities are currently dominated by fixedstandards and other relevant information. The
overhead lighting, and a variety of electricalfocus of this comprehensive analysis provides
devices that are typically wired for the building'sdecision makers with an insightful look into the
lifetime rather than the occupant or residentscurrent and future opportunities and threats
evolving needs. In fact, although opportunitiesavailable in the dc building power supply market.