Energy
Efficiency Household Lighting Toolkit
Key Issues
Power Factor
The power factor of an AC electric power system is defined as the ratio of the real power to the apparent power and
is a number between 0 and 1 (see FAQs for Power Factor). Real power is the capacity of the circuit to perform its
work in a particular time. Apparent power includes the reactive power that utilities need to distribute even when it
accomplishes no useful work. Low-power-factor loads can increase losses in a power distribution system and result
in increased energy costs. Read more about power factors here.
Many electronic sources including CFLs are capacitive. In general the grid tends to be more inductive because of the
high amount of motor loads and in industry, power factor compensation (PFC) capacitors are frequently installed.
Incandescent lamps and electronic ballasts with power levels above 25 W have a power factor equal to 1, but
electronic ballasts because an active PFC circuit is needed in order to satisfy the harmonic current limits of standard
EN 61000-3-2 note that there is no direct limitation on the power factor itself in the standard but it is a consequence
of the harmonic current requirement and the technology used.16 Hence CFLs that capacitive are unlikely to create
strong negative grid influences because they rather compensate inductive loads and are unlikely to dominate the
total active power demand of the grid. There is a general misconception that the low power factor of CFLs actually
increases their energy consumption, and associated emissions, because of system losses. This is not true. An
excellent discussion of power factor issues related to CFLs is provided in a report by the Electricity Commission of
New Zealand.
Compared to incandescent lamps, CFLs with electronic ballast represent nonlinear loads for distribution networks.
While the savings for consumers are related to lamp efficacy (lumens per watt), savings for utilities are somewhat
compromised if replacement lamps‟ power factor is too low. In this case, the still high current needed to cope with
peak demand translates into unnecessary distribution and network losses. The unused power, known as reactive
power, is partially wasted in the process of being transferred and retransferred, and takes a toll on the infrastructure
of the distribution system leading to overheating of transformers, cables and motors; premature aging of capacitors;
and interference with telecom systems. CFLs with a high power factor (HPF) are an attempt to make up for the
waste and stress on networks caused by regular CFLs. HPF CFLs mimic linear demands and so make up for
conflicts between how power is supplied and how CFLs use power.
According to the technical studies conducted under the sponsorship of the European Commission to prepare for the
regulation on household lamps, even if they have a poor power factor, CFLs are overall much more energy efficient
than incandescent lamps. Moreover, the EU regulation on household lamps requires a minimum power factor for
CFLs. The European Council for Energy Efficient Economy (ECEEE) recommends that a few large-scale field tests
with high CFL saturation should be set up and closely measured in order to settle the issue. The ECEEE also
supports the European Commission’s approach of gradually tightening the power factor requirements. ECEEE
further believes that making HPF mandatory at this stage would be counter to the interest of consumers,
manufacturers and society as a whole. HPF lamps should rather be introduced in the standard, not made mandatory.
Households would not necessarily get any additional benefit from 0.85 PF lamps. It is the utility and the electricity
distribution companies that will get the benefit out of the HPF lamps.
Energy Efficiency Household Lighting Toolkit