Maybe you just got to the office, grabbed some coffee and pulled up to your desk to start your day. Your printer sits innocuously next to your lamp, computer and phone, but they feed an insatiable monster -- they all draw electricity around the clock. This drain, called plug load, which accounts for about a third of commercial building energy use, might be why your electricity use has increased over the past few years.
As electricity demand increases, new power plants are constructed around the country. But the Rocky Mountain Institute looks at this issue from the other side: Rather than focusing first on energy production, have we utilized all possible ways to lower demand? Our buildings are responsible for 41 percent of U.S. primary energy use. Improving building energy efficiency is vital to the cleaner energy future that RMI envisions in Reinventing Fire. Reducing energy demand in our buildings can also create job opportunities and free up financing for renewable energy sources.
The revolution toward energy-efficient buildings is well under way. Increasing energy prices and demand for healthier buildings put pressure on the construction industry to build greener buildings. The market is being transformed by many efforts, including retrofitting lighting and HVAC systems, the increasing popularity of high-performance window and envelope systems, more stringent energy codes, and the influence of recent green-building-rating systems and efficiency programs such as LEED and Energy Star. However, considering the urgency of carbon emissions reduction, we must ramp up our efficiency efforts to reduce the amount of CO2 in the atmosphere to safer levels.
Any effort to realize the full efficiency potential of the existing building stock must address end uses that have historically been overlooked, including plug loads. Plug load is a term for the energy consumed by devices plugged into electric outlets, such as computers, TVs, kitchen appliances, phone chargers, servers and task lights. Almost any device in our buildings consumes electricity while on standby or even when switched off. This is known as phantom (or ghost, or vampire) load.
Finding the monster
Plug loads are a major contributor to building energy consumption, especially in offices. In commercial buildings, plug loads are one of the fastest-growing end uses in terms of energy consumption and typically account for 30-35 percent of the total electricity used.
Plug loads are becoming more and more important in efficiency efforts. Because lighting retrofits are the most common energy-efficiency measure, lighting loads have remained stable as commercial floor space has increased. HVAC loads have grown proportionally to the 0.9-1.2 percent average annual growth in floor space. But even though efficiency of electronic devices has constantly improved, proliferation and increased use of office equipment continues to elevate plug loads as a percentage of the total building energy use. Since 1995, plug load energy consumption has increased about 235 percent. Since the building shell and major building systems are becoming more efficient and the solutions for reducing plug loads are challenging to implement, plug loads become a larger and larger piece of a shrinking pie.