Energy and Buildings, Vol.47, 74-83, 2012
Novel instrumentation for monitoring after-hours electricity consumption of electrical equipment, and some potential savings from a switch-off campaign
An increasing cause of electricity use and greenhouse gas emissions is from IT equipment such as computers, printers, and servers, with worldwide computer use increasing from 1000 million PCs in 2006, to 1400 million in 2010, and estimated to cause 3% of global electricity demand. Significant energy may be saved if un-used devices are switched off. It was noted that the switch-off rates in the USA for desktop computers in 2006, could be as low as 30%, and there clearly is a need for up-to-date information. It has been difficult to provide accurate figures for switch-off rates, since previous monitoring of IT use has been expensive. requiring specialised equipment and electrical work, labour intensive (using walk-through surveys), or both. This paper demonstrates two low-cost techniques for estimation of unoccupied PC use. Precision and tracking for both were compared with actual power consumption, and subcircuit switch-off rates appeared to be under 76%. Whole building IT related use (including servers) was around 40% of electrical baseload. A desktop switch-off campaign was instigated for accessible equipment, resulting in a 20% reduction in electrical baseload. Extrapolation to a weeknight campaign suggests annual electricity savings of around 12%. (C) 2011 Elsevier B.V. All rights reserved.