FAQs - Energy Efficiency Services

Energy efficiency related information and how operational and running costs can be reduced.

The most common measure for energy efficiency in a datacentre is the ratio known as Power Usage Effectiveness (PUE). PUE is the ratio of the Total Amount of Energy used by datacentre divided by the amount of energy delivered to the servers and data function. PUE is a datacentre specific energy efficiency measure developed by the Green Grid. The ideal ratio for PUE is 1.0.

PUE = Total Facility Energy / IT Equipment Energy = 1 + Non-IT Faciliyy Energy / IT Equipment Energy.

PUE is the inverse of the Data Centre Infrastructure Efficiency (DCIE) measurement.

The energy efficiency of a room air conditioner is measured using the Energy Efficiency Ratio (EER) which is the ratio of the cooling capacity measured in British thermal units (Btu) to the power input in Watts. The higher the EER, the more energy efficient the air conditioner.

Efficiency is a measure of the quantity of work or energy conserved in a process and is normally expressed as a percentage of the energy output divided by the energy input.

Energy Efficiency = Energy Output / Energy Input x 100%

When the Energy Efficiency ratio is less than 100% energy is lost in terms of heat or noise or converted to another form. The ratio cannot be more than 100%.

The Climate Change Levy (CCL) is a tax on energy delivered to commercial and public sector users (not domestic) in the UK. It a government initiative to increase awareness and drive organisations to initiate energy efficiency improvement programmes and reduce their carbon emissions. Where a UK business qualifies for reduced VAT they may also be exempt from the Climate Change Levy.

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