Thin clients can reduce power consumption by up to 80%

Do not operate independently
Thins clients only operate in a network connected to 1 or more terminal servers. They cannot operate as stand alones. All user functionality is lost when a thin client is disconnected from the network.

Currently not widespread
The technology has existed for many years but has not yet captured a large market share. In 2007, 25,000 thin clients were sold in Denmark, which is a lot less than the 1.3 million desktop computers sold in the same year. According to IDC, the numbers of thin clients sold will increase to ca 30,000 units in 2012. The 4 largest suppliers are HP, NEXTerminal, Fujitsu-Siemens and VXL Instruments, which have a combined market share of 80%.

Advantages of thin clients
Thin clients for computer networks have many advantages compared with desktop computers including:

• Less energy consumption: 30-80% compared with desktop computers
• Worth less to thieves: because they do not work without a terminal server and do not store sensitive data. This makes them less valuable to thieves
• Space saving: compared with ordinary computers
• Durability: typically last for 5 years and seldom break down
• Virtually silent: no hard drives or fans
• Produce very little heat: on account of low power

Electricity consumption by thin clients
Thin clients use less power than desktop computers, but about the same amount as energy efficient notebooks. Although savings can be achieved by switching from desktop computers to thin clients, there are virtually no savings to be made by switching from notebook computers to thin clients.

Thin clients use very little power in their own right, and only operate in a network connected to 1 or more terminal servers. They cannot operate as stand alones. Terminal servers typically have constant power consumption.

Savings achieved by switching from desktop computers to thin clients depend on whether there is already a terminal server. In many places, networks are constructed so that desktop computers operate more or less in the same way as thin clients. If a terminal server needs to be installed, the amount of power saved also depends on the efficiency of the terminal server.

See the Trust’s data covering power used by different thin clients

Requirements for electricity consumption
The Trust’s 2009 Purchasing Guidelines include requirements for thin clients. However, the Trust also recommends the following:

Thin clients
- Choose thin clients in the table with the least power consumption
- Efficiency of power supply should conform to the Trust’s purchasing requirements
- Off: max 2 watt
- Clients should switch off or go into power saving mode after max 30 minutes and switch off monitor after max 15 minutes

Terminal servers
- Combined terminal server and backup server: max 7.5 watts per thin client
- Min. 40 thin clients per terminal server and backup server

Companies without a terminal server
Thin clients require a terminal server with constant power consumption. If a company does not already have a terminal server then it may not always be worth switching to thin clients.

Companies with a terminal server
Companies which already have a terminal server can save considerable amounts of electricity (60-80%) by switching to thin clients because of the difference in power consumption between desktop computers and thin clients.

Percentage savings achievable by replacing desktop computers with thin clients

Assumptions
Replace 60 desktop computers with 60 thin clients
Time in On mode: 1,600 hours
Time in Off mode: 7,160 hours
Efficient thin client: 6 watts (On) and 2 watts (Off)
Inefficient thin client: 20 watts (On) and 2 watts (Off)
Terminal server: None
Efficient desktop computer: 21 watts (On) and 2 watts (Off)
Inefficient desktop computer: 50 watts (On) and 2 watts (Off)

Companies without a terminal server
Companies which do not have a terminal server can save 15-50% by replacing inefficient desktop computers.

Percentage savings achievable by replacing desktop computers with thin clients

Assumptions
Replace 60 desktop computers with 60 thin clients
Time in On mode: 1,600 hours
Time in Off mode: 7,160 hours
Efficient thin client: 6 watts (On) and 2 watts (Off)
Inefficient thin client: 20 watts (On) and 2 watts (Off)
Efficient terminal server: 3.5 watts/thin client
Inefficient terminal server: 5 watts/thin client
Efficient desktop computer: 21 watts (On) and 2 watts (Off)
Inefficient desktop computer: 50 watts (On) and 2 watts (Off)