Multi-standard mobile devices are allowing users to enjoy higher data rates and ubiquitous connectivity. These advances are achieved on the expense of higher energy consumption requirements due to the continuous connectivity and the multiple active wireless interfaces. In this paper, we use one advantage of the multiple interfaces, namely short range communications. Mobile terminals use short range cooperative network to take advantage of the good channel quality of short range links to save energy in multi-standard mobile terminals. In this cooperative network, the combined energy of all MTs is treated as a pool of resources, which is used by all MTs in the network. Toward this end, we propose cooperation between mobile terminals using short-range technology to achieve energy savings. We conduct a quantitative numerical analysis to show the energy saving gains that can be achieved. We derive the energy gains in different use cases, considering different combinations of technologies (WiFi-WiMedia, WiMAX-WiFi and WiFi-WiFi) and different channel conditions. We show that up to 80% energy savings can be achieved when using a combination of WiMedia as short range and WiFi as long range technology, compared to using WiFi without cooperation. We also show that short range cooperation can be used to extend the lifetime of the whole network. In such scenario, terminals, which are running out of battery or low in energy, can still relay their data through other mobile terminals, even if this will result in a slight increase in the total consumption of all mobile terminals. This way, source mobile terminals with low battery level benefit from the good condition of the short range channel, extending the lifetime of their batteries. The increase in the energy consumption of the relays can hence be compensated by some kind of payment, which opens opportunities for new business models involving source mobile terminals, relays and network operators.