Patients 'living in deprived circumstances' are among the groups the DH wants practices in England to target by pointing them towards advice on heating, insulation and welfare benefits.
The Cold Weather Plan for England 2012, published last week, says practice teams should take action before winter begins to protect patients against the cold.
But the RCGP warned practices needed resources and support to deliver the plans.
The Cold Weather Plan for England was first published in 2011 to prepare the NHS for the impact of winter on the public's health. It is designed so the NHS can respond to alerts from the Met Office's severe cold weather warning system.
This year's plan advises practice teams to identify all patients who may be vulnerable to the cold this winter. Examples include children aged under 5, the elderly and patients with dementia, learning difficulties or those at risk of falls, but also patients 'living in houses with mould' or in deprived circumstances.
Identified patients should be 'opportunistically' pointed towards local services during regular consultations. The DH suggests as many as 20% of all patients - around 1,200 people in an average-size practice- could be identified, totalling up to 11m across England.
Vulnerable people should also be encouraged to take preventive steps 'such as obtaining insulation or having a benefits check'.
The DH gave the example of the Making Every Contact Count programme from Yorkshire and Humber, which encourages front-line NHS staff to ask patients whether they have adequate heating in their home.
Local agreements vital
The department said it was important to forge agreements with local services so GPs and practice staff can 'easily signpost patients who could be in need of energy efficiency, benefits or other support'.
It also suggests 'planning takes place early in the year and before severe cold and winter weather sets in', despite publishing the plans in late-October.
North Yorkshire GP Dr Simon Stockley, who led the RCGP's input into the DH plans, said evidence supported the idea that GPs could help protect people at risk from the cold by pointing them towards local services. He said a DH-backed project in Manchester showed practice computer systems could be used to flag up potentially vulnerable patients.
But he warned GPs needed appropriate resources and support to carry out the work. 'The key element for me is that this should be a planned and co-ordinated multi-agency approach, involving social services, local government, PCTs, etc.
'Similarly there needs to be understanding of the resources GPs need to deliver this advice. It is not necessarily something individual practices can do for themselves.'
He said the plans would provide further evidence of whether such interventions by GPs could save lives during the winter months.
England's CMO Dame Sally Davies and deputy NHS chief executive David Flory wrote to the NHS to announce the plan last week. They said: 'Severe cold weather is a major public health challenge in England. The effect of cold weather on health is one of the most significant, yet least recognised, factors causing death and illness in the country.
'The Cold Weather Plan sets out a series of clear actions to minimise the effects of severe cold weather on health, to be taken by the NHS, social care and other public agencies, professionals working with vulnerable people, and individuals and local communities.'