Speaking to HSJ ahead of his speech to the NHS Confederation conference tomorrow, the chair of the Sustainable Development Commission said he was 'mystified' by the NHS's progress.
'There is little impediment to the NHS to change as it does not cost them more money and the evidence is so strong,' Mr Porritt said.
Only a minority of NHS organisations were tackling the issue and the take-up of the majority was too slow, he said.
It was 'disappointing' that only one in four NHS organisations had signed up to the commission's good corporate citizenship assessment tool, which assesses organisation's environmental footprint.
Mr Porritt said the assessment tool was designed to show NHS organisations could embrace sustainable development and tackle health inequalities through their day-to-day activities.
The tool pulls together guidance and resources to help the NHS analyse their impact on the environment in six key areas: transport, procurement, facilities management, employment and skills, community engagement and new buildings.
Trusts must also assess the environmental impact of new hospital builds and plan accordingly,. he said.
'In terms of capital expenditure is does mean that contract costs are more, but that expense is recouped very quickly in terms of operational costs.
'The fact that some organisations have been able to work this into the system whilst others have not is very frustrating,' Mr Porritt said. 'Budgets need to be pooled. so outcomes are shared between the health service and local. authorities.'