Davey was energy secretary under the coalition government from 2012 until 2015 and is currently the chairman of community energy company Mongoose Energy.
Heappey was elected as the Conservative MP for Wells in 2015 and was a member of the Energy and Climate Change Committee until it was disbanded in October.
The two will join Labour shadow energy and climate change minister Alan Whitehead as vice presidents of the ADE.
“At a time of great political change, it is more important than ever that the ADE understands the importance of how this sector is perceived across the political spectrum and the addition of these two vice presidents will enable us to represent our members’ needs better,” said ADE director Tim Rotheray.
Davey said: “The leadership role of the ADE in the challenge to decarbonise heat across our economy – from homes to businesses – is a key reason for me joining them, as the country thinks through the different options for this huge task.”
Heappey said: “The digital revolution gives us an opportunity to engage more energy users in the system. I am delighted to be working with the ADE as they raise the profile of the key opportunities that exist within the decentralised energy sector.”