As part of your action plan, it would be useful to have a dedicated person to oversee the energy efficient initiatives and priorities for the project. It would be helpful for the church to agree its net zero carbon priorities and make a plan to protect the budget because unfortunately, usually when costs rise, the first items to go are the energy efficient options.
As well, you can develop a phased plan of maintenance and works that could be included in the build to retrofit zero carbon options. For example, there will be scaffolding up, what other energy efficient options could be fitted at the same time? You can also speak with the architect about ways to reduce wastage during the build and by making a plan to recycle materials.
As well, you can ask your architect about environmental options and how they fit with local authority guidelines. Economic, Environmental and Social sustainability must work hand in hand. There’s no point using a new environmentally friendly product within your project if it isn’t sustainable. Don’t use a new woodchip boiler if you’ll find supplies of woodchips difficult to come by or if you won't have the volunteers to maintain it.