Provisions for on-site electricity, water

Some items will need to be designed early on so that future installation is both quick and inexpensive. Most notable are rainwater harvesting systems and solar panels, to either generate electricity (photovoltaics PV) or produce hot water (solar thermal) and there are hybrid panels which can do both  

Ireland typically has no shortage of rain but in some parts of the country the supply of mains water is creaking under the pressure of demand. The cost of treating water is high so storing water from rain and using it to water your garden or wash the car is very environmentally friendly and relatively low cost if you plan your external roof water drains correctly at the start of the build. Be aware that water stored in such a way will start to become stagnant if left too long so using it regularly and topping it up with fresh rainwater will keep it good.