Design – Provisions for on-site electricity, water

DESIGN

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.

To further improve rainwater usage, the rainwater storage system can also be linked to a SUDs system which manages rainwater build up over hard surfaces. More complex systems will utilise storage tanks and pumps.

It is also possible to convert rainwater to potable water using particulate filters, UV sterilisation and carbon filters but these systems are not cheap and are really only viable where there is no other source of drinking water.

Solar energy is the other add-on you may consider. PV produces its electricity during the daylight hours and is at its peak on sunny summer days. If your energy consumption matches this scenario then you are onto a winner however, for most people the peak energy usage is the early morning and evening.  

If you are lucky enough to have a stream or river alongside the site, small or micro hydroelectricity systems are worth considering, as they will produce electricity all day, all year round. Bear in mind that permission to install one may be required from the water authority.

Exporting excess electricity to the grid is possible in NI and in ROI however the price paid is very small. Instead you can use the excess power to heat water via an immersion however, but solar thermal panels are much more efficient at this task. Electricity is a form of energy that is difficult to store and losses can be high when attempting to do so, even with a battery. 

The payback period for PV has been dropping rapidly due to economies of scale and advances in technology but the game changer will be low cost battery storage. Batteries store electricity until you need it but also offers the possibility of fast charging your electric car. Electric Vehicle (EV) chargers are mandatory to install on all new builds – the good news is, grants are available. However, efficiency (e.g. depth of discharge) and also product longevity are limiting the uptake as well,  considering batteries contain chemicals that may not be straightforward to recycle.

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