Energy

While most buildings will be connected to the mains electricity supply, off-grid options may be suitable in some circumstances.

There are three options for electrical supply:

• Connection to the national electricity grid (mains or grid supply).
• Stand-alone generation (off-grid), which relies solely on generating power on site. Power generated is stored in batteries.
• On-site generation with grid back-up (distributed generation or DG systems, sometimes called on-grid). With a distributed generation system, the property owner, or groups of property owners, generate their own power and also connect into the grid network. The generated power is used on site, but if more power is generated than being used, the excess may be sold to the grid through an import/export meter and the supplier is given a credit for the power they have supplied.

Future supply changes

At present, all domestic consumers are charged a standard line charge. It is proposed that, in 2013, lines companies may no longer be legally required to supply power to lines they consider to be uneconomic. They may also be able to charge substantially higher line charges to some customers, which may affect the economics of supply considerably. However, this policy is currently under review and may change.

The uncertainty of supply may have an impact on design considerations regarding whether to opt for a grid connection or to design a stand-alone energy system.