Renewable energy projects, such as solar power, come with a high up-front investment, but offer a big payoff. For solar photovoltaic installations, your building must have a large roof area or a south-facing wall to reap the most benefits. These solar photovoltaic measures can offer compelling long-term returns under the Feed-in Tariff program. You can also go the solar thermal route, which also requires a large roof area or south-facing wall, and can be used to pre-heat domestic hot water or ventilation air. Ground-source heat exchange can provide dramatic efficiency improvements in certain suitable buildings.