By Steve Graham, Networx

If you have large, south-facing windows, you may already be using solar power in your house. If the windows turn a room into a sauna in the summer and a fridge in the winter, some touchups can lower winter heating bills and minimize summer heat.

Passive solar design, also known as climatic design, effectively uses abundant solar power without panels or other mechanical systems. Passive solar principles should be applied to new, energy-efficient construction. Simple retrofits can also boost the passive solar capacity of any home, with windows, walls or dedicated passive solar rooms. Also consider dark, heat-absorbing floors (particularly stone, concrete, or other masonry) to make any passive solar design more efficient.