Install building insulation
Adding insulation can increase your building's resistance to heat loss and gain, and may be the most important building envelope improvement to make. If your building is both heated and air conditioned, insulation works year-round In winter it reduces your heating bill, in summer it cuts your air-conditioning bill. Adding insulation can lead to significant reductions in energy bills, particularly if there is currently no roof insulation at all, but it isn't necessary a good bet in every building. To make sure you make the right decision, get the help of a reliable firm before you invest.

Insulate and shield windows
Single pane window glass conducts a great deal of heat; its thermal resistance (R Value) is very low, only 0.9. Single pane 'storm' windows that fit over existing windows, and multi-layer 'thermal' replacement windows can rise the R value considerably and resist the passage of a lot of heat. If your present windows are in good condition and you are interested in maximum transmission of light, consider adding storm windows. If an area is uncomfortable because of overheating, or glare from too much sunlight, consider applying reflective or 'solar' film on the inside of the windows.

Install new windows
If you are remodeling and planning to replace your existing windows, you will find that advanced window technology gives you a number of exciting energy saving options. Advanced performance windows are available with R values of two to eight, many times higher than older standard units. Windows are available which tune your building to the local climate by emphasizing reduction of solar signs in cooling climates or minimizing heat loss in heating climates.