Upgraded electrical system from 100 Amps to 200 Amps; replaced wall A/C unit with central A/C; added 8" additional attic insulation; added attic exhaust fan to roof which makes attic much cooler in summer and lowers A/C costs; replaced wooden windows which had lead paint sashes with double-glazed aluminum windows; replaced back door and back storm door; added heavy living room drapes which keeps both heat and cold outside; thanks to Frederick County Refrigerator Exchange Program and am in the midst of replacing 1986 fridge with a much more energy efficient refrigerator