Energy efficiency improvements reduce operating costs and environmental impact. Insulation upgrades improve thermal performance. Cavity fill improves existing walls. Adding rigid insulation on exterior increases R-value. Infiltration reduction seals air leaks. Weatherstripping and caulking seal gaps. Air sealing under conditioned space prevents energy loss. Window replacement with high-performance units improves thermal performance. Low-E coatings reduce solar heat gain. Triple-glazing provides superior insulation. HVAC system upgrades improve efficiency. High-efficiency boilers reduce fuel consumption. Heat pumps provide heating and cooling efficiently. Proper sizing prevents oversizing and waste. Controls improvements reduce energy use. Programmable thermostats reduce heating when spaces are unoccupied. Zone controls allow temperature adjustment by area. Lighting efficiency reduces consumption. LED technology uses 75 percent less energy than incandescent. Occupancy sensors turn lights off when spaces are empty. Daylighting reduces need for artificial light. Water efficiency reduces consumption. Low-flow fixtures reduce water use. Insulation of hot water pipes reduces energy loss. Renewable energy including solar reduces grid consumption.