use is low, sophisticated and expensive central heating systems are not often required. Hence, even electric resistance heaters may be used. Electric heaters are typically only used on the coldest winter nights when overall demand for electricity in the rest of the house is low. Other forms of backup heater are widely used, such as wood pellets, wood stoves, natural gas boilers or even furnaces. The cost of a superinsulation retrofit should be balanced against the future cost of heating fuel (which can be expected to fluctuate from year to year due to supply problems, natural disasters or geopolitical events), the desire to reduce pollution from heating a building, or the desire to provide exceptional thermal comfort. During a power failure, a superinsulated house stays warm longer as heat loss is much less than normal, but the thermal storage capacity of the structural materials and contents is the same. Adverse weather may hamper efforts to restore power, leading to outages lasting a week or more. When deprived of their continuous supply of electricity (either for heat directly, or to operate gas-fired furnaces), conventional houses cool rapidly and may be at greater risk of costly damage from freezing water pipes. Residents who use supplemental heating methods without proper care during such episodes, or at any other time, may subject themselves to risk of fire or carbon monoxide poisoning. See also The first superinsulated houses used standard stud-wall construction, but other building techniques can be used: Building insulation materials Building insulation Earth-sheltered Earthship Energy conservation Insulating concrete form (ICF) Quadruple glazing Seasonal thermal energy storage (STES) Straw-bale construction Structural insulated panel (SIP) Zero-energy building Notes References Computation and description of an outside insulation house: To build for tomorrow (translated from French) Booth, Don, Sun/Earth Buffering and Superinsulation, 1983, Marshall, Brian; and Robert Argue, The Super-Insulated Retrofit Book, Renewable Energy in Canada, 1981 , Shurcliff, William A., Superinsulated houses: A survey of principles and practice, Brick House Pub. Co, 1981, 1982 Shurcliff, William A., Superinsulated Houses and Air-To-Air Heat Exchangers, Brick House Pub Co, 1988, External links Joe Lstiburek's 10-20-40-60 rule Optimization of the Building Shell with Superinsulation Super-Insulated House Plans (Mother Earth News) Why Superinsulation is so important in building to passive house standard Drawings and specs of 12 different superinsulated wall assemblies Superinsulation retrofit of a 1915 Sears Roebuck house Resources on the History of Superinsulation Building biology Building engineering Energy