(1) "Heating degree day" means a unit, based upon temperature difference and time, used in estimating fuel consumption and specifying nominal heating load of a building in winter. For any one day, when the mean temperature is less than sixty-five degrees Fahrenheit, there exist as many heating degree days as there are Fahrenheit degrees difference in temperature between the mean temperature for the day and sixty-five degrees Fahrenheit.

(2) "Local government" means a county or municipality and may be used to refer to the governing body thereof or the area under the jurisdiction of said governing body.

(3) "Municipality" means any home rule city, town, or city and county, statutory city or town, territorial charter city, or municipal corporation which incorporated pursuant to territorial or general incorporation law and which has not reorganized.

(4) "Overall thermal transmittance"(U0) means the overall average heat transmission of a gross area of the exterior building envelope, expressed in British thermal units per hour per square foot per degree Fahrenheit. The U0 value applies to the combined effect of the time rate of heat flows through the various parallel paths, such as windows, doors, and opaque construction areas, comprising the gross area of one or more exterior building components, such as walls, floors, or roofs or ceilings.

(5) "Renovation" means any additions, alterations, or repairs to an existing building. When additions, alterations, or repairs exceed fifty percent of the value of an existing building, such building shall be made to conform to the renovation standards promulgated by the board for energy efficient building standards. The renovation standards promulgated shall recognize the individuality of each renovation project. Any additions shall conform to the energy conservation requirements for new buildings as they relate to the new construction only.

(6) "Residential building" includes all one- and two-family dwellings or multifamily dwellings not to exceed three stories above grade.

(7) "R-value" (R=1/U) means the reciprocal of the average overall coefficient of heat transmission in BTUs (British thermal units) per hour per square foot per degree Fahrenheit. The term is generally applied to usual combinations of insulation materials, as generally recognized and accepted in the residential building construction industry.

(8) "Thermal transmittance" ((U) (U = 1/R)) means the overall coefficient of heat transmission, air to air, expressed in British thermal units per hour per square foot per degree Fahrenheit. It is the time rate of heat flow. The U value applies to combinations of different materials used in series along the heat flow path, single materials that comprise a building section, cavity air spaces, and surfaces air films on both sides of a building element.

(9) "Value" means the estimated cost to replace the building in kind, based on current replacement costs, as determined by the local building official.