Over one hundred Iowa schools are releasing classes early today due to the heat. No one in state government nor in research positions knows how many Iowa schools are air-conditioned. Architectural firms say new schools are being equipped with air conditioning, but it’s a big expense. Lisa Bartusek of the Iowa Association of School Boards says nationalsurveys indicate between 60 to 80 percent of existing school buildings in America are air-conditioned. Bartusek says with talk of longer school years and use of school buildings for all sorts of activities, most new Iowa schools are being built with air conditioning.Some Iowa school districts have installed window air conditioners in individual classrooms to deal with the heat, but electrical systems had to be upgraded to handle the load — and window air conditioners are not very energy efficient. Architectural firms building schools in Iowa say 1990 was the last year they designed a new school which did not have air conditioning.