That drafty 1950s home has charm—and sky-high heating bills. Request 12 months of utility bills from the seller and talk to neighbors about their monthly costs. An energy audit can reveal insulation gaps, leaky windows, or an inefficient furnace that costs you $2,000+ extra per year. That $30/month difference adds up to $360 annually, or $3,600 over a decade. Factor utility costs into your true monthly housing expense before making an offer.