A furnace malfunction caused a smoke condition inside a Brookfield building early this morning.  Firefighters responded to the building on Stoney Farm Lane around 6:30am.  There were elevated levels of Carbon Monoxide in the building, which was then ventilated.  The furnace was taken out of service.  A smoke alarm activated in the basement alerted occupants to the problem. 12 firefighters were on scene for about half an hour.  Brookfield fire officials urge everyone to have working smoke and CO alarms, and make sure furnaces or boilers are properly maintained.