just like jr said put bigger sets on. The best thing I bought a few years ago was a space heater (Big gas blower) usually buy 2 or 3 gas bottles through the winter (often get 1 or 2 purchased by client) turn it on full blast for 10-20 mins in the morning then leave it on low for a few hours, heats a house up really quick. This time last year we did a large barn conversion in the south hams (devon) thermometer was showing -1 outiside and -4 inside ( no windows or doors in, nightmare) hung dust-sheets over the openings, got the gas blower on the go, had no problems.