It is almost certain that next winter demand for patio heaters will be extremely high, as bars and restaurants try and keep their smoking customers warm outside. (newlawjournal.co.uk)
This would seem to indicate you need around 11,000 sq feet to meet the average winter demand. (realclimate.org)
'' by the Massachusetts Attorney General's office, which concluded a reduction in natural gas supplies will not lead to peak winter demand period electric system «deficiencies» through 2030, under existing market conditions. (utilitydive.com)