if your intention is to create a space for your own private practice or even share it with others and you just don’t have the funds to build it with better materials there are ways you can put a hot room together if you would not mind sacrificing ventilation and fresh air.
If one were to take a bathroom and wastefully leave the shower on while they worked out for 90 minutes that might make you sweat but at what cost.
I suggest choose an interior room in a location without outside walls to heat. Line the interior of the room with at least 1″ of insulation or bubble wrap or Low-E insulation the more the better. Line the walls and ceiling for best effect. Next get foam puzzle floor tiles from eBay or buy Zebra 1″ yoga flooring or Fuji 5/8″ yoga flooring and then look online for old electric heaters which do not have the 90 F cutoff’s – they stay on.
For steam choose 2 large rice cookers or large coffee urns. each electric heater will produce about 1200 watts of heat and each Coffee pot or Rice cooker will use about 400 watts . Most homes will have limited power in each room so running an extension cord from other rooms may be required.
If you put 3-4 electric heaters and 2 coffee urns or rice cookers in a 12 x 12 room with insulation and a towel blocking the under door drafts , you could get by for a while.
Just remember these basic concepts
heat flows from warm to cold – any cold surfaces in the room will attract heat and absorb it so a cement or tile surface can make heating impossible and require 10-20X more power than if it were insulated.
10 minutes is all the warm up time you need- after that you are losing too much heat.
there are 2 types of insulation
1-thermal -like foam or fiberglass sheet which block absorption into the structure – sheetrock etc
2- radiant – like mylar or reflective foam or bubble insulation or foil which reflect Radiation.
so if you reflect the heat inwards even from behind the electric heaters with foil you can double their efficiency.
I do not think direct electric heating is safe for the long term and i believe radiation is harmful and cumulative so proceed at your own risk.
The more you insulate the less radiation it will require to heat a yoga room and each person can give off 1500- 2000 BTU of heat so it is possible to work out in a highly insulated space with no extra energy source other than you.
Of course we sell forced air heaters as well as an occasional radiant panel system – sometimes used . So we are always thinking of ways to enable your practice on a budget.