air:
  special heat 1000 J / (kg * K)
  density 1.2 kg / (m3)
  
wood
  thermal conductivity:
    0.12 w/(m2*K) if wall is 1 m thick
    if wall is 0.25m, then from each m2 for each degree difference
	  in celsius will go 0.48 w
  
Calculate:
  How many joules we need to heat one cubic meter of 
     air by 1 degree Celsius -> 1200 J
	 
We have room 6 x 3 x 3 meter. 
How many joules we need to heat air in this room by 
   1 degree Celsius? 54m3   64800 J / degree
  
We have starting temperature 0 degree celsius in room. 
And heater 1 kW. 1000 J / sec -> 60000 J / min. 
How warm is room after 1 minute?

Area of cuboid 3 x 3 x 6 m = 2*3*3 + 2 * 3 *6 + 2 * 3 * 6 = 90 m2

If inside temperature is 20 celsius, outside 0 celsius.
Wall 25 cm. How many j/s heat energy go out?
0.48 w/(degree*m2)  
0.48*20*90=864 J/s

heater on/off
make simulator:
temperature in each second, starting temperature 0 celsius inside room 
outside is always 0 celsius.