thinking of buying a 10 by 8ft summerhouse for my daugher are they safe to sleep in her friend has been living in hers for 2 yrs due to lack of space in her house she has electricity bed tv and a heater in it do they need ventilation also whats the best way to insulate it keep it warm if anyone has any pic of inside summerhouses i woull love to see them i have been looking online the pic dont really show inside of them