problems with temp

Hey guys, i have a big grow room.. it is in my bedroom. there is a little 3x2 cutout in the wall that you can go into and it brings you into a 10x10 storage/attic room thing. It is right under the roof so its kind of an attic so the room is just a big triangle roof if you know what an attic looks like lol. anyways its connected to the outside. It is VERY cold outside. Due to poor insulation my grow room is often very cold. i have about 6 plants about 2 weeks old still young about 2-3 inches tall. as of about a few days ago i realized this was a problem so i put them in a 2x2 box and cut 2 holes in the tops to put the lights on. They are 2x 27watt CFLs which i have screwed into some portable "heatlamp fixtures". anyways it gets very cold. I dont really have the money to buy some high tech HPS light and the ballast which is gonna cost me >< anyways im obviously planning on getting more of the lights i have, very soon. I know CFL's dont put out much heat but its gonna be summer soon. What can i do in the mean time? Btw i am using an organic soil medium. not any problems with plants.. just planning ahead. So any feedback as to how i can better unsulate this grow room or build something with homemade supplies would be very helpful. keep in mine i am young and i am in school so i dont have lots of money to spend. thanks

PS: Is there anything i can do to ventilate/heat inside this shitty little cardboard box(assuming no1 has ideas about how to fix this grow room insulation problem)

i would leave the trap door open and let the heat from the house go up there, you should really try and insulate the room a bit, you can get the foam board for cheap

If i leave trap door open then all my household heat is going outside... and idk how much that would help... idk bout insulating >< thanks for the feedback tho..anyone else?