Help with a heat transfer question

[Zeynaz]

Homework Statement

The human body emits heat radiation. At the same time, body receives heat radiation from the environment. If the ambient temperature is lower than the body temperature there will be a net loss of heat.

Someone has a skin area of 1.8 m2 and a skin temperature of 32 Celsius degrees. The ambient temperature is 15 C.

- Calculate the net heat loss in joule for one hour.

Relevant Equations

Stefan-Boltzmann's Law --- P= (S-B constant)*A*T^4
wavelength-max= (wiens constant)/T

This question is in a unit about emission and absorption, Atomic Physics

So far, I calculated the Power that the person gives off which is by using the S-B law formula.
P= (s-b constant)*1.8*305K^4= 883 W (or Joules per second)

for the ambient i used the same formula and found P= 702 W

I tried to take the difference in these and divide it it by 60 to find joules per hour but the answer is wrong.
I am not sure which way i should go. I thought about Wiens law to find the max wavelength of each places and apply this to E=hf= hc/wavelength. Then just take the difference between them. would that be a correct way?

 

[haruspex]

divide it it by 60

Would you lose more heat in a second or more in an hour?

 

[Zeynaz]

Would you lose more heat in a second or more in an hour?

Ohh i see. I had to multiply it by 60

 

[haruspex]

Ohh i see. I had to multiply it by 60

Right.

 

[Zeynaz]

I tried it like that but it didnt work out. i found the loss of heat per hour for both the body and the environment. and i added these together (because loss of heat of human plus the environment). Because my answer was wrong i tried to subtract these values but still not correct.
The correct answer is 6.5E5 J but i don't know that to get there.