Conductive Heat Loss in a house

1. Sep 22, 2009

plexxity

1. The problem statement, all variables and given/known data
If only conductive heat loss was significant for a house, then by what percentage would you lower the heat loss if the temperature was reduced inside from 73°F to 67°F, when the outside temperature is 21°F? (Hint: Try using a ratio.)

2. Relevant equations
Unknown

3. The attempt at a solution
I do NOT want the solution just need to know what formula i should use to find the answer.

possibly a example problem but NOT the answer please, i want to learn how to do it.

2. Sep 22, 2009

mgb_phys

The heat loss is proportional to the temperature difference.
So as an equation you would write Power = k * (Tinside-Toutside)
The value of K would depend on your units for temperature, the material the house is made of and it's insulation - the important point is that k does not change.

Remember as well that you need T in absolute units.

3. Sep 22, 2009

But because the power is proportional to the temperature difference you can express the temperatures in Celcius as well as kelvin.Both give the same answer.

4. Sep 22, 2009

plexxity

Thanks you guys are awesome

5. Sep 28, 2009

phys-unit

Could someone give me the answer the this problem? I have a similar problem and need help.

6. Sep 29, 2009

plexxity

so what would the value of k be then? thats what i cant figure out.

7. Sep 29, 2009

plexxity

i have Power=k(19.4C-(-6.1C))

k isnt given in the problem?