Science Buddies: "Ask an Expert"

CONTINUATION FROM PRIOR POST RE: MORE THAN ONE CONTROLLED EXPERIMENT:

we are exhausted. Building the concrete house was a bear and it still wet of course. So after talking while we were working we have decided to go with one of the experiments. I guess all our work and building 6 structures is for nothing! (Or maybe he will figure out some way to use in a continuation project next year). Anyway, we decided to go with the Wood Frame building with the tin roof since this is more like an actual barn on a farm would be constructed (his real world application).

Our new question is this....we need some very fast data to hand in to the teacher by December 4 (she said we can then take out time to collect data before regional competition in February). Our structures are 2x2x2 and there are 2 of them. We can not rely on data from the outside temperature alone at this point because we do not have enough significant variation this time of year in Florida. For the "heated" portion of the experiment my son came up with one room in our house that has its own AC system. The temp could be turned up high and temp inside both coated/noncoated houses recorded at different times. WHAT ABOUT COLD TEMPERATURES? Anyone have any ideas how we could locate these structures somewhere at extremely cold temperatures so we could record data? I was thinking about a walk in freezer but do not even know who to ask about something like this. The thermostat in that one room in our house would probably only drop the temperature to 68 or so at a minimum and he is looking for lower temperatures than that. I am not sure about any rentable chillers or anything. DOES ANYONE HAVE ANY IDEAS?

Try thinking about the problem in reverse. You are trying to measure thermal transfer between inside and outside. You found a way to increase the outside temperature by raising the temperature in your test room. Why not use various 40w to 200w light bulbs in a ceramic (so it won't melt) fixture to raise the inside temperature instead of cooling the outside. 4 cubic feet should be easy enough to heat up with a light bulb. Start with the lower sized bulbs and work your way up.

Unless something in the air or in the structure changes phases with a temperature change, temperature difference is temperature difference.

You might want to think about wind (simulated with a fan). Your coating will likely change the convection and air infiltration properties of your structure. Wind should make these differences show up in your tests.

By not using lower temperatures, the moisture barrier properties will not be investigated. To me this sounds like a good compromise given your short period to conduct the initial experiments. Note: water vapor is something that can change state with temperature changes.