On a daily basis, do I use more energy to heat a house from 32 outside or cool a house from 90 outside?

Answer 1

Taking as a basis that you would want to heat a house to say 65 in winter and cool it to say 70 in summer the temperature differences are 33 and 20 respectively. These differences govern both the heat required to heat/cool the house and the rate of heat loss/gain. Heating systems are likely to be of the order of 50% more efficient than cooling systems so the answer is that it is roughly the same energy to cool a house given your parameters and my assumptions.

Answer 2

In heating a house, you pay for the fuel gas and the electricity to operate the blower.

In cooling the house you pay for the electricity to operate the refrigerant compressor and the electricity to operate the blower, but there is no fuel cost.

Without trying to do a detailed analysis of the energy use of operating the blower, paying for the fuel gas, and operating the compressor, all I can say is that with a central air conditioning system, that my winter heating bills are at least 300% to 400% more than my summer cooling bills.

However I live in Denver where we have cool summer nights, and our air conditioner in the summer months doesn't kick in till between 11:00 AM and 1:00 PM if we leave a couple of windows open at night and close them in the morning. Also, the air conditioner very seldom operates after 11:00 PM in the evening in the summer because the evening air cools down so much as soon as the sun goes down.

Now, if we lived in Phoenix, or Miami I am sure that our costs would be just the opposite, where our air conditioning would use the biggest % of the energy, and the energy used to heat the house would be much lower.

So, the amount of energy that you use to heat and cool your house probably has more to do with the type of climate where you live than anything else, and there is a tremendous difference in climates throughout the USA.

Answer 3

Heat = Area X (Temp1 - Temp 2) / R-value

Since the R-values and areas are the same, it becomes a function of Temp1 and Temp 2.

Assuming the inside is set at 70F

f(heating) = 70 - 32 = |38| temp difference
f(cooling) = 70 - 90 = |20| temp difference

More energy is needed for heating, but gas heating is cheaper than electric cooling, so dollar-wise even though cooling needs less energy, the cost of the energy may be more expensive.

Answer 4

The answer depends on the interior temperature and the thermodynamic efficiencies of your heater / cooler. And probably the humidity, since some work is consumed condensing water vapor. Also, if there is ice or snow in contact with house, some enery will be consumed overcoming the latent heat of fusion--melting the ice. This could be HUGE if the house in question is poorly insulated.

Efficiency is probably the biggest factor. The the efficiency of heaters is quite high. The efficiency of refrigerated air units is much lower and decreases with increase in temperature diffence. Therefore, it probably takes more energy to cool the house.