Efficient heating

The winter has arrived the northern-hemisphere, which means heating is becoming necessary to lots of family. In the regions that suffer from the brutally cold weather, there's nothing better than staying in a building that is heated. However, in order to provide heat, extra energy is required, which means that the consumption of energy increases. The higher consumption of energy leads to the more emission of greenhouse gas. We certainly do not want to give up the heating when the temperature is unbearably cold, but we can't ignore the problem embedded in the increased energy consumption. Therefore, we have to find a alternative solution.

There are two types of heating. One is the conventional furnace, the other one is the heat pump. Furnaces generate heat by combusting the fuel such as natural gas, oil, and woods. Heat pumps, on the other hand, use electricity to pump the heat in or out side of the buildings. With the current technology, the efficiency of the furnace can reach 80% to 90%, which means only about 20% to 10% of heat leaks out through the exhaustion pipe. The heat pump, however, can reach a higher efficiency that is 300% or above. The 300% efficiency of the heat pump means that it use one unit of electricity to transfer three unit of heat. Heat pumps achieve the transition of the heat by condensing and vaporizing the coolant. When the refrigerant change the phase between liquid and gas, heat is released.

When the refrigerant passes the compressor, it is compressed to a high temperature hot gas, when this hot high pressure gas passes the condenser, it transforms to liquid form and releases some heat. Although the high temperature releases some heat, it is still hot, and when it passes the expansion valve, it becomes gas form and cools down a lot. When the refrigerant becomes cool gas, it absorbs heat from the environment. After the refrigerant absorbs the heat, it will be sent to the compressor and condenser again, releasing the heat. When this cycle keeps going, the heat will be transferred from one space to the other constantly. That is how heat pumps work. Actually, most of family have heat pumps, that is, the air-conditioner. Air-conditioners keep the building cool by pumping the heat out of the building. However, the heat pumping of the air-conditioners is one way, which means that they can not heat houses by pumping heat into the building. Air-conditioners can only heat houses with the heat generated by the electric resistance. The new generation of heat pumps have switches inside that can reverse the cycle. In the summer time, heat pumps can pump heat out of the house. In the winter time, heat pumps can pump the heat in to the house. However, heat pump have a disadvantage. It can not work when the outdoor temperature is very low. Heat pumps heat the house by heat exchanging of the refrigerant. When the temperature is too low outside, the heat exchange of refrigerant will be very slow. Therefore, the heating will be inefficient and slow. In the areas that have temperature lower than -20 degree Celsius, furnaces are better than heat pumps. Despite the fact, heat pumps are more efficient than furnaces at most of the places.

Heat pumps are energy efficient. They can heat and cool houses with lower consumption of energy. Therefore, using heat pumps for residential heating and cooling can lower the cost on energy. More importantly, it can reduce the greenhouse emission associated with heating and cooling.