Q: Is it really more economical to use electric space heaters where the people are than to heat the whole house?
Asked by Mary Fahnestock, ’70, Oxford, Ohio
This question is particularly interesting because it is usually not something the average consumer thinks of when he or she is trying to save money. Usually, we take the existing technology in our homes and use it. And because there is no price-tag hanging off the thermostat knob every time we come over to turn it up, we usually don't think about the money—and carbon dioxide—that we're sending up the smokestack. The realization of how much we have spent comes once or twice a month, when the bill shows up.
Central Heat Technologies
Central heat tends to be integrated into HVAC, or the Heating, Ventilation and Air Conditioning system, and its heart is a boiler or furnace. A boiler will heat water and send it or the steam coming off through a series of pipes and into the building's radiator locations. A furnace will heat air and circulate it through ducts around the house. Steam boilers tend to require higher operating temperatures and are less efficient than hot water boilers. Both of these systems need energy, though, so what kind of energy is it and where does it come from?
In order to answer this question, we must consider the efficiency of the system. A fuel utilization efficiency value is assigned to each heating system. It represents the amount of energy in the fuel that is actually transferred to directly heating the house. Electricity-powered central heating has the highest value at about 97 percent, while heating powered with gas tends to follow at about 85 percent. Seems like the decision is clear enough, right? Unfortunately, these numbers can be misleading and fail to take into account some of the more important factors involved.
Environmentally speaking, electricity generation from coal produces twice as much CO2 as natural gas and more than two-thirds of nitrogen oxides emitted into the air in the United States. The government estimates that household heating and cooling ultimately produces more greenhouse gases than any other individual action, even driving. It is crucial to remember that even though electricity has a higher efficiency rating in your home, most electricity is generated by burning coal, where about two-thirds of the energy is lost during the coal-to-electricity conversion. Not only is the coal burned, generating fossil fuel emissions, but it also needs to be mined with heavy machinery (which has its own lifecycle impacts), water needs to be heated, and finally a turbine needs to be propelled.
Space Heater Technologies
When burning material like wood, vent-less combustion heaters tend to bring dangerous off-gases and byproducts into the room, such as carbon monoxide, while exhausting the air quality. In addition, this heating type is a fire hazard and absolutely cannot be left unattended.
In contrast, the different types of mobile electric heaters that exist do not tend to have such effects. Usually, these heaters act like their central heating counterparts in that they depend on air circulation through cold air sinking and warm air rising—or convection. In this case, the more efficient models will use oil for high heat storage capacity, thus decreasing the amount of electricity input needed to continue providing the heat level we have set.
Alternatives
For those of us craving more options or who are at the point of choosing what to put in our homes, there are alternatives. If you wish to be the most environmentally friendly, solar energy is the way to go. If constructing a home, warmth absorption materials can be utilized for walls and flooring (which will give off heat during cold nights), while large windows facing the afternoon sun are best. If your house is already built, solar panels can be installed on your roof or in your yard. This system is considered "active" because it stores the heat accumulated during the day as solar radiation falls on the panels and returns it on demand.
If solar heating is not an option financially or because of the region you live in, consider pellet heating. These appliances burn pellets—1-inch pieces of bark, vegetable crop waste, cherry pits, beets and similar organic supplies. Their heating efficiency exceeds that of wood burning stoves and conventional fireplaces by many times and they give off so little smoke that they are known to be the cleanest fuel heaters made for the home. When used correctly, pellet heaters are nearly carbon neutral in that the CO2 generated during burning is equal to the amount normally cycling in the air. On the other hand, burning coal, gas or other fossil fuels adds additional CO2, that had previously been stored in the fuel. Pellet heaters act as strong space heaters and should be put into the most frequently occupied room in the house.
But what about clothing? Wool is made up of fibrous protein and has the distinction of being crimped, which allows it to be easily spun; air pockets produced from this structure are excellent at conserving heat. Not only is it wearable, but bedding made from wool can allow you to forget about the heater at night. Apart from being a fire-resistant material and having excellent thermal regulation, its ergonomic properties relieve pressure in the body.
You might ask, could I get overheated while I sleep? That's very unlikely because wool naturally maintains optimum temperature via its moisture-absorbing properties and insulation, which can act to keep heat out. As for the environment, wool is a natural product and does not require the resource input that synthetic materials do. Sheep wool is also renewable, since it is shorn once a year off the animal and subsequently re-grown. If using high quality natural material is important to you, you can find soft, organic bedding made in the United States, or outerwear such as suits, sweaters and skirts made from fine Italian merino wool.
Having come from Russia where the temperatures regularly fall to 20 degrees Celsius below zero, I can appreciate the difference in heating needs for those of us living in Palo Alto versus those in places like Ohio. In areas where winter means bundling up and seeing snow, combining the use of central heat to keep house temperatures at a universal minimal temperature with space heating to provide direct in-room warmth may provide more efficient results.
As you can see, no matter your location, financial situation or construction plans, there are options to change or improve your heating system to fit your specific needs. In the long run, your investment will not go unnoticed by your purse strings.
Marina Oster is a PhD student in the biosciences.
