Quiz: What You Don't Know About Home Heating


Photograph by Ilya Naymushin, Reuters

You know enough to come in out of the cold, but how much do you really know about the energy spent to keep people warm?

How much of the world's energy use is for generating heat?

  • 27 percent
  • 37 percent
  • 47 percent
  • 57 percent

Demand for heat dominates world energy consumption, far higher than transportation, which accounts for just 27 percent.

The hypocaust was a central heating system used in ancient Rome's public bathhouses. A continuously burning fire channeled heat into an open space beneath the bathhouse floor. What do today's engineers believe was the system's main drawback?

  • Carbon monoxide risk
  • Chance of floor collapse
  • Inadequate heat distribution
  • Connecting it to city aqueducts

Engineers believe deadly fumes easily would have escaped into the main room from the subfloor. However, the principles of the hypocaust are at work in today's water-circulating radiant floor heating systems.

Benjamin Franklin invented the mid-room cast iron furnace that became popular for heating homes throughout America and Europe in the late 1700s. What was the flaw with the original design?

  • It vented smoke from the bottom.
  • It required more wood than a wall fireplace.
  • The heat dissipated too quickly.
  • It created a home fire hazard.

The Franklin stove was an efficiency breakthrough that generated heat in all directions and provided warmth even when the fire went out, but fellow Philadelphian David Rittenhouse made the critical improvement of adding a chimney to the design to vent smoke.

Before the forced air systems that are typical today, steam heating was common in homes and apartments. Heat circulated from the basement on the simple principle that steam rises. But a banging sound often came from steam radiators. Why?

  • Rapid expansion of heated air
  • Clogged radiator air vents
  • A radiator that is tilted
  • Mineral build-up in the pipes

Among the many issues with this inefficient system is that floors get warped beneath radiators, causing them to tilt in a way that prevents proper water drainage. When the system heats up, steam passing through the trapped water causes banging.

What is the most prevalent method of home heating today in the United States?

  • Oil
  • Natural Gas
  • Steam
  • Electricity

Nearly 60 percent of homes in the United States are heated with natural gas, making it the most popular residential heating fuel.

Which of these appliances would a home in Japan be most likely to use for heat?

  • Geothermal heat pump
  • Kerosene space heater
  • Natural gas furnace
  • Hydronic radiant floor system

Room space heaters are far more typical in Japan than centralized systems, and kerosene is a popular fuel.

Russia's spending to heat homes is double that of fellow Arctic nation, Canada, in terms of energy “intensity” (heat consumed per unit of GDP). This is due to many factors, EXCEPT FOR:

  • Russia has colder average temperatures than Canada.
  • Soviet planners forced large numbers of homes to be located in the coldest regions of the country.
  • People in parts of Russia typically open their windows in winter to vent warm air.
  • At least one quarter of heat generated is lost in Russia's city heating distribution systems.

Canada has colder average temperatures, but its people live in the nation's warmer areas. Russia's energy waste is equal to all the energy consumed in France, but the nation recently has embarked on an efficiency drive.

Geothermal heat pumps, which channel the Earth's natural heat into the home, are among the most efficient heating technologies available. They are currently being installed in about 2 percent of new U.S. homes. What percentage of homes in Sweden have them?

  • 10 percent
  • 20 percent
  • 30 percent
  • 40 percent

Sweden's “technology procurement program” in the 1990s—aimed at developing reliable, efficient, and affordable heat pumps—jump-started the market, making this nation a world leader in this energy-efficient technology for the home.

What is the Annual Fuel Utilization Efficiency (AFUE) rating on the most efficient home furnace or boiler you can buy?

  • 80
  • 90
  • 95
  • 97

Some natural gas furnaces (and a handful of oil models) achieve super-high efficiency by condensing the water vapor produced in combustion, and using the heat from this condensation. In the more common 80 AFUE furnaces, 20 percent of the fuel goes up the chimney as exhaust.

In operating a central home heating system, what causes lost energy—and wasted money?

  • Dirty air filters
  • Leaky ductwork
  • A fan that operates longer than it needs to
  • All of the above

Although they need much less maintenance than old steam systems, oil-fired furnaces should be tuned and cleaned annually, gas-fired systems every two years, and heat pumps every two or three years to cut heating costs and ensure safe operation.





Excellent! Your knowledge of heating is red hot.

You're picking up steam! Fire up the quiz again to improve your score.

Not so hot. But treat this as just a warm-up, and try again.

Don't sweat. Try learning more about heating at The Great Energy Challenge, and then retake the quiz to see how much you've learned.

Retake Quiz

More Energy Quizzes

  • Photo of three Gorges Dam on The Yangtze River in China.

    Quiz: What You Don’t Know About Energy in Asia

    You know that demand in Asia is moving energy markets around the world, but how much do you really know about the needs and resources of the world's most populous continent?


  • ** FILE ** In this June 1, 1973 file photo, Leon Mill spray paints a sign outside his Phillips 66 station in Perkasie, Pa. to let his customers know he is out of gas.  The downturn that is probably already under way is powered by the collapse in the housing market and sharp restrictions on credit that are now putting severe pressure on consumer spending and on businesses.  That is a very different environment from 1973, when an oil crisis was the culprit, squeezing U.S. businesses and consumers who were forced to line up at gas stations for hours.  (AP File Photo)

    Quiz: What You Don’t Know About Oil Crisis History

    Historians say the modern era of energy began on October 17, 1973, when Arab exporters unleashed the "oil weapon" with an embargo against the United States and its allies. How much do you know about the global oil shocks of the past 40 years and how they changed the world?


  • Emperor penguins near a crack in the sea ice in Antarctica.

    Quiz: What You Don’t Know About Climate Change Science

    Every few years, the Intergovernmental Panel on Climate Change (IPCC) releases a new summary of the scientific consensus on climate change. How much do you know about the forces altering the Earth's temperature, according to the IPCC's September 2013 report?


  • A polar bear mother with cub consider attacking a male narwhal.

    Quiz: What You Don’t Know About Energy in the Changing Arctic

    You know that climate change is reshaping the Arctic, but how much do you really know about how shrinking sea ice is opening up the resources at the top of the world for exploration and development?


  • A battery collection.

    Quiz: What You Don't Know About Batteries

    You know how often you need to charge your smartphone, but how much do you really know about the batteries we rely on for energy storage?


See all quizzes »

@NatGeoGreen on Twitter

Working Toward Smarter Cities

  • panamacity.jpg

    How to Make Cities Sustainable?

    From better mass transit to a stronger mix of renewable energy, what is the most important thing we can do to make cities smarter when it comes to energy use?

  • Istanbul skyline with rush hour traffic in the foreground

    Powering Our Urban Future: Spotlight on Turkey

    Istanbul, the only city in the world that spans two continents, is a perfect setting for a close look at the energy and sustainability challenges of our increasingly urban planet.

See more »