Home Energy and Heat Storage

The United States wastes almost 85 percent of all the commercial energy it takes off the power grid. People waste by not conserving energy in their daily activities: leaving lights on, letting television play with no one watching, or running small laundry loads. Faulty appliances and inefficient machines and vehicles waste additional energy. Energy waste also occurs naturally due to the second law of thermodynamics that states that some energy is always lost when being converted from one form to another. Considering these opportunities for potentially usable energy to escape, engineers now design structures that have several different systems for conserving, recapturing, and reusing energy, whether the energy is in the form of light, electricity, or heat.

New homes contain many improvements in energy management that older houses from the 1950s through the 1980s did not possess. Insulation, seals, doors, windows, and roofs have all been improved for the purpose of retaining household energy, usually in the form of heat.

A new type of construction called a superinsulated house contains features so efficient in holding heat that sunlight, appliances, and residents provide enough heat to keep the indoors warm. Superinsulated houses contain some or all of the following features: (1) very thick insulation with R values of R-40 to R-60, meaning they have high thermal resistance and so prevent heat transfer across their boundaries; (2) triplepaned insulated glass in windows; (3) few or small north-facing windows; (4) airtight seals; and (5) an air-to-air heat exchanger. Air-to-air heat exchangers are appliances that transfer heat across a barrier from warm, stale indoor air to cool, fresh outdoor air. By this process, heat exchangers ventilate the indoors and capture and reuse heat to prevent heat waste. Superinsulated houses are also likely to contain thermal mass materials that hold heat.

Older houses often waste energy as heat loss that can never be recaptured, but even these houses can be improved with simple fixes. The following steps help transform an energy-wasteful house into an energyefficient house:

1. plug leaks around windows, doors, in cracks, and in holes
2. replace old insulation
3. replace old windows with insulated, energy-efficient windows
4. install a heat exchanger or a heat pump (removes warm air and replaces with cool air)
5. use energy-efficient appliances and lighting
6. replace large tank water heaters with a tankless instant water heater
7. install good seals on doors to attics and unheated basements and keep doors closed

 Homeowners need not wonder how well they do in saving energy because each home has a meter that shows electricity and heating fuel usage. The basics of energy measurements used by energy utilities are described in the sidebar on page 126 “The BTU and the Kilowatt.”

American architect Edward Morse
designed a wall in the late 1800s in
which a sheet of glass covered the wall’s
masonry. This design increased heat
transfer from outside to the inside of
the building and reduced heat loss. In
the 1960s French designer Félix Trombe
improved on the concept, and the wall
now bears his name. The Sun’s heat
passes through a doubled-paned window
and warms the masonry next to it. The
masonry then releases the heat into the
interior. (MultiwallSystems.com)