Blog Archives

Electromagnetic Fields

Electric and magnetic fields are commonly discussed as if they were a single entity termed electromagnetic fields or EMFs. In fact, the two phenomena, although interrelated, are distinctly different and they will be discussed separately in this chapter. Chart 16.1 presents a comparison of the two.

Magnetic Fields

Basic Home Wiring and Net Current

Although the relationship between human health and elevated fields remains contro­versial, there are definite safety concerns as­sociated with wiring techniques that cause magnetic fields. In recognition of such haz­ards, the National Electrical Code has man­dated safer wiring...

The addition of filters to ventilation and forced-air heating and cooling systems allows for greater control of air quality. As discussed above, indoor air is often too polluted to prop­erly nourish occupants. The first line of defense against such pollutants is to provide an ample supply of fresh outdoor air through ventila­tion. Unfortunately, “fresh” air, although con­siderably cleaner in most cases than indoor air, often contains allergens in the form of molds, pollens, and manufactured pollutants,

Until the 1960s, ventilation in homes occurred naturally, obviating the need for intentional ventilation systems. Homes were loosely built, allowing enough outside air to make its way through the home to keep it fresh. By some ac­counts, this loose construction contributed to as many as three to four air exchanges per hour. Although there were ample air exchanges, there was also an unacceptable amount of en­ergy required to run such a home, and uncon­trolled ventilation through air leakage can cause serious harm to a building. Currently, with energy-efficient construction, much of the unintentional air exchange has been elim­inated...

Heat pumps are far more energy efficient than electric resistance heat and can be used for both heating and cooling. Heat pumps extract heat from outside air or, in some cases, from a water source. Air-source heat pumps are most common in areas where winter tempera­tures seldom fall below 30 degrees Fahrenheit and where summer cooling loads are high. As temperatures fall below 30 degrees, the heat pump must rely on electric resistance heat­ing to make up the difference, at which point the system loses its economic advantage. Tire main advantages of a heat pump are that heat­ing and cooling needs are met by a single unit, humidity is not added to the air, and opera­tion is quiet.

Cooling Systems

Common types of air conditioners include condensing or refrigerated air conditioners, electr...