One of the best methods of reducing the level and impact of indoor air pollutants and excess humidity is to mix the indoor air with fresh, dry air from outside the house. Heat recovery ventilators (HRVs) use fans to continually bring air in from outside the house. Glass doors on the front of an open fireplace help increase the efficiency, but there is still a lot of heat going up the flue that could better be used to heat the house. The metal radiates heat into the room, an adjustable opening on the front of the insert allows control of the air going into the firebox for more efficient burning, and many inserts are available with glass panels in the doors, which provide a view of the fire. Like fireplace inserts, the metal radiates heat in all directions, the burning of the fire is controlled by regulating the flow of air into the firebox, and many stoves come with glass panels that allow the fire to be seen. In the overall span of that time, only relatively recently have people sought to increase the benefit of wood’s heat-producing ability by containing the burning process inside a metal enclosure.

And while burning wood can reduce our dependence on oil or gas, the fact remains that wood has to come from somewhere. What’s more, an individual’s body temperature can vary by a degree or more during the course of a day, with the lowest reading usually occurring in the early morning and the highest in the evening. Investment in an individual wind turbine is expensive, even more so for onsite power storage with sufficient capacity to power an entire house. But the willingness of utility companies to purchase power from individuals with excess power-generating capacity might spur further investment in alternative power systems. Plus they need replacement when their capacity to store power has been exhausted. If you need to resort to occasionally ventilating by opening doors and windows, the heat loss will be minimal if you don’t leave them open for too long. Homeowners also can change the type of equipment they use to heat and cool their homes. When the generator is producing excess power, it can be sold to the utility company. Connection to the grid ensures that that you can use some of the utility company’s power when your wind generator is not producing.

Biting the tongue or cheek can result in a large amount of blood but is rarely serious. Worse, this type of fire gobbles up a huge amount of room air that is used to help combust the fuel and convey it up the chimney. Wood, of course, has been used as a heating fuel for as long as people have been on the earth. For example, the methanol fuel used in Indy cars has the advantage that it can run at extremely high compression ratios (meaning more power — see How Car Engines Work for details). An HRV can be installed either as a stand-alone system or tied into forced-air furnace ducting. An HRV installed correctly should be virtually unnoticeable to the homeowner. An HRV can also be shut off when it is not needed. And while there is not a 100-percent heat transfer, the exchange is efficient enough that the incoming fresh air can be quickly warmed by the home’s heating system. Because the two air streams never mix, the only thing transferred from the outgoing air stream to the incoming one is heat. It works based on one very simple principle: there are two inputs of water on the top.

It’s hard to make an older home so airtight that indoor air pollution becomes a major problem — or at least one that can’t be solved by taking one or two simple steps to alleviate the condition. If you happen to live in one of these low-lying wetland areas, consider adding a rain garden to your landscape. On one day, a compañero would leave us, on the next day another, and many requested assignments in the city that often entailed much more risk but that meant an escape from the rough conditions in the countryside. Still, more research is needed to evaluate the link between short-term water fasts (24-72 hours) and blood pressure. The renal system actively regulates the levels of sodium and chloride in the blood within a very narrow range around 9 g/L (0.9% by mass). Recirculating-type range hoods are somewhat effective at removing airborne grease, but they do not take combustion byproducts out of the air. Odors from cooking and pets, off-gassing from building materials and furnishings, radon gas, combustion byproducts from gas ranges, and other pollutants can accumulate.