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Wind: ventilate buildings naturally.

Ventilation, filtration, and communication can help clear indoor air.

Poor indoor air can cause a variety of health problems, including headaches, respiratory problems, dizziness, fatigue, and fever.

The causes, too, are plentiful. Such products as adhesives, carpeting, copy machines, and cleaning agents may release harmful contaminants into the air. Pollutants in outside air, such as vehicle exhausts, can enter a building, and biological contaminants, such as bacteria, molds, pollen, and viruses, can circulate throughout a facility.

Standards organizations are taking action. A revised Standard 62-1989R, Ventilation for Acceptable Indoor Air Quality from the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE), Atlanta, could increase the amount of outside air required to be circulated throughout a space.

"As the standards get changed, it certainly will create some additional problems for building owners to provide more air within their facilities," says David E. Stouppe, senior engineer at Hartford, CT-based Hartford Steam Boiler Inspection and Insurance Co.

Noise and energy are two concerns. "The higher you push the fresh air requirement, the more fan power you need for air distribution, and the more energy you need to heat or cool that air. So there's a tradeoff," says Ron Judkoff, director of the Buildings and Thermal Systems Center at the U.S. Department of Energy's National Renewable Energy Laboratory in Golden, CO.

There, are, however, other solutions - solutions that save energy. One is natural ventilation, or using natural forces to circulate fresh air. The two main methods of achieving natural ventilation are by the stack effect and wind pressure.

According to Judkoff, design of natural ventilation systems involves proper placement, sizing, and control of air intake, distribution, and exhaust elements. For buildings that are sufficiently tall, the stack effect is the main mechanism for inducing airflow, he says. Fresh air is introduced at the bottom of the space through inlets and is warmed by interior sources of waste heat. Warm air is less dense than cool air, so it naturally floats upward as it is displaced by cooler air from below. Wind can be used to enhance the stack effect and to induce cross-ventilation.

"Naturally ventilated buildings work best when they are the result of an integrated approach to low-energy design. Daylighting to minimize internal gains from electric lights and shading devices to reduce unwanted solar gains through glazing in summer are important corollary strategies," says Judkoff. In some climates, the natural ventilation system can be integrated with a forced ventilation and displacement cooling system.

These methods are not easily retrofitted into a facility. "From the very start, you have to decide this is what you're doing and it has to be incorporated into the geometry and siting of the building," Judkoff says.

Other fresh-air strategies can be incorporated into any facility, however. An economy cycle on a ventilation system can bring in more outside air when ambient temperatures allow, for example, and air filtration systems can be enhanced to filter out smaller particulates. To prevent the growth of biological organisms, building staffs can clean filters, ducts, and air-conditioning water condensation points. They can stop leaks wherever they occur. They can also implement a good pest control problem, because pest droppings can pollute indoor air.

Most of all, buildings professionals can communicate with their tenants, says Austin-based Quade Stahl, chief of the Indoor Air Quality Branch at the Texas Department of Health. He says buildings professionals should not discount concerns, but should ask tenants questions, such as what time of day they feel sick and when it started, and in what part of a room they smell an odor. "Most of my successes have been because of people really giving me the information I need to actually find [the problem]," he says.

Maureen Patterson ( is an associate editor of Buildings magazine.
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Title Annotation:It's Elemental, part 2
Author:Patterson, Maureen
Date:Jul 1, 1997
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