Homes Plus
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Dear Jim: During winter when we heat or summer when we air condition, the indoor air becomes stale. How can we get fresh air into the house without losing a lot of heat or letting in hot, sticky, humid air? — Carol M. Dear Carol: The unpleasantness of stale indoor air may be the least of the problems. It is not uncommon for indoor air in an energy- efficient house to be more polluted and unhealthy than outdoor air. Household prod- ucts such as cleaners and synthetic materials emit unhealthy chemicals, many which have never been tested for safety. Although it sounds inefficient, opening a couple of windows on opposite sides of the house for a few minutes during winter or early spring,does not lose much energy. House building materials don't lose heat that quickly. During summer, this is not as effec- tive because it allows humid air to come in along with allergens such as pollen and mold spores. If you choose to try this low-cost fresh-air technique during summer, run a room-size dehumidifier in the room where the outdoor air comes in. The specific room may change based upon the wind direction. The dehumid- ifier pulls more moisture out of the moisture- laden air. The air conditioner will circulate the fresh air throughout the house. The most effective method for year-round fresh indoor air is an automatic heat-recov- ery ventilation system. It can save more than 70 percent of the energy. Incoming cold fresh outdoor air captures heat from the outgoing warm stale air during winter. During sum- mer, incoming hot fresh outdoor air is pre- cooled by the outgoing air-conditioned stale air. Two blowers running in opposite directions are ducted from indoors to outdoors. The air flows through a heat exchanger where heat from the warmer air is transferred to the cooler air without mixing. Stale air is drawn from bathrooms or the kitchen and fresh air is ducted to a living room or hall. This system works well in many climates; however, in very dry or humid climates, the fresh indoor air becomes uncomfortably dry or humid. Even though the HRV system has an effective air filter, extremely dry or humid indoor air can exacerbate allergies and skin issues. In these areas an energy-recovery ventila- tion system is better. An ERV is similar to a HRV except the heat exchanger also transfers moisture. This is effective year-round, but most effective during summer because outgo- ing cool stale air dehumidifies the incoming fresh humid air. The most commonly used automatic con- trol method is a humidity sensor. Stale indoor air tends to be more humid. This sensor determines how long and how fast the blow- ers run. There is a manual sensor override to run it for extra fresh air. The following companies offer HRVs and ERVs: Aprilaire, (800) 334-6011, www.april aire.com; Broan, (800) 558-1711, www.broan. com; Fantech, (800) 747-1762, www.fantech. net; Honeywell, (800) 328-5111, www.yourhome.honeywell.com; and Renewaire, (800) 627-4499, www.renewaire.com. MARCH 2016 HOMES PLUS 3 JAMES DULLEY How to let fresh air in without letting heat out Distributed by: ©2016 by Conley Media Waukesha County Homes Plus is published monthly by Conley Media - Waukesha County, 801 N. Barstow St., Waukesha, WI 53186. Contents of this publication may not be reproduced in any form without the written consent of the publisher. A publication of Conley Media Sales Director: Jim Baumgart 262/513-2621 jbaumgart@conleynet.com Editor: Dan Muckelbauer 262/513-2626 dmuck@conleynet.com Production: Patricia Scheel 262/513-2690 pscheel@conleynet.com Homes Plus Volume 5 ■ Number 3 ■ March 2016