Roanoke Times
Copyright (c) 1995, Landmark Communications, Inc.
DATE: TUESDAY, August 22, 1995 TAG: 9508240011
SECTION: EXTRA PAGE: 3 EDITION: METRO
SOURCE: DAVID BUTLER
DATELINE: LENGTH: Medium
A: Keeping tabs on the weather and other environmental conditions not only has a practical side, it can be lots of fun. How cold did it get last night? How hard was the wind blowing during that thunderstorm? How much rain fell last week? Most people are surprised when they discover the extent that local conditions can vary from regional weather reports.
Although most home automation systems are perfectly capable of gathering weather data, such an approach would be overkill if that's all you want to do. A stand-alone weather monitor will accomplish the same thing for a lot less money. A basic system typically includes a display console and two outdoor sensors: an anemometer and a temperature sensor. Prices start at under $200.
The anemometer measures wind speed and direction. It should be mounted in an unobstructed location atop a utility pole or rooftop mast. The most common design consists of three rotating cups with a rudder-like vane. In most cases, the temperature sensor mounts on the same mast with the anemometer. Special enclosures are available to shade the temperature sensor from direct sunlight.
From the console, you can monitor barometric pressure, wind, indoor and outdoor temperature, and wind-chill factor. You can also check daily highs and lows for each condition. One model logs heating and cooling degree days, useful for comparing annual energy consumption. By adding an outdoor humidity sensor and a rain collector, you can have a complete home weather station.
One of the most common uses for weather monitoring equipment is to support agriculture. Whether you're a backyard gardener or a professional grower, success often depends on your ability to react to changes in the weather. Most monitors allow you to set "alarms" based on high or low values for each condition. This feature can come in handy if you have plants that might suffer from an unexpected frost.
If you have a personal computer, you may want to choose a weather monitor with a serial connection - a standard feature on most models. The requisite software, usually offered as an option, supports advanced features such as data logging and histograms. Even casual users will appreciate the convenience of a comprehensive display.
Environmental sensors are also available to help automate various home systems. For example, sun sensors are often used to control retractable awnings and motorized window coverings. Soil moisture sensors are a natural companion to an irrigation system. One company offers a complete line of snow and ice sensors for controlling pavement and other types of de-icers.
A growing number of commercial greenhouses use environmental sensors to regulate temperature, humidity, light and soil moisture. Automation can lead to dramatic improvements in plant quality, yield and timing. Serious home growers can achieve similar results with a home automation system. In most cases, the same sensors can be used by both commercial and home systems.
To receive a list of 12 manufacturers of weather monitors and environmental sensors, please send $1.50 (please don't send cash) and a self-addressed envelope to David Butler F-513, Department TWN, 14713 Pleasant Hill Road, Charlotte, N.C. 28278-7927. The list includes toll-free phone numbers and a summary of each company's products. You'll also receive a list of companies that manufacture environmental control systems for greenhouses.
TechTalk: Analog sensors must be used when measuring temperature, humidity and other environmental conditions. The sensor's output varies over a continuous range - in other words, it can measure "how much." Unless you have access to precision reference instruments, it's best to buy pre-calibrated sensors. As a rule, higher accuracy demands a higher price.
by CNB