Everybody talks about the weather but how do you use it?

Because without weather information your automation solution knows nothing about your environmental conditions.  Is it hot? cold? windy? rainy?

Here are three examples of how users work with weather data.

A user in Phoenix adjusts his thermostat set point based upon the outside temperature.  When it's really hot he bumps up the cooling setpoint, when really cold he lowers the heating setpoint a bit.  In this way he trades off a small bit of comfort to save a lot on energy costs. 

Another user in the San Juan Islands in Washington State has retractable awnings that can get damaged in the big winds they sometimes get.  When the average wind speed in the last 30 minutes gets too high, or any gust over his threshold happens, HCA energizes the relay which runs the motor and the awnings roll up.

The last example has been done by many people we hear from:  If it's too windy, or too hot, or raining, the garden watering sprinklers don't run.  After all why waste water?

So don't you need an expensive weather station?

No!

HCA can acquire weather data in three different ways:

First, if you have a Davis Instruments Vantage Pro or Weather Monitor II and a computer interface for them, HCA can read weather data directly from them.  In this way HCA is directly connected to the weather station serial port.

Second, if you have any weather station supported by two weather programs, Weather Display or Virtual Weather Station, you can use these programs to interact with the weather station and have the programs periodically export current weather data to a file.  HCA is then configured to periodically read the current data from that file.

This has two major advantages. First, many makes and models of weather stations are supported (see the long list of supported hardware for each program).  Second, these programs are the ones working directly with the weather station.  After all, HCA is a great automation program but it is really not in the weather business.  In this way you can use one of the weather programs to create graphs, charts, forecasts - weather data is cool! - and still have HCA use that data in whatever way makes sense in your automation solution.

The third option is to get your weather data from the internet.  Airports all over the country take hourly weather observations.  They give you an indication of temperature, humidity, wind speed, and rain.    Isn't that too inaccurate? After all who lives right near an airport?  Well, it's probably good enough if you don't need too much precision.  If you are looking for an indication of "too hot", "too cold", "too windy", or "too rainy", then almost always weather data from a nearby airport will do.

And best yet, the internet weather data is free.  You can try it out and see how it works and then decide if it helps out your automation solution.

Want more info?  A whole section in the HCA User Guide Appendix is devoted to weather data.  There is also a weather technical note that fills in the last details.

So why do we publish our weather data with Weather Underground? Why not!  Each hour a file is produced for upload to Weather Underground.  Also every 10 minutes a HTML file is produced that HCA reads to get the current weather data.  This is all done with a Weather Monitor II station and the Davis Weather Link software.