Originally published in Interiors & Sources

01/01/2009

Integrate Weather Data into Building Automation

Weather data can help facilities professionals make decisions that dramatically reduce the amount of energy and water used by building systems

 

On-Site Weather Station vs. XML Weather Feed
Weather data can be generated from weather stations with an on-premises IP connection or provided by a weather-tracking service. There are benefits and drawbacks to both.

Though it won't provide forecast data, an on-site weather station can provide useful information about current conditions. "Utilizing local stations can be highly effective, as they can track elements such as wind speed and direction. They can also track lighting levels that can be used for thermal calculations and energy-cost predictions," says Terry Hoffmann, director of building automation systems marketing for Johnson Controls' building-efficiency division, Milwaukee.

The other option is more common and less expensive. Vendors have a network of weather stations throughout North America, and they supply the information via a Web-based XML program. If your facility isn't located in an urban area, however, this data may not reflect your microclimate. Another downside: The weather data is usually the property of the service provider.

With sensors to detect humidity and outside air temperature, most building-automation systems (BASs) are already making informed - albeit limited - decisions about mechanical-system operations based on outdoor conditions. Momentum is growing, however, for BASs to use more extensive weather data to optimize building systems.

"Imagine having, at your fingertips, the ability to track such factors as temperature, humidity, rain levels, wind speed, Doppler radar forecast, severe-weather alerts, heat index, and barometer/pressure," says Ronald Greaves, product manager, Siemens Building Technologies Inc., Buffalo Grove, IL.

This kind of weather data can help you make decisions that dramatically reduce the amount of energy and water used by your building systems. It can also explain year-to-year variances. "For instance, a building manager sees a 20-percent increase in energy efficiency from Monday to Tuesday. But, the change may be the result of a 20-percent drop in heating degree days, which would mean that the efficiency is actually on par," explains Greg Turner, director of global offerings, Honeywell Building Solutions, Morris Township, NJ.

Turner is not the only one who sees this as a benefit. "I believe the greatest value might be using weather data to calculate an accurate key performance indicator concerning energy usage," says Terry Hoffmann, director of building automation systems marketing for Johnson Controls' building-efficiency division in Milwaukee.

Here are some more examples of how integrating weather data into a BAS can be beneficial.

You can improve mechanical-system performance. Weather-related information is especially useful when targeting ways to increase the efficiency of HVAC (chillers, boilers, and chilled-water and ice storage). "Weather data can help determine when to use a smaller chiller at full capacity vs. a larger boiler at half capacity to save energy and maintenance costs," explains Turner. This can be beneficial for load shedding.

You can determine the viability of on-site alternative energy. According to Greaves, weather data can help you make informed decisions about the feasibility of installing photovoltaics or wind turbines, as well as predict a realistic return on investment.

You can respond when it rains. When forecast and weather data are integrated into a BAS, it can:

  • Bypass the municipal water supply (used for landscape irrigation) on days with a high probability of rain, which saves water.
  • Check rainwater-collection tank levels.
  • Alert the operator if stormwater storage tank overflow is imminent.

You can receive alerts about severe weather. Be it a blizzard or a tornado, or other inclement weather, having access to forecast data helps ensure that both the building and its occupants are safe from Mother Nature. "Continuous access to real-time and forecast weather allows building officials to notify occupants of approaching inclement weather conditions," says Greaves.

If your BAS doesn't have the capability to incorporate weather data, don't worry. "For [systems] that don't have it built in, it usually doesn't require a significant investment in hardware or software to make it happen," says Turner.

You might not be able to control the weather, but if you integrate weather data into your BAS, you can at least control how your building reacts to it.

Jana J. Madsen (jana.madsen@buildings.com) is editor at Buildings magazine.

 

 
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