4  FM quick reads on HVAC

1. HVAC Efficiency Should Be Part Of A Broad Strategy

Today's tip from Building Operating Management comes from Daniel H. Nall of Flack + Kurtz. For facility managers interested in efficiency, the HVAC system offers a significant opportunity. But the opportunity to boost HVAC efficiency should not be addressed in isolation. To be most effective, HVAC efficiency tactics should be part of a broad strategy to reduce energy use.

The pursuit of energy efficient buildings involves the integration of multiple strategies and systems. These systems include architectural enclosure, lighting, domestic water heating, vertical transportation and HVAC.

For HVAC systems, the loads come primarily from five sources: the building envelope (heating and cooling), lighting (cooling), occupancy (cooling), equipment for programmed use (cooling) and ventilation (heating and cooling).

Ventilation load is a function of either the number of persons occupying the space or of the mechanisms necessary to control contaminant concentration and introduction to the space. In most climates of the eastern and southwestern regions of the United States, minimization of outside airflow is an effective energy conservation strategy for some portion of the year, when the outside air is either warm and humid or very cold. Control of ventilation rate determined by occupancy, referred to as demand-control ventilation, is a common energy conservation strategy, especially for spaces with intermittent dense occupancy. Conventional practice would require continuous provision of the maximum calculated ventilation rate, allowing the peak occupancy to be averaged over several hours. Demand-control ventilation would provide the exact flow rate required for actual occupancy at a point, but would allow ventilation to be reduced to a minimum when the space is "in use," but unoccupied. Procedures for implementing demand-control ventilation are described in detail in ASHRAE Standard 62.1, the ventilation standard for acceptable indoor air quality.

With heating and cooling loads reduced to a minimum, utilizing a high-performance building envelope, high-performance lighting with daylight-responsive lighting controls and occupancy sensors, Energy Star office equipment and demand-controlled ventilation, the energy efficiency of the HVAC systems themselves can be addressed.

Fault Detection And Diagnostics (FDD) Is Attracting Industry Interest

Today's tip from Building Operating Management comes from Jim Sinopoli of Smart Buildings LLC. Fault detection and diagnostics is attracting industry interest.

If you are buying books or music from an online site, it's likely that the e-commerce company analyzes your purchases, creates a profile of what type of books or music, authors or performers you like, and then proactively sends you email regarding other items you may be interested in purchasing. Those firms regularly mine data to improve their business performance. Generally facility managers haven't fully embraced such data analytics. However, that is changing.

Today, a new generation of analytics is becoming available to facility managers. The most prominent of these new analytics tools is fault detection and diagnostics. Fault detection and diagnostics finds problems within building systems that are causing the HVAC system to waste energy.

The idea of fault detection and diagnostics for HVAC systems is not new. Research, development and testing of fault detection approaches have been around for about 20 years or so. What is new is the increased interest in and actual use of fault detection. For example, Microsoft has seen promising results with fault detection and diagnostics. Another example of industry approval of data analytics and fault detection and diagnostics came in October 2011, when the U.S. Green Building Council announced a technology agreement that would allow building owners to use an automated fault detection tool with the LEED Online platform, thus supporting the commissioning of buildings. USGBC's interest is that the tool generates reports for LEED Online, including diagnostic functions and faults during the building's performance period.

Another sign of industry interest comes from a Lawrence Berkeley National Laboratory study on monitoring-based commissioning, which uses building diagnostics. Lawrence Berkeley established an average energy savings of 10 percent through the use of monitoring-based commissioning, with as much as 25 percent in some cases.

Repair Or Replace The Boiler: Four Questions To Answer

Today's tip from Building Operating Management comes from James Piper, a contributing editor for Building Operating Management and Maintenance Solutions magazines: When deciding whether to repair or replace a boiler, facility managers should answer these four questions.

Boilers and water heaters have finite service lives and eventually require replacement, even with comprehensive maintenance. But even though a unit's age is a key consideration, it is not the only factor facility managers must consider. While no rules exist for this decision, facility managers must address several important questions.

  1. What is the age of the equipment? Maintenance costs rise as boilers age. Replacement costs will always exceed maintenance costs, unless something major goes wrong. But watching the trend in maintenance costs is more important. If these costs remain relatively flat, the better option is repairing the boiler or water heater. Costs that rise consistently and rapidly indicate replacement, as does difficulty in getting replacement parts.
  2. What is the equipment's operating history? Identical boilers that operate in similar facilities often have much different operating histories, depending on set-up, operating practices, and maintenance. Operators and managers need to review the equipment's history to determine if any findings suggest that replacement is the better option.
  3. Is the equipment efficient? New boilers offer substantial increases in annual operating efficiency compared to boilers only 10 years old. So when evaluating options, managers need to consider the annual savings from installing a new, higher-efficiency unit.
  4. What is the configuration of the equipment? Older installations of central boilers and water heaters tend to feature one or two large units. That set-up often forced operators to cycle one boiler to match part-load operating conditions.
By comparison, new, centralized systems use several smaller boilers, which allows operators to better match system capacity to facility needs and improve operating efficiency. To make a smart decision on whether a cost benefit exists in installing new, modular boilers, managers should review historical building loads.

Fault Detection And Diagnostics (FDD) Shows Promising Results

Today's tip from Building Operating Management comes from Jim Sinopoli of Smart Buildings LLC. Fault detection and diagnostics shows promising results at Microsoft.

Microsoft's main corporate campus provides a look at what the future may hold for facility managers looking to mine the mountain of data available from most buildings. Microsoft is using a software analytics tool known as fault detection and diagnostics to help meet a corporate mandate related to energy and sustainability. Not only did Microsoft discover faults within their HVAC system they were not aware of, the software application also allowed their engineers to save significant time in addressing operational issues. The tool both identifies faults and also provides information about corrective action.

What's more, the fault detection and diagnostics tool has the capability to monetize faults. After the tool identifies a fault, it estimates the duration of the problem and calculates the cost of the uncorrected fault, typically based on wasted energy consumption. For example, the leakage of an outdoor damper might cost $500 per year. Monetizing faults allows Microsoft to give priority to tackling the most costly problems. In addition, this tool compresses Microsoft's typical 5-year campus retro-commissioning cycle to just one year. Annual energy cost savings for Microsoft from automated fault detection alone may exceed $1 million.

Microsoft is in the vanguard of a movement that is likely to transform the way buildings are managed. Software analytics promise to become a critical tool for facility managers to keep buildings operating efficiently. A variety of factors are driving the move to analytics. For one thing, buildings are becoming increasingly complex, and the introduction of new systems is making them even more complex. That complexity is changing the skill sets and expertise required to operate buildings. What's more, nearly everyone who occupies, manages or owns a building is focused on energy and sustainability.


HVAC , Ventilation

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