HVAC System
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Introduction
HVAC (heating, ventilation and air conditioning) refers to the equipment, distribution network and terminals that provide heating, ventilation and/or air conditioning to a building. HVAC accounts for 40% to 60% of the energy used in commercial and institutional buildings, and 12% to 15% in industrial facilities. This represents an opportunity for substantial energy savings using proven technologies and design concepts. A recent study estimates that California commercial businesses alone have the potential to save 46% of their energy costs through cooling and ventilation energy efficiency efforts by 2011.
Technology Options
HVAC systems are typically replaced or upgraded when they have reached the end of their useful life. Because HVAC systems are expensive, it may not be cost-effective to replace them on the basis of improved performance or estimated annual energy savings alone. To optimize the purchase and selection of these systems, perform an energy analysis and review the purchasing tips provided below.
When early retirement of the HVAC system is not an option, there are two general guidelines for improving the energy performance of existing HVAC systems:
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Routine maintenance of an HVAC system should be performed at least annually. Inspect motors, belts and steam traps, and rebuild or replace them as necessary. Filters should be replaced, dampers adjusted to ensure a tight seal, and linkages, boiler heat transfer surfaces and coils should be cleaned. Other low-cost improvements to improve your HVAC unit's efficiency include:
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More extensive and expensive system improvements can be considered as well, such as: | ||
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Efficiency Benefits
Between Pacific Gas and Electric (PG&E), Southern California Edison (SCE) and San Diego Gas and Electric (SDG&E), there is a total of 2432 GWh and 1069 MW of savings potential for cooling and ventilation alone. This is particularly important in terms of peak demand. Energy efficiency measures addressing high-efficiency chillers and packaged units, as well as chiller tune-ups and controls, make up a large share of total potential savings in this area. There also are potential savings from improving the performance of existing package and chiller units through better maintenance and operating practices as described above.
The following table shows savings as a percentage of total commercial sector energy consumption and peak demand for the three utilities across HVAC potential measures, aggregated across market segments and utilities in California.
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Measures | GWH Savings |
Cumulative GWH Savings |
Energy Cost $/kWH |
Percent Savings |
HE Chiller | 478 | 1,990 | $0.017 | 2% |
HE DX | 246 | 769 | $120 | 4% |
Prog. T-Stat | 46 | 815 | $135 | 4% |
Chiller Pumps | 73 | 1,572 | $224 | 9% |
Cool Tune-ups | 186 | 2,394 | $372 | 13% |
HE Vent. Motor | 28 | 2,422 | $397 | 13% |
Pre-Cooler | 95 | 3,396 | $587 | 19% |
Vent. VSD | 26 | 3,422 | $596 | 19% |
Levelized | ||||
Measures | MW Savings |
Cumulative MW Savings |
Demand Cost $/kW |
Percent Savings |
HE Chiller | 315 | 315 | $26 | 2% |
Prog. T-Stat | 277 | 2,616 | $0.022 | 3% |
Vent. VSD | 453 | 5,251 | $0.034 | 7% |
HE DX | 445 | 9,658 | $0.066 | 12% |
HE Vent. Motor | 156 | 9,814 | $0.071 | 12% |
Chiller Pumps | 110 | 11,802 | $0.148 | 15% |
Cool Tune-ups | 308 | 12,110 | $0.225 | 15% |
Pre-Cooler | 170 | 14,444 | $0.326 | 18% |
Manufacturers
The annual HVACR Directory & Source Guide for HVAC contractors, wholesalers, reps and engineers has a comprehensive list of manufacturers.
Some of the largest HVAC manufacturers include:
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Purchasing Tips
When purchasing new equipment, several items need to be evaluated before proceeding. Specify the highest-efficiency boiler, furnace, chiller, air handler and rooftop unit that your wallet allows. In determining an acceptable cost limit, take into account the achievable energy savings over the life of the equipment.
Evaluate thermal loads as well before installing equipment, since changes to the building are likely to have occurred since the original equipment was purchased. Downsizing equipment can save substantial energy when replacement cooling or ventilating equipment is needed. Other efficiency measures such as reducing lighting levels, sealing duct leaks, installing low-emissive (low-e) windows and integrating building operations with an energy management system may allow smaller equipment to cool and ventilate your building.
The U.S. Department of Energy maintains a directory of HVAC software tools. Specialized design and analysis tools are available to help you select optimal HVAC systems:
American Society of Heating, Refrigeration, and Air-Conditioning Engineers (ASHRAE)
Publishes a set of four handbooks focused on HVAC systems.
Co$tWorks98
Offers an HVAC cost comparison program that calculates annual heating and cooling costs for a building and simple payback between two heating/cooling systems with different efficiencies or fuel types. It includes weather data for more than two hundred U.S. cities, and it remembers fuel rates for your location from use to use.
APACHE
APACHE (Applications Program for Air-Conditioning and Heating Engineers) is a comprehensive program for analyzing the thermal performance and energy use of buildings. It covers a wide range of requirements from basic design to detailed simulations of HVAC systems.
Building Energy Analyzer
Provides quick economic analysis of commercial and industrial buildings. This program estimates annual and monthly loads and costs associated with air conditioning, heating, on-site power generation, thermal storage and heat recovery systems for a given building and location.
CL4M Commercial Cooling and Heating Loads
Uses ASHRAE methods and algorithms to calculate cooling loads, heating loads and air requirements for each space in commercial buildings, as well as coil specifications.
Energy Trainer for Energy Managers HVAC Module
Contains about 4 hours of instruction on HVAC energy efficiency, and focuses on HVAC system operations and maintenance in existing buildings.
Emerging Technology
Advanced technologies have already demonstrated success in increasing the energy efficiency of heating, cooling and ventilation, without compromising occupant comfort or equipment performance. Yet the opportunity for further energy efficiency improvements remains large. There are several related advances that affect HVAC usage as well, such as cool roofs and evaporative pre-coolers. At this time, costs and savings estimates are less certain for these measures.
One direction pursued by Department of Energy (DOE) research and development is improved performance in chiller systems used in cooling large commercial facilities. Another promising direction is advanced combined, heat and power (CHP) systems that use waste heat to cool and heat buildings, significantly increasing system efficiency. According to DOE officials, integrated CHP systems can offer up to a 30% to 40% improvement in building efficiency. DOE goals for CHP development include helping manufacturers integrate their components into packages and ready them for the marketplace.