When a new construction project is under design, the factors that influence load on the HVAC system should be considered. "The design stage of a project offers several opportunities for energy efficiency and minimization of the amount of energy required by the HVAC systems," explains Lisa Raffin, vice president, professional services, VFA, Boston. The orientation of a building on the site, the type of glazing used, the amount of insulation, the quantity of outdoor air introduced into the building, as well as the type of lighting systems employed will all impact the demand for heating, cooling, and ventilation. Work closely and discuss options with architects, engineers, and other building-team members.
Making purchasing decisions isn't easy. Use ratings and standards to help judge a product or system's efficiency. "Buildings and their components should, at a minimum, meet the requirements of ANSI/IESNA/ASHRAE Standard 90.1-2004," says Andrew Wilcox, global marketing manager, Trane Control Systems, St. Paul, MN. Other considerations include compliance with ENERGY STAR[R], LEED, or the New Buildings Institute's standards and documents.
Additionally, make sure to "right-size" HVAC systems. "Greatly oversized equipment operates less efficiently and costs more than properly sized equipment," explains Carl Ian Graham of Steven Winter Associates in High-Performance HVAC, a resource provided by the Whole Building Design Guide. Raffin offers the following advice:
* If chillers don't make sense, packaged rooftop units with scroll (rather than reciprocating) refrigerant compressors may be considered. These units usually have increased condenser bundle sizes as well, which also improves efficiency.
* A Variable Air Volume system (rather than a Constant Air Volume system) uses less fan energy. In this case, a Variable Frequency Drive should be used in lieu of inlet guide vanes.
* Direct Digital Control systems offer increased accuracy and the ability for the buildings' systems to be computer controlled. Increased energy efficiency will result with the proper control strategies and a properly commissioned system.
Once the equipment is installed, it's critical that you ensure proper operation. "Commissioning is the process of ensuring that the building systems are designed, installed, functionally tested, and capable of being operated according to the owner's operational needs," explains Raffin.
MODERNIZING and MAINTAINING
The only way to ensure that the energy-efficient equipment you've installed is running at its optimum level is maintenance. Develop a routine schedule for inspections, cleaning, and filter changes. "Follow the recommendations of the manufacturers of the equipment [and perform the] annual periodic maintenance that's required for each system. At a minimum, you should be doing preventive maintenance at least twice a year--once at the beginning of the cooling season and once at the beginning of the heating season," explains Stephen R. Yurek, general counsel, vice president, policy and public affairs, Air-Conditioning and Refrigeration Institute, Arlington, VA. Keep a log documenting the equipment's performance to help diagnose long-term problems.