|Give HVAC a Closer Look for Efficiency
Published: April 4, 2012
When it comes to your HVAC portfolio, what’s your strategy? Do you try new things or go with the old reliable? Are you willing to retrofit units to squeeze out long-term savings, or do you address HVAC system efficiency only when you need to replace a major unit?
In recent years, facility energy managers who are actively engaged in energy efficiency have arguably been more attentive to lighting than any other energy-using technology. Lighting is relatively easy to address (although basic behavior-change strategies are probably even easier—and cheaper), provides quick paybacks, and offers a wide array of available technologies. However, new advances in HVAC system design should make you take a closer look at your heating and cooling strategies and efficiency efforts.
As Peter Criscione wrote in a recent report (for certain E Source members), “Several new retrofit devices are now available for single-zone rooftop-unit (RTU) air conditioners, and in preliminary independent tests, one of these devices demonstrated demand savings of 41 percent and annual energy savings of 52 percent. RTUs are notoriously inefficient because they’re often oversized, improperly installed, and inadequately maintained. In addition, all but the high-end single-zone units are incapable of much, if any, variable-speed operation. All of these new retrofit devices, which are being offered through start-up companies, can help address some, if not all, of these problems because they offer variable-frequency drives (VFDs) and a mix of energy-saving control strategies that haven’t been readily available before as a packaged product. Moreover, these devices will be able to provide continuous performance-monitoring capabilities, which could enable savings persistence from the devices themselves and from RTU tune-ups.”
Peter is just one HVAC expert on E Source’s staff. Another, Mary Horsey, recently produced a video Tech Brief (for certain E Source members) about hybrid ground source heat pumps (HyGSHPs) for commercial buildings. The “hybrid” in HyGSHP refers to a strategy in which a small supplemental chiller or boiler is matched to a traditional GSHP system. Although the GSHP system provides the vast majority of the space conditioning needs, the chiller or boiler picks up the peak cooling or heating load. This strategy enables technicians to install a much smaller ground heat exchanger unit that is sized to meet the average annual building cooling or heating load, while the supplemental equipment picks up the infrequent peak-load needs. Generating the same energy savings as a conventional GSHP (that is, 15 to 25 percent improvement over conventional HVAC), the hybrid offers a much-reduced first cost and a simple payback period over the conventional GSHP.
Peter and Mary will both be presenting at the upcoming 19th Annual E Source Energy Managers’ Roundtable, May 6–9, 2012, in Boulder, Colorado. In addition to their presentations on the latest in HVAC strategies and other technologies, we’ll see presentations on building energy management systems, discuss futuristic ideas with top technologists in the lighting and facility energy management industries, and talk with luminaries in the “practical sustainability” world.
If you’d like more information about heating and cooling strategies for energy efficiency, please contact us.
About the Author
DIRECTOR OF ENERGY MANAGEMENT SERVICES
Kevin Vranes has more than a decade of experience working on greenhouse gas (GHG) and climate-change issues. He has worked with numerous corporations and utilities on GHG management (inventories, auditing, and reporting), carbon risk, supply chain emissions and life-cycle assessments, and project analysis. Kevin was a senior legislative staffer in the Washington, DC, office of Senator Ron Wyden, where he worked on energy and environmental legislation, including the Energy Policy Act of 2005. He holds a PhD in geophysics (physical oceanography, climatology, and atmospheric sciences) from Columbia University, and he was a Public Policy Fellow of Columbia’s School of International and Public Affairs.