Have you gone “green” yet? Here’s a reality check: whether you believe in global warming or not, the U.S. is jumping on the big GREEN WAVE that’s building momentum worldwide, soon to reach tsunami proportions. It’s become part of our language with words like carbon footprints, carbon credits and white tags now being bandied about in Hollywood and corporate boardrooms.
In other words, green is here to stay. Green means many things, but it can also mean the color of money. So regardless of your beliefs, you might as well ride the green wave. Our industry’s biggest contribution to being green, besides the trucks we drive, or how we handle refrigerants, is the energy usage of the systems we install and service.
The first wave of energy efficiency hit in the late 1970s, and lasted nearly three decades. This was the “equipment efficiency” wave, where manufacturers raced to see who could get the highest SEER and AFUE ratings on their boxes.
In the early 1990s the government stepped in with EPACT and began mandating minimum efficiencies. Utilities jumped on board and began offering rebates for higher SEER and AFUE. These efforts had a mixed bag of results.
On one hand, we now have equipment that runs more efficiently. On the other hand most of it isn’t running anywhere near advertised efficiencies. We’ve measured thousands of systems across the country, revealing average Btu delivery at 60% of the published rating.
Before we organize a lynch mob to hang the manufacturers, let’s take a good look at ourselves. To a great degree, equipment isn’t delivering performance because it’s installed incorrectly. It’s not about how it’s wired or piped. It’s about the part of the system that has the most effect on delivered efficiency: the air distribution system.
Sometimes weak blower motors are the culprit, but most of the fault lies squarely with the distribution system. There are many excuses for this, but the bottom line is we’re the HVAC experts. We should know better, yet most of us still install the same way we have for years.
Tough pill to swallow? Here’s an even tougher one: Round II energy efficiency “experts” from outside the industry have convinced government and utilities that sealing ducts is the way to deliver efficiency. Utilities are now ramping up their duct sealing programs to meet the demands of PUCs (Public Utility Commissions). California led the way with Title 24, where it’s law, and consumers must pay for it, like it or not.
Sealing Alone CAN Make It Worse
On the surface, duct sealing seems like a good move. You lose less BTUs and save more energy — congratulations, job well done. But wait: When you seal up a poorly designed and installed duct system, it causes static pressures to rise so high that airflow drops to half or worse.
The net result is typical delivered efficiencies of 40% to 70%. Why? The Btus don’t get transferred, yet the condensing unit amp draw remains almost the same. This is typical in many energy-efficient homes. The symptoms are poor comfort, massive short cycling, and high utility bills.
The only way to get true energy efficiency is to fix the system. Of course ducts need to be sealed, but only after addressing the real culprits of poor performance: undersized ducts, restrictions due to poor duct design, abuse of splitter boxes, poorly installed flex, too many elbows, and the list goes on. Once a system is renovated, sealed, tested and balanced, and the blower is pushing against total static pressures of 0.5-in. WC (a bit higher on variable speed), you can achieve typical delivered performance of 90% or higher.
That being the case, let’s send a message to government agencies like EPA and DOE, plus utilities and PUCs: Let’s not end up with another crop of failed energy programs and egg on our collective faces by just focusing on sealed ducts.
We must send a clear message that true efficiency and performance occurs only when the entire system is working together, and the Btus are actually doing the job they’re supposed to do in the first place: deliver comfort!