Learn from the Raters

By now, most of us have met up with a HERS Rater or two. HERS stands for Home Energy Rating System. These forks are used by government and utility programs to rate the performance of homes so builders and homeowners can receive tax breaks and utility incentives. Quite a number of them are great building and HVAC system performance testers. I've written about these folks several times, because like it or not, they are becoming a very real presence in our industry.

We've been receiving many interesting phone calls from around the country and have been reviewing some amazing findings made by a dozen prominent Home Energy Raters. We're beginning to see a dynamic new twist in the home energy efficiency rating process that actually includes the testing of the HVAC systems.

Raters are charged by the government to rate the performance of homes. The EPA approves a standard that is used by several energy software companies to model a typical U.S. reference home and established its energy usage as a score, called an index, of 100%.

The goal in most states is to prescribe a scoring method for energy-saving construction standards and appliances, etc. to reduce the apparent energy usage of the home to meet an index of 85 or less, roughly 85% of the energy usage of the model home. The lower the index, the greater the projected energy savings are expected to be. Lower is better, like a golf score.

Weak Sauce HVAC Testing Requirements
Currently, the only rater testing required to rate HAVC systems are duct tightness tests using duct pressurization and blower door technology. Then they record the equipment model numbers and the ARI and GAMA rated efficiency. It's assumed this testing accurately depicts the functioning efficiency of the HVAC system. It does not. It simply tests one factor of performance, duct tightness, and documents the highest possible level of performance that the equipment achieved in the laboratory.

It's not surprising to find 10 to 20% of the students in a typical HVAC testing seminar to be raters. Many of these guys and gals are pretty amazing testers. Hire one to do your blower door testing and you'll see for yourself the passion many of them have for increased building performance.

I have been impressed with how well many of them have incorporated NCI testing to their services and added this new dimension to the currently accepted home rating protocol. The results of this testing is changing the rating industry.

Their Findings and Numbers
What our Rater friends have found is quite similar to the results that most contractors report from around the country. When following HVAC industry test protocol to rate the performance of an installed system, the typical unimproved, residential existing or new construction HVAC system is found to be performing at an effective efficiency from 50 to 68% of equipment rated capacity — this is an average effective efficiency measured is about 59%. These numbers are very consistent with the results of a national study we conducted in 2006.

But wait, there's more.

Raters have computerized programs that rate the performance of the entire building. In these programs, there is a data entry point in the rating software for something called Heating / Cooling Performance Adjustment. This function allows the rater to enter an efficiency adjustment to the building based on a score of the performance of the HVAC system.

It's interesting that prior to learning HVAC methods of rating systems, virtually every one of these raters rated every HVAC system at 100% of ARI or GAMA efficiency ratings as they were taught to do in their original HERS training. In other words, normal protocol assumes the HVAC system is operating at peak performance and delivering 100% of the equipment rated BTU into every home.

What's Changed?
The difference is that HVAC trained raters now are entering installed system effective efficiency ratings in their rating reports in the Heating/Cooling Performance Adjustment section. With this added data point, the change in the building efficiency is quite significant.

After gathering data from six raters across the country, the obvious result we discovered was before the building can achieve a satisfactory rating, the HVAC systems must be renovated to improve its performance in more than 90% of the case studies we reviewed.

Prior computerized ratings showed average home energy efficiency index was 83. Meaning these homes used only about 83% of the energy used by the typical U.S. reference Home. Previously, literally every one of these homes were rated assuming the HVAC system was functioning at 100% of capacity. Once again, this was done by leaving the 100% default in the Heating / Cooling Performance Adjustment in the rating software.

Once these raters began to add HVAC system performance measurement to their ratings they began to enter the system's measured effective efficiency into their computerized ratings. With an average of 59% efficiency, the typical home shows a new rating index of between 100 and 110. Meaning the home now uses 100% to 110% of the energy used by the typical US Reference Home. That's a typical increase in energy usage of more than 25%. Pretty interesting.

Furthermore, these programs automatically project the annual energy usage of each home. With the actual HVAC performance entered, the estimated energy cost increased by just over $1,200 per year. How's that for energy savings and carbon reduction?

Interesting Twist
The bottom line is that we're learning there is a serious flaw in the rating methods if the performance of the HVAC system is assumed and not measured.

We know how difficult it has been for the HVAC contractors to wrestle with the fact that our typical systems don't work so well. But we've been able to change our systems one at a time and work at our own pace. We're not sure how a government sponsored organization can make such a sweeping change or if they will.

Our experience has taught us when there is room for improvement, opportunity exists.

For many of us that are contractors, it's automatic to diagnose and prescribe repairs to our customers. It's our job, it's what we do. It's a different story for the rater industry should they add HVAC system performance measurement to their ratings. Each rater is a third party, separate from the project, submitting a report revealing serious defects with another party's work and exposing a massive defect in nearly every building they rate.

Perhaps we should move forward slowly. Maybe begin with existing homes, and ease into the new construction market. This is the approach many people who are raters and HVAC Contractors have taken. They are collecting fees to measure and rate HVAC system performance on homes, and are then offering a menu of repairs to renovate and balance duct systems for their customers.

Most raters are unlicensed to perform HVAC system repairs. Quite a number are securing their license, many are partnering with top quality HVAC contractors who are trained and able to repair systems and solve the problems revealed by their new rating skills.

I see opportunity for all of us. I see delighted homeowners well educated through the testing process and anxious to live in comfortable and efficient homes.

What do you see?

Rob "Doc" Falke serves the industry as president of National Comfort Institute a training company specializing in measuring, rating, improving and verifying HVAC system performance. Contact Doc at [email protected] or call him at 800/633-7058. Go to NCI's website at nationalcomfortinstitute.com for free information, technical articles and downloads.

Hide comments


  • Allowed HTML tags: <em> <strong> <blockquote> <br> <p>

Plain text

  • No HTML tags allowed.
  • Web page addresses and e-mail addresses turn into links automatically.
  • Lines and paragraphs break automatically.