Energy Stewards International, an NCI Company in Des Moines, completed an interesting study in Iowa providing new evidence that although most equipment is significantly oversized it performs so badly, that it is actually about the right size.

If this is true, new opportunity is available for contractors that can actually size equipment correctly and get systems to perform as they should.

Heating Equipment Sizing
The first phase of the study focused on 200 systems. ACCA Manual J load calculations were completed to evaluate the design heat loss of the homes. The average heating equipment was sized at just less than 90,000 BTU output. The Manual J calculations showed the average home should lose less than 50,000 BTU per hour. The average equipment was oversized by 179%.

Cooling Equipment Sizing
The next step was to look at the cooling equipment sizing. Load calculations showed the average heat gain of the homes was just over 20,000 BTU. However the actual average equipment was sized at nearly 45,000 BTU. That made the average cooling equipment oversized by 210%. Are we beginning to see a pattern emerging?

Downsize! Downsize!
At this point in the story, the energy consultants are screaming Downsize! Downsize! According to the assumptions of the industry, nearly all of the equipment rated BTU makes it into the building, or does it?

Well before the panic button was mashed, we recommended the study move into its second phase. Over the years we have learned from experience that perhaps systems don’t work as they are designed to and perhaps there is more to the story than traditional engineering would have us believe.

Heating System Performance
The next step was to evaluate the measured BTU delivery of those systems to compare the capacity of the equipment to the delivered capacity of the system.

Although the average equipment was sized at nearly 90,000 BTU the installed systems were performing at less than stellar levels. The actual system delivered BTU was just over 50,000 BTU! In other words, only 59% of the rated BTU was making it into the home.

So if the load of the building was just under 50,000 BTU and the system was actually delivering just over 50,000 BTU, the equipment was sized as it should have been. If only the lousy performance of the system was entered into the load calculation, the equipment would have been sized about right. Scary, isn’t it?

Cooling System Performance
Finally the actual performance of the cooling systems was measured. Can you guess what we found? Although the equipment was sized at over 45,000 BTU, the actual average BTU delivery of the systems was less than 2 tons or 24,000 BTU of cooling. Or only 61% the rated BTU made it into the building.

Same story, different characters.

Opportunity?
The industry as a whole may look at this study as a shameful disaster. When new information is brought to light for the first time that would be a typical response. We can all hear the politicians proclaim, “Something must be done!” But what is to be done? In Iowa, the state and the utilities are paying attention and the winds of change are blowing in the right direction. Awareness is high and the shift to measured performance is well under way.

But what if you don’t live in Iowa?

Unfortunately, oversized and under performing systems aren’t isolated to Iowa. In many instances, Iowa systems may be better performing and sized closer to actual building load than they may be in your area of the country.

The truth is the results of this study reveal that for the rest of your career, opportunity will stand before you with almost every system you touch. The next system you touch will undoubtedly be oversized and under performing.

However performance is invisible. It cannot be determined by the yellow energy efficiency sticker on the equipment. The system may look like it was perfectly installed and still performs at less than 50% of capacity. Airflow, pressure, temperature and BTUs are invisible. In order to be interpreted these system performance indicators must first be measured.


The opportunity to improve system performance is unveiled by measuring the performance of the system.

What if you could offer your customers equipment half the size of your competitors and be paid 50% more than they charge? This is the new frontier in the HVAC industry. Learn to measure and deliver HVAC system performance.


Rob “Doc” Falke serves the industry as president of National Comfort Institute a training company with technical and business level membership organizations. If you're an HVAC contractor or technician interested in a free procedure describing how to measure system total external static pressure, a key system performance indicator, contact Doc at robf@ncihvac.com or call him at 800-633-7058. Go to NCI’s website at nationalcomfortinstitute.com for free information, articles and downloads.