ENERGY STAR HVAC Design
ENERGY STAR HVAC design is not hard, really…all that needs to be done is a proper Manual J, select equipment using Manual S, and design the duct system according to Manual D. Yet…we are constantly finding “a failure to communicate” between Raters and HVAC Contractors.
ENERGY STAR HVAC design is simply following the ANSI Standard for Quality Installations of HVAC, ACCA’s Standard 5. I imagine the EPA is discovering that many Raters are passing HVAC checklist items that should not have made it through. Advanced Energy has reported numerous cases where the Rater has simply checked off boxes- instead of actually using the checklist as a guide for doing the work.
One of the challenges in the ENERGY STAR HVAC design process is when the documentation for the HVAC design is handed off to the Rater. Typically, that happens at the end of the game AFTER the equipment is installed and commissioned. Then, it is too late to do anything about improperly selected equipment based on improper HVAC design. However, the Rater is NOT required to verify that Manuals S & D were done…yet. I’ve recently highlighted that issue to the EPA and they are in the process of re-writing the guidelines for HVAC Quality Installation oversight organizations.
Simple checks to see if a Manual S & D were performed, requirements of an ENERGY STAR HVAC design process:
- Check the HVAC Contractor-recorded capacities at design conditions. Does the total capacity magically match the total capacity on the AHRI certificate? If the answer is yes, they didn’t do a Manual S- which would require them to use the interpolated capacities at design conditions from the OEM expanded product performance data. Since the AHRI tests are done at specific conditions (80 degrees inside, 95 degrees outside- with a 67 degree indoor wet bulb), unless the house in question is at those conditions- the capacities will be different. Some manufacturers like Carrier even provide a web-based interface that calculates the capacities at design conditions…so it really isn’t hard. Oh- it’s also required by the 2009 IRC.
- Check the duct design static pressure. Compare it to the HVAC Contractor-measured External Static Pressure. Is the measured ESP within 25% or 0.10 i.w.c. of the duct design static pressure? If not, it does NOT meet the ANSI Standard for Quality HVAC Installations (required by the EPA for HVAC contractors)…and a clear indication a Manual D was not performed….and Manual D is also required by code (or an equivalent).
I can foresee Raters getting asked to perform these types of HVAC design checks in a future revision of ENERGY STAR- especially since many of the homes that have HVAC designed under the current “we’ve always done it this way” method are ending up with comfort complaints…which get blamed on ENERGY STAR for requiring the HVAC contractor to use the 1% and 99% outdoor design values for the closest location to the home.
And that, my friends, is a real crock of…well, we all recognize it for what it is. Blaming the outdoor design values when the rest of Manual J is ignored, no Manual S procedures followed to match the equipment with the load profile, and ignoring good duct design and installation to deliver what was promised- that is simply childish.
It is really disheartening to hear that some HVAC contractors (who know better) are taking that exact approach to cover their ass with the builder and drive the builder away from high performance homes using comfort fears (which are realized when you DON’T follow the quality HVAC design process).
But it underscores something even more disturbing- the integrity of a trade contractor who signed an agreement with an oversight organizations stating they would comply, then signed an agreement with the EPA agreeing to abide by the rules, then signed a contract with a builder that promised to deliver ENERGY STAR quality HVAC design and installations- and then the contractor COMPLETELY IGNORED every single commitment they made and continued with business as usual. My dad would have fired them on the spot.
In the construction industry, it isn’t about what you promise- it’s what you deliver that counts.
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