Energy codes have come a long way from when they were first established in the ’80s, said Tom Flanagan, manager of multifamily and LEED services at EnergyLogic Inc. Flanagan explained at the Rocky Mountain Green conference in Denver on Thursday that it’s not a big leap from a code-minimum home to one with efficiency certifications that set a builder apart from competitors.
A code-minimum home built to 2012 standards or later is 40% to 50% more efficient than homes built 20 or 30 years ago, he said.
“They’re really not that ‘minimum’ anymore,” Flanagan said.
The 2006, 2009 and 2012 code cycles made aggressive changes to increase efficiency results by 15% each time, according to Flanagan. Subsequent updates were relatively stable, and Flanagan expects that stability to continue through the 2021 update.
“It doesn’t seem likely that they’ll really be able to do much more,” he said. “They may increase a couple requirements for insulation levels or something like that, but they’ve been fought successfully every time they’ve tried to increase insulation levels in the past.”
As the code has stabilized, he said, builders can take a more holistic look at the homes they build, considering how elements work together.
Mandatory tests required by the 2012 and 2015 codes include:
Envelope testing. Envelope testing has a target of three air changes, “which is a really tight target.”
He noted that many jurisdictions have relaxed those requirements for attached or multifamily homes. “They’re basically acknowledging that a smaller home has a harder time meeting that target, or a home with a lot of shared walls that can’t be sealed as well.”
Duct leakage. Builders are encouraged not to install duct work outside the building envelope.
Efficient hot water distribution systems
Whole-house ventilation. Systems must meet the the ASHRAE 62.2 minimum. He said Colorado builders typically utilize a “smart fan with a dumb switch or a smart switch with a dumb fan.”
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He recommends builders use balanced ventilation with energy recovery ventilators where homes are designed for ventilation.
A HERS rating of 100 indicates the home meets the code minimum from 2003, Flanagan said. The average score over the last few years is in the low 60s, he said, while the average HERS score in Colorado is in the mid-50s.
“A HERS score of 40 is about as low as you can get in the scale without installing some kind of renewable energy.”
To qualify for rebates from Xcel or on federal taxes, builders must show a HERS score for their homes, according to Flanagan.
Beyond code minimums
Flanagan said that many of his builder clients are being required by land developers to meet additional sustainability programs beyond what’s required by code. Between 35% and 40% of his clients are building above code.
He shared a “ladder” of building programs that help builders step up from code-minimum to more efficient homes.
“These steps from one program to the next are pretty simple … and fairly complementary to each other; adding one gets you halfway to another,” he explained.
ENERGY STAR. The Environmental Protection Agency’s long-standing program requires a thermal enclosure checklist, duct leakage and envelope testing.
Flanagan noted ENERGY STAR blower door targets are easier to meet than code targets.
Indoor airPLUS (IAP) and WaterSense. IAP is an add-on EPA program that builds on ENERGY STAR and requires upgraded filters and VOC-free products. WaterSense is a standalone certification program that requires steps to prevent leaks in plumbing or irrigation systems.
“We don’t really see a lot of WaterSense home certification,” Flanagan noted, but “a bunch of the other programs have taken pieces of the water efficiency measures in WaterSense to add to their programs.”
DOE Zero Energy Ready Home (DOEZERH). The Department of Energy’s program aims to build “future proof” homes that are in position to be made net-zero in the future. That doesn’t mean builders have to build net-zero homes to qualify, Flanagan said. Instead, the program builds off ENERGY STAR and the 2012 code insulation requirements.
Certifying for DOEZERH requires IAP certification. Additionally, homes must be ready for solar PV systems to be installed, and have efficient hot water delivery systems. Flanagan said builders who earn this certification often install on-demand water heaters with built-in recirculation pumps. These homes typically earn HERS scores in the low 50s, he noted.
LEED. A home that qualifies for DOEZERH scores 37 out of 40 points in LEED v4.1 for single-family homes, Flanagan said. Builders can get those last three points by adding water efficiency measures.
Some LEED credit categories that won’t be met by other rating systems include location; access to transit (farther-flung homes will have to be more efficient to offset increased transportation impacts); access to open space; and integrated project teams.
“It’s really encouraging [for] the process of the project to stay focused on the sustainability goals.”