Meta analysis of deep energy retrofits – anyone else seen this?
While browsing the depths of the EPA and DOE’s website, I bumped into a nationwide meta analysis of deep energy retrofits (DERs) in 2014 done under grant by one of the National Labs. Their results were eye opening … and shocking. Anyone else seen this? https://eta.lbl.gov/sites/default/files/publications/a_meta-analysis.pdf
They even cite Martin and the GBA! “It has been commonly reported on a popular green building blog, that a typical DER costs over $100,000 (Holladay, 2012)”. Martin — they’re not disagreeing but their data indicates costs vary, often by region, while admitting that DER should get an authoritative definition that means energy savings >=50% so maybe your definition is harder (and more expensive) to attain 🙂
The “meat” of the data is in the appendices at the end of that report, but a couple quotes I found eye-opening or shocking:
1) “Air leakage reductions were generally very impressive, averaging 63%.” pg 13
2) “… cannot compare these HERS reductions to reductions in net-site energy use, because nearly all homes that reported HERS ratings did not report any actual energy use data.” pg 16
3) “DER homes generally had higher than average energy consumption pre-retrofit” pg 17
4) “Net-energy reductions did not vary reliably with house age, airtightness or reported project costs, …” pg 17
5) “each DER project effectively removed a “home” from the electrical and gas grids” pg 18
6) “several projects that chose to switch from natural gas to electricity for heating end-uses, and which incurred severe source energy penalties as a result. ” pg 22
7) “[Pacific Northwest studies] found the drivers of variability [in model prediction errors] to be occupant behavior …” pg 22
8) “half of projects had increased monthly costs post-retrofit” pg 28
9) “it is not yet clear exactly how the costs of a DER contribute to increased home value (as few DERS have yet been resold)” pg 29
10) “The capitalization rates [of solar panels during resale] varied with neighborhood characteristics, such as education level, political affiliation and Prius concentration (these variables were controlled for), so value may not accrue to all DERs equally” pg 30
Penny for your thoughts 🙂
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Replies
Vap0rtranz,
Thanks for sharing this. I haven't read it, but hopefully I can find find some time to browse through it soon.
The two points that you have summarized that intrigue me the most are #5 and #8. That each retrofit “...effectively removed a 'home' from the electrical and gas grids...” is encouraging. Of course, it's easy to be encouraged when someone else is paying for the project. Along those lines however, it would be great if the conclusion of #8 turns out to be an appreciable increase in home value. That equity could be the tipping point for many of these projects which may otherwise not be able to achieve an economic ROI for the homeowners.
Hey Brian,
Agree on #5. It's really compelling to hear the result being described in those terms, aka. carbon footprint and energy usage in a relatable way instead of complicated units of measure; or at least compelling for those of us who believe in communal responsibility. :)
Justin