Archive Of The Category ‘zero net energy‘


Back in the Swing!

girl sitting on swing

Image via Pexels


It’s been a bit more than a year since I posted, and what a year it’s been! Besides all the global madness, I moved last July from Pacifica to Petaluma, California. I love it here and feel a bit like that girl on the swing. Life is good. Notwithstanding — you know. These are exciting times, change is afoot, and I still have faith that I’ll see great things happen in my lifetime.

I have three things to share today:

  1. Team Zero’s annual residential zero energy/zero carbon inventory is ON, for the 5th time! Add new projects or provide updates about projects you’ve inventoried before, HERE. We’re especially excited to learn more about what’s powering North American zero energy homes: what’s the mix of sun, electricity from the grid, and fossil fuels? Help us find out, so we can report on this to you all in the fall!
  2. With my dear friend and co-conspirator, Peter Yost, I’ve started a monthly blog series on Green Building Advisor. (It’s behind a paywall, but there’s a free trial available, and/or you can subscribe monthly — and GBA is a great resource, in case you don’t already know that.) Pete and I call the series “Building Bedrock,” but GBA uses the more sedate title of “Best Practices.” It’s a ton of fun. Each month Pete and I take on a new theme and expound on it from our unique perspectives. You get to see where we converge and diverge. So far, we’ve posted an intro and Part 1 (“Setting Priorities”), with nine more in the works. Beam in on the third Thursday of each month for the next installment.
  3. My esteemed colleagues at Zero Energy Ready Oregon have put out a new online resource, “Cost Effective Steps to Zero.” It’s a nice overview with clear illustrations and simple steps. This is a good introduction to the topic for novice audiences, and includes lots of links to deeper dives (including several of my publications, I’m happy to add).

Happy Solstice Week, my friends!

Things are Popping!

Here’s a sampling of some of the great happenings out there in the big wide (and ever-expanding) world of energy efficiency, zero carbon, and green.

DOE Launches Home Improvement Expert

DOE’s Building America program has a new resource called Home Improvement Expert, developed to help homeowners with energy-related home improvements by using 21 individual home improvement checklists. These can be attached to vendor contracts to help ensure quality work and help vendors be more competitive. This is important because research shows energy-related home improvements are significantly non-compliant with industry best practices concerning performance and savings.

More information on the checklists is available on the DOE website.

Meritage’s CR Herro My Latest Hero

Quoted in Builder Online magazine, Herro makes several points that I frequently rant about in my classes and talks:
  1. We need to fix how valuations are done to capture the benefits of above-code energy features
  2. Getting to zero is about figuring out how to spend your budget wisely
  3. Roofs need to get simpler to reduce cost and better accommodate solar arrays
  4. Educating the value chain is key to success
  5. “It’s much better to be your own disruptor than to have disruption done to you.” Well said!!

Thanks to RMI’s Bruce Nilles and NYT writer Justin Gillis for this excellent article on why electrification makes sense — including giving up your gas stove! Kudos!

New ZNE Homes Resource

Congratulations to author Ed Dean and the team at Southern California Edison for their new publication, Zero Net Energy Case Study Homes, Volume 1 — and to all the project teams whose work it describes!

My favorite thing about the book is that, with just five case studies, it demonstrates that ZNE performance is achievable across a wide spectrum of housing types: new single-family homes (the easiest), a single-family renovation, a modestly-sized modular home, single-family production-built homes, and new multifamily housing.

Here’s an excerpt from my foreword:

Members of the ZNE community outside California – in places that have “real” weather – sometimes scoff at the lack of challenge of accomplishing ZNE here. Admittedly, our populous coastal areas benefit from benign climates, but we also have both very cold climates, such as Redding (similar in heating degree days to Chicago), and very hot ones, such as Palm Springs. Other factors also make this a challenging environment for housing innovation, among them high costs, a highly mobile workforce, and a notoriously litigious culture. Thus creating successful, marketable, ZNE projects is a non-trivial feat.

All the projects represented here have met the pinnacle of ZNE achievement: verified site ZNE. That is, not only was each project designed to be capable of achieving ZNE, but utility bills provide objective evidence of occupants’ energy use yielding ZNE in actual operation over the course of a full year. Further, site ZNE (explained in the introduction) is the most difficult definition to meet. These projects therefore demonstrate, importantly, that operational site ZNE (to which source ZNE is equal, for all-electric projects) is an achievable benchmark. These proofs of viability are absolutely critical to supporting the State’s likely push towards residential electrification in years to come. The project developers whose work is showcased here are thus to be both congratulated and thanked for their significant contributions to the future of housing in California, and beyond. Read on, and benefit from their experience.


‘Zero Progress’ in California

Luminalt solar installation - Getty Images

Luminalt solar installation on San Francisco home (Getty Images)

Ha! Got you, didn’t I?!

The real story is about the progress we’re making toward zero carbon. A couple of recent milestones are adoption by the California Energy Commission (CEC) of the State’s building energy standards, Title 24-2019, effective January 1, 2020, and CA Senate passage of SB 1477 (Stern, Low-Emissions Buildings Market Development); the bill is now making its way through the State Assembly.

Title 24

While much has been published about the landmark solar mandate in Title 24-2019 — the first time a state has required installation of photovoltaics (PVs) on residential projects — mainstream media outlets have largely overlooked the significance of this code update as a step on the journey, set in motion in 2006, towards the State’s “big, bold” zero net energy (ZNE) goals. Requiring PVs doesn’t achieve ZNE, as the arrays are only required to offset ‘typical electric uses’ — i.e., excluding the typical (and not inconsequential) gas loads of space and water heating, cooking, and clothes drying. However, it’s a step in the right direction. Of particular note is that this version of Title 24, like all its predecessors, was required to meet stringent rules ensuring cost-effectiveness — that is, the standards must save consumers more than they cost. While many who work in this field (myself included) believe the cost-effectiveness test needs to be updated to encompass societal costs associated with fossil fuel combustion, the current rules do ensure that the solar mandate will not pose a financial hardship to new home buyers (notwithstanding propaganda to the contrary by nay-sayers).

In today’s San Diego Union-Tribune, CEC’s Commissioner Andrew McAllister provides a good overview of the requirements. “From day one, the savings from lower electricity bills more than offset any additional payment associated with financing through a mortgage. Costs will be even lower by 2020, especially in large developments where solar equipment will be procured and installed in bulk. The standards also allow larger, community-scale solar instead of individual rooftop systems — another potential cost-reducer. And exemptions to the solar requirement apply for shaded sites and infeasible roof configurations, and where local power is uncommonly inexpensive.” McAllister goes on to remark that the new standards also “encourage grid-friendly technologies such as battery storage, thermal storage and demand response to be installed alongside solar. The standards also make it easier to build an all-electric home — a clean, low-carbon trend that is expected to grow.” Furthermore, as an alternative to purchasing PVs outright, home buyers will have the option of leasing a PV system at very low or no up-front cost.

While it’s somewhat doubtful if California will ever truly mandate ZNE on individual residences — for perfectly good reasons, including the emergence of potentially more cost-effective alternatives such as the community solar approach that McAllister cites — the State is forging ahead on the path to zero carbon, which is, after all, the real goal; ZNE was simply conceived as a means to that end.

SB 1477

SB 1477 is described in a support letter submitted to Senator Stern on June 13 as providing, “technology-neutral incentives directly to builders and developers to design and build low-emissions buildings, and [spurring] innovation in the market for space and water heating equipment in California … This bill also targets incentives to Californians who need and deserve the most support. Higher incentives will go to low income housing and buildings in disadvantaged communities. In addition, space and water heating equipment that are most likely to improve the health, safety, and energy affordability of low-income households will be prioritized.”

The letter, signed by Design AVEnues and nearly 40 other organizations, was drafted by Natural Resources Defense Council (NRDC), which has been leading the lobbying efforts on this important climate change bill. NRDC’s Pierre Delforge reports, “Following amendments in the Senate, the bill now proposes that the market development programs be funded from an annual allocation of 5 percent of the cap and trade allowance revenues received by electric and gas utilities. SB 1477’s incentive programs are well aligned with the purpose of the cap and trade allowance revenue to fund GHG reduction programs, and using this funding source would avoid any impact on rates.” The bill will be heard by the Assembly Utilities Committee on June 27, and support letters are due by June 21. The draft bill can be reviewed and comments can be submitted on the State’s website (here).


ZNE guidance for CA architects (& others!)

AIA ZNE Primer cover image

AIA ZNE Primer cover image

The American Institute of Architects California Council recently published the Zero Net Energy Primer. I had the privilege of developing the Primer for them under a contract with PG&E. The Primer (if I do say so myself) is a handsome, concise, and accessible guide — a mere 24 pages, including lots of pictures of ZNE homes of all flavors (small, large, single- and multifamily, luxury and affordable). The AIACC’s goal in publishing the document is to ease the task facing California architects with the roll-out of the State’s 2019 energy code (“Title 24”). The new code will go into effect January 1, 2020 and — while it doesn’t quite get us to ZNE — represents a significant advance in residential energy performance, and the first time that homes will be required to install renewable energy systems. (Of course, there will be byes for projects where it’s simply not feasible to install them.) The Primer will, I hope, help architects get a handle on the ZNE requirements ahead of the looming 2020 deadline.

Kudos and many thanks to designer Debra Turner for the engaging design, and to architect Steven Lee for his terrific illustrations.


Obsessed with roofs

Newburyport, MA, ZNE home -- Steven Baczek, architect

Newburyport, MA, ZNE home — Steven Baczek, architect

A recent email thread involving a group working on a video about ZNE design prompted me to raise one of my favorite subjects. Say I, “Will you talk about the critical importance of roof design?” Queried Steve Mann in reply, “Do you have something more specific in mind?”

I’m so glad he asked! It gave me an opportunity to vent (pun intended) about this topic, which I find is absent from far too many conversations about ZNE home design. Here’s what rolled off the keyboard.

  1. You need to know your (approximate) energy loads early on, so that you have an idea how much solar-appropriate roof area you’re going to need. [That requires a calculation — for example, using NREL’s PVWatts.]
  2. You need to factor in code-required clearances around the solar array, and depending on the size/shape/proportions of the roof plane(s) in question, those margins can eat up a hefty fraction of the total area(s).
  3. You need to NOT have vent stacks and other obstructions interrupt that oh-so-critical PV roof area.
  4. All of the above — to those who are realistic and paying attention — dictate the simplest practicable roof form.
  5. The less attention you pay to the above considerations, the harder you will have to work on the enclosure and other efficiency measures to achieve ZNE — e.g., adding in more and more expensive measures, such as imported windows.
  6. Conversely, the MORE attention you pay to (simplifying) the roof, the more flexibility you will have with other building features.
  7. The simpler the roof:
    • the more money you’ll have for other features;
    • the less it will cost to develop elaborate architectural details to ensure thermal & moisture integrity;
    • the easier it will be to air-seal and insulate the whole building;
    • the more likely that the air-sealing & insulation will be done well;
    • the better the building will perform; and
    • the less the risk of later thermal, moisture, condensation, and rot problems.

So a simple roof is an all-around win: save money, improve thermal and moisture performance, get to ZNE more easily.

It’s time that we rekindle a time-tested aesthetic, one that finds beauty in simple, elegant, well-proportioned forms, robust materials, and quality of craft. One of my favorite architects who has complete mastery of this approach is Steve Baczek. Not coincidentally, Steve spent many years working with Joe Lstiburek and Betsy Pettit at Building Science Corporation — he’s also thoroughly conversant with building science. Take a look at Steve’s portfolio for inspiration!

A Tirade on Energy Models (or, It’s All Relative!)


From Predictability of Energy Use in Homes, Lachut, D., et al. (

Lots of people complain about energy models — specifically, how they don’t accurately predict how much energy the occupants of a home (or building) will actually use. This complaint misses the point.

The REAL problem with energy models is that there is widespread confusion about what they can/should be expected to do. Predicting actual energy use for one specific household is not on the list of realistic expectations. Approximating the amount of energy a reasonably large aggregation of households might use? Yes, perhaps, in skillful hands.

The main thing that energy models can and should be used for is to compare the relative effects of different variables on a building’s energy performance, holding constant certain assumptions about the occupants’ usage patterns — which, even in the best circumstances, are fundamentally unknown and must be generalized.

It’s important to remember that a home (except in extraordinarily rare instances) outlives any particular set of occupants and behaviors many times over; those are subject to frequent change. Even one set of occupants will change energy-using behaviors after a time — for example, as toddlers outgrow bathtubs and graduate to shower usage … and then avoid bathing at all … and then evolve to multiple changes of clothing and multiple showers a day (think: soccer and muddy shorts and shoes).

Thus it’s a pointless exercise to attempt a precise fit of behavioral assumptions to a specific set of occupants, or think that we can predict their energy use for any but the most fleeting time period. What we should be doing is designing homes to efficiently serve any household that might reasonably be expected to live there over the life span of those homes.

\With that understanding, and the use of standard occupancy assumptions*, we can certainly use models effectively to compare the relative effects of different features on energy use.

Oregon Goes to Zero! All new residential construction to be ZNE-ready by 2023

Congratulations to our friends at the Zero Energy Project — they have just announced that today the governor of Oregon signed an executive order that they have been lobbying for. It includes changes in building codes requiring that all new residential construction be zero net energy-ready by 2023, including solar-ready features, electric vehicle chargers, and more.

Press release here.
Executive order here.

Is there such a thing as TOO MUCH PV on your roof?

My view: NO.

The State of California, however, has another view, revealed through planned changes to our venerable energy code, Title 24 Part 6.

Around a decade ago the State set “big, bold” goals for all new homes to be ZNE by 2020 (also, for all new commercial buildings to be ZNE by 2030). However, in the intervening years since those goals were established, a few devils have been found amidst the details. One such Aha is that, while conceptually having a home produce enough energy to supply its own needs on an annual basis makes perfect sense, at high rates of adoption this presents some grid-level challenges. Specifically, most of the renewable energy production will come from rooftop photovoltaics on sunny afternoons … hmmm … but that’s not when most of the demand occurs! The demand peak occurs later in the day, when people come home and start to cook, tinker with their thermostats, etc. This imbalance is illustrated in the rapidly-becoming-famous “duck curve” graph.

So now there’s concern about “grid harmonization,” and the State is indicating that future versions of the energy code will limit “excess” PV and/or require that it be countered by onsite energy storage to address this imbalance. Even now, “excess” solar energy production is effectively discouraged by utility rate structures that ensure you will never see good value for PV capacity above and beyond your own annual electricity load — not even when it’s there to compensate for natural gas use, for example.

Paradoxically, the State has also acknowledged that as it moves to higher levels of clean energy (via increases in the renewable portfolio standard, or RPS), in the next couple of decades most of the new renewable energy supply will come from PVs. A bit of a disconnect?

Notably absent from presentations on State plans to address the “duck curve” are discussions of providing UTILITY-LEVEL energy storage. While eager to point out that PV is more economical at utility scale (true), they don’t seem to be nearly so quick to comment on whether it might be equally more economical to provide energy storage at utility scale (that seems likely to be true, no?!). This seems an obvious omission and should be added to the public discourse, promptly.

Also absent from the blithe comments about how, really, we should be looking to install utility-scale PV rather than putting it on all the little rooftops, is any observation about the massive ecological impacts associated with utility-scale solar developments.

My vision for a clean energy future includes a diversity of solutions, with solar on rooftops both small and large, wherever it is productive. Just as nature is not efficient, but rather smart, simple economics are not the final determinant of what makes sense. What makes sense is to preserve wilderness for all its uniquely important values, and limit the footprint of intrusive human developments such as solar farms to the greatest extent possible.

Reflections here provoked by some of the presentations at this week’s excellent Symposium on Zero Net Energy Buildings and Beyond, presented by the Emerging Technologies Coordinating Council. My thanks to all of the organizers and speakers for your contributions!

Webinar 9/26: To Zero and Beyond – North American Trends in Zero Energy and the Virtuous Cycle

Join me at 1pm PDT on September 26 for this global webinar event during the WGBC’s World Green Building Week, focused on the hottest growing trend in residential building: Zero Energy (ZE).

Register at

Get the latest insights on the exciting growth in ZE residential development in the US and Canada. The Net Zero Energy Coalition will present highlights from its recently published 2016 Residential ZE Report, along with findings on the drivers behind that growth and keys to ZE builders’ successes. We will also hear lessons learned from California’s pioneering efforts in ZE code and policy development, along with other insider perspectives on where zero energy is headed.


Gene Myers is owner and CEO of Thrive Home (formerly New Town Builders), Denver’s leader in building green, energy efficient production homes and recent winner of the U.S. Department of Energy’s Housing Innovation Award. THRIVE is Denver’s largest builder of for-sale affordable housing.

Mindy Craig, Principal and Owner of Blue Point Planning, was the lead author on California’s New Residential Zero Net Energy Action Plan for the CPUC and Existing Buildings Energy Efficiency Action Plan for the CEC. She is currently working on developing the New Commercial Buildings ZNE Action Plan and is leading the implementation of the ZNE Residential Plan.

And yours truly — Ann Edminster, M.Arch., principal of Design Avenues and NZEC Board director. Read more about me at

Register at After registering, you will receive a confirmation email containing information about joining the webinar.