Is net-zero energy on site the right goal?

I think all of the above points are valid but as we make additional progress toward time matched (hourly and seasonal) renewable energy we will quickly realize there is no such thing as zero energy with only on-site resources.  Also, over time the cost disparity between DER and utility scale will grow even further. I think the question is what should we be doing right now to help accelerate renewables adoption and that brings me back to the topic of additionality which is getting harder and harder to prove/feel good about.  The wild west of carbon offsets isn't generally very comforting either. My suggestion: put as much renewables as you can on-site but also focus heavily on ensuring that your building load profile compliments the future grid generation profiles to the extent possible (ie. short term load flexibility/dispatchable resources plus optimized energy performance for winter months).  And of course reduce embodied carbon.  What's left over might not be as marketable but will have the largest impact.

To benefits, I would add the real ecological benefit of "yes in my backyard" power generation, versus out-sourcing it to a more polluting but unseen source. This was big for me in going fully on-site, off-grid in my home when I built it in 2007. I didn't want the 20% base load nuclear that I was getting from Vermont Yankee. Things have changed since then but it can be a guiding thought for some projects. It's not all simple, though, when you factor in extraction, supply-chain, and end-of-life with solar and batteries. But it should be on the list of considerations. Maybe this will all be a blip that is perfectly manageable, but I have a hunch that 10 to 30 years from now there will be a lot of buildings where solar was installed in the early 2000s and there are questions of "why did we do this?" I can think of a few buildings where factors like roof replacement complication, PV maintentance and cleaning issues, bureaucratic headaches around the deal structures and utility incentives going in now, could be a real pain. Perhaps it would be helpful to brainstorm a list of considerations that might lead you away from on site solar, such as:

• Competes with other land use goals such as agriculture, open space, or wild space. (Sometimes there are synergies, sometimes there aren't.)
• Roof installation is complex.
• No benefits to on-site resilience are installed or are likely to be installed in the foreseeable future.
• Or simply, the benefits aren't enough of a priority on a fixed budget compared to something else.

what else?  

In addition to those on the list, I would recommend to look at net zero in three steps in this order. You will mostly likely get the best return on investemnt ($/EUI): 1. Reduce demand on site with efficient and well designed buildings and spaces and systems 2. Provide supply on site with renewables. 3. Provide supply off site with renewables. There is the issue of transmission loss depending upon how far away the energy is generated. I am not an expert, but understand that a significant element of power loss occurs in the transmission wires from source to site. If you are closer (i.e. on site) the power loss is less to none.

I'd toss in as a reason for on-site: what else are we doing with roofs? At BEST, we're talking limiting heat island effect/green roof stuff. But at worst, it's unused space. It takes a bit of a perspective change, but why wouldn't we (in an ideal world... which is, I believe, what we're aiming for) want to find ways to make that space something regenerative? I'm also in the camp that if you have the opportunity to create renewable energy on-site, that's a net good even if it's simply lowering the demand on the existing grid, regardless of how renewable the initial generation source is (and, let's be clear: as green as the grid here in the Pacific Northwest is, there are all kinds of ongoing discussions about salmon habitat, indigenous land use, etc. that, at least to me, further incentivize on-site power generation.) I agree with above that it's the wild west when it comes to offsets. I think I've brought this up before, but I'm a fan of offsets from goldstandard.org. Those, at least, seem to be ones you can truly measure (and, unsurprisingly, they are not cheap.)

Wtih solar/wind capacity factor, curtailment, electrification and general economic growth, I think it's obvious that the vast majority of renewables will be off-site over time even without considering cost.  I think the value of rooftop solar depends on the setting: if urban, people and plants should be a higher priority but the pragmatic issues Tristan brought up plus cost disparity with utility scale will be a huge driver in the future. One other quick note: transmission losses are typically only around 6%.  Most of the difference in site-to-source is btu's into the atmosphere at traditional power plants.  Also fun to note that power plant cooling towers consume more fresh water than any other single use in the US (~40% of all)...

Hi Becky, Jay (and any others with expertise), Side conversation, thanks for mentioning Gold Standard: We have been researching REC, carbon offset (using the term generically) and power purchase agreement quality and rigor and are still very confused as to the best solution for us and our clients. If you and anyone else would be interested, we can share our research (we have no conclusions yet) to talk through this complicated area. kanderson@lmnarchitects.com * The Oxford Offsetting Principles appear to be a great source for understanding the classifications of off-site carbon projects. * Green-e seems to require a decent quality of projects and is referenced in LEED/ILFI certifications, but I haven’t always been impressed or able to find what is actually being bought. Here is a 1uote from a quote on Green-e certified RECs: “However, a REC should not necessarily be used for claims of carbon neutrality. This is because a REC does not have to prove additionality, whereas a Carbon Offset must go through these additional rigors.” * Evidently carboncure and some forests already count and perhaps sell carbon credits, so these should not be counted again for a building project * The verifiers we’ve found, but don’t yet have an opinion on the rigor of, are: · Verified Carbon Standard · Climate Action Reserve · Gold Standard · American Carbon Registry -Kjell From: Jay Wei

This question comes up on every project, all the time, and I wish we had a clearer answer to provide. Working backwards, the biggest issue we have with NZE/C is the fact that the offsite options available to most projects are often (always?) meaningless, convoluted, and a distraction. I'd argue that NZE/C projects should do what they can onsite and end all of the offsite focus. Further, there should only be NZC, not different rules for NZE and NZC (as we currently have in ILFI and USGBC programs). And it should include efficiency, electric, onsite RE where feasible, and some level of embodied carbon reduction. Then you should include EV charging capacity and a TDM program (since transportation carbon is likely your biggest source of emissions). That’s something any project can do. It’s simple, and it focuses on what matters. That means that projects won’t be powered 100% by renewable energy, but we’re fooling ourselves if we think that any project really is.     Regarding the question of the value of additional onsite renewables: this depends on your location but is still generally a good thing in most places. If you look at the grid in MN, another 50-100 MW of solar is still likely to drive down fossil use for power. And if you go to a California situation with curtailment and a duck curve, then you should focus on storage, but would need a utility program (rate structure or incentive) to support doing so. Most of the country isn’t there yet. If you're in Xcel territory, you might say that since they will be 85% reduced by 2030, and at 100% reduced by 2035, then the act of decarbonizing the grid is just going to happen one way or another. In CO, this is reinforced by legislation. So, whether the 50-100 MW is on your site or goes elsewhere in Xcel territory doesn't really matter from a system perspective, but I'd argue closer to load is better, and it enables projects to use the power directly in an outage if they have storage. It’s worth noting that Xcel may get the REC credits either way (their incentives are linked to them getting the RECs to meet their 85% goal); same with their community solar garden programs. But being an active participant in those programs is important and creating RECs in service of decarbonizing the system is a good thing, even if they aren’t yours. So, if you have the roof space, you should do what you can onsite (after you've followed the three P's of rooftop prioritization: People, Plants, PV). To speak to your issue of having solar on multiple buildings and dealing with the metering issues, these are challenging. In CO, Xcel has a program that they don’t advertise very much called Aggregate Net Metering where you can take a contiguous site with multiple meters and net out the PV production and load across the site. This lets you not worry so much about the specific allocation behind each meter. If you can’t do that, they you are limited to what each meter can accommodate.    

I’ve recently realized how much double-counting there is in our carbon world. In the situation below where Xcel owns the RECs, is it reasonable for the project to make any claims from the project-funded renewables re: carbon reduction of the project? If Xcel owns the RECs then the team should not take credit, right? A Virtual Power Purchase Agreement is a robust and direct route to the goals of the project below, if it is possible to get one. A contract is signed for 15 years or so for renewable energy from a specific site, including the environmental attributes (RECs) and energy use (virtually). If ASHRAE 228P guidelines are followed and the energy is truly ‘additional’ then it seems it could reasonably be claimed. Additionality means that the new renewable energy is in excess of that required for Xcel to meet per state mandates and this does a very positive effect on carbon emissions. New renewable energy in excess of Xcels mandate can meet the goals earlier, and since operating costs are low, and will very likely be used to displace energy from more expensive plants that use fossil fuels. -Kjell From:

Thanks Becky for eliciting such a vigorous "debate"! My comment may seem slightly tangential, but I'm going to risk it given how engaged folks are in this particular discussion.
TL;DR warning, this is my attempt at a bit of a call to arms for this illustrious group. I think our industry needs to change our relationship with the term "Net Zero". What I mean by this is that we need to begin the long hard work of getting "Net" out of the phrase. Currently the green building world (both LEED and LBC) has identified "Net Zero Energy" as THE goal we need to achieve, when in reality, as Josh rightly points out, the real goal for our industry should be based on eliminating carbon emissions.  Given this, I would submit that the goal should be "Zero Carbon Emissions", not "Net Zero Carbon Emissions". To achieve this, our whole industry, and its sprawling supply chains (including all of us) need to shift our focus towards "grid adaptive" buildings, and away from "Net Zero Energy" buildings. The time-based nature of how dirty all of our grids are at various points in the day, is the dirty-little-secret that gets swept under the rug when we allow "Net Zero" to be our goal. Virtually all of the NZE projects that are built are currently using energy that is "dirty" (to varying degrees) at certain times of day, and the "Net Zero" calculation allows us to offload (externalize?) the problems/challenges associated with the dirty energy to the Utilities and the transmission system. We wipe our hands clean, we collect our plaque, and we and our clients all take credit for having achieved another "Net Zero" project. To be clear, NZE is a challenging and worthy achievement, but until we get to "Whole Zero Carbon" buildings (i.e. zero carbon emissions from both operational and embodied energy) our work isn't done.  Depending on how you count, it's taken our industry 15-20 years to get really good at developing NZE projects. We're now at a place where financial institutions, investors, owners, developers, designers, engineers, contractors, facility maintenance firms, realtors, etc., ALL know, to some degree, how to participate in and deliver a NZE facility, and we now even have politicians, media outlets and the public who at least have heard of what NZE is, and believe it to be a big achievement (which it is). It took a lot of work to get here, with A LOT of that great work being done by people on this thread, and it is now widely accepted that it's doable by a variety of project types in a variety of locations, which is a huge change from where we were 15 years ago when NZE really came on the scene. This is all good, we needed to develop this foundation of knowledge, expertise, and experience in order to now take on the real work - the work of getting all of the carbon emissions from the built environment to zero.  It seems to me that our industry (especially the 200+ firms on this Green Gurus forum) needs to really start "flipping the script" from "NZE" to "Grid-Adaptive" as the goal that we, our most aspirational clients, and our certification systems should be striving for. It's going to take all of the analysis and expertise we already use for NZE (including the worthy discussion on this thread about where and how our project's clean energy is produced and accounted for) and add whole new sets of questions around the time-based carbon intensity of each utility's grid, as well as how and where we're going to store the right amounts of clean power we'll need for when the grid's power is still dirty. Note: This "grid-adaptive" work will be complimentary to, and help accelerate, the "greening of grid", an outcome we're all starting to talk about, and are keenly looking forward to. It's worthy work, this is the right group to do the work, and we're all going to need great projects/clients like Becky's to advance this discussion... and I submit that the time to start having those discussions is now. We don't have another 15 years to get good at this. Apologies for the soapbox rant (especially to those of you like Kjell who've heard it before) - but with all of the great input being offered on this thread regarding on and off-site solar+RECs and offsets, I couldn't help myself. I do appreciate this group! Clark

Yes to most everything that's been said but there's important recent research that should be more widely known: The least-cost path to a decarbonized grid is not 100% centralized clean power & storage nor 100% decentralized / rooftop solar & storage connected to grid-responsive buildings.  The least-cost path is a mix.  The really intriguing conclusion is that having substantial Distributed Energy Resources (DERs) allows the grid to deploy more centralized clean energy while maintaining grid stability than a centralized-only approach would.   This analysis starts with the observation that "the grid" is really comprised of both interstate highways (high-voltage lines connecting utilties and central plants) and local roads (lower voltage distribution systems within cities). As we "Electrify Everything", we need to upgrade both the interstates and the local roads to keep the grid stable. They find that investments in grid-responsive buildings with local solar + storage allow the grid to be stable with more modest investment in upgrades to the both the high-voltage and lower-voltages systems. From a policy perspective, this means that we want to pay building projects for this savings they enable in grid investments that would otherwise need to be made.  The policy makers are still noodling on how to do this.  [Note that in this research, 'distributed' means things tied in anywhere on the lower-voltage (<69kV) side of the grid--rooftop solar, yes, but also community-solar installations.  Getting down to the rooftop scale has certain resilience benefits that they don't try to assess or place a value on.] Nationally, they find that the optimal deployment mix is about 30% distributed / 70% centralized.   But regionally, areas prone to frequent power outages may find that the economics of local solar+storage shift dramatically when you take into account the costs of being without power and the benefits of onsite generation. Most of us in this group make buildings and seek to use that work as a lever to influence transformation at a larger scale than our projects.  I'd like to make this abstract policy conversation more real (more memorable?) by telling some stories:

It's Mardi Gras season here in New Orleans. Last night was the  parade Krewe du Vieux (say it quickly), where people walk through the French Quarter (the Vieux Carré) with costumes and floats that combine satire and sexual humor.  One, recalling the 8 days our city was left without power after Hurricane Ida featured a giant, um, flaccid member and was titled "Entergy Can't Keep It Up".  

But the next float that followed featured a huge Earth and was titled "Think Locally, Act Globally."  Nice flip.

Green Gurus is all about taking global awareness and putting it into local action through individual projects.  But we do these individual projects as a means of demonstrating what's possible, to provide something that policy makers can cite.  And it's OK if the policy that emerges is not "Everyone should copy this project literally" but rather that every project can be shaped from what was learned.

Some of you may know that my firm recently completed an affordable ($164/sf) housing project (50 apartments) designed for net zero operation with the ability to island off the grid, called SBP St Peter.  What you may not know was that this was not our intent through almost the entire design process. The non-profit client was just trying to build very inexpensive housing and, as we were wrapping up CDs, a board member innocently asked whether, given our frequent power outages here in New Orleans, it might be possible to use batteries for backup--he'd seen a video about a project (the Lamar Buffalo Ranch in Yellowstone National Park) where they put 208 used Toyota Camry hybrid battery packs in a log cabin, charged by solar, to allow this off-grid field station to stop using its diesel generator.  Now, our power outages here usually come after a tropical storm has passed through, followed by sunny weather, so we put together a concept proposal that said with equal investments in efficiency, solar, and batteries, we could take this project to net zero with ability to island the whole building (not just a few rooms) off the grid for $1M (adding $22/sf to the original $142/sf budget).  

This was mostly a thought-exercise.  But then the local utility became embroiled in a scandal when it was learned that their campaign for a natural-gas-fired peaker plant (pitched as a source of resilient power in case the feeder lines to the city were cut off in a storm) was augmented by actors paid to protest in favor of the plant at city council meetings.  So this thought-exercise was shaped as a proposal to that utility for a donation, which they quickly made.

The project opened in February 2020 and the battery system carried them through an 8-hour power outage after Hurricane Zeta (October 2020). But the real test came after Hurricane Ida, when all the feeder lines to the city of New Orleans went down and the whole city was left without power for 8 days--and it was learned that the new natural gas peaker plant did not have the ability to "cold-start" (re-start without being connected to power from other utility plants).  Without cooling, at least 10 people died due to the heat, and 2 more died due to carbon monoxide poisoning from generators.

But while the city was without power, the buildings that had solar + batteries, including SBP St Peter, carried on, and received national attention.  I experienced it directly in my own home, first built in 1880 but with efficiency, solar, and storage as we found ourselves flipping daily pattern to use excess solar electricity by day after the batteries were charged up ("Turn the thermostat down!  Quick, let's bake something!") as the batteries carried us through the night for 8 days. It turns out that decentralized / rooftop solar + storage is coming in at about the same levelized cost of energy as a natural gas peaker plant; the difference is that (at least here in New Orleans), the rooftop solar + storage power was there when we needed it, while the natural gas peaker plant was not.

After Ida, the conversation here in New Orleans and throughout Louisiana has changed.  As the saying goes, "There is nothing so contagious as an example."  

• The Governor just accepted the Climate Action Plan of the Climate Iniatives Task Force he'd appointed (with industry, academic, and community members), which maps out a pathway to net zero carbon emissions by 2050 through a mix of centralized and decentralized clean power and storage, conversion of our industry via electrification and (clean) hydrogen.  Admittedly, to get industry to sign on there were the nods to carbon capture and sequestration (CCS)--which some say they see as a way to keep doing what they're doing with some new grants and subsidies--but CCS accounts for a remarkably small part of the total decarbonization.  
• At the city level, initiatives are underway to install solar+storage at churches and community buildings to act as cooling centers while carrying on their food pantry functions after disasters.  The city council is talking about mandating some solar + storage in new construction.
• The regional housing advocacy group has centered efficiency+solar+storage at the heart of their efforts to reduce housing vulnerability due to energy cost burdens (those living at or below 30% of area median income spend an average 22% of their income on energy bills) while improving resilience; spikes in their energy bills can force people to lose their homes.

So I'd say that Net Zero on a building-by-building or project-by-project basis isn't really the goal we should focus on.  But simply "Electrify Everything" and let the clean grid take care of us won't get us there either.  We live in a connected world and we should shape our design work and policy advocacy around that.

Thanks Z for your perspective and your story! In it you mention the utility making a "donation" to SB St Peter... was it just cash for or donation of some aspect of the solar + storage? Or was it some sort of grant agreement that allows the utility to control the batteries during non-outage time periods?  

Clark, the donation came from the utility's charitable foundation, and was a straight $1M cash donation to the non-profit developing the housing.  Their top officials were present at the groundbreaking. The fact that the non-profit was able to purchase the solar+storage (rather than receive donations in kind) meant that the financiers who absorbed the low-income housing tax credits could also absorb the solar tax credit (which can cover solar + batteries), which helped the money go even further. 

During the initial pitch we framed the project as an opportunity for the utility to use the project as a "test-bed" to explore how projects of this scale (178kW DC solar module capacity, 125kW/371kWh battery) could serve as a dispatchable source, but they have never returned phone calls or e-mails on the topic. It's a big parent company... Because the project has a single connection to the utility (they use a 3rd-party submeter system for individual tenants), the project still has to pay demand charges like any commercial customer, though they enjoy net metering on consumption charges.  To limit demand charges, the system uses its battery to do peak-shaving, limiting consumption from the grid to 35kW (that's just an average of just 700W per apartment, less than a toaster!). What I'd do differently: During design, we looked into a lot of sophisticated load management / load-shedding system for conserving battery power during extended outages, but couldn't find one that cost less than a few thousand dollars per apartment, and decided we'd rather put that money into more solar & storage.I believe these load-management systems have come down in cost since construction began in 2019, and if I had the choice to do it again, I would have circuits we could shed (oven, heat pump water heater...) and maybe the ability to limit AC setpoints during off-grid periods.  For now we're dependent on voluntary occupant engagement, which has its limitations.  Another Hurricane Ida realization was that our ability to remotely monitor what was going on during an outage was dependent on internet connectivity, and when that failed, cellphone data.  But both cable internet and cellphone data systems were down for the first few days of the blackout.  So it took people being on site. I know all these comments are about operation during "exceptional" periods after disasters, but thinking through them is important as extreme events (heat waves in Canada, cold waves in Texas, selective blackouts to avoid triggering wildfires in California...) become more commmon.  

I appreciate all the perspectives and insights. I 'second' the motion for NZE to evolve into plain and simple 'Zero Emissions' projects as the default goal and only backing into minor degrees of on-site combustion as dictated by finances and physics. "net" is where all the dubious slight of hand occurs. net can be great. net can be not great. net can be confusing, and to accelerate the required growth in zero emissions proejects, i hope we all keep in mind with clients and policy makers the old adage "if you are explaining, you're losing."   (but not here! i like the explainations and reasonings being put forth! :) )

also, it's mentioned above and i'll restate: Transportation is now the highest source of Carbon emissions in the US. Please be sure to consider how the parking in your projects is hurting or helping the Zero Emissions goal. today's considerations for on-site battery storage being too expensive and taking up too much building sqft will likely be very different in a few years with a networked, grid-connectioned  bi-directional parking lot.

Thank you.

PS-I've mentioned it locally to some designer friends, and it may seem rediculous to you, but I've asked them to STOP rendering gas cars in there drawings. IMO Seeing the sleek new project renderings with EVs forces into our collective consciousness "Wait, how are we accomodating and integrating this phase change in our projects!?! What opportunity are we overlooking?"

Assuming folks reading this have already seen these back and forths:  https://www.buildinggreen.com/feature/net-zero-energy-isn-t-real-goal-8-reasons-why  https://www.buildinggreen.com/op-ed/why-net-zero-energy-goal-we-can-all-get-behind  RE language and "net" - this debate has been ongoing since the beginning of net/ze/zc and surely will continue.  ILFI dropped "net" about five years ago as it was considered implied.  However I do pretty regularly now see some folks think there is a difference between "net" and no net.  My suggestion at a minimum is that we keep this debate/decision internal to the movement so as to not cause eye glazing by average folks that just think the general idea is good/cool. Re onsite - absolutely yes.  The clincher for me has been a movement by rural conservatives in Washington State to limit solar and wind in rural areas - viewing these are urban areas pushing their blight on rural areas.  Whatever you might think about this unusual philosophical turnabout, it reinforces to me the need to maximize what we are doing in urban areas.  As others have said, roofs are just sitting there, waiting for use.  That, plus the ability to create a resiliency solution, minimize line losses, and build occupant stoke and knowledge are all reasons to do it.  Finally, there are no guarantees about what will or will not be installed by utilities in the future - starting now, onsite puts a stake in the ground, reinforces self-responsibility, and starts the accrual clock too, which is critical now, not in 10-20 years.   BTW, McKinstry is on track to install 30 mw of site based solar this year - we have many many clients who get all of the above.  Our solar biz is growing exponentially.   Tristan, I hear you, but I think the key is to line up solar really closely the roof replacement.  Personally, I learned and paid for this (literally) when we had premature aging of our home roof and I had to pay about 1/3 of our original install cost for a de/reinstall with the reroof (and a lesser quality reinstall to boot).  Commercially, at McKinstry always consider roof age and try to line up solar with the roof replacement cycle - part of a Zero Over Time strategy (credit to RMI for the term).   Kjell, the topic of utility purchases of RECs was something we considered at length when I was at ILFI - we decided then, and it still stands, that when a utility, or a governing body through a utility, uses REC purchases essentially as an incentive mechanism, as happens in many parts of the US, that as long as the RECs are retired, that we would consider that to be ok.  IE, a utility commission establishes a mandated renewables target for utilities, utilities put real money into making that happen in part via financial incentives to projects, and use RECs as an implementing mechanism.  We felt like while it wasn't perfect, we didn't want to force at the time all the projects in NE states (where this approach is typical) to forego what was essentially the incentive mechanism.  In reality, WA State did not buy the RECs from its original production incentive - but did actually "count" those renewables in its "portfolio".  We felt like maintaining a higher perspective was appropriate.  I still hold - ZE/ZC buildings and their kin are NOT the norm and we need to fight like crazy to scale right now and not get too caught up in details - we need big numbers.  The tundra's thawing.