Zero Energy Buildings – The Equation is Easier Than You Think!

Kelly: (00:06)
welcome to buildings and beyond

Robb: (00:09)
the podcast that explores how we can create a more sustainable built environment

Kelly: (00:13)
by focusing on efficiency, accessibility and health.

Robb: (00:18)
I’m Robb Aldrich

Kelly: (00:19)
and I’m Kelly Westby

Robb: (00:21)
and before we get into this week’s episode, we wanted to let you know about a couple of upcoming events and Dylan Martello, who was a passive house consultant here at SWA and is really instrumental in putting this podcast together, helping to produce the podcast. He’s going to be speaking at both of these conferences and he’ll give you a little bit of Info about.

Dylan: (00:40)
Thanks Robb. The first is building energy NYC conference taking place on October 3rd and fourth in New York City. The conference, which is presented by Northeast Sustainable Energy Association or NESEA, n e s e a, has become a staple for professionals and practitioners in the field of high performance building, energy efficiency, and renewable energy. We’ve been to the building energy conferences for many years now and my colleagues and I are looking forward to returning for another great event. Visit NESEA.org For more info.

Robb: (01:09)
Yeah. I’ve been involved with NESEA for 20 years or so, and really good people and I’ve learned tons at NESEA conferences over the years.

Dylan: (01:17)
Next is the North American Passive House Network Conference and expo taking place at the David l Lauren’s convention center in Pittsburgh, Pa. Join US October 17th through the 21st where we’ll be speaking on a variety of topics related to passive house visit naphnconference.com for more info.

Robb: (01:35)
Thanks Dylan. This week we’re talking about zero energy buildings, ZEB’s which is an acronym, probably a lot of people hear or see more. I certainly do. It’s a big topic. We don’t get to the bottom of it, but we do our best. I’m talking with Paula Zimin who is director of sustainable building services here at Stephen Winter associates, she is an RA, but also does really a lot of energy modeling and she focuses on larger buildings, larger multifamily buildings, commercial buildings, and institutional buildings. And I’m also talking with Karla Butterfield, who is a sustainability director here at SWA and she’s all about residential from single family residential homes all the way up to large, tall multifamily buildings and everything in between. And she does a lot of work with certification programs, zero energy ready home, which we talk about here, LEED national green building standard among several others. So this episode really we talk about all types of buildings, small to large, different programs, different systems, different paradigms. And even, I think we started the episode with the discussion of different meanings of zero energy buildings. What does this really mean? So let’s get to the end.

Robb: (02:57)
Welcome Karla and Paula Thanks for being here. So zero energy buildings is a big topic. It’s, I think even getting into kind of the mass media. I see it in newspapers and stuff, not only in the magazines and journals and conferences I’ve been going to for a decade or whatever. So it’s a growing topic, growing in popularity. And you guys have certainly dabbled in it and it’s a growing trend.

Karla: (03:29)
I would say it was a Buzzword tenish years ago, where most people in the industry knew what zero energy buildings or zero energy construction meant, and then went through kind of a controversial period of what does that really mean and what do we really call it. But you’re right, it is in the mainstream now. And most people who are at all familiar with the built environment know what zero energy means.

Robb: (03:56)
So what does zero energy mean, Paula and zero energy building?

Paula: (04:00)
So I think in my world, because I work more in the commercial sector and larger buildings, zero energy buildings, gets limited to a building scale, which can be very difficult to do. So in my world, I think that we’re approaching zero energy on a broader scale at the community scale. So it’s certainly a low energy building a focus. There might not be the ability to get to zero energy, but there is certainly the drive to how can we as a community or a larger set of buildings get to zero.

Robb: (04:35)
So I mean it seems that at the core level we’re talking about very efficient buildings, very low energy needs, be it electricity or fossil fuel or wood or whatever low energy needs and you can meet all of those energy needs with renewable energy, wind or solar or whatever. That’s kind of the general idea?

Karla: (04:57)
That’s the general idea. A lot of people will argue there’s no such thing as a zero energy building because of the fact that you are using a fuel and so it’s really a net zero or net neutral fuel building.

Robb: (05:14)
So that was, yeah, so I’ve had people like jump down my throat when I say it’s a zero energy building and they say, no, no, no, no NET zero energy building. And I actually seriously don’t, I don’t understand that distinction

Karla: (05:24)
Right. And then saying net zero energy also is somewhat offensive to some people. So they want to say, you know, what we are is we’re, we’re neutral with fuel. So one fuel offsets the other.

Robb: (05:35)
So if you use some natural gas, you generate even more electricity from PV or something to offset that natural gas.

Karla: (05:44)
Right. And that’s easier to do in low rise buildings. Especially single family buildings are really small. Multifamily buildings, like Paula indicated. Harder to do in more commercial or high-rise buildings because you don’t have enough room for that PV to offset if it’s on your roof. There’s a lot of other solutions for that too. I’m sure you’re going to ask that question in a bit.

Paula: (06:04)
A lot of controversy is that even though you’re a net zero building, you’re still using the grid. And how does the grid get its energy? Usually through fossil fuels. So if you’re really talking about a carbon neutral building, that’s very hard to do from the building scale unless if your grid is carbon neutral. So unless if you’re grid is hydro or some other, you know, non fossil fuel source. So you could also be off the grid potentially to be carbon neutral. So it’s a difference between a net carbon neutral building versus a net zero energy building and your relationship with the grid.

Robb: (06:44)
Okay. Okay. So as a catch-all term “zero energy buildings, “you’re going to get disagreement about that?

Karla: (06:51)
It all comes down to how you want to define it. You have to define what zero energy means to you, whether it’s zero carbon, net zero, or some other sort of definition.

Robb: (07:06)
Which is not, they’re not necessarily zero energy costs.

Karla: (07:08)
I think to keep pushing this into the mainstream and have it be more than a buzz phrase, it has to be something catchy, which is why zero energy or zero energy buildings has caught on. Even though we can see there’s many layers

Robb: (07:22)
All right. Well there’s actually some papers. Maybe we can include in the show notes the different definitions if people want to dig into that more.

Paula: (07:30)
Sure. And I think that one of the definitions is either the modeling approach or the actual utility bills.

Robb: (07:36)
Oh good distinction. Right, right. So, and you guys both do a lot of energy modeling- and Karla, you’re, as you said, you focus on residential, single family all the way up to larger multifamily. And Paula, you’re on kind of larger multifamily and also commercial institutional, right? And Carla, it’s easier with single family. And you’ve worked on several?

Karla: (07:58)
I’ve worked on several single family or duplexes that have done either approaching zero or zero energy and we have verified it in a couple of different ways, both with an energy model and then with 14 to 16 months’ worth of utility bills to show that they actually were energy cost neutral or negative in some cases. And for other projects just with the energy model that either predicted the usage and then test it out and gave it what we all know is the HERS index, the Home Energy Rating score index to indicate that it could be a zero energy building.

Robb: (08:32)
So I’m sure we’ll get into this in future podcasts, but the HERS index, you know, a 100 is kind of like a mediocre average home and zero is theoretically a zero energy home. So lower is better

Paula: (08:45)
lower is better. And in the northeast where we do most of our consulting anyway with the zero energy stuff, we have to get down somewhere around 40 or maybe even 35 to get to kind of the sweet spot to then put on Pv to get the HERS index to zero.

Robb: (09:01)
All right, interesting. So what do you do? Those homes that have a HERS index of 30 or 45 before and in renewable energy, right? What systems do you see?

Paula: (09:11)
Right. So, and we see this in the single family homes and duplexes and also the low rise multifamily. We’ve done a couple of projects, one in Ithaca and we have a few more on the drawing board that had been successful from 15 units in four stories to 60 units in three stories. Strategies are kind of similar. It’s usually a high efficiency assembly. And that can be either a double stud wall so that we’re doubling up on the insulation value or some rigid insulation on the exterior of the wall that’s then put siding over it. So obviously you don’t see it. So that’d be a high efficiency or a high performing wall assembly. And then in most cases we’re looking at triple pane windows. And then the roof in our region has to be really well insulated, sometimes as high as an R90. In some cases we can be closer to 60, but we’ve had projects that have had to go as high as 90 in the attics or on the flat roofs

Robb: (10:04)
These are like passive house backs where some of these passive houses that got to zero energy?

Paula: (10:09)
Yeah. So the Ithaca project I mentioned, the rest of the community, the duplexes and single family homes, some of them are passive house certified. Several of them were LEED for home certified. All of them were energy star, indoor air plus and the doe zero energy ready home program. And then the multifamily, the 15 unit, followed all the protocols but didn’t go through the certification processes.

Robb: (10:30)
Okay. So programs, that’s another question for both of you. Zero energy programs. You mentioned zero energy ready home, which I always stumble over that name. That’s DOE. And that is in a nutshell- Can you give us?

Paula: (10:48)
In a nutshell, that is a high performing apartment building or a home that has a HERS index of 45 or lower.

Robb: (10:58)
Is that a hard line or is that like an approximate line?

Paula: (11:02)
I’m pretty sure that’s a hard line for, at least in our zones that we work in. I’m not sure if it changes in zones one and two.

Robb: (11:10)
So kind of a practical line, you haven’t seen it really work… All the zero energy ready homes have had 45 or less or it’s like you just have to get 45?

Paula: (11:20)
in order to answer that question you’re asking me at point blank because it also goes with some of the state programs. So NYSERDA has a hard line for sure. And then Connecticut does as well for the tiers that in qualifying. And if you qualify for those tiers, you also have to be zero energy ready. So anyway, it gets, you know, it gets kind of an alphabet soup of confusing. But yes, there’s the doe zero energy ready homes, which can apply to anything that can be energy star labeled. So it has to be energy star labeled, it has to meet indoor air plus requirements and it has to meet a pretty stringent domestic hot water delivery requirement, which is a bit tricky for multifamily. So that’s what a ZERH is

Robb: (12:03)
and indoor airplus is an EPA air quality certification?

Paula: (12:07)
It is, it’s a companion certification to the energy star program. And then there’s the living building challenge. There’s an energy peddle in the living building challenge. There’s also a separate pathway for zero energy certification in the living building challenge. And we’ve had one project achieve that. A single family. And that program can also apply to any building type, commercial, residential. It’s open, the requirements are very simple. You’d have to demonstrate zero energy. It’s measured

Robb: (12:43)
So larger buildings, Paula, either of you, have you worked with multifamily buildings that have gotten a zero energy score?

Karla: (12:54)
zero energy larger buildings, not on the commercial side, on the multifamily side. So the push with the multifamily side has been, everything that pushes this really, are incentive programs and financing- either requirements or incentives through financing.

Robb: (13:11)
So in your experience, people aren’t just trying to get to zero, they’re not hordes of people trying to get to zero Energy

Karla: (13:20)
There aren’t hoards in general. And there’s certainly not in the multifamily sector. It is pushed for the affordable multifamily developers by their financing. And the requirements that come in the state of Connecticut and Pennsylvania specifically have enhanced the application process. If you do passive house, you get more points and it, since it’s such a competitive process for financing, those points become very important. So that’s where we’ve seen an uptick in passive house, which is our great pathway to zero energy building.

Paula: (13:53)
Yeah. The problem though was getting zero energy on multifamily buildings, anywhere from like three to four stories and above, is just that you have a much larger building, volume to available rooftop ratio. And the ability to offset all of your energies within that limited area,, it’s just a matter of numbers. You just don’t have the amount of area that you would need, which is why you would, if you were interested in a zero energy building, you start thinking about buying a green energy from a portfolio, from a community distributed energy resource.

Robb: (14:26)
Okay. I worked on one, I had a very small role in one zero energy multifamily project up near Albany. And we just did some consulting on the HVC and the units. He wanted to get away with very, very simple heating and cooling systems. But I think it was three or four stories

Paula: (14:48)
yes. that’s about the limiting range. Three, four stories.

Robb: (14:52)
But I think the PV was like covered parking, Pv covered parking so that, you know, it’s not a building, it’s kind of the site

Paula: (14:58)
surprised that we don’t see that more often. The covered parking PV over covered parking, particularly in the more suburban areas, maybe it’s the cost of the additional structure that you would have to install, but that would be a great place to put Pv for our multifamily buildings. Three to four stories or other otherwise garden style apartments. But it isn’t often seen.

Karla: (15:21)
I think that it’s not that it’s not accepted, but it’s not something that we see in the northeast. I see it a lot more down south. I’ve seen covered parking in Florida quite a bit. And we have one project in north Massachusetts. Is that where Amhurst and those schools are? They were looking so hard for places to put the PV because they are targeting zero energy for a dormitory. And so they’re lifting up above HVAC equipment on the roof, on, you know, pedestals for the PV as well as on the car ports. So, you know, when you think outside the box, there’s places for it to go. But that’s a pretty rural area up there. And you have to have the space for it. It’s not going to work in Manhattan. It’s not going to even work in Cambridge. We have another project in Cambridge with a university and when they came when they came to us, one of the first goals was we want to be zero energy – We want this seven story dorm to be zero energy. And quickly found that as hard as we were working with the envelope and the model which Paula is working on, they weren’t going to reach zero energy

Robb: (16:34)
not within the building footprint. They’d have to look beyond.

Karla: (16:39)
Well this dorm also has a cafeteria and some other amenities spaces. And so the usage is pretty high. \

Robb: (16:46)
So, Paula, when you get into bigger multifamily buildings, how does the modeling change? How do the programs change?

Paula: (16:52)
In terms of zero energy, similar to what Carla was saying, there’s really only the international living futures pedal certification for zero energy buildings. There’s a voluntary self-reporting that you can report to the National Building Institute, NBI, to claim that you are zero energy and that can be either modeled or actual. But that’s sort of, you know, you’re self-reporting, it’s on you to prove it. But there’s no other, you know, a particular program in the commercial market.

Robb: (17:33)
But modeling tools are different for commercial?

Paula: (17:37)
Yeah. Whereas Carla often uses HERS software primarily, we can use any number of ASHRAE approved or DOE 2 modeling programs. We primarily use EnQuest or open studio for that modeling. The concept for zero energy is the same though, whether you do a single family home or do a, you know, a school or an office building, you primarily just want to know what your loads are on the inside, balance out what the envelope needs to be, and provide a robust envelope, and then downsize your HVAC equipment and be thoughtful about your ventilation systems. And you at least can get to a low energy building if not a net zero if you don’t have the ability to install renewables onsite.

Robb: (18:31)
So if somebody comes to you in and says, one of these clients you’ve been talking about, “we want a zero energy building, we want a zero energy dorm” First step is?

Karla: (18:42)
tell them that the residents cannot bring in extra refrigerators or tell them that they’re limited to one laptop per student.

Robb: (18:50)
I guess this one, when I talked to Lois about passive houses, I mean it was like, it all depends on where in the design process they are. I mean, if they come to you very, very early, you didn’t really focus on the design. And the envelope, I assume you get the envelope as good as possible and modeling helps on that front.

Paula: (19:08)
You really have to model, you really have to model to understand the equipment that an owner anticipates in the building to understand the schedules of that building. You know, an apartment building is going to be different than a dorm cause obviously the density is different in terms of people and the kind of equipment families versus you know, Young 20 somethings in a dormitory, and the equipment that they can bring in versus a school which might only have like two computers per classroom or maybe a high school has computers and all their classrooms for every student. So the level of equipment can be anywhere across the board.

Karla: (19:46)
But ideally it is during schematic design, if not, definitely during design development and the mileage. I would say even design development is almost too late in some cases. Probably for the bigger buildings or the more complicated ones. And there should be continual iterations in the modeling as the designs are being developed. And there should be several plan reviews, usually a 50% design development, a hundred percent design development. Then again at 50 construction documents. And then after when they do that, that really horrible thing called value engineering, which isn’t really what it’s supposed to be. So after a VE set or a VE session, we get our eyes back on the plans again to make sure that none of the critical elements have been taken out and not properly replaced.

Robb: (20:35)
You mentioned the downsize of Hvhc and that’s one of this kind of concepts that I remember hearing talked about 20 years ago, but in practicality, rarely seen. But that’s I think coming into play. I mean if you go an awesome high R air tight envelope, there are opportunities to save some money on the HVAC

Karla: (20:59)
and the equipment is available in the sizes that are appropriate for the single family homes. Right. So when we get down from, we might’ve seen a house that had load calculation saying they needed five tons for the cooling and when properly calculated room by room low calculations, it’s comes down to two tons, and that piece of equipment and is available. So that’s great. But when it comes to the multifamily, where the loads are incredibly low and the high performing buildings like per apartment you make per apartment. And most cases, this is going to be a per apartment situation because the owners very seldom want to own the utilities. They might be willing to own, say natural gas bill for the domestic hot water for a central system, but they don’t want to own all of the tenants electric. So these are sub metered or individually metered, which means that every apartment has its own heating and cooling source. And so to get those really small, that’s when it gets tricky.

Robb: (21:59)
Gotcha. And on institutional buildings, commercial buildings, the loads are often like internal gains driven, not so much envelope driven.

Paula: (22:08)
Well, most of the time we find that in commercial buildings or even the more dense, higher, bigger and multifamily buildings, you don’t really need more than about an R20 opaque wall assembly. We always recommend better windows, always recommend triple pane. The windows are always the weakest link in your envelope assembly. But what is really driving the energy of the building are those internal loads, are all the equipment, all of the people, all of the ventilation within the building, that’s driving cooling and heating loads. The envelope, you know, doesn’t really keep too much out when you have to ventilate the building to the level that you want your building to be healthy, and you don’t want to fight that. But that was always a balance when we’re talking about commercial buildings, of how much ventilation you want to provide, how healthy do you want the interior to be versus the energy use of that building. Because More ventilation is going to be more energy.

Robb: (23:05)
Another reason why it’s easier for smaller buildings, I guess for single family, right? Because it’s really envelope driven rather than internal gas driven. So we mentioned schools, we mentioned colleges, but Paula there are a lot of interest in like public schools. Some school agents used to go this way. Is that, is that a whole different can of worms?

Paula: (23:23)
I think net zero certainly is possible and more so in public schools because it’s a, it’s very repeatable building typology. And I think that there’s a lot of studies that are out there typically. Typically, low rise urban schools are going to have a little bit more difficulty when they are approaching the four or five story limit, they have a smaller footprint that they can work in. But certainly in the burbs, where you have a two or three story school, you can absolutely get to net zero fairly early. But again, you do need to be cognizant of how you’re designing the building and what the loads are of the building, particularly kitchens. We had talked about kitchens previously, that one dorm kitchens can have a very high load that can make it difficult to meet your energy goals.

Karla: (24:10)
And remember we had the conversation about net energy or zero net energy or net zero energy. And so when you’re talking about the use of the building, and this will even come up with the dorm that we were just talking about, of whether or not it will be open in the summer for camps. And so that changes the dynamic because normally universities are closed for at least a couple of months. The dorms are being used for a couple of months and the same would hold true for a school, so easier in an annual period to show that you’re a zero energy.

Robb: (24:37)
Gotcha. You’re generating lots of electricity if you have PV when you’re not using much at all. Right?

Speaker 6: (24:44)
And that interests a introduces an interesting dynamic with the grid because if your school, which is producing the most amount of energy in the summertime is otherwise shut down your exporting most of that generated energy to the grid. And you know, is there a payback with your local utility for that export it energy? Is there a benefit to you or not and that that could play a role if it’s a financial decision

Karla: (25:12)
Well, we’ve seen it play a role too with nonprofits. So senior care facilities deciding not to go with PV because they’re already locked into a very low rate for what they pay for the electricity. So there’s no payback there to go.

Robb: (25:25)
Right. Gotcha. Yeah. And that’s getting back to something you mentioned earlier with the schools who have all this electricity, excess electricity and in the summertime, maybe that opens up opportunities for zero energy communities? Doing that?

Paula: (25:38)
Absolutely. I think We really need to start thinking beyond just the boundaries of our buildings and start thinking about communities and how either commercial buildings can use that exported electricity nearby and develop those relationships so that it’s not necessarily a burden to the grid because as we see in California and Hawaii, there’s a lot of renewable energy, it’s too much at the wrong time. Right, so in California, Hawaii, they really need to start talking about energy storage so that they can use that energy that they’re producing, just not at the time that is being produced. I think that’ll start being part of our conversation as we start talking about these community district energy systems so we can maintain that all within our communities.

Robb: (26:27)
So how about codes? I mean, I’ve heard lots of talk about California mostly, but also New York, Massachusetts, trying to move to zero energy codes. what does that mean? I’ve got to say I’ve heard a lot more talk substance on this topic.

Karla: (26:44)
Well, it’s a little easier to do out in California quite frankly because, you know, the installation goes a lot further. The PV goes a lot further. I mean, you’d need less installation and you need a little more PV and you can get to zero a lot faster in those zones because of the climate. And that’s not true everywhere in California for sure. But yeah, it’s definitely more of a challenge in zones four and five, which is Massachusetts and New York state, and Six of course. Yes. As you get up further north.

Robb: (27:20)
Yeah. All right. Yeah. The last I think I read, California was kind of backing off on the whole zero energy mandate and zero electricity as a first step. Is that to be determined? But are you involved in New York policy or any other policy on the east coast? I think, well, I think you were talking about schools

Paula: (27:43)
In New York City, they have developed the stretch code, which we anticipate. And then in the coming months, the stretch code I think is trying to get to be 20% better than current code. I’m a little bit skeptical on it because n knowing how energy modeling works, the regulated load, within our current code is already so low. And this percent better thing that we’ve done for so long is starting to be less effective. We need to start moving toward an absolute target of some sort. similar to how passive house has a target of 38, for example, for new construction, 38 SEUI, Source Energy use intensity. so it’s an energy per square foot on the source basis. So however much energy goes into generating the electricity from the power plant and that goes into that calculation. I don’t think that 38 is the right number for all building typologies. but I think we need to start talking about absolute numbers as opposed to this percent better cause this percent better starts to just be an obscure number that is very difficult to get to potentially. We’ve been finding that the percent better could be much more restrictive than a passive house, for example. So you can design a passive house building that doesn’t necessarily meet stretch code. That’s a problem.

Robb: (29:13)
That’s tough. All right. Yeah, so if we come back and five years and talk about this again, what will we be talking about?

Karla: (29:23)
We’ll probably be having a very similar conversation, however we’ll have many more examples. I do think we’re going to see the construction of some of these near zero, or you know, the multifamily is just not going to get to zero, but we’re, so, I don’t know what we’re going to call them, but we’re going to more construction. We’re going to see the fear factor go away.

Robb: (29:43)
The fear factor of, oh, zero energy is way too expensive. It’s too weird.

Karla: (29:49)
It not what we normally do, we can’t build like this. It’s outside of the way we do things kind of thing. We’re already seeing that change with sort of the second phase of developments that I’ve done, either passive house or close to zero or just getting to HERS index of 40 to 45 which is a big jump for some developers in multifamily that might be used to 20 points higher in a HERS index. So we’re moving in the right direction and I think well hopefully we’ll get the terminology down so that we’re not spending half of the podcast talking about the words without coming to any consensus.

Paula: (30:23)
I think terminology is hopefully what we’ll see a change in my industry, in the commercial world, we often say high performance buildings and I think we need to change that nomenclature to be low energy buildings or low carbon buildings. because a Maserati and Ferrari are high performance cars and yeah, they ride really well, but what’s their mpg? Right? we need the smart cars. We need, you know, the little electric cars or hybrid cars or something a little bit different. That’s going to be our solution.

Robb: (31:08)
Hopefully won’t get too many emails about that. People loving those smart cards. All right, so it’s not going to become standard practice, but people are going to be much more familiar with it and comfortable with it and we’ll have maybe metrics that are more meaningful. I think so. Nice. Cool. Anything else on the topic or we’ll talk about it again in five years. Maybe sooner than five years. Okay, great. Yeah, thanks a lot. Thanks rob.

Speaker 7: (31:46)
Thank you for listening to buildings and beyond. For more information about the topics discussed today, visit www. swinter.com/podcast and check out the episode show notes buildings that beyond is brought to you by Steven Winter Associates. We provide energy, green building and accessibility consulting services to improve the built environment. Our professionals have led the way since 1972 and the development of best practices to achieve high performance buildings. I’ve production team for today’s episode includes Dylan Martello, Alex [inaudible], and myself. Heather Breslin, thank you for listening and we’ll see you next week.