Recently I’ve talked about my new net zero home I’m building, but not all net zero buildings have to be homes or houses. The same net zero, passive house concepts can be scaled up to large buildings, offices, and apartment buildings. In fact, I had a chance to visit the first net zero hotel in the United States and got to see some of the creative concepts at work. Stuff like this…
“These are KONE elevators. They actually generate electricity when they’re going down. They’re also DC powered.” -Bruce Becker
“Woah. Wait, you just blew my mind. Okay. So it’s basically regen braking on your car.” -Matt Ferrell
“Yeah, it’s like your electric car. In fact, I read something that someone had a concept for energy storage. Take a building that has regenerative elevators and you put carts of weights in the building. At night when power is free, you lift all the weights up to the top floor. Then, in the middle of the day when there’s need for power, you put the weights and bring them down.” -Bruce Becker
There’s even more just like from their solar and battery system, to all the heat pumps, to trying to get the hotel passive house certified. What does it look like when you scale these concepts up to that size? And does it even make sense? And will they even be able to achieve their goal of producing as much energy as they use? Let’s find out.
I’ve been sharing my experiences of building a new net zero home, with the goal of being able to produce as much energy over the course of a year as I use by pairing solar & batteries with an incredibly efficient and air tight house. There are many paths you can follow whether you’re building new or retrofitting an old house (be sure to check out my other videos on that). Passive House has very clear guidelines around insulation, reducing thermal bridging through the envelope of the home, and controlling heat loss from exchanging fresh air through the use of energy recovery ventilators (ERVs). While I’m not going after passive house certification on my house, it will take all of those aspects into account.
However, this is one of the reasons I wanted to visit Hotel Marcel in New Haven, Connecticut, which officially opened in May 2022. The story around this building is kind of fascinating. It was designed by the modernist architect, Marcel Breurer and built in the late 1960’s. It was used as an office building by the Armstrong Rubber Company and Pirelli Tires, but between the late 1990s and early 2010s it was basically vacant. That’s when Bruce Becker comes into the picture. He’s an accomplished architect who has spent a good deal of his career rescuing buildings just like this and restoring them.1 Not only that, but he’s passionate about sustainability and is pushing past the way things are usually done in construction. Basically, paying tribute to the history of the building while using modern sustainable techniques.
“There’s nothing in here that’s arbitrary. Everything that’s here, there’s a reason for it that sort of either reinforces our sustainability mission or our historic preservation mission.” -Bruce Becker
During my tour we started off with one of my favorite topics: energy storage.
“Here is one of our two battery rooms.” -Bruce Becker
“Oh wow.” -Matt Ferrell
“For the typical hotel guests, they don’t know that there’s Cat 6 cabling that is powering their lights and their shades. This looks like a regular network rack, but this is how all of the digital electricity gets conveyed to all the lights and the shades in the building.” -Bruce Becker: (01:37)
Just to jump in for a quick second, I’ll be getting back to that whole digital electricity thing a little later. It’s pretty cool.
“Here’s one of two battery rooms that we have. They’re lithium iron batteries. These are made by LG. Each one of these 17 battery modules weighs 200 pounds. I can tell you that because my son and I brought these in and put them on the rack. They’re monitored remotely.” -Bruce Becker
“The thermal management system is pretty sophisticated. I’ll use this key to open this up. This is our inverter. Don’t get too close to it because it’s high voltage. But this is an inverter made by EPC and it’s a sophisticated inverter because it does what’s known as grid forming. A lot of solar inverters when the grid goes down, the inverters go down too, because they don’t have a way of generating the sign waves for the alternating current. But what this does is it synchronizes the power from the batteries, from the solar and from the grid so they can all work together unison, or you can work with just two of the three sources or just one by itself. All you need is one to power the whole building. And we’ve had situations already where the building was filled, there was a special event, the grid in the neighborhood went down, but we were able to keep going without any kind of interruption. In fact, it doesn’t even flicker, it just goes continuously.” -Bruce Becker
“We also have a micro controller system made by a company called Ageto. We can actually monitor in real time what’s actually happening. I can pull it up on my iPhone here.” -Bruce Becker
“You can see the yellow line here is the power that’s being exported to the grid. The green line is the solar production. You can see that we had drawn down this. The pink line is the battery charge level. This line here’s about 92%. We typically will draw down from the batteries at night to do what’s known as peak shaving to keep our demand charges sort of in a reasonable level that we’re really not subject to demand charges. If you look closely, you can see these orange line, which is the load for the building spiking. That’s whatever our laundry is doing, drawing of sheets. We monitor this. Our goal is over the course of the year to be a true net zero building. So that we would produce as many kilowatt hours as we’re using.” -Bruce Becker
So there’s a lot to unpack there, but in short the hotel is set up like a microgrid. It’s not that different from what my new home will be like with solar and battery storage. It can operate in conjunction with the grid, selling back excess energy production into the grid to help reduce their demand charges. It also helps to support the local community with clean energy production, but it also means the hotel can operate independently, which I know is a huge motivator for most people to go solar on their own homes. But will the hotel actually be able to achieve net zero?
“We won’t know for sure. We certainly can’t make that claim until we’ve seen a whole 12 months of production and energy use. My current expectation is we’re going to have to add more solar powers because I think we actually slightly understated the amount of energy the dryer uses. The dryer actually when they’re both on, they actually use as much, actually more than the whole rest of the building together.” -Bruce Becker
“Wow! Just from the dryers” -Matt Ferrell
“Just from the dryers because that’s the only resistance electric use in the whole building.” -Bruce Becker
After that we made our way up to the roof of the building to see the solar panels, which includes over 1,000 solar panels from the company SunPower. About a quarter of the panels are on the roof and the rest are on solar canopies over the north parking lot, where they have a bunch of EV chargers.
So that covers their energy generation and storage, but when it comes to passive homes, one of the most important factors is the insulation and air tightness of the home. All houses breathe, even if the windows are closed, but that comes from air working its way through cracks and holes in the house’s envelope. That’s why air tightness is key, but an airtight envelope brings some problems, like … oh … say fresh air for breathing, which brings us to energy recovery ventilators (ERV).
These silent, efficient devices can provide continuous, filtered, fresh air to the house, while pushing the stale air out. ERVs transfer heat in order to achieve maximum efficiency and healthy inside air quality. In winter, the system uses the warm, stale air exhausted from the inside to pre-heat the incoming fresh air. In summer, the system conditions incoming warm, humid air by passing it over coils or channels containing stale, cool air being exhausted from the house.23
So what does the Hotel Marcel’s ERV system look like? I’ll give you one hint: big.
“These are the ERVs. Here’s your way to get this turn on. These are made by Swegon. They’re super efficient … all the hotel rooms have a hundred percent outdoor air. We actually monitor the CO2 levels in the air that’s going to the public areas. And the fan speed is actually increased if we get above about 600 parts per million.” -Bruce Becker
“So ramped based on how much CO2 is actually in the?” -Matt Ferrell
“Exactly. In fact, we had an event for about 250 people here on Friday. I can show you a screenshot … we can see in each room that the event’s in. This was at 573 and I just checked. They just started to ramp up because they really don’t want it to go above 600. Although, it’s pretty routine if you go to a typical hotel to see 900, a thousand above. Most people don’t even know what their CO2 concentration is. This is something that we monitor and it’s tied into our building control system.” -Bruce Becker
“And so these handle the entire hotel?” -Matt Ferrell
“There’s two. There’s one on each side here. All the fresh air comes in from above one ERV serves the upper portion of the building. One goes straight down.” -Bruce Becker
It shouldn’t be a surprise to hear that they’re making a lot of use out of heat pumps, which is the most energy efficient way to heat and cool things. Not just for heating and cooling the air, but also for hot water. I’ve got another video that walks through why heat pumps are essential for the future that you can check out. But for the Hotel Marcel, they’ve got an impressive heat pump hot water system that’s broken up into two parts. The first one is inside…
“Heat pumps typically have an indoor and an outdoor unit. But the same is true for the domestic hot water. This is the indoor unit for the domestic hot water, which provides virtually all the thermal heating. There is a resistance coil in here if needed, but it’s really never needed. We get hot water 142 degrees. These are just storage tanks in case we have all 165 rooms using showers at the same time. But we haven’t had a single complaint here with hot water, which is an achievement.” -Bruce Becker
And the second part of the system is outside…
“Those are two of the first domestic hot water heat pumps that Mitsubishi makes. These two here. Then these are just a larger version of what you have at your house. We have an array of them here as well as up on the ninth floor in the Mezz meets. But there’s no combustion, it’s all electric. Basically, just moves thermal energy from one place to another very efficiently.” -Bruce Becker
But what about the rooms? Well, it’s not completely passive house related, but because the hotel is using digital electricity and power over ethernet systems, it makes it really easy to not only deliver power to things like lights, but you can add smart controls through the same cable. It’s data and power.
“These are the corner suites which are pretty special. One of the things that’s sort of fun is with these shades, we can control them centrally. There’s actually a button that you can press if you want to go to sleep, you press the night button and all the blackout shades come down together. There’s also a morning button. On the touch screen as you come in, there’s even a romance button. I can’t tell you where that is.” -Bruce Becker
“These shades are made by a company called PowerShades. We asked them if they could make powershades that would work with Power over Ethernet. They said sure because these shades are DC control. They have ones that will just work off of solar energy. But these are fantastic.” -Bruce Becker
“The majority of the wiring in this hotel is like Cat 5, Cat 6?” -Matt Ferrell
“Yeah. You don’t have to have a licensed electrician. There’s actually a lot less wiring because from the nodes in the corridor we just have twisted pair that is then daisy chained to each set of lights that’s on the same circuit.” -Bruce Becker
The Hotel’s digital electricity system is powered by equipment from Voltserver, which converts AC to DC from the grid, but also allows the hotel to use the DC power generated from the solar panels directly. Keeping that power as DC means you don’t lose efficiency in the DC to AC conversion and can get more bang for your buck from your solar and battery system. We don’t really see this type of thing in homes yet, but it’s picking up steam in large scale buildings and offices. One of my patrons is the founder of a company called Lumen Cache, which has a very cool modular system that can easily scale for home use, so I’m expecting we’ll see more and more of this in the coming years.
Some eagle eyed viewers on my first net zero home build video noticed that there are railroad tracks not far from my new house. They asked if I was concerned about noise, which I’m not because passive house quality homes and buildings like this are actually pretty well sound insulated. A good example was right in the hotel.
“The other thing you’ll notice, because this is designed to be passive house compliant, is how quiet the windows are.” -Bruce Becker
“I cannot hear any traffic whatsoever.” -Matt Ferrell
“Yet you have huge tractor trailers whizzing by only 400 feet away. That’s the great thing about, and I’ll pause so you can actually hear how quiet is.” -Bruce Becker
“I cannot get over how quiet it is.” -Matt Ferrell
“When you design a building to passive house standards, the emphasis is on insulation and ceiling. Those things do a great job of reducing the thermal demands of the building by about 80 to 90%. One byproduct is they’re super quiet. For someone who’s trying to sell hotel rooms, that’s one of the primary demands of savvy guests is having a room quiet. We score very highly on that.” -Bruce Becker
All of this brings me back to this moment for me…
“These are KONE elevators. They actually generate electricity when they’re going down. They’re also DC powered.” – Bruce Becker
“Woah. Wait, you just blew my mind. Okay. So it’s basically regen braking on your car.” -Matt Ferrell
Whether you’re building new or retrofitting an older building, there are so many solutions that are easily accessible to improve how well a home holds onto its heat, how it reuses that heat, how it generates and optimizes its own energy. The elevators regenerating electricity every time they go down is such a simple concept and great example of that. Hotel Marcel has even more of this that I haven’t even touched on, like how they don’t use any natural gas in the building, and the hotel’s kitchen uses inductive cooktops … a far more energy efficient way of cooking. You can bring a pot to a boil in a fraction of the time compared to a gas cooktop. This all raised the big question for me, what about cost? And why aren’t we seeing this everywhere? On that, Bruce had this to say…
“So would you say doing this for your hotel is worth the investment?” -Matt Ferrell
“Oh yeah. I don’t think it costs more than conventional. It probably took a little more time to commission, but it definitely saves energy because rather than having to have transformers at every light fixture, which basically wastes 30% of the energy every time you’re converting from AC to DC, we have a very efficient system for distributing the DC throughout. The lighting in this building only uses like 5,000 watts when it’s all on. I mean it’s amazing. It’s sort of hard to conceive, but you could just get a little Honda portable generator that could go in your trunk and you could power, power all the lighting cause it’s so efficient. So a little more thought and planning just it’s all really takes. Yeah. And yeah, we’re trying to think of the future. I mean I’m an architect developer and I have the ability to just study options and pick one.” -Bruce Becker
“In the hotel world, the pattern is to just repeat a prototype … so if you’re trying to introduce some new concepts like an all at your kitchen or not using any fossil fuels, it’s not in the book. So we had to write our own book.” -Bruce Becker
“Do you think you’ve kind of rewritten the book?” -Matt Ferrell
“We have a new book and I think that the problem with the hotel world is there wasn’t an example. Now there’s an example. There’s a lot of interest in this. We’re going to be hosting sustainability conferences and hotel conferences. You can only do so much with one project. But, I’m hoping that when word gets out about this, people get to come see it and see that it does work. It saves money. Primarily, that it’s easier to market a sustainable hotel than one that isn’t sustainable. That this can be a prototype and this’ll be a new chapter in the book that people follow.” -Bruce Becker
There’s a lot we can learn from the work Bruce Becker is putting into the world with projects like Hotel Marcel. I’m insanely curious to hear how their first year of electricity use goes and if they need to add more solar to hit net zero. You don’t have to give up comfort and quality of life to be sustainable … in fact, I’d argue that some of these things make your own life more comfortable and raise the quality of life.