Olive Passive House

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DEMO Architects founder Alessandro Ronfini will present the Olive Passive House at the Global Passive House Showcase on January 19. Alessandro designed and built the Olive Passive House as a prototype to prove that sustainability and comfort can coexist with most of the elements and materials defining contemporary architecture. The 1500 square foot Phius-certified project was the recipient of Phius’ Best Project by a Young Professional award in 2021. During his presentation Alessandro will talk through the design and construction process, explain some of the most relevant details, and highlight challenges and lessons learned from the project.

Alessandro Ronfini:

Today, I'm here to present the Olive Passive House. This is one of the first project that we as DEMO architects completed. This is also my own house, my second home in upstate New York actually. It's a pretty small house, approximately 1500 square feet interior area, which has been certified Passive House this past July.

So, I wanted to mention a little bit where I'm coming from and my expertise or my experience just to help. I guess it will help, a little bit, explain why I'm going to focus on certain details and certain aspects of the project.

So, I grew up in Italy, studied in Venice and then moved first to Denmark to work for Bjarke Ingels Group. Then with that company, I moved to New York to continue working on DOS-57, a large project in New York City. While working on that project, I decided to actually change my career and started working for a curtainwall company, Enclos.

And for five years, I work on really, really large buildings. Complete opposite of this, no lumber whatsoever, just glass and aluminum and some steel here and there. So working on really, really detailed items and figuring out exactly how compensation can be resolved and how manufacturing can be done offsite, et cetera, et cetera.

So a lot of really technical expertise, that in 2019 when we decided to join forces with Daniel Kidd, he's also in this call, came pretty helpful to actually accomplish some of the project and to actually show that despite being a young office, we had the knowledge and the ability to actually build things.

So, now architects, we have a lot of projects for the most part. Except for my house and another house, they're in construction because as all of you who are architects know, it takes a lot of time to actually build a portfolio of build projects. And having started in 2019, definitely two years is not enough, but we're working on a lot of interesting projects and a lot of passive houses right now, for the most part in upstate New York. So it's very exciting. Future looks bright so far.

So this house, in 2017 my wife and I decided to start looking for a land and build a house. The idea was that we couldn't afford an apartment in New York city or nothing bigger than a studio. So we're like, why not looking for land, building something bigger? It's an investment, it's going to be a fun project and maybe one day we'll move there.

So we looked through a million land and then finally we saw this beautiful piece of property, which of course was twice our budget, but we fell in love with it. And we decided, oh, okay, let's just buy it and see what we can do with it.

And this, just to orient yourself a little bit, this is not really a view that I get most of the time. This is more like from the neighbor because my house is on this side, so I don't really see the mountain, but I actually have south exposure and the view of the pond.

So after camping on the property for quite some time, and being Italian, I cannot not have my mocha even on a campsite, we finally decided where to put the house and we finally conceived an idea for the house. So, this is the final product and I kind of want to step back a little bit and talk about how we got here.

So the idea was to have like a really basic house. A really, really simple, the kind of house that a kid will draw like the one on the right or that an artist that tries to draw as a kid, like Oakley, would draw. So really basic element, vertical walls and a pitch roof.

Of course, this is nothing new. A lot of architects, these days especially, are trying to use this archetype of a house for new construction. For example, the Vitrahaus by Herzog & de Meuron. The idea, however, was to take this volume, and in a way like similar to a geode or similar to the way that a beaver kind of carves in a very interesting way the exterior of a tree to reveal its warmer interior, we decided to carve the volume.

Once again, nothing new. I haven't invented anything, I know that. Steven Holl is definitely a master in that and actually I really like. And both these building, in a way, have something very similar to what we've been trying to do with the Olive Passive House. So the idea for these carvings on the building was to actually justify them in a way that was relating the building to the site and also in a way that could organize the interior and exterior space.

Alessandro Ronfini:

So the house is oriented 30 degrees southeast. It's kind of like the maximum angle we could put it at in order to still get some view of the pond and not miss on the sun exposure towards the south. At the same time, on the south here, there's the only neighbor is inside. Of course, they have a view of the pond there. So we kind of wanted to maintain some privacy. Still, very far, but nonetheless wanted to maintain some privacy and not really point the view directly onto the neighbor house.

Alessandro Ronfini:

So, what we decided to do is to carve out these wedge shape out of the house, out of this very simple volume at an angle of 23 degree from the actual axis of the house in order to re-orient the view directly onto the pond. So that this interior space, that is actually sitting on that side of the house, can look straight out onto the water without seeing the neighbor and without the neighbors seeing inside the house.

Alessandro Ronfini:

What that translates to is this angle, this 23 degree angle, that because of this cutout onto the south volume creates this odd shape onto the volume itself with a big glass window, that again, looks over to the pond. This cutout also kind of continues underneath here creating a cover porch on the south side, which is perfect for dining, for working, et cetera, et cetera. And then it continues on the east side with an outdoor shower and the condenser unit.

Alessandro Ronfini:

Upstairs and at the entrance, this cutout also creates a little recessor for a cover entrance. And then this angle orients the stairs, mechanical room and this loft upstairs that looks down onto the double-height living room space.

Alessandro Ronfini:

The idea of this geode, though, the idea of a beaver chewing through a trunk is kind of what we try to express with the house. The house is this very well protected shed that is this black steel, very simple shape. And then every time we carved out an opening, we revealed the warmth of the interior through the use of wood as a siding material. So the result, as you can see again, very simple volume and then every time we cut out what is the entrance, balconies, the porch, et cetera, et cetera, it reveals a very warm interior.

Alessandro Ronfini:

So now onto the construction. So the construction of this house from day one, and probably because I came from the curtainwall comp industry, I wanted to use a prefabricated technique. So the house is actually a panelized system. I talk with the usual names in the industry, Bensonwood, Ecocor, et cetera, et cetera. And then eventually I found out a small company in Kingston, Threshold Builders. They had just started building panels with the TJI outriggers, dense pack cellulose, building passive houses. Unfortunately, after this house because of pandemic and the two partner of this company took different paths and they're no longer in business, but they did a great job in building these panels in the factory.

Alessandro Ronfini:

I'm going to talk about exactly how they're detailed, so you can see. Sorry. So all the panels were built over the span of a couple months. And then the construction for the most part, for all the ground floor and the second floor, everything except the roof was installed in a span of three days. So this is a camera that I set on site, so you can see setting of the panels. It's not going very smooth, but it's happening. So all the panels, there we go, second day.

Alessandro Ronfini:

Again, all the panels were prefabricated in Kingston, which is roughly 25 minutes drive from the project site. So really close by, not a lot of travel distance, so built locally in a way. And there you see the big beam over the porch on this side.

Alessandro Ronfini:

So onto the details of the construction of these panels. So the panels, pretty standard. There's a lot of panels very similar to this. They are built with two by four interior, two by four structural framing, Zip Board as an interior air barrier.

Alessandro Ronfini:

The use of Zip Board, I know, in the passive house community is a little controversial. In this case, it was actually, I think it was a good way of resolving the detail because it's actually in both the sheathing and as an interior air barrier. So helps a lot with avoiding any risk of condensation on the exterior or in the sandwich of the insulation and as a sheathing material. So there's no actual extra material that needs to be added on top of it. So it was cost saving and performance that drove that decision.

Alessandro Ronfini:

TJI outriggers. This house is kind of pushing the limit of how small a house can be and still be simplified passive house. This is, again, just short of 1500 square feet interior area, so the walls are really thick, R-60, 16 inches of dense pack cellulose. It's driven both by the performance and by the risk of condensation, so both things were in place here.

Alessandro Ronfini:

And then on the outside, the SOLITEX MENTO PLUS, taped all edges and then two layers of furring strips for the rain screen. The siding is standing seam metal roof on most of the exposed surfaces and then everywhere where the house is protected is Siberian Larch.

Alessandro Ronfini:

The roof, for the roof ... Also, because of our value that we had to hit, we decided to actually put exterior insulation in this case, so just not to oversize the joist on the interior and create additional structure that was unnecessary.

Alessandro Ronfini:

So the rafters are 12 inches I-joists with dense pack cellulose. And then on the exterior, again, Zip board as our interior air barrier. The dense pack cellulose is one thing that I wanted to highlight. Also, this picture is actually not contained by your typical INTELLO or any interior air barrier, so it's allowed to actually dry to the interior. And once again, the Zip Board is acting as interior air barrier and as the sheathing.

Alessandro Ronfini:

And then on the exterior, EPS. And on top of that, again, SOLITEX. In this case, SOLITEX UM, which is a membrane with a mesh on top of it so you can apply the metal roofing directly on top of that and maintain some circulation underneath. The slab, finally, slab R-32, 42, sorry. Slab was all prefab EPS, I think from E-Z Frame, EzCore, something like that. So, whole pre-design was as simple as setting up construction with LEGOs to put it all together, secure it in place, and then prep it for the concrete pour.

Alessandro Ronfini:

The windows, so another, of course, important component on the facade. So, of course, the main element in the house is this big double-height space with this big curtain wall. The curtain wall is the stick-built wood aluminum curtain wall, so with wood mullions and Pressure Cap Aluminum on the exterior. The windows are all Aluminum-clad pine windows from Batimet from Germany.

Alessandro Ronfini:

These windows show a couple of things, this picture here show a couple of things that unfortunately happened. So the manufacturing was pretty good, but there were definitely some problem in some of the gaskets and how they were installed, so we had to fix that onsite. But nonetheless, the quality of the window, and I want to point out that it's really hard to find at a decent price, a welded angle [inaudible 00:14:37] face aluminum window and all the details in this were really, really great.

Alessandro Ronfini:

So some other pictures of the curtain wall, just to show how it worked. The curtain wall was over designed in terms of the depth of the mullion, just to contain the thickness of the wall more than just a structural load. So the horizontal member, the transom, they're more than just the transom. They don't only support the glass, but they can become a little seat at the bottom and a shelf on the upper level.

Alessandro Ronfini:

Some details here, also, for the curtain wall system. So this is a typical curtain wall, and then this detail, this is something that I spent a lot of time detailing. So because of this big extent of glass facing south, we of course wanted to protect it from excessive solar heat gain. So there are some shades that are hidden behind the siding in there.

Alessandro Ronfini:

The shades are stagger, and I don't really, I looked for an hour finding a picture of them. And even though I'm at the house, it's too cold to actually run them now, but they're stagger. They all work, I promise, they're all automated. So they don't have a sensor, but you can control them remotely with the remote control. And they're completely invisible from the exterior. So I go back here, they're hidden behind here, one, two, three and four. And again, completely invisible from the interior and exterior, when they're not dropped down.

Alessandro Ronfini:

So construction of the house, everything went relatively smooth until March 2020, when of course, the pandemic hit and there was a stop work order for most construction, or non essential construction, in New York. So at this point, that's a picture from then, so the interiors were kind of all wired and all mechanical systems in place. And then, of course, no finish on the exterior. We barely had started a roofing on the opposite side, but not completed.

Alessandro Ronfini:

So, at that point, it was kind of like a lot of stress, but at the same time, a very fun experience. We just asked friends to help and my wife and I took more work that we were supposed to ... we were already planning to do some of the interior finishes ourself, but we decided to do a lot more. So we did all the kitchen, we did the entire wood siding of the house ourselves, we did the floors.

Alessandro Ronfini:

So the siding was actually a fun experience. I have not really done a lot of woodwork. A few things, a few millwork, fun projects here and there, but installing siding for an entire house is a different project. A little bit of an undertaking, had to rent tools like this guy here, but at the end of the day it was fun. It was a great experience.

Alessandro Ronfini:

As an architect, I learned a lot by doing things ... how to detail connections, what to expect and what not to expect, internal tolerances in terms of precisions of the execution of the details. So even though it took much, much longer than anticipated and a lot more work and stress, it was definitely a fun experience and a big learning experience.

Alessandro Ronfini:

And the floors, please don't ever do floors yourself or you're getting very close to divorce. The stairs, I did those as well. Then we did all the casing for the windows, so this is all red oak. Luckily, the couch was also very late, so we had all of the living room for ourself to set up shop and set all of these boxes. We built them on the floor and then installed them onto the windows. Very proud of those, that was a fun project.

Alessandro Ronfini:

So here's the house, completed house. So the house actually won at the latest PhiusCon, the award for Best Project by a Young Professional. I was 35 at the time of when I started the project, but really the professional, and I have to credit him is Owen O'Connor. He was the builder and the PHIUS Rater and he was 34 when we started the project, so under 35.

Alessandro Ronfini:

So the house now is finally complete. There's still a few things that we're working on. Some furniture missing here and there, but overall we're really happy with the result. It's been great as an architect to have a project that you complete, that you don't have to ask a client to visit with the other potential client. It's an incredible value and this has been very successful in getting our company new projects.

Alessandro Ronfini:

On the interior, some fun things. These tables, something that my wife and I designed. And the two legs here, there was an unfortunate mistake. One of the builder actually cut the ridge beam too short, or one of the parts of the ridge beam too short. So we had a 20 foot ridge beam that was an expensive mistake for the builder, but also something that I didn't want to bring back home. And so we just cut it in parts and gave it to a friend who was a millworker and they used it to build the likes of this table. And we still have some pieces we're going to build more furniture with.

Alessandro Ronfini:

More views of the house, of the interior. So this big curtain wall, as you can see, points the view really towards the pond on the side. On the interior, kitchen cabinet, this is the big double-height space and then upstairs with the mini split unit. And we're going to talk about mechanical system in a second.

Alessandro Ronfini:

And then interior, the bathrooms, even though the house is modern, we didn't want to have super modern interiors. More and more, we're buying more and more furniture from auctions, from secondhand stores, et cetera, et cetera. This sink, for example, we built kind of the whole bathroom around it, that was the first thing. We went to Zaborski in Kingston. If anybody has been to Kingston knows of that place, it's an architectural salvage place and really like a labyrinth. So we found this sink from the 50s, from American Standard, and then we built everything around it. Ordered these faucets from Italy. The tiles are really standard Daltile, but it's a really bright and very colorful bathroom that we really love.

Alessandro Ronfini:

And then the other bathroom, definitely more calm in terms of colors, but also really modern, but not excessive. More of the interior with the stair that we did. You see that there's one, if you're an architect, you know that there's one too many steps here without a hand rail. We are planning to build something there, but it's not there yet. Luckily, the inspector didn't raise any question there.

Alessandro Ronfini:

So mechanical systems. So the house, of course, we're using ERV system. In this case it's a Zehnder Comfoair 350. Here are the mechanical drawings, but it's all pretty straightforward in the bathrooms and mechanical rooms and the exhaust in the living spaces. Because of these double-height space and because of the construction system, we actually have the supply and the return under the ceiling of the kitchen. Which is a little far, that's one of the lessons learned and I'm going to talk about that, too. It's a little far to cover the entire space, so we've had to actually add a ceiling fan to take care of that.

Alessandro Ronfini:

In terms of heating and cooling the house, well for cooling it's just one floor mounted, actually, Mitsubishi Mini Split Heat Pump. It's a 9k BTU, so the smallest you can get and still over dimension for the system. For heating, though, we also have an additional post-heater, it's the Stelpro. That warms the ERV supply air to 67, 68 degrees, which is four or five degrees on average more than what will come out of the ERV naturally. And that helps a lot, actually keeping some of the rooms, especially the ones on the east and the north, a little warmer in the winter.

Alessandro Ronfini:

For domestic water, that's another thing. So this is a second home, remember, and it's pretty narrow, so after a lot of debate I decided to go with a tankless electric water heater. Because again, I'm not using the water all the time, mostly on weekends and then sometimes we're there for a whole week. And I think, even though there's a higher load of course when you're calling for some hot water, on the long term, this is actually going to be less expensive than even a heat pump water heater because there's no tank that needs to be constantly filled and kept warm.

Alessandro Ronfini:

Range hood, I'm going to talk later about that. We have a recirculating fan, very standard 400 CF. Probably not the best solution, but it works enough for this house.

Alessandro Ronfini:

So after the work was finally completed sometime in May, we managed to test the house to achieve the certifications. So we did blower door test, the results were great. So air changes per hour, 50 Pascals, 0 27 with the target of 0.6, of course. So really in very airtight house, especially considering how small it is.

Alessandro Ronfini:

Here are some data for the nerds in the call, the ones that are interested in all the data. We can go back to this and take a look in detail if you have questions, but basically already from day one we designed the house with the goal to achieve a PHIUS 2018 certification and we hit all the targets.

Alessandro Ronfini:

I added a note. I don't know if somebody from PHIUS is here, but there was a lot of debate with PHIUS about the off site renewable energy production, so I needed to add the 2,800 kilowatt hour of that. PHIUS, I don't even know if they have changed the standard because of how stubborn I was, but their requirement for using a community farm, a solar community farm rather than installing solar on site, is to actually purchase those panels. And instead, I had a contract for 20 years to use those panels, which is a lease versus a purchase. And after a lot of back and forth, finally PHIUS approved this method and currently that produces almost half of what is needed for my house.

Alessandro Ronfini:

So these are the data, and I want to point out some data here. For example, the total source energy, 13,000 kilowatt hour/year. So because it's my house, I can see the bills. It's again, it's a second home, but I nonetheless, I wanted to show some numbers and show the energy consumption of the house. Because even though I'm not here all the time, and I would say probably approximately 20% of the time the house is used.

Alessandro Ronfini:

The temperature, so heating and cooling. Again, despite the fact that there's no human load in the house and no windows are open, but also no shades are dropped down in the summertime. The temperature was kept for the past year. The house finally had all the mechanical systems already last winter, so it's been a year of a running house.

Alessandro Ronfini:

So temperature kept at a minimum of 65 in the winter and a maximum of 74 in the summertime and you can see here the consumption. So on 2021, the actual consumption was just shy of 7,000 kilowatt hour. We had an estimated of 13,000. Off of that, 46% of that was actually produced with off sites for production, so very happy with the result. Of course, I wasn't expecting to hit the 13,000 because it's second home, but nonetheless being half of that it's a very good result, I think.

Alessandro Ronfini:

Another thing that of course we all value, hopefully, in passive houses is air quality. So I got myself a little Awair. Not the best tool, of course, on the market. It's maybe not the professional tool and it's kind of annoying how it cannot go back in time and extract the data, only a month. But I looked at this past month, since I was here the entire month and extracted week by week for the four weeks of December, the data from the house.

Alessandro Ronfini:

So as you can see, this is the overall score. Pretty high from 91, on minimum 91, top of 97. Of course there are always some peaks and some low. For example, this 70 might have been me cooking a steak or something like that. Such small things can actually affect dramatically the value on these results. So for example, if we look at the PM 2.5, there's a lot of peaks here and there, not a lot of lows. And these TVOCs and the CO2 for the most part, these are dependent on yes, human activity in the house. So cooking, even if I turn on a candle, that affects actually the interior quality, which is really impressive how little it takes to change the air inside the house. Vacuuming is also something that lifts a lot of dust, even though a lot is collected, a lot is lifted just because of the fan running.

Alessandro Ronfini:

And then the temperature, also this is pretty good. Median temperature oscillates a little bit of course, but that also depends on where the sensor is located. The data that definitely is not all green is the humidity. So on average, the house is dry in the winter. And the reason for that is mostly because of course, well, it's dry outside. And the house not always occupied, even though we're talking about a month where I was here. And all air system to warm the house, so of course that dries also the air and creates some, well not problems, but slightly below ideal indoor humidity. So some of the problems and lessons learned.

Alessandro Ronfini:

How am I doing with time? I have another couple minutes, probably. I'm good.

Zack Semke:

Yeah, go for it, Alessandro.

Alessandro Ronfini:

Okay, perfect.

Alessandro Ronfini:

There's a million problems and there's a million things that I've learned in this house and I like to point those out to clients and say, "Don't do it like that, that was a mistake." But a lot of those are small things. Like, I should have had a bigger overhang over my entrance. And I maybe should have thought of a way of warming up the concrete at the entrance because it gets really slippery when it snows and the ice forms immediately on it. So few things like that design problems in here. I really wanted to highlight the passive house related issues that I encounter. None of them is a big problem and actually I'm on the way of solving all of them, I think.

Alessandro Ronfini:

But one thing, it was definitely distributed temperature. So the ERV alone, even though it was tested, it was calibrated, a rep from Zehnder came here and calibrated the system. Nonetheless, there's definitely a difference in temperature that is noticeable between the rooms on the ground floor on the east side. The bathroom and the bedroom in here are definitely colder than the rest of the space. In the living room, well, where we stay, we don't float in space, but of course, on the ground floor it's a little colder than upstairs. If you go in the loft, you feel definitely a difference in temperature.

Alessandro Ronfini:

The reason being that the heating system for the most part is upstairs. So the mini split is here, even though this is set to only blow down the floor level, still there's not enough air. There's not enough circulation to actually warm the rooms on this side. And sometimes, again, the lower part of this floor, of course, heat tends to go to the top. But this is never a problem in the summertime. The summertime, the whole house is exactly the same temperature. It's only something that happens in the wintertime.

Alessandro Ronfini:

So the solution, there's two solutions that I'm actually trying to install if I can get this equipment because as you know, supply is a problem everywhere. So we're going to install a little electric radiator in this room, 500 watt. Probably going to be set at the minimum temperature, and it has built in thermal status so it's going to turn itself off when we get to 72 degrees, to keep this area warm. This really is only needed, I would say, from early December to probably late February. So for three months. And then this is a plug-in, so potentially we can even just unplug it and put it in a closet. But it's pretty minimal, so it's probably just going to stay under the window.

Alessandro Ronfini:

We actually had a tower warmer in the bathroom that was supposed to do the work of this. And then for budget reason and because of, well with the pandemic, there were a lot of problems with the electrician suddenly having a lot of other jobs more interesting than this, we cut it out and that was a mistake. We should have kept another source of heat in that area because again, being on the northeast, it's definitely colder than the rest of the space. And the window being under the porch doesn't get as much solar heat gain.

Alessandro Ronfini:

In this area here instead, there was a very dumb mistake. And we use fan in other houses with double-height, so I don't know why ... Well, I know why I didn't put it, because I didn't want to see it. But that was a big mistake. And of course, we're going to put one now. And found a nice model, which is actually not this one. So it's here waiting for the electrician to install it. Hopefully that's going to happen soon.

Alessandro Ronfini:

Right now, I know that this is going to work because right now I have a very simple tower fan that I put in the loft. And that's enough to actually create this air circulation to bring that warm air from the heat pump in the entirety of the space. And so that the median temperature is at 70 degrees and there are no problems.

Alessandro Ronfini:

Another, not an issue, but something that could be improved and something that definitely I'm trying to do different in the next projects is the range hood. So I have a very simple Elica recirculating range hood 400 CFM. So it basically, this is cut out, but it's under here, sucks the air and then there's a little exhaust at the top, so it just recirculates the air like that.

Alessandro Ronfini:

Whenever I cook something like a steak or anything that is smelly or even humid, even cooking a pasta, I turn the ERV booster on. So the Zehnder has a booster that increases the capacity, increases the fan speed, so more air is extracted and more air is brought into the house. While this helps in keeping the smell low and kind of cleans the air pretty quickly, after having cooked, still there's a lot of humidity, there's a lot of condensation. Again, if you're boiling some water here, condensation happening underneath because the fan is not strong enough to pull it out, and those peak in pollutants that I talk about earlier.

Alessandro Ronfini:

So next house, especially if it's a house where a family's supposed to live full time, probably a fan that exhaust to the exterior is a better solution. And I know that Dan agrees to that.

Alessandro Ronfini:

So another thing is the humidity level, that's another thing I would talk about earlier. In the winter, the house is pretty dry. Now this solution here for when I'm not at the house, well, I don't really have a solution and I don't think it's a big problem. We're talking about around five to 7% less humidity than comfort.

Alessandro Ronfini:

When I'm at the house, the solution is very simple. We have a couple of these, it's actually a diffuser, but it works perfect as a humidifier. They will run at night. At night is really when we're not taking showers, when you're not cooking, where the humidity actually drops because all that is happening is the heat pump is running and the air is warmed and dried. So we just have a couple of these in the bedrooms and that's enough to really feel the difference. I don't have a sensor for the humidity in the bedroom. I might move my Awair to the bedroom just to test it and see if it's actually, beside what I feel, is also corresponding to an actual comfort level much better than what I have right now. But it's a pretty simple and definitely very inexpensive solution. This is a hundred bucks versus a humidifier for the whole house that runs in the thousands of dollars.

Alessandro Ronfini:

And that's it. I forgot to mention this little guy. This was a great help before, during the construction of the project, was our stress release. Spanky, a little donkey living next door. Great friend. Helped us really a lot during the construction, keeping our mental health in place.

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