We sat down with Chad Ludeman and Nic Darling, the guys behind the highly acclaimed 100K House, to find out about their company’s next project, which is to build even more energy efficient homes than before–with a wider selection of design options. Their development company, Postgreen, is building two so-called "passive homes" just blocks away from the 100K House in north Philadelphia.
Keystone Edge: Tell me about your latest project, the so-called "passive houses" you’re building on Amber Street right now.
Chad Ludeman: The passive house was something we researched during the design of the 100K House and took some of the principles. But basically it’s a German standard, been around for a little over ten years, that tries to reduce heating and cooling loads by 80 or 90 percent. In Germany they’ve built tens of thousands of these and the UK is moving to it in order to reach their net zero energy goal for all of their homes in 2012. It’s not taking off in the US right now. There are only about a dozen certified passive homes.
KE: But this is the standard in Germany?
Chad: Yeah this is the standard in Germany. It’s starting to spread throughout Europe. You build a house in Germany and this is the way you build it, basically. Over there, the climate is a little milder; it’s kind of like Virginia here. They don’t require any heating or cooling over there in their passive homes. They’ve completely eliminated it.
KE: How have they done that, exactly?
Chad: It’s mainly super insulating the house–very high insulation levels and very, very tight homes, as far as air sealing. This is a big difference between this house [100K] and those [passive houses on Amber Street]… The big difference is that we’re using slightly thicker panels for both of the walls and the roof, about two inches in each case. But we’re going through the same manufacturer, same concept, same panels for the most part. We are putting an inch of ridges on the outside of the homes in addition to the panels since there is a little bit of framing still in the SIPs around the windows and doors and at the corners. That helps eliminate that thermal bridge completely, and adds to the insulation value a little bit. Then we are really taking air sealing to a ridiculous level, compared to these homes. We tape all of the seams in the SIPs on the inside. We tape the window frames and doorframes to the inside SIPs. We have plastic underneath the slab that has all the seams taped. Everything that comes through the slab, every electrical or plumbing piece that comes through the slab is taped and filled with spray foam.
KE: And how will you heat it? With sunlight?
Chad: No. A lot of people in the U.S. get it confused with this passive solar home movement that started in the 60s and 70s where that’s more the idea. But this is a little bit different in that it focuses more on super insulation. So we still have heating and cooling in these homes but we use a very small air-to-air heat exchange or split ductless system. And that’s very efficient; it heats and cools the entire house.
KE: I’ve heard you guys use the term "net-zero energy" in reference to these passive homes. Can you explain that a little?
Nick: So we’re putting solar panels on there which will hopefully produce more energy than the house uses. So we net-meter it, meaning that you’re selling energy back to the grid when you’re making it and you’re buying energy when you need it. That way you don’t have to have a big battery array or anything like that; the system is grid-tied. In the end the hope is that, particularly in the passive house, we will reach net-zero energy–where the homeowner is making more money than they’re purchasing, and thus getting checks from PECO instead of paying bills to PECO. Because the houses are all electric that means the energy bill for those homes is non-existent, and in the best case scenario you get a couple hundred bucks a year from PECO. That’s the goal.
KE: when you guys built the 100K homes, did you have the idea of buying a bunch of plots in Fishtown and building a bunch of different models of super efficient homes?
Nick: The concept was always to create a production model, not a one-off experiment. That was important both for our business plan, what we want to do in the future, and also for the people we work with, our team members, to get them on board with the idea that this was going to turn into a good number of homes down the line… The amount of effort that went into the design and production of [the 100K House], even though our construction costs weren’t that great, there was a lot of design work that maybe isn’t completely paid for by the process. So it was important to build more to justify all that work.
KE: It seems that these other projects are moving quickly. Is that because of all of the work that was initially put in?
Nick: Yeah, we learned a lot from what we did in these projects and have applied it to the next ones and hopefully they’ll go considerably smoother. Of course, we’ve also introduced a lot more extreme goals for the project, so that may end up slowing us down here and there as we try to attend to the air sealing stuff and the insulation details. But we predict that the build will go significantly quicker than this one.
KE: what’s the target date of completion for the two passive homes on Amber Street?
Nick: We’re hoping some time in mid-August. Right now that’s what we’re aiming at.
KE: Tell me a bit about the design website you’re planning for Postgreen.
Nick: We’re launching a website, the goal is July 30 for the web launch party; we’re planning a party, it’s going to be a big event. We’ll launch the Postgreen homes website, which is a site where you can come on and actually customize one of our homes: change the flooring, countertops, kitchens, give them alternative energy stuff, bathroom layout and design, and on and on. Almost model them like sort of a Dell or Apple website or one of the customized little car websites. At the end of the process, if you customize one within our projects, let’s say you pick one of the lots down the street, you customize it how you want it. When you finish the process you’ll have a printout of all of your customization options and a price for what the home would cost with your options, and that price will be pretty exact.
John Davidson is the editor of Keystone Edge. Send feedback here.
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Nic Darling showing custom exterior options (John Davidson)
The passive homes construction site on Amber Street (John Davidson)
Chad Ludeman (courtesy of Postgreen photographed by John Rozier)
Nic Darling (courtesy of Postgreen photographed by John Rozier)