This 2,200-square-foot house in southern Vermont stays comfortable all winter using less power than a hairdryer.
It's a Passive House, and it's the next big thing in energy-efficient construction.
Snowy house

A short note on wiring and instrumentation...

Submitted by Ted on October 4, 2012

Peter has been asking us about doing the final installation of the monitoring system for our house, so that he can get some data out of it (finally!). In order to make that happen, we needed to finish the electrical work, and that's been a bit of an obstacle because of various lighting needs and also because our electrical subcontractor, Andy Harkness, has been in high demand recently. But we managed to lure him and one of his electricians, Karl, up to the house over the past two days to finish up the electrical work.

Imagine my excitement when Andy called me down to say "Ted, can we combine any of these circuits? The panel's full!" It turns out that we are able to keep all the circuits separate, at the cost of having _zero_ free space in the panel. If we need to add even one more circuit, we'll have to add a secondary panel.

Why so many circuits? Peter wants to be able to measure the power consumption patterns of individual devices and rooms. Along with the per-room temperature sensing and an outside weather station, this will give him (and us!) a really good idea of how the house is actually performing.

The snarl of wires coming out of the wall here are the wires to individual temperature sensors in each room, all of which terminate in the utility closet. There's also network wiring, of course—that's the other, smaller snarl of wires.

This is the control/status monitoring panel for the solar hot water. We may collect some data off of this as well.

This is a flow meter that will detect the flow rate of the hot water. We also want a flow meter for the glycol, but had some trouble sourcing one that would be reliable—Peter originally sent us a flow meter that's mostly made of plastic, and Gary, our solar subcontractor, took one look at it and refused to install it. When I called Peter about it, he told me that there had actually been some problems with the device in the field (nothing serious—one leaked a tiny bit, and another failed after a year). So we aren't installing this particular device—Peter's researching other options.

Oh, the reason for the weird bend in the pipe that comes into and out of the hot water flow meter is that we need a certain length of pipe after a bend or a valve before the flow meter, or the turbulence caused by the water flowing around the bend or through the valve will affect the measurements.

This is the flow meter for the well. We're not actually measuring this—it's just used by the sewer department for billing. But it's a meter, so I included it... :)

A gratuitous picture of fall foliage..

The spiral stairs, from above...

Interior photos at last!

Submitted by Andrea on September 11, 2012

My parents came to visit this weekend, so I borrowed my dad's camera to take some interior shots (the wide-angle lens on my iPhone is a bit sub-par).

Yes, the house is a mess. We just moved, after all! If my mom could handle it, I'm sure you can.

Here's the main downstairs view, just after you walk in the front door. The curved staircase is from York Spiral Stair in Maine.

And here's the same view from one floor up. It's a little hard to see in the photo, but the ceiling vaults upward toward the south windows. The closed-off area on top is a utility loft containing our solar inverter and heat recovery ventilator.

The 2x4 barnyard-style railing around the atrium is temporary — the eventual railing will match the stair railing and balusters.

Below is the opposite view, taken from the office area below the utility loft. The windowy area on the right (with the uninstalled door) will be an indoor garden space, taking advantage of the eastern and southern exposures. The clerestory windows along the hallway will bring south light into the guest bedroom.

Here's a view from the bedroom at the end of the hall, looking south at the indoor garden area. The two rooms will be separated by glass doors, bringing south light into the bedroom. (I kept the north windows quite small.) The loft space above the garden area will be accessible by a ladder. Ted and I dubbed it the "Manatee cave."

Back downstairs, here's a peek into the kitchen. My mom is doing an admirable job ignoring the huge mess everywhere!

Don't worry, I haven't forgotten about you construction geeks out there. Here's the hot water heater (hooked up to a solar collector), in the utility room near the back door:

And behold the mighty HRV ductopus in the utility loft upstairs:

Finally, a photo of the elusive Andrea (me!) in front of my treasured 1938 Deagan Imperial marimba, out of storage at last:

Overheating from south windows

Submitted by Ted on July 22, 2012

Andrea and I started sleeping in the house two nights ago, so some things that I've been noticing about the heating profile of the house are starting to become clear.

When we finally got the HRV running a few weeks ago, I was disappointed to notice that we don't have the kind of evenness of temperature between the upper and lower stories of the house that we were hoping for. My first panicked theory about this was that the HRV wasn't working. Panicked, because the tubes are all nice and snug behind walls now, so if we got it wrong, it's going to be a real pain to fix. The good news is that I don't think the problem is the HRV, although I'm contemplating one tweak to the vent layout which we could do without any wall surgery.

When we talked with Peter Schneider about overheating, he reported his experience with some of the houses that Efficiency Vermont has designed up in Charlotte, Vermont. These all have lots of south-facing windows, and Peter hasn't seen problems with overheating in the summer. Based on Peter's reports, we were kind of hoping to get away without doing one of the features we've got on the plan: active shading on the south-facing windows.

If you look at the drawing of the house at the top of the blog page, which is a view of the south face, you'll see that the lower windows have what looks like louvers on them. These are part of the solar shading plan—the idea is to install them in spring and keep them around until fall, and then take them off and stash them for the winter. These louvers will prevent high-angle light from making it through the window in the summer and heating the interior space. By installing them on the outside, we minimize heat gain inside—hopefully most of the heat that is generated when sunlight is absorbed by these shades will re-radiate into the outside air, rather than heating the inside of the house.

Why is Peter seeing different results? I don't know, but I have a theory. I think the windows in the houses in Charlotte may not have the same solar heat gain coefficient as ours, and may reflect more high-incidence light, while letting low-incidence light in, so that they gain more heat in the winter than they do in the summer, even if the same amount of light is hitting them.

The way our house is set up, we have a heat pump indoor unit on the wall downstairs, right in the center of the house. We have nothing upstairs. So the reason I was worried that the HRV wasn't working is that one possible interpretation of the data is that we're cooling the house adequately, but the HRV isn't doing its job in redistributing the heat evenly throughout the house. If that's the case, it's kind of a big problem.

But having just spent the morning sitting down next to the windows with the heat pump off, I have a different theory. For most of the morning, it was nice and cool downstairs, but as more sun came in and the day went on, it started to get hot, just as it is upstairs in the afternoon. In other words, the heat coming in from the windows is heating the upstairs and downstairs evenly; the reason that it feels hotter upstairs is because the cooling effect of the heat pump completely counteracts the heating effect of the windows. I've confirmed this by turning the heat pump back on.

So this gives me some real confidence that when we get around to building and installing the louvers, we will stop experiencing overheating in the south part of the house. I'm still a little tempted to add one more supply vent on the south side of the house upstairs, but that's something I'm hoping to have a chance to debate with the guys at Zehnder. If it needs to be done, it's a really easy fix, because I can do it up in the utility loft, which doesn't have a finished floor.

Head boppage averted!

Submitted by Andrea on June 26, 2012

Due to a last-minute change in roof pitch (my fault), we wound up with a structural beam at perfect head-bopping height at the top of our garage stairs. But today it was fixed!

Eric (6'-3") and Eli (5'-7") plan out the surgery:

Don't worry — we didn't carve out an LVL without checking first with a structural engineer. Eli consulted with engineer Ben onsite several months ago, shortly after the garage was built. Ben had a good laugh at our error and told Eli where he could safely cut.

"What's the problem here? This header height seems fine!"

(At 5'-6", I wouldn't have had a problem either. But I would not have enjoyed seeing Ted bump his head several times a day.)

Post-op photo:

It cleaned up real nice, no?

You could do that, but you will not get into Dwell...

Submitted by Andrea on June 16, 2012

When Ted and I started this endeavor in 2009, I didn't know the slightest thing about construction. I couldn't have told you how a stud wall is built, or even described with confidence what a 2x4 looks like.

My how things change! Just last night I dreamt I was quizzing a contractor about air barriers and external insulation, while harboring deep suspicions that he hadn't properly managed the vapor barrier on the 2x6 walls of the house he was rehabbing. I was gearing up to explain why polyisosyanurate was a better choice than extruded polystyrene (XPS) for above-grade rigid insulation, since the blowing agent used to produce XPS has a much higher GWP (global warming potential) than the one used for polyiso... but then I woke up.

I honestly never intended to jump into the deep end of residential construction theory! We simply wanted to build a comfortable and energy-efficient house, which led us to Passivhaus, which led us to our energy guru Marc Rosenbaum, who opened my eyes to the rough and tumble world of building science.

By all accounts, one of the roughest tumblers in building science is Dr. Joseph Lstiburek. I've never met him or heard him speak, but he's a principal of the Building Science Corporation and is famous in the green building world for being brilliant, outspoken, and highly opinionated. Martin Holladay published some choice quotes from a recent seminar taught by "Dr. Joe", including this doozy:

I have a problem with the Passivhaus people, because they are building ugly freaking boxes. The only way to get a building to last a long time is if the building is maintained, and people have to want to take care of it. People do not take care of ugly things.

Ouch! That one hurt a bit, probably because I sometimes worry that our house is an example. The exterior is nowhere near as bad as some passive houses I've seen pictures of, but it is not quite as handsome as I would have liked:

I should mention that this is the house's least flattering angle, and it looks particularly odd without the solar collector that will attach to those two white strips on the facade (probably making the house look even odder). I'll post more flattering and accurate photos below, but you can see that we have indeed built a big freaking box.

The house didn't start out like this. We got invaluable advice from our friend Camilo, an architect in New York, and he designed something a lot more stylish:

But reality intervened, and we had to stray far from his plan. Our building site is both sloped and ledgy (i.e. lined with bedrock), so a stem-wall foundation was impractical, and we needed to shorten the house from 58' to 46' to keep the lower piers from rising ludicrously high. This meant lopping off some space (which we probably won't miss at all), and it made it easier for us to reach Passivhaus numbers, but it also made the house more boxy and less "architectural."

We were very sad to have to reverse the roofline, since it drastically reduced the amount of space for solar electric panels. We therefore added the overhang to the top of the south wall, which turned Camilo's dramatic design into a stark-looking quasi-saltbox.

That said, I don't think our house is ugly enough to invite future neglect. In real life, it looks a good deal better than that first photo would suggest. You can't really see the garage in that photo, and the garage's south-facing roofline complements the house nicely:

It looks even better from the road (which of course is how most people will see it):

And the best part, frankly, is the interior. While we mercilessly chucked most of Camilo's exterior design, we consulted him regularly about the floor plan and followed his advice even when it would have been cheaper or easier to ignore it. We refused to replace his vaulted ceiling with a standard attic, which meant we had to find joists that were deep enough for Passivhaus insulation and also strong enough to bridge a 26' clear span. We also sacrificed upstairs floor space to preserve an atrium-like expanse above the dining area. I spent countless hours in SketchUp tweaking and tuning the interior, and now that the house is drywalled I can see that my time was not entirely wasted. It really is a cool space, and it doesn't feel generic or boxlike at all.

So no, our house is not likely to make the cover of Fine Homebuilding's annual "Houses" issue, and it's definitely not swank enough for Dwell (or, alas, Unhappy Hipsters), but I don't think it's too horrible a case of green building gone aesthetically awry.

The inevitable post about toilets

Submitted by Andrea on May 15, 2012

We all knew this time would come. I've shared way too many details of our construction process, so it can't come as a surprise that I'm going to tell you this one as well. So sit down, relax, and read all about how we chose a toilet.

First some background: Ted grew up about 15 miles from Brattleboro and I'm from the Chicago suburbs, so we both consider northern climates the norm. But we spent much of the last decade in Arizona, which radically skewed our definition of normal. In Arizona it can go months without raining—the so-called rivers are just sandy washes that occasionally flow with water after a heavy storm. Summer enters full swing by the end of April (daily high temps in the 90s, surpassing 100° in May), and it doesn't really cool off until mid-October (highs in the 80s). The hardest part for me was the lack of shade, since desert trees have very tiny leaves and don't grow especially tall.

This developer clearly had a sense of irony

But in 2010 we moved to Vermont, and after six years in Tucson (plus a year and a half in rural Cochise County) we felt as if we'd returned to Earth after living on a poorly-terraformed planet. Seasons! Tall shady trees! Plants that don't puncture you! Rivers with actual water!

It therefore seemed unnecessary to keep worrying about water conservation. Indeed, we had a dramatic excess of water last summer, and installing low-flow toilets seemed like a low priority. But my friend's recent blog post about toilets made me realize I wasn't actually off the hook, so I turned once again to the folks at BuildingGreen for some advice.

They told me that water conservation is, in fact, quite important hereabouts. Wet regions like New England are uniquely vulnerable to drought simply because we have so much to lose. Reduced rainfall could seriously change the ecosystem here, harming numerous existing plant and animal species. After a dry month or two, spring-fed wells can dry up, sometimes forcing homeowners to drill deeper at great expense. So we mustn't get complacent about water use, even though it's rained nearly every day for the last few weeks (not that I am bitter).

Ted and I therefore reevaluated which toilet to install in the house. Last fall we had followed our plumber's advice and selected the American Standard Cadet 3, which uses either 1.6 or 1.28 gallons per flush (I honestly can't remember which version I chose). But I hate the idea of flushing away 1.6 gallons of pristine water every time we urinate, and Ted's sense of smell prevents us from being an "If it's yellow let it mellow" household.

I thought our best alternative would be a dual-flush toilet, but Peter Yost recommended the Niagara Stealth, which he installed in his house more than a year ago. The Stealth ($300) is a single-flush, vacuum-assisted toilet that uses a mere 0.8 gallons per flush (most dual-flush toilets use that amount for only the small flush, and more for the big flush). It's very quiet (Peter let us test his) and by all accounts works great. We even asked a disinterested plumbing supply rep about it, and he told us that a customer with multiple rental properties is gradually buying them for all his units because it's saving him so much on water, and the tenants haven't had any complaints.

I obviously won't be able to fully endorse the toilet until we've been using it for a while, so if you're interested please remind me to post an update next year. And let us all hope that my tendency to overshare does not make you wish you'd never asked.