Today was the last day of the Fair. It was a long day, but fortunately not as busy as Sunday. Just before the exhibit closed, Mike and I savored the shading structure one last time – it’ll be a shame to see her go…

With the Fair over, I’d have to call the demonstration house a success. Those who bothered to read the boards or talk to a student left pleasantly surprised (or so it seemed to me). A lot of eyes lit up when we told them the cabin was designed a built by students. Others were impressed by the reduction in energy usage.

In all of those conversations – hours and hours’ worth – a few questions came up again and again. Naturally, that starts to where on a person. We managed to stay polite outwardly, I think, though our thoughts may not have been. Here are some of the questions I was most frequently and what I was thinking as I answered…

‘How much does that window cost?’ I honestly don’t know; yes, they’re expensive, but windows always are. I am not a salesman and this is not a product showcase. I’d rather talk about their role in the building’s thermal envelope. Windows are just sexier, I guess.

‘What’s with the rocks?’ They’re for shedding water. They’re called gabions, g-a-b-i-o-n. No, they’re not loadbearing; it’s a cladding. No, they’re not loadbearing, either. Please don’t kick them.

‘Is that how the walls are gonna look?’ Yes, this is the final finish; we will not be plastering. The slats are another of our cheap and easy solutions. They do help with air circulation, but they’re more a product of the clients’ request to be ‘rustic’. No, it’s not very private, but it’s a loft.

‘Are you with the U?’ Nope. North Dakota State, actually. But kudos to the U for their support.

‘How thick are the walls?’ About sixteen inches. It’s a lot, but it’s necessary to super-insulate the walls and windows to reduce our energy use. The 2×6 assembly defined in the building code is the minimum, but there are other ways to build a wall.

‘So you have a bunch of solar panels?’ No. Photovoltaics and passive solar are completely different things. PV may be a good option if you’re tired of big electricity bills (geothermal, too). But the point of this demo is to show just how little energy is required by a passive house. Unless you’re absolutely intent on a net-zero project, you’re better off investing in a passive design.

‘What’s the per square foot here?’ If I tell you, you’ll stop listening. Per square foot is not always a good way of comparing prices. Our design had an estimated cost that was very high per square foot, but it was complicated by a number of factors including small scale, donated labor, student labor, and DIY projects. Instead of talking about that, though, I’ll quote the 15% figure from PHIUS and direct your attention to the materials in the wall assembly.