Yannell PHIUS+ House is a Speculative Renovation

Designed for the market by an all-woman firm, it shows how to fix existing housing.

Before and after
Before and After.

HPZS/ Christopher Barrett

The press release starts by noting that "HPZS has designed the very first certified single-family Passive House Institute US (PHIUS 2018+) Renovation in Chicago." One could ignore the rest and just parse this single sentence, there is so much packed into it.

HPZS is a fascinating firm with a long history in architectural preservation, working to promote the "preservation and restoration of the buildings that comprise the historic fabric of the city." It is now 100% woman-owned. The overlap in a Venn diagram of firms doing historic preservation and those doing ultra-high performance design is really, really small.

It's certified. So many projects we see are "passive house inspired" because the architects or clients don't want to compromise on some design idea or pay more for windows or even just pay for the certification, but as Elrond Burrell wrote a few years ago, certification is about quality assurance, accountability, and performance that lasts.

They call the house the Yannell PHIUS+ House, rather than, say, the Yannell Passive House. I believe this is really important. Ever since the schism between the Passivhaus Institut (PHI) and Passive House Institute US (PHIUS), there has been confusion – not to mention the even older confusion between Passive House and passive design. I think putting PHIUS+ upfront is great branding for the organization and hope to see a clear separation between Passivhaus and PHIUS+ with "passive house" being a "big tent" for high-performance building. (See North American Passive House Network and Passive House Accelerator, both big tents.) This may be the beginning of the end of all this confusion.

It's a renovation. We tend to show a lot of new efficient houses and buildings, but there are millions of existing homes across North America that have to be fixed if we are going to hit any of our 2030 targets for carbon emission reductions. Renovations are not nearly as exciting, but we need to show how it can be done.

It's speculative, being offered on the open market. This is one of the most important points. "The objective of this ground-breaking retrofit low-energy project was to transform the speculative renovation market in the Midwest."

I cheated a bit there, the speculative bit was in the second sentence, but now let's look at what they have actually done.

When you watch the very well done video (seen on the Passive House Accelerator, which is how I learned about the house), you see that this was a total gut job right down to the frame and sheathing boards. Some might question whether this even makes sense, whether it wouldn't be cheaper and easier just to demolish and replace. However, in many jurisdictions, it is faster and easier to get approvals for renovations. In Chicago's sister city Toronto where I live, new houses have to comply with setbacks and area limitations and pay more fees, so people go to great lengths to leave those walls and call it a renovation. And of course, we always say that the greenest building is the one already standing.

Sustainable stragegies


The walls are insulated to R-48 by wrapping the house with graphite-infused expanded polystyrene insulation (EPS). While EPS is still a petrochemical product, the blowing agent that foams it up is air rather than a greenhouse gas. The graphite adds internal reflectivity, reducing radiant transmission. Inside, the walls have foamed-in-place polyurethane insulation, not our favorite material but one that is often used in renovations where space is limited. The roof is insulated with three feet of blown-in mineral wool.

Kitchen and Breakfast

HPZS/ Christopher Barrett

A critical measure in any passive house is the airtightness which tested out at 0.0596 cfm per 50/SF. There is also an energy recovery ventilator for fresh air and 2.8 KW of solar panels on the roof.

Once you hit the PHIUS+ standard, everything else is easy, so of course, it is Net Zero Ready (ZERH), RESNET HERS 27, EPA Indoor airPLUS (even with polyurethane foam).

A big question that I cannot answer yet is how they dealt with the basement; I have asked the architects and will update if I receive a response.

Living Room

HPZS/ Christopher Barrett

It's all a fascinating project, but the toughest question may be what the market thinks. The architects write:

"By adding an addition to the property and renovating it, the team at HPZS designed a five-bedroom, three-bathroom solution to meet the needs of the speculative homebuilding market in the Ravenswood neighborhood of Chicago - with the express goal of demonstrating this could be done at a profit - proving it a replicable model for de-carbonizing existing housing stock in order to meet 2050 climate goals."

HPZS/ Christopher Barrett

I have been complaining forever about how the market isn't willing to pay for performance (which is why this house has the big kitchen counters and the trendy freestanding bathtub) and have written essays and done lectures on how to market Passive House designs, which can be hard to do. I wrote earlier:

"Selling Passive House has always been a problem because there is nothing to see here, folks. You could build your fancy net-zero smart house and get thermostats and ground-source heat pumps and solar panels and Powerwalls, so much to see, to play with, to show your neighbors! People love all the active stuff. By comparison, Passivhaus is boring. Imagine telling your neighbor, “Let me describe my air barrier,” because you can’t even show it, or the insulation. It is all passive stuff that just sits there." 

This house has some solar panels for that bit of conspicuous conservation, but otherwise, everything else is in the walls. Perhaps the world has changed, and people are beginning to get this, the advantage of passive overactive. It will be interesting to see how the market responds.