After writing a post on an Irish county becoming the first in the English speaking world to make Passive House standard mandatory, there were some inquiries about the beautiful grey house used as an illustration. There were also a few comments asking what a Passive House is. Fortunately this house was covered in Passive House + magazine with a wonderful article written by the owner and self-builder of the house, Ross Cremin. He is a quantity surveyor, the English term for cost consultant.
He has a lovely way of defining Passive House by what it delivers rather than diving into the math:
We wanted a house that would be bright, healthy, draught free, warm in winter and with low running costs. We wanted it to be future proofed against changes in building regulations and rising energy costs. Great indoor air quality would be a bonus too.
Quantity surveyors are very fussy about money. Unlike Oscar Wilde’s aphorism that we throw around a lot on TreeHugger, they know the price of everything and the value of everything.
When designing a Passive House system one uses a giant spreadsheet, the PHPP (the passive house design software) to calculate the right amount of insulation, the right amount and quality of windows, pushing here and pulling there until you get below the maximum energy consumption per unit area. Some have questioned the value of that last inch of insulation, or the extra cost of those windows. (see Martin Holladay here) Even Cremin notes that “The windows and mechanical ventilation were substantially more expensive than their non passive certified competitors. I struggled with this as the financial payback was questionable.”
Others have criticized it as “design by spreadsheet.” Quantity surveyors live in spreadsheets so the appeal of this is obvious, but they also know value; Cremin writes “My training and work taught me that any additional costs must provide an economic benefit — would a passive house achieve this?”
This is where it gets interesting, because the Passive House people care about energy and quantity surveyors care about money. His architect ( Sarah Cremin from CAST Architecture) prepared a simple design “as an architect might say, a “modern interpretation of the vernacular”; this is good for passive house because every bump and jog and corner goes into the dreaded PHPP as a possible thermal bridge. However the house deserves Bronwyn Barry’s famous hashtag: #BBB, Boxy But Beautiful.
The house is built fairly conventionally of wood frame and simple materials; lots of birch plywood on the interior, a steel roof on top. It’s not big at 1500 square feet. (Lots of technical details on the materials and insulation at the end of the post here). There is no furnace; just a big German sealed wood stove. Cremin writes:
The heating system was substantially cheaper than for a conventional build, with the stove being the most expensive component. There are no touch screen control panels, smart phone apps or automation sequences. We saved the bells and whistles for the home entertainment system. Many people, including some of the professionals, were surprised by the “risk” we took by going down this minimal route. But there is simply no need for central heating in a passive house.
There’s no need for a lot of the stuff that we see in our North American Net Zero Smart Houses:
We also chose to avoid any “green bling”, as it seems to be referred to these days. We have no heat pumps, solar panels or rainwater harvesting. I feel that by building to the passive standard, we have reduced our energy demand to such a low level that we’re already making a much smaller impact on the environment.
That’s the key to the Passive House model, why I write In praise of the dumb home. It doesn’t have all this smart stuff, the gizmo green. You don’t need to pay for it. It’s why if done properly, a Passive House shouldn’t have to cost much more than a conventional build, and this one didn’t. And furthermore, he and his family have, as he puts it, lived “happily ever after”.
Read the whole lovely story over on Passive House +