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The Spiegel Residence Passive House Renovation
Lafox, Illinois
September, 30, 2011

When our leaky 21-year-old windows and siding needed to be replaced, we decided to use the opportunity to thoroughly update our house. We also had issues with mice; no natural light in basement; thermal discomfort especially in the “wings of the house”.

As builder and consultant, having helped families to greatly improve their thermal comfort and energy efficiency, I had the strong desire for my family to enjoy the quality of life that comes from living in a passive house.  The thermal comfort and indoor air quality are superior to any other type of structure. The energy savings of 80% and long-term environmental benefits speak for themselves.

Before renovation in spring 2010

Complete house
After renovation in summer 2011

Renovation opportunities come along only a few times during a building life. Using those opportunities with more thought and improving many building qualities at once help ensure the value of buildings. It is also more sustainable through lower use of resources and fewer halfhearted fixes when looking at the impact of buildings over their life cycles.

Often, renovations are done in small steps and then repeated after a few years. That prevents building owners from enjoying multiple, long lasting improvements in efficiency, quality and comfort of buildings. It is the least material intense and economical approach to do things right at once, and not have to worry about it for a long time. Specifically, if envelopes are improved first, then heating and ventilation systems which have been sized for the old envelope can now be reduced and simplified. It is this overlapping of efficiency effects which passive house approach embodies.

Our renovation first overhauled the entire envelope, approximately doubling of the insulation levels and air tightness.

r values 1.png
Symbolic cross-section through house showing before and after insulation levels

In 2009, energy modeling allowed us to predict that meeting Passive House Standard is technically possible. An important element was the use of imported German windows with a U-value of 0.12 and a Solar Heat Gain Coefficient of 0.48.

In May 2010, we started excavating around the foundation. We cleaned, sealed and insulated the foundation from the outside with 6in extruded Polystyrene.  The R-value of the foundation wall is R39, considering the finished interior walls before.

Next, we removed our old roof shingle, siding to repair and seal the exposed OSB sheathing.  We cut off the overhangs of the old roof before framing a 2x6 new roof structure on top of the old one and doubling the size of the overhangs and insulating with PU and XPS boards.  Finally, we closed of the roof with a new roof deck and shingles. Total R-value of the roof is R61.

Windows from Unilux / Germany with a U-value of 0.13 (R8) were installed to replace our old double-hung ones. What a difference.  

Once the roof was complete and windows were assembled, we added between 5 and 8in high density EPS (Expanded Polystyrene) to the exterior walls.   The facade was completed with two layers of stucco.
Intermediary stage of adding 8in exterior foam to the "wings" of the house


In late January 2011, we installed our Paul Heat Recovery Ventilator with a 93% heat recovery rate. It was very cold with nightly lows way below zero F. Only after we installed the Ground Loop to Air Heat Exchanger two weeks later, pre conditioning the incoming cold air to reliably over 36degF, this new HRV configuration worked properly. Once the Configuration was complete, our new stale air returns spread through the house, the system works great. CO2 levels never exceed 800ppm.

During the unusual cold winter of 2011, our house was a delight. The family appreciated the hugely improved comfort. Memories of the old conditions were still fresh. Heating cost for February and March, when our systems were functioning and complete, were around $1/day (excluding hot water and laundry dryer).

We look forward to our first winter with a complete system.

Stay tuned,