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#UnfreezePA: SWA at the Helm of the PA Icehouse Demonstration

On Tuesday, June 6, 2017, leaders of Pennsylvania’s clean energy movement took to the steps of the State Capitol Building. The cause? To demonstrate just how much room PA State Energy Codes have to improve. Amidst a cohort of speakers and presenters, USGBC’s Central Pennsylvania chapter erected two sheds, each filled with 1,080 pounds of ice: one built to 2009 Code requirements, currently in place under PA state law; and the other built to Passive House standards. Over the course of the month of June, the public will be able to watch as the respective blocks of ice melt within their structures. Ultimately, the difference in the rate of ice melt between the Code House and the Performance House (Passive House) will illustrate the degree to which current energy laws and codes are lacking, while simultaneously offering a model for advancement.

Code Icehouse 3pm 6/14

Performance Icehouse 6/14

In 2009, the International Energy Code Council (IECC) developed energy-saving standards that were adopted by most U.S. state governments. While the 2009 Code was widely instituted in the period following its publication, several states have since embraced even more efficient requirements that are quickly replacing outdated terms. For instance, the state of Maryland – comparable to Pennsylvania in terms of climate, population, and demographic spectrum – is operating under requirements equivalent to 2015 IECC standards.  New York, New Jersey, Massachusetts and Vermont are other states in the same geographic region and general climate zone that have opted towards more energy efficient codes.[1]

Passive House, on the other hand, is a set of design principles that aim to attain a “quantifiable and rigorous level of energy efficiency within a specific quantifiable comfort level.[2]” More simply, Passive House projects go above and beyond the statutes of any enforced codes to follow a “maximize your gains, minimize your losses” approach to building design. The Passive House Institute of the United States (PHIUS) provides the following summary of Passive House principles:

  • Superinsulation and airtight construction provide unmatched comfort even in extreme weather conditions
  • Continuous mechanical ventilation of fresh filtered air provides superb indoor air quality
  • A comprehensive systems approach to modeling, design, and construction produces extremely resilient buildings
  • Passive building principles offer the best path to Net Zero and Net Positive buildings by minimizing the load that renewable are required to provide

The Pennsylvania Icehouse demonstration aimed to illustrate how these Passive House principles are not only possible, but also fairly accessible within the scope of modern design practices. Steven Winter Associates, Inc. (SWA)’s own Sustainability Consultant, Scott Pusey, was at the forefront of the Icehouse idea from inception through installation, ultimately making major contributions to the demonstration’s success and impact.

Engineers used energy modeling and 30-year average weather data for Harrisburg, PA (where the state capital is located) to better understand the climate characteristics of the specific area. The goal was to estimate the hourly heat gains to each icehouse for the month of June, and then calculate the corresponding amount of ice necessary to absorb it. Below are the parameters of each icehouse, and thus the differences that ultimately contribute to their respective building envelopes and overall energy conservation:

Input Parameters Baseline Passive House
Ceiling/Roof Insulation R-38 w/ rafters 16” oc R-60 w/ rafters 24” oc
Floor Insulation R-19 cavity R-20 continuous
Exterior Wall Insulation R-21 cavity w/ framing 16” oc R-21 w/ framing 24” oc + R-20 continuous
Window Performance U-0.35


Infiltration 7 ACH50 0.6 ACH50


Incorporating these parameters in their climate research, the Icehouse team came up with the following predictions for Code House and Passive House performances;

Baseline icehouse heat gain over three weeks:                                                                220,173 Btu

Starting ice mass necessary to be fully melted after three weeks:           1,370 lbs. (34.5” cube)

Passive House icehouse heat gain over three weeks:                                    96,740 Btu (56% < baseline)

Melted ice in Passive House icehouse after three weeks:                           603 lbs.

Remaining ice in Passive icehouse after three weeks:                                   767 lbs. (28.5” cube)


Subsequently, with 1,080 pounds of ice in each house, the team doubted the Code (baseline) House’s capacity to last even three weeks. But after the initial days of exposure – and a heat wave blazing across the Northeast – it became clear that the Code House ice block would not last more than a few days. On Wednesday, June 14, right around noon, the last puddles of the Code House ice block evaporated, leaving the interior of the shed completely dry. A few feet away, within the ultra-insulated envelope of the Performance (Passive) House, an only-slightly-wilted, 34-inch-high block of ice remained – in relative alignment with the predictions above.

What does that mean, exactly?

Consider this: you are that Code House block of ice. And that summer heat wave?  No one knows how long it’s going to last. There’s no way you’re going to spend eight days melting within the confines of a building lacking any sort of HVAC system; so instead, you pay to cool your house. But for every dollar you spend pumping cool air, up to 30 cents[3] escape through the cracks between your windows, the space beneath your doors, and even through your walls. In a state where the average person spends more than $3,000[4] on heating and cooling over the course of a year, that’s a loss of almost $1,000, not to mention a grossly inefficient use of the Earth’s ever-dwindling resources.

While we understand that Passive House standards may not (yet) be attainable under state laws and codes, the Pennsylvania Icehouse Demonstration is an important reminder that net-zero – and even net-positive – structures are not outside the realm of possibility. In fact, Passive House is already widely used in residential and commercial building projects around the world.

It is clear that the 2009 Energy Code is out of date. It is clear that Pennsylvania – and much of the United States – has an obligation to achieve more modern energy standards. And it is clear, by the achievements of Passive House, that improvement is possible, and there is ample room to grow.




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