Residential Metal Roofing Executive Report

Passive House Design and Metal Roofing: A Perfect Fit

Issue #175 | June 8, 2021 | Ethan Young

Welcome back to the Executive Report, a twice-a-month article on sales, marketing, and installation in the metal roofing world. Our last story was on reasons to join industry groups, mainly for their benefits and capability to further your business. In this issue, we’ll discuss a unique way of homebuilding: passive house design.

Passive is complacent, unassuming, or indirect, all traits we avoid. We think negatively and react poorly to passive words and feelings. But, passive doesn’t have to be wrong in every context. When it comes to home design, passive is efficiency without effort, results without reliance on expensive heating/cooling solutions. With a passive strategy, a house controls its temperature through its construction for a comfortable living space.

According to phius.org, passive house design originated in the US and Canada in the 1970s, then took off in Germany with the founding of the Passivhaus Institut in the 80s. The PHIUS (Passive House Institute of the United States) has furthered the cause since then, pioneering the first passive buildings in North America. Many are still built today, with passive design more practical than ever, thanks to improved insulation and window technology.

PHIUS outlines the five principles of passive homebuilding as:

1. Extremely efficient whole-home insulation and eliminated thermal bridging
2. Airtight seals house-wide, including those around doors, windows, and vents
3. Energy-efficient doors and windows placed to optimize heating in the winter and cooling in the summer
4. Heat and moisture recovery ventilation to manage the temperature and reject mold/mildew
5. Minimal use of air conditioning/heat, dependence on the other four principles

Passive homes use thicker walls, improve seals on doors and windows, and erase thermal bridging (heat transfer between outside and inside). Also, they are oriented to the sun, with windows and doors positioned to gather and retain sunlight for heat and illumination. Roofs hang over a little extra to shade the house and keep heat in too. Designs match the climate, and insulation values increase as temperatures drop, with Alaska requiring several times the insulation of Florida. Very high R-value insulation is necessary for all passive buildings, though, regardless of climate.

So, why build a passive house? What are the advantages? The most significant benefits are the savings on energy bills and the reduction in energy consumption. What makes passive design so intriguing is the relative simplicity of the principles compared to their efficacy. Harnessing the power of the sun and modern building materials, a house or even a high-rise can drastically cut down on operating costs. And, just like the name suggests, once passive elements are in place, they get to work without outside interference.

The main disadvantages of passive design are the extra cost and the increased design considerations needed to execute a successful project. The up-front investment takes time to pay off, but after time, the energy savings will make up the cost. Passive design also relies on air conditioning/heating to make conditions pleasant. While the system used in a passive house might be much smaller and more efficient than a typical unit, it’s still crucial until technology surpasses the need for it. Passive elements can make a home efficient, but some minimal air conditioning/heating is necessary for true comfort.

What does metal roofing have to do with passive design? Metal roofing is the best pairing for passive design:

1. It excels at managing heat, better than any other option. With reflective coatings, metal roofing lowers interior temperatures, making the design more effective.
2. Both last with minimal maintenance.
3. It facilitates solar panel installation better than any other roofing material.

Metal roofing minimizes conductive, convective, and radiant heat transfer while requiring little to no work after installation. With non-destructive mounting options available for solar panels and an increased lifespan, metal is the best choice for passive design.

Passive design evolves continually with the adoption of greener building codes and positive attitudes toward green construction. While it isn’t best for every project, it brings measurable benefits and might become commonplace with future advancements. All homes benefit from its ideas; increased quality of insulation, seals to minimize heat loss, and reduced possibility for mold/mildew growth.

Metal roofing continues to be the best choice for energy efficiency, heat management, and reduced thermal bridging. Although passive houses are niche, we can integrate similar design principles into ordinary homes and buildings. And as passive house design improves, metal roofing will be the best partner along the way.

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