Passive house
A passive house is a building designed to achieve high energy efficiency while minimizing environmental impact. This construction methodology prioritizes creating an airtight structure that significantly reduces reliance on conventional heating and cooling systems, leading to energy savings of up to 80% compared to standard buildings. Although the initial construction costs are higher—estimated at an additional 3 to 5%—the long-term energy savings can offset these expenses within a few years. The passive house concept originated in North America during the energy crisis of the 1970s but gained traction in Europe, particularly in Germany, where the Passivhaus-Institut established rigorous standards for certification. These standards emphasize high-performance insulation, special windows, and robust ventilation systems that allow for energy recovery.
While passive houses are predominantly found in Europe, their popularity is growing in North America, especially in sustainability-focused projects and affordable housing initiatives. Key features include superinsulation, triple- or quadruple-paned windows, and a continuous ventilation system that maintains comfortable indoor temperatures without traditional HVAC systems. The movement has seen notable success, with thousands of certified passive houses constructed in the U.S. by 2024, reflecting a shift towards energy-efficient building practices in response to rising energy costs and climate change concerns.
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Passive house
A passive house uses a set of design principles intended to maximize energy efficiency. The goal of a passive house is to be environmentally friendly by reducing its energy footprint. The basic premise behind this construction methodology is to create an airtight, contained structure that does not rely on traditional heating and cooling processes. As a result, such structures use up to 80 percent less energy than standard buildings. Passive houses are more expensive to build, but the savings provided by their greater energy efficiency are intended to offset the initial increased costs within only a few years after their construction or upgrade.
Passive houses are found mostly in Europe, where energy costs are higher. In Germany, where the passive house movement is strongest (and where it is called passivhaus), this construction method has been used for many building types, including homes, apartments, grocery stores, schools, and public buildings. To gain certification and adhere to passive house standards (which vary among countries), completed buildings must meet established energy performance targets while demonstrating that they provide maximum comfort for their inhabitants.
Brief History
Despite the heightened popularity of passive houses in Europe, the movement's origins began in North America. During the Organization of the Petroleum Exporting Countries (OPEC) oil embargo of the 1970s, researchers in the United States and Canada began to explore methods to reduce energy expenditures. From this era of research, building concepts such as energy recovery ventilation, solar power, airtight technology, and superinsulation gained increased focus.
In 1977 scientists from the National Research Council and Saskatchewan Research Council created the Saskatchewan Conservation House using some of the methods explored during this era of heightened energy conservation. The building used thermal insulation, airtight technology, and a heat recovery system. A similar project by architects at the University of Illinois Small Homes Council led to the creation of the Lo-Cal House in Urbana, Illinois—perhaps the first passive house–style building in the United States. Once the oil embargo and resulting energy anxieties lessened in the late 1970s, however, interest in such technologies faded in North America.
Further exploration of the proto–passive house movement moved to Europe. By 1996, German physicist Wolfgang Feist and Swedish scientist Bo Adamson had founded the Passivhaus-Institut (PHI) in Darmstadt, Germany. This group created a standardized system that relied on high-performance windows, heavy insulation, airtight building enclosures, and, perhaps most importantly, a continuous ventilation system that allows for energy recovery. As of 2024, PHI remained one of the standard-bearers for passive house techniques worldwide.
Overview
In many European countries, energy taxes and average fuel prices tend to be much higher than they are in the United States. As a result, the incentive to accept the higher built-in costs of a passive home is greater, as these initial expenses are likely to be offset more quickly by the savings these homes provide. Builders estimated that passive house construction techniques add an additional 3 to 5 percent to the regular building expenses. In the United States, it can take more than a decade to offset these expenses through reduced energy bills.
However, passive home methodologies are becoming more popular in North America. For instance, Marvin Windows, one of the major US suppliers of windows, started manufacturing passive home–compatible windows in 2013. In addition, a growing number of builders and architects in the United States are receiving training in passive home construction techniques. This is partly in response to the growth of the sustainability movement, but also due to worries about growing energy costs and climate change concerns. Buildings in the United States account for an outsized share of energy costs and carbon emissions. As of 2013, only ninety homes in the United States had been certified as having met passive house construction techniques. By 2015, however, five hundred such homes had been built in North America, and that number rose to three thousand by the end of 2017. Roughly 5,800 passive houses had been constructed across the United States by 2024.
In the United States, this methodology has found its greatest use in affordable housing projects, though this construction style has seen greater acceptance in building projects ranging from apartments to more upscale developments around the country. In 2020, construction on one of the largest passive houses in North America was completed. The structure, which is in New York City, contains 154 low-income housing units, and 46 of them are for the formerly homeless. Two years later, another enormous passive house was completed in the Bronx. Most of the twenty-six-story building will be used for residential purposes. As of 2024, it was the largest passive house project to date.
Europe has increasingly adopted reduced energy construction as a requirement. Beginning in 2020, all new buildings must use a "Nearly Zero-Energy" methodology in construction. As a result, passivhaus has become a standard construction method throughout the region. In the United States, the Pacific Northwest, which has a climate similar to Germany's, has emerged as one of the strongest markets for passive houses.
Passive houses offer many benefits. They are more energy efficient, quieter, and healthier than their counterparts built using traditional construction techniques. In addition to their energy benefits, passive houses' tight seal prevents outside noise from entering, making them immune to external noise pollution. Further, they maintain a steady temperature between 70 and 74 degrees Fahrenheit, regardless of the temperature outside and without the benefit of a standard air conditioner or heating unit.
Passive houses use a variety of techniques to achieve their high energy efficiency. Among these is superinsulation, which requires at least eleven inches of high-density cellulose insulation material between walls. This reduces heat transfer through walls. However, these demands may result in smaller internal square footage in homes that are refurbished to passive house standards. Another passive house innovation is the use of special windows that are triple- or quadruple-paned to reduce sound and create the airtight envelope upon which passive houses are structured.
These buildings are designed to be airtight so that internal air—whether cold or hot—does not leak outside, forcing the cooling or heating systems to turn on. In the winter, heat-recovery ventilators draw fresh air from outside and mix it with existing heat found in outgoing air. (They do the reverse in summer.) This system relies on a combination of vents that enables this exchange of air throughout the building. As a result, the typical passive house requires only two fans and a radiator to cool and heat.
Bibliography
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